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37 commits

Author SHA1 Message Date
Scott Lystig Fritchie
94e4eac12c WIP: added trim_proj_with_all_hosed(). Convergence fails
This is the first effort for trying to modify the projection
to take into account the all_hosed list.  It doesn't work,
but there are a couple things here that need to move together.

1. The implementation & use of trim_proj_with_all_hosed() itself.

2. Any additional compensation that needs to take place, e.g.
   in react_to_env_A20().  I added some hack experiment there,
   but more work in A20 is needed at least, I think.
2015-03-06 11:40:40 +09:00
Scott Lystig Fritchie
54851488cc Last preparation before disruptive proposal changes with AllHosed info II 2015-03-06 00:07:19 +09:00
Scott Lystig Fritchie
e0c6aeac94 Automate check for unanimous all_hosed 2015-03-06 00:02:25 +09:00
Scott Lystig Fritchie
f2ee7b5045 Add partitions2num_islands 2015-03-05 23:50:56 +09:00
Scott Lystig Fritchie
fab03a90c6 Last preparation before disruptive proposal changes with AllHosed info 2015-03-05 22:51:38 +09:00
Scott Lystig Fritchie
f89c9c43d3 Fix stupid bug in all_flap_counts_settled calculation, plus minor cleanup 2015-03-05 22:50:28 +09:00
Scott Lystig Fritchie
2f16a3a944 Undo flap-start-time goop added by commit 6566420e32 2015-03-05 21:29:10 +09:00
Scott Lystig Fritchie
7817d7c160 Comment cleanup 2015-03-05 20:39:13 +09:00
Scott Lystig Fritchie
6566420e32 Add flap-start-time element to all_flap_counts 2015-03-05 20:36:20 +09:00
Scott Lystig Fritchie
8ff177f0c5 Change flapping_i flap_count and all_flap_counts to include start time
%% Each manager keeps track of the starting time that it
          %% first observed itself flapping.  This time is stored in
          %% the 'flapping_i' proplist in #projection.dbg to help
          %% other nodes tell when some other manager is having a
          %% flapping episode at time T+x that is different from the
          %% flapping episode at an earlier time T.

In a later commit, we'll use this time for a couple of reasons.

1. If I'm flapping and if all other nodes that I see are flapping
   *and* they're flapping without changing their own relative start
   times, then things are stable enough.

2. If some remote manager M notices itself flapping and starts recording
   a flap count and then it crashes/hangs, we want to be able to use
   that M's flap start time as an alternative decision criteria.
   M is crashed/hung, so M's flap count cannot continue to increase
   as we hope that it will.
   (For calculating all_flap_counts_settled)
2015-03-05 16:53:30 +09:00
Scott Lystig Fritchie
666a05b50b Comment out debug diag output 2015-03-05 16:53:30 +09:00
Scott Lystig Fritchie
8cdf69c8b9 Remove expensive debugging diag when not needed 2015-03-05 16:53:30 +09:00
Scott Lystig Fritchie
f129801f29 Good news: all_hosed list agreement in all simulated cases & is correct (mostly!)
Occasionally, all_hosed will include a node from the previous
simulation round that isn't included in the current round.
I believe that this is expected, since machi_chain_manager1_test
is not trying to "reset" state to no-partitions before switching
to the next partition scenario.

Please note that the #ch_mgr.flap_limit constant is a *hack*
and needs a better implementation!
2015-03-05 16:53:30 +09:00
Scott Lystig Fritchie
2fe2a23c79 Undo proposed improvement from commit cebb205b52, it was harmful. 2015-03-05 16:53:27 +09:00
Scott Lystig Fritchie
6ed7293b02 WIP: debugging, with some good insight now (read on...)
I'm getting closer, I think.  The data that's being written to the
'flapping_i' proplist is more accurate, thanks to previous commits.
Fixing inaccuracies there can only be helpful.

We still have this basic problem:

% cat /tmp/foo16 | awk '$1 == "SET" { for (key in a) { print a[key]; a[key] = ""; } print; } { if ($3 == "uses:") { a[$2] = $0 }}' | sed -e 's/uses:.*all_hosed/uses: [...] all_hosed/' -e 's/all_flap_counts.*//'
[...]
SET partitions = [{c,a}].
01:31:55.934 d uses: [...] all_hosed,[a,c]},{
01:31:53.674 a uses: [...] all_hosed,[]},{
01:31:55.961 b uses: [...] all_hosed,[a,c]},{
01:31:52.799 c uses: [...] all_hosed,[a]},{
SET partitions = []

The 'all_hosed' values should be converged, but they aren't.  It's
very interesting that a's all_hosed list is completely empty, oops.
But it's also becoming clear that the public epochs "surrounding"
each of a's public proposals do indeed have decent all_hosed info.

For example, a's report above @ "01:31:53.674" corresponds to:

01:31:53.674 a uses: [{epoch,514},{author,a},{upi,[a]},{repair,[b,d]},{down,[c]},{d,[{flapping_i,[{flap_count,0},{all_hosed,[]},{all_flap_counts,[]},{all_flap_counts_settled,false},{bad,[c]},{da_downu,[c]},{da_hosedtu,[a,c]},{da_downreports,[{513,b,[]},{512,a,[c]},{511,d,[]}]}]},{ps,[{c,a}]},{nodes_up,[a,b,d]}]},{d2,[[]]}]

... and to:

     {514,a,
      {projection,514,
          <<173,82,84,188,162,136,57,149,29,171,29,97,139,30,241,15,128,76,236,
            126>>,
          [a,b,c,d],
          [c],
          {1425,486713,673377},
          a,
          [a],
          [b,d],
          [{flapping_i,
               [{flap_count,0},
                {all_hosed,[]},
                {all_flap_counts,[]},
                {all_flap_counts_settled,false},
                {bad,[c]},
                {da_downu,[c]},
                {da_hosedtu,[a,c]},
                {da_downreports,[{513,b,[]},{512,a,[c]},{511,d,[]}]}]},
           {ps,[{c,a}]},
           {nodes_up,[a,b,d]}],
          []}},

So FLU a knows that FLU c is down, but it just isn't flapping yet.  And it
hasn't incorporated any flapping_i from other FLUs.  If I look at the epochs
mentioned in the 'da_downreports', I see 513, 512, and 511.

513 is authored by b, flapping_i says: {flap_count,68}, {all_hosed,[a,c]},
512 is authored by a, flapping_i says: {flap_count,0}, {all_hosed,[]},
511 is authored by d, flapping_i says: {flap_count,12}, {all_hosed,[a,c]}

Looks promising, yeah?
2015-03-05 01:33:12 +09:00
Scott Lystig Fritchie
b8063c9575 Refactoring, plus some intermediate bug hunt results, see below
See the TODO comment for details.  The scheme that I've been using
at test time is:

    make test |& tee /tmp/foo7

  and elsewhere:

    cat /tmp/foo7 | awk '$1 == "SET" { for (key in a) { print a[key]; a[key] = ""; } print; } { if ($3 == "uses:") { a[$2] = $0 }}' | sed -e 's/uses:.*all_hosed/uses: [...] all_hosed/' -e 's/all_flap_counts.*//'

Which prints our sub-optimal results like:

SET partitions = [{c,a}].
21:09:06.603 d uses: [...] all_hosed,[a,c]},{
21:09:04.203 a uses: [...] all_hosed,[]},{
21:09:06.640 b uses: [...] all_hosed,[a,c]},{
21:09:03.409 c uses: [...] all_hosed,[a]},{

FLU a should definitely be seeing enough information to avoid
all_hosed=[].  Gadz.  To be resumed tomorrow.
2015-03-04 21:11:06 +09:00
Scott Lystig Fritchie
b558de2244 Refactor: long-overdue for some proplists code sharing 2015-03-04 19:58:01 +09:00
Scott Lystig Fritchie
4e01f5bac0 Fix checksumming bug: dbg2 is not checksummed 2015-03-04 19:26:07 +09:00
Scott Lystig Fritchie
cf56e2d388 Fix ?REACT() tags from edit long ago {sigh} 2015-03-04 18:20:33 +09:00
Scott Lystig Fritchie
cebb205b52 Improvement: if I am in all_hosed, goto A50 directly, BUT! ...
... but it also appears to have a negative impact on the gossip-hack
that I've added to try to detect when everyone stabilized on a
value for all_hosed.  {sigh}

So, it isn't clear if this patch is worthwhile!
2015-03-04 18:19:13 +09:00
Scott Lystig Fritchie
6e4e2ac6bf Trivial cleanup: comments & unused vars 2015-03-04 16:48:48 +09:00
Scott Lystig Fritchie
fbdf606128 TODO future research: does this flapping constant make a significant difference? 2015-03-04 16:48:17 +09:00
Scott Lystig Fritchie
938f3c16f2 Add all_flap_counts_settled, minor cleanups 2015-03-04 14:37:26 +09:00
Scott Lystig Fritchie
24fc2a773c Move calculate_flaps() call to A30 2015-03-04 14:37:24 +09:00
Scott Lystig Fritchie
77f16523f4 Swap A20 and A30's code 2015-03-04 14:37:23 +09:00
Scott Lystig Fritchie
07e477598a OK, asymmetric network partition handling is stable. Time for next stage.
Sketch:

1. Exchange the roles of A30 and A20

2. Query each participants' public & private stores, use them for A20 and A30

3. Determine if there's flapping *before* calculating a new latest.

3b. In flapping_i props, keep non-flapping UPI+Repairing and Down list.
      When calculating unique UPI+Repairing history and the unique Down lists history, use the non-flapping version if it exists.

grrr/alt idea/bogus??.... Change the calculation of the unique UPIs and unique down lists. If the UPI & Down list looks the same as last time, and last time we were flapping, then we're still flapping.

4a. Calculate a proposal using the standard Down info.
4b. If there is flapping, then use Down <- All_Hosed instead of calculated down.

5. If 4b's proposal is used ('cause flapping exists), preserve the non-flapping histories from 4a in each new proposal
2015-03-04 14:37:22 +09:00
Scott Lystig Fritchie
ecd56a194e Yay, back to stability, I believe 2015-03-04 14:37:19 +09:00
Scott Lystig Fritchie
187ed6ddce Yay, back to stability, I believe 2015-03-04 14:37:18 +09:00
Scott Lystig Fritchie
b03f88de43 Yay, back to stability, I believe 2015-03-04 14:37:16 +09:00
Scott Lystig Fritchie
2ae8a42d07 WIP: broken, alas, still wip 2015-03-04 14:37:14 +09:00
Scott Lystig Fritchie
50dd83919a WIP: getting closer to transitive flap_count counting, but not there yet 2015-03-04 14:36:56 +09:00
Scott Lystig Fritchie
35c9f41cf4 WIP: back to PULSE model for experimenting 2015-03-04 14:36:54 +09:00
Scott Lystig Fritchie
4f28191552 Clean up some of the convergence_demo_test() code, add lots of documentation 2015-03-04 14:36:51 +09:00
Scott Lystig Fritchie
1488587dd9 WIP: by golly, it seems to work 100% well with asymmetric network partitions?! 2015-03-04 14:36:48 +09:00
Scott Lystig Fritchie
0b4e106635 WIP: getting closer. Add i_flapping info to all proposed projs @ B10.
The placement of this flapping stuff is suboptimal.  I'd prefer it to be
at A20 where all of the real projection calculation is done.  But this
is still a prototype ... I'm still trying to figure out where & how is
the best place to react.  Moving the calculation from B-something to
A-something can come later.
2015-03-04 14:36:45 +09:00
Scott Lystig Fritchie
27f17e88ad WIP: try to store flapping/asymmetric network partition information, then act upon it 2015-03-04 14:36:39 +09:00
Scott Lystig Fritchie
f4a2a453bd WIP: experiments with flap detection and mitigation 2015-03-04 14:36:37 +09:00
260 changed files with 26940 additions and 70613 deletions

32
.gitignore vendored
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@ -1,33 +1,9 @@
prototype/chain-manager/patch.*
.eqc-info
.eunit
deps
dev
*.o
ebin/*.beam
*.plt
erl_crash.dump
eqc
rel/example_project
.concrete/DEV_MODE
.rebar
edoc
# Dialyzer stuff
.dialyzer-last-run.txt
.ebin.native
.local_dialyzer_plt
dialyzer_unhandled_warnings
dialyzer_warnings
*.plt
# PB artifacts for Erlang
include/machi_pb.hrl
# Release packaging
rel/machi
rel/vars/dev*vars.config
# Misc Scott cruft
*.patch
current_counterexample.eqc
foo*
RUNLOG*
typescript*
*.swp

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@ -1,7 +0,0 @@
language: erlang
notifications:
email: scott@basho.com
script: "priv/test-for-gh-pr.sh"
otp_release:
- 17.5
## No, Dialyzer is too different between 17 & 18: - 18.1

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@ -1,35 +0,0 @@
# Contributing to the Machi project
The most helpful way to contribute is by reporting your experience
through issues. Issues may not be updated while we review internally,
but they're still incredibly appreciated.
Pull requests may take multiple engineers for verification and testing. If
you're passionate enough to want to learn more on how you can get
hands on in this process, reach out to
[Matt Brender](mailto:mbrender@basho.com), your developer advocate.
Thank you for being part of the community! We love you for it.
## If you have a question or wish to provide design feedback/criticism
Please
[open a support ticket at GitHub](https://github.com/basho/machi/issues/new)
to ask questions and to provide feedback about Machi's
design/documentation/source code.
## General development process
Machi is still a very young project within Basho, with a small team of
developers; please bear with us as we grow out of "toddler" stage into
a more mature open source software project.
* Fork the Machi source repo and/or the sub-projects that are affected
by your change.
* Create a topic branch for your change and checkout that branch.
git checkout -b some-topic-branch
* Make your changes and run the test suite if one is provided.
* Commit your changes and push them to your fork.
* Open pull-requests for the appropriate projects.
* Contributors will review your pull request, suggest changes, and merge it when its ready and/or offer feedback.
* To report a bug or issue, please open a new issue against this repository.

630
FAQ.md
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@ -1,630 +0,0 @@
# Frequently Asked Questions (FAQ)
<!-- Formatting: -->
<!-- All headings omitted from outline are H1 -->
<!-- All other headings must be on a single line! -->
<!-- Run: ./priv/make-faq.pl ./FAQ.md > ./tmpfoo; mv ./tmpfoo ./FAQ.md -->
# Outline
<!-- OUTLINE -->
+ [1 Questions about Machi in general](#n1)
+ [1.1 What is Machi?](#n1.1)
+ [1.2 What is a Machi chain?](#n1.2)
+ [1.3 What is a Machi cluster?](#n1.3)
+ [1.4 What is Machi like when operating in "eventually consistent" mode?](#n1.4)
+ [1.5 What is Machi like when operating in "strongly consistent" mode?](#n1.5)
+ [1.6 What does Machi's API look like?](#n1.6)
+ [1.7 What licensing terms are used by Machi?](#n1.7)
+ [1.8 Where can I find the Machi source code and documentation? Can I contribute?](#n1.8)
+ [1.9 What is Machi's expected release schedule, packaging, and operating system/OS distribution support?](#n1.9)
+ [2 Questions about Machi relative to {{something else}}](#n2)
+ [2.1 How is Machi better than Hadoop?](#n2.1)
+ [2.2 How does Machi differ from HadoopFS/HDFS?](#n2.2)
+ [2.3 How does Machi differ from Kafka?](#n2.3)
+ [2.4 How does Machi differ from Bookkeeper?](#n2.4)
+ [2.5 How does Machi differ from CORFU and Tango?](#n2.5)
+ [3 Machi's specifics](#n3)
+ [3.1 What technique is used to replicate Machi's files? Can other techniques be used?](#n3.1)
+ [3.2 Does Machi have a reliance on a coordination service such as ZooKeeper or etcd?](#n3.2)
+ [3.3 Are there any presentations available about Humming Consensus](#n3.3)
+ [3.4 Is it true that there's an allegory written to describe Humming Consensus?](#n3.4)
+ [3.5 How is Machi tested?](#n3.5)
+ [3.6 Does Machi require shared disk storage? e.g. iSCSI, NBD (Network Block Device), Fibre Channel disks](#n3.6)
+ [3.7 Does Machi require or assume that servers with large numbers of disks must use RAID-0/1/5/6/10/50/60 to create a single block device?](#n3.7)
+ [3.8 What language(s) is Machi written in?](#n3.8)
+ [3.9 Can Machi run on Windows? Can Machi run on 32-bit platforms?](#n3.9)
+ [3.10 Does Machi use the Erlang/OTP network distribution system (aka "disterl")?](#n3.10)
+ [3.11 Can I use HTTP to write/read stuff into/from Machi?](#n3.11)
<!-- ENDOUTLINE -->
<a name="n1">
## 1. Questions about Machi in general
<a name="n1.1">
### 1.1. What is Machi?
Very briefly, Machi is a very simple append-only blob/file store.
Machi is
"dumber" than many other file stores (i.e., lacking many features
found in other file stores) such as HadoopFS or a simple NFS or CIFS file
server.
However, Machi is a distributed blob/file store, which makes it different
(and, in some ways, more complicated) than a simple NFS or CIFS file
server.
All Machi data is protected by SHA-1 checksums. By default, these
checksums are calculated by the client to provide strong end-to-end
protection against data corruption. (If the client does not provide a
checksum, one will be generated by the first Machi server to handle
the write request.) Internally, Machi uses these checksums for local
data integrity checks and for server-to-server file synchronization
and corrupt data repair.
As a distributed system, Machi can be configured to operate with
either eventually consistent mode or strongly consistent mode. In
strongly consistent mode, Machi can provide write-once file store
service in the same style as CORFU. Machi can be an easy to use tool
for building fully ordered, log-based distributed systems and
distributed data structures.
In eventually consistent mode, Machi can remain available for writes
during arbitrary network partitions. When a network partition is
fixed, Machi can safely merge all file data together without data
loss. Similar to the operation of
Basho's
[Riak key-value store, Riak KV](http://basho.com/products/riak-kv/),
Machi can provide file writes during arbitrary network partitions and
later merge all results together safely when the cluster recovers.
For a much longer answer, please see the
[Machi high level design doc](https://github.com/basho/machi/tree/master/doc/high-level-machi.pdf).
<a name="n1.2">
### 1.2. What is a Machi chain?
A Machi chain is a small number of machines that maintain a common set
of replicated files. A typical chain is of length 2 or 3. For
critical data that must be available despite several simultaneous
server failures, a chain length of 6 or 7 might be used.
<a name="n1.3">
### 1.3. What is a Machi cluster?
A Machi cluster is a collection of Machi chains that
partitions/shards/distributes files (based on file name) across the
collection of chains. Machi uses the "random slicing" algorithm (a
variation of consistent hashing) to define the mapping of file name to
chain name.
The cluster management service will be fully decentralized
and run as a separate software service installed on each Machi
cluster. This manager will appear to the local Machi server as simply
another Machi file client. The cluster managers will take
care of file migration as the cluster grows and shrinks in capacity
and in response to day-to-day changes in workload.
Though the cluster manager has not yet been implemented,
its design is fully decentralized and capable of operating despite
multiple partial failure of its member chains. We expect this
design to scale easily to at least one thousand servers.
Please see the
[Machi source repository's 'doc' directory for more details](https://github.com/basho/machi/tree/master/doc/).
<a name="n1.4">
### 1.4. What is Machi like when operating in "eventually consistent" mode?
Machi's operating mode dictates how a Machi cluster will react to
network partitions. A network partition may be caused by:
* A network failure
* A server failure
* An extreme server software "hang" or "pause", e.g. caused by OS
scheduling problems such as a failing/stuttering disk device.
The consistency semantics of file operations while in eventual
consistency mode during and after network partitions are:
* File write operations are permitted by any client on the "same side"
of the network partition.
* File read operations are successful for any file contents where the
client & server are on the "same side" of the network partition.
* File read operations will probably fail for any file contents where the
client & server are on "different sides" of the network partition.
* After the network partition(s) is resolved, files are merged
together from "all sides" of the partition(s).
* Unique files are copied in their entirety.
* Byte ranges within the same file are merged. This is possible
due to Machi's restrictions on file naming and file offset
assignment. Both file names and file offsets are always chosen
by Machi servers according to rules which guarantee safe
mergeability. Server-assigned names are a characteristic of a
"blob store".
<a name="n1.5">
### 1.5. What is Machi like when operating in "strongly consistent" mode?
The consistency semantics of file operations while in strongly
consistency mode during and after network partitions are:
* File write operations are permitted by any client on the "same side"
of the network partition if and only if a quorum majority of Machi servers
are also accessible within that partition.
* In other words, file write service is unavailable in any
partition where only a minority of Machi servers are accessible.
* File read operations are successful for any file contents where the
client & server are on the "same side" of the network partition.
* After the network partition(s) is resolved, files are repaired from
the surviving quorum majority members to out-of-sync minority
members.
Machi's design can provide the illusion of quorum minority write
availability if the cluster is configured to operate with "witness
servers". (This feaure partially implemented, as of December 2015.)
See Section 11 of
[Machi chain manager high level design doc](https://github.com/basho/machi/tree/master/doc/high-level-chain-mgr.pdf)
for more details.
<a name="n1.6">
### 1.6. What does Machi's API look like?
The Machi API only contains a handful of API operations. The function
arguments shown below (in simplifed form) use Erlang-style type annotations.
append_chunk(Prefix:binary(), Chunk:binary(), CheckSum:binary()).
append_chunk_extra(Prefix:binary(), Chunk:binary(), CheckSum:binary(), ExtraSpace:non_neg_integer()).
read_chunk(File:binary(), Offset:non_neg_integer(), Size:non_neg_integer()).
checksum_list(File:binary()).
list_files().
Machi allows the client to choose the prefix of the file name to
append data to, but the Machi server will always choose the final file
name and byte offset for each `append_chunk()` operation. This
restriction on file naming makes it easy to operate in "eventually
consistent" mode: files may be written to any server during network
partitions and can be easily merged together after the partition is
healed.
Internally, there is a more complex protocol used by individual
cluster members to manage file contents and to repair damaged/missing
files. See Figure 3 in
[Machi high level design doc](https://github.com/basho/machi/tree/master/doc/high-level-machi.pdf)
for more description.
The definitions of both the "high level" external protocol and "low
level" internal protocol are in a
[Protocol Buffers](https://developers.google.com/protocol-buffers/docs/overview)
definition at [./src/machi.proto](./src/machi.proto).
<a name="n1.7">
### 1.7. What licensing terms are used by Machi?
All Machi source code and documentation is licensed by
[Basho Technologies, Inc.](http://www.basho.com/)
under the [Apache Public License version 2](https://github.com/basho/machi/tree/master/LICENSE).
<a name="n1.8">
### 1.8. Where can I find the Machi source code and documentation? Can I contribute?
All Machi source code and documentation can be found at GitHub:
[https://github.com/basho/machi](https://github.com/basho/machi).
The full URL for this FAQ is [https://github.com/basho/machi/blob/master/FAQ.md](https://github.com/basho/machi/blob/master/FAQ.md).
There are several "README" files in the source repository. We hope
they provide useful guidance for first-time readers.
If you're interested in contributing code or documentation or
ideas for improvement, please see our contributing & collaboration
guidelines at
[https://github.com/basho/machi/blob/master/CONTRIBUTING.md](https://github.com/basho/machi/blob/master/CONTRIBUTING.md).
<a name="n1.9">
### 1.9. What is Machi's expected release schedule, packaging, and operating system/OS distribution support?
Basho expects that Machi's first major product release will take place
during the 2nd quarter of 2016.
Basho's official support for operating systems (e.g. Linux, FreeBSD),
operating system packaging (e.g. CentOS rpm/yum package management,
Ubuntu debian/apt-get package management), and
container/virtualization have not yet been chosen. If you wish to
provide your opinion, we'd love to hear it. Please
[open a support ticket at GitHub](https://github.com/basho/machi/issues/new)
and let us know.
<a name="n2">
## 2. Questions about Machi relative to {{something else}}
<a name="better-than-hadoop">
<a name="n2.1">
### 2.1. How is Machi better than Hadoop?
This question is frequently asked by trolls. If this is a troll
question, the answer is either, "Nothing is better than Hadoop," or
else "Everything is better than Hadoop."
The real answer is that Machi is not a distributed data processing
framework like Hadoop is.
See [Hadoop's entry in Wikipedia](https://en.wikipedia.org/wiki/Apache_Hadoop)
and focus on the description of Hadoop's MapReduce and YARN; Machi
contains neither.
<a name="n2.2">
### 2.2. How does Machi differ from HadoopFS/HDFS?
This is a much better question than the
[How is Machi better than Hadoop?](#better-than-hadoop)
question.
[HadoopFS's entry in Wikipedia](https://en.wikipedia.org/wiki/Apache_Hadoop#HDFS)
One way to look at Machi is to consider Machi as a distributed file
store. HadoopFS is also a distributed file store. Let's compare and
contrast.
<table>
<tr>
<td> <b>Machi</b>
<td> <b>HadoopFS (HDFS)</b>
<tr>
<td> Not POSIX compliant
<td> Not POSIX compliant
<tr>
<td> Immutable file store with append-only semantics (simplifying
things a little bit).
<td> Immutable file store with append-only semantics
<tr>
<td> File data may be read concurrently while file is being actively
appended to.
<td> File must be closed before a client can read it.
<tr>
<td> No concept (yet) of users or authentication (though the initial
supported release will support basic user + password authentication).
Machi will probably never natively support directories or ACLs.
<td> Has concepts of users, directories, and ACLs.
<tr>
<td> Machi does not allow clients to name their own files or to specify data
placement/offset within a file.
<td> While not POSIX compliant, HDFS allows a fairly flexible API for
managing file names and file writing position within a file (during a
file's writable phase).
<tr>
<td> Does not have any file distribution/partitioning/sharding across
Machi chains: in a single Machi chain, all files are replicated by
all servers in the chain. The "random slicing" technique is used
to distribute/partition/shard files across multiple Machi clusters.
<td> File distribution/partitioning/sharding is performed
automatically by the HDFS "name node".
<tr>
<td> Machi requires no central "name node" for single chain use or
for multi-chain cluster use.
<td> Requires a single "namenode" server to maintain file system contents
and file content mapping. (May be deployed with a "secondary
namenode" to reduce unavailability when the primary namenode fails.)
<tr>
<td> Machi uses Chain Replication to manage all file replicas.
<td> The HDFS name node uses an ad hoc mechanism for replicating file
contents. The HDFS file system metadata (file names, file block(s)
locations, ACLs, etc.) is stored by the name node in the local file
system and is replicated to any secondary namenode using snapshots.
<tr>
<td> Machi replicates files *N* ways where *N* is the length of the
Chain Replication chain. Typically, *N=2*, but this is configurable.
<td> HDFS typical replicates file contents *N=3* ways, but this is
configurable.
<tr>
<td> All Machi file data is protected by SHA-1 checksums generated by
the client prior to writing by Machi servers.
<td> Optional file checksum protection may be implemented on the
server side.
</table>
<a name="n2.3">
### 2.3. How does Machi differ from Kafka?
Machi is rather close to Kafka in spirit, though its implementation is
quite different.
<table>
<tr>
<td> <b>Machi</b>
<td> <b>Kafka</b>
<tr>
<td> Append-only, strongly consistent file store only
<td> Append-only, strongly consistent log file store + additional
services: for example, producer topics & sharding, consumer groups &
failover, etc.
<tr>
<td> Not yet code complete nor "battle tested" in large production
environments.
<td> "Battle tested" in large production environments.
<tr>
<td> All Machi file data is protected by SHA-1 checksums generated by
the client prior to writing by Machi servers.
<td> Each log entry is protected by a 32 bit CRC checksum.
</table>
In theory, it should be "quite straightforward" to remove these parts
of Kafka's code base:
* local file system I/O for all topic/partition/log files
* leader/follower file replication, ISR ("In Sync Replica") state
management, and related log file replication logic
... and replace those parts with Machi client API calls. Those parts
of Kafka are what Machi has been designed to do from the very
beginning.
See also:
<a href="#corfu-and-tango">How does Machi differ from CORFU and Tango?</a>
<a name="n2.4">
### 2.4. How does Machi differ from Bookkeeper?
Sorry, we haven't studied Bookkeeper very deeply or used Bookkeeper
for any non-trivial project.
One notable limitation of the Bookkeeper API is that a ledger cannot
be read by other clients until it has been closed. Any byte in a
Machi file that has been written successfully may
be read immedately by any other Machi client.
The name "Machi" does not have three consecutive pairs of repeating
letters. The name "Bookkeeper" does.
<a name="corfu-and-tango">
<a name="n2.5">
### 2.5. How does Machi differ from CORFU and Tango?
Machi's design borrows very heavily from CORFU. We acknowledge a deep
debt to the original Microsoft Research papers that describe CORFU's
original design and implementation.
<table>
<tr>
<td> <b>Machi</b>
<td> <b>CORFU</b>
<tr>
<td> Writes & reads may be on byte boundaries
<td> Wries & reads must be on page boundaries, e.g. 4 or 8 KBytes, to
align with server storage based on flash NVRAM/solid state disk (SSD).
<tr>
<td> Provides multiple "logs", where each log has a name and is
appended to & read from like a file. A read operation requires a 3-tuple:
file name, starting byte offset, number of bytes.
<td> Provides a single "log". A read operation requires only a
1-tuple: the log page number. (A protocol option exists to
request multiple pages in a single read query?)
<tr>
<td> Offers service in either strongly consistent mode or eventually
consistent mode.
<td> Offers service in strongly consistent mode.
<tr>
<td> May be deployed on solid state disk (SSD) or Winchester hard disks.
<td> Designed for use with solid state disk (SSD) but can also be used
with Winchester hard disks (with a performance penalty if used as
suggested by use cases described by the CORFU papers).
<tr>
<td> All Machi file data is protected by SHA-1 checksums generated by
the client prior to writing by Machi servers.
<td> Depending on server & flash device capabilities, each data page
may be protected by a checksum (calculated independently by each
server rather than the client).
</table>
See also: the "Recommended reading & related work" and "References"
sections of the
[Machi high level design doc](https://github.com/basho/machi/tree/master/doc/high-level-machi.pdf)
for pointers to the MSR papers related to CORFU.
Machi does not implement Tango directly. (Not yet, at least.)
However, there is a prototype implementation included in the Machi
source tree. See
[the prototype/tango source code directory](https://github.com/basho/machi/tree/master/prototype/tango)
for details.
Also, it's worth adding that the original MSR code behind the research
papers is now available at GitHub:
[https://github.com/CorfuDB/CorfuDB](https://github.com/CorfuDB/CorfuDB).
<a name="n3">
## 3. Machi's specifics
<a name="n3.1">
### 3.1. What technique is used to replicate Machi's files? Can other techniques be used?
Machi uses Chain Replication to replicate all file data. Each byte of
a file is stored using a "write-once register", which is a mechanism
to enforce immutability after the byte has been written exactly once.
In order to ensure availability in the event of *F* failures, Chain
Replication requires a minimum of *F + 1* servers to be configured.
Alternative mechanisms could be used to manage file replicas, such as
Paxos or Raft. Both Paxos and Raft have some requirements that are
difficult to adapt to Machi's design goals:
* Both protocols use quorum majority consensus, which requires a
minimum of *2F + 1* working servers to tolerate *F* failures. For
example, to tolerate 2 server failures, quorum majority protocols
require a minimum of 5 servers. To tolerate the same number of
failures, Chain Replication requires a minimum of only 3 servers.
* Machi's use of "humming consensus" to manage internal server
metadata state would also (probably) require conversion to Paxos or
Raft. (Or "outsourced" to a service such as ZooKeeper.)
<a name="n3.2">
### 3.2. Does Machi have a reliance on a coordination service such as ZooKeeper or etcd?
No. Machi maintains critical internal cluster information in an
internal, immutable data service called the "projection store". The
contents of the projection store are maintained by a new technique
called "humming consensus".
Humming consensus is described in the
[Machi chain manager high level design doc](https://github.com/basho/machi/tree/master/doc/high-level-chain-mgr.pdf).
<a name="n3.3">
### 3.3. Are there any presentations available about Humming Consensus
Scott recently (November 2015) gave a presentation at the
[RICON 2015 conference](http://ricon.io) about one of the techniques
used by Machi; "Managing Chain Replication Metadata with
Humming Consensus" is available online now.
* [slides (PDF format)](http://ricon.io/speakers/slides/Scott_Fritchie_Ricon_2015.pdf)
* [video](https://www.youtube.com/watch?v=yR5kHL1bu1Q)
<a name="n3.4">
### 3.4. Is it true that there's an allegory written to describe Humming Consensus?
Yes. In homage to Leslie Lamport's original paper about the Paxos
protocol, "The Part-time Parliamant", there is an allegorical story
that describes humming consensus as method to coordinate
many composers to write a single piece of music.
The full story, full of wonder and mystery, is called
["On “Humming Consensus”, an allegory"](http://www.snookles.com/slf-blog/2015/03/01/on-humming-consensus-an-allegory/).
There is also a
[short followup blog posting](http://www.snookles.com/slf-blog/2015/03/20/on-humming-consensus-an-allegory-part-2/).
<a name="n3.5">
### 3.5. How is Machi tested?
While not formally proven yet, Machi's implementation of Chain
Replication and of humming consensus have been extensively tested with
several techniques:
* We use an executable model based on the QuickCheck framework for
property based testing.
* In addition to QuickCheck alone, we use the PULSE extension to
QuickCheck is used to test the implementation
under extremely skewed & unfair scheduling/timing conditions.
The model includes simulation of asymmetric network partitions. For
example, actor A can send messages to actor B, but B cannot send
messages to A. If such a partition happens somewhere in a traditional
network stack (e.g. a faulty Ethernet cable), any TCP connection
between A & B will quickly interrupt communication in _both_
directions. In the Machi network partition simulator, network
partitions can be truly one-way only.
After randomly generating a series of network partitions (which may
change several times during any single test case) and a random series
of cluster operations, an event trace of all cluster activity is used
to verify that no safety-critical rules have been violated.
All test code is available in the [./test](./test) subdirectory.
Modules that use QuickCheck will use a file suffix of `_eqc`, for
example, [./test/machi_ap_repair_eqc.erl](./test/machi_ap_repair_eqc.erl).
<a name="n3.6">
### 3.6. Does Machi require shared disk storage? e.g. iSCSI, NBD (Network Block Device), Fibre Channel disks
No, Machi's design assumes that each Machi server is a fully
independent hardware and assumes only standard local disks (Winchester
and/or SSD style) with local-only interfaces (e.g. SATA, SCSI, PCI) in
each machine.
<a name="n3.7">
### 3.7. Does Machi require or assume that servers with large numbers of disks must use RAID-0/1/5/6/10/50/60 to create a single block device?
No. When used with servers with multiple disks, the intent is to
deploy multiple Machi servers per machine: one Machi server per disk.
* Pro: disk bandwidth and disk storage capacity can be managed at the
level of an individual disk.
* Pro: failure of an individual disk does not risk data loss on other
disks.
* Con (or pro, depending on the circumstances): in this configuration,
Machi would require additional network bandwidth to repair data on a lost
drive instead of intra-machine disk & bus & memory bandwidth that
would be required for RAID volume repair
* Con: replica placement policy, such as "rack awareness", becomes a
larger problem that must be automated. For example, a problem of
placement relative to 12 servers is smaller than a placement problem
of managing 264 seprate disks (if each of 12 servers has 22 disks).
<a name="n3.8">
### 3.8. What language(s) is Machi written in?
So far, Machi is written in Erlang, mostly. Machi uses at least one
library, [ELevelDB](https://github.com/basho/eleveldb), that is
implemented both in C++ and in Erlang, using Erlang NIFs (Native
Interface Functions) to allow Erlang code to call C++ functions.
In the event that we encounter a performance problem that cannot be
solved within the Erlang/OTP runtime environment, all of Machi's
performance-critical components are small enough to be re-implemented
in C, Java, or other "gotta go fast fast FAST!!" programming
language. We expect that the Chain Replication manager and other
critical "control plane" software will remain in Erlang.
<a name="n3.9">
### 3.9. Can Machi run on Windows? Can Machi run on 32-bit platforms?
The ELevelDB NIF does not compile or run correctly on Erlang/OTP
Windows platforms, nor does it compile correctly on 32-bit platforms.
Machi should support all 64-bit UNIX-like platforms that are supported
by Erlang/OTP and ELevelDB.
<a name="n3.10">
### 3.10. Does Machi use the Erlang/OTP network distribution system (aka "disterl")?
No, Machi doesn't use Erlang/OTP's built-in distributed message
passing system. The code would be *much* simpler if we did use
"disterl". However, due to (premature?) worries about performance, we
wanted to have the option of re-writing some Machi components in C or
Java or Go or OCaml or COBOL or in-kernel assembly hexadecimal
bit-twiddling magicSPEED ... without also having to find a replacement
for disterl. (Or without having to re-invent disterl's features in
another language.)
All wire protocols used by Machi are defined & implemented using
[Protocol Buffers](https://developers.google.com/protocol-buffers/docs/overview).
The definition file can be found at [./src/machi.proto](./src/machi.proto).
<a name="n3.11">
### 3.11. Can I use HTTP to write/read stuff into/from Machi?
Short answer: No, not yet.
Longer answer: No, but it was possible as a hack, many months ago, see
[primitive/hack'y HTTP interface that is described in this source code commit log](https://github.com/basho/machi/commit/6cebf397232cba8e63c5c9a0a8c02ba391b20fef).
Please note that commit `6cebf397232cba8e63c5c9a0a8c02ba391b20fef` is
required to try using this feature: the code has since bit-rotted and
will not work on today's `master` branch.
In the long term, we'll probably want the option of an HTTP interface
that is as well designed and REST'ful as possible. It's on the
internal Basho roadmap. If you'd like to work on a real, not-kludgy
HTTP interface to Machi,
[please contact us!](https://github.com/basho/machi/blob/master/CONTRIBUTING.md)

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@ -1,297 +0,0 @@
# Installation instructions for Machi
Machi is still a young enough project that there is no "installation".
All development is still done using the Erlang/OTP interactive shell
for experimentation, using `make` to compile, and the shell's
`l(ModuleName).` command to reload any recompiled modules.
In the coming months (mid-2015), there are plans to create OS packages
for common operating systems and OS distributions, such as FreeBSD and
Linux. If building RPM, DEB, PKG, or other OS package managers is
your specialty, we could use your help to speed up the process! <b>:-)</b>
## Development toolchain dependencies
Machi's dependencies on the developer's toolchain are quite small.
* Erlang/OTP version 17.0 or later, 32-bit or 64-bit
* The `make` utility.
* The GNU version of make is not required.
* Machi is bundled with a `rebar` package and should be usable on
any Erlang/OTP 17.x platform.
Machi does not use any Erlang NIF or port drivers.
## Development OS
At this time, Machi is 100% Erlang. Although we have not tested it,
there should be no good reason why Machi cannot run on Erlang/OTP on
Windows platforms. Machi has been developed on OS X and FreeBSD and
is expected to work on any UNIX-ish platform supported by Erlang/OTP.
## Compiling the Machi source
First, clone the Machi source code, then compile it. You will
need Erlang/OTP version 17.x to compile.
cd /some/nice/dev/place
git clone https://github.com/basho/machi.git
cd machi
make
make test
The unit test suite is based on the EUnit framework (bundled with
Erlang/OTP 17). The `make test` suite runs on my MacBook in 10
seconds or less.
## Setting up a Machi cluster
As noted above, everything is done manually at the moment. Here is a
rough sketch of day-to-day development workflow.
### 1. Run the server
cd /some/nice/dev/place/machi
make
erl -pz ebin deps/*/ebin +A 253 +K true
This will start an Erlang shell, plus a few extras.
* Tell the OTP code loader where to find dependent BEAM files.
* Set a large pool (253) of file I/O worker threads
* Use a more efficient kernel polling mechanism for network sockets.
* If your Erlang/OTP package does not support `+K true`, do not
worry. It is an optional flag.
The following commands will start three Machi FLU server processes and
then tell them to form a single chain. Internally, each FLU will have
Erlang registered processes with the names `a`, `b`, and `c`, and
listen on TCP ports 4444, 4445, and 4446, respectively. Each will use
a data directory located in the current directory, e.g. `./data.a`.
Cut-and-paste the following commands into the CLI at the prompt:
application:ensure_all_started(machi).
machi_flu_psup:start_flu_package(a, 4444, "./data.a", []).
machi_flu_psup:start_flu_package(b, 4445, "./data.b", []).
D = orddict:from_list([{a,{p_srvr,a,machi_flu1_client,"localhost",4444,[]}},{b,{p_srvr,b,machi_flu1_client,"localhost",4445,[]}}]).
machi_chain_manager1:set_chain_members(a_chmgr, D).
machi_chain_manager1:set_chain_members(b_chmgr, D).
If you change the TCP ports of any of the processes, you must make the
same change both in the `machi_flu_psup:start_flu_package()` arguments
and also in the `D` dictionary.
The Erlang processes that will be started are arranged in the
following hierarchy. See the
[machi_flu_psup.erl](http://basho.github.io/machi/edoc/machi_flu_psup.html)
EDoc documentation for a description of each of these processes.
![](https://basho.github.io/machi/images/supervisor-2flus.png)
### 2. Check the status of the server processes.
Each Machi FLU is an independent file server. All replication between
Machi servers is currently implemented by code on the *client* side.
(This will change a bit later in 2015.)
Use the `read_latest_projection` command on the server CLI, e.g.:
rr("include/machi_projection.hrl").
machi_projection_store:read_latest_projection(a_pstore, private).
... to query the projection store of the local FLU named `a`.
If you haven't looked at the server-side description of the various
Machi server-side processes, please take a couple minutes to read
[machi_flu_psup.erl](http://basho.github.io/machi/edoc/machi_flu_psup.html).
### 3. Use the machi_cr_client.erl client
For development work, I run the client & server on the same Erlang
VM. It's just easier that way ... but the Machi client & server use
TCP to communicate with each other.
If you are using a separate machine for the client, then compile the
Machi source on the client machine. Then run:
cd /some/nice/dev/place/machi
make
erl -pz ebin deps/*/ebin
(You can add `+K true` if you wish ... but for light development work,
it doesn't make a big difference.)
At the CLI, define the dictionary that describes the host & TCP port
location for each of the Machi servers. (If you changed the host
and/or TCP port values when starting the servers, then place make the
same changes here.
D = orddict:from_list([{a,{p_srvr,a,machi_flu1_client,"localhost",4444,[]}},{b,{p_srvr,b,machi_flu1_client,"localhost",4445,[]}}]).
Then start a `machi_cr_client` client process.
{ok, C1} = machi_cr_client:start_link([P || {_,P} <- orddict:to_list(D)]).
Please keep in mind that this process is **linked** to your CLI
process. If you run a CLI command the throws an exception/exits, then
this `C1` process will also die! You can start a new one, using a
different name, e.g. `C2`. Or you can start a new one by first
"forgetting" the CLI's binding for `C1`.
f(C1).
{ok, C1} = machi_cr_client:start_link([P || {_,P} <- orddict:to_list(D)]).
Now, append a small chunk of data to a file with the prefix
`<<"pre">>`.
12> {ok, C1} = machi_cr_client:start_link([P || {_,P} <- orddict:to_list(D)]).
{ok,<0.112.0>}
13> machi_cr_client:append_chunk(C1, <<"pre">>, <<"Hello, world">>).
{ok,{1024,12,<<"pre.G6C116EA.3">>}}
This chunk was written successfully to a file called
`<<"pre.5BBL16EA.1">>` at byte offset 1024. Let's fetch it now. And
let's see what happens in a couple of error conditions: fetching
bytes that "straddle" the end of file, bytes that are after the known
end of file, and bytes from a file that has never been written.
26> machi_cr_client:read_chunk(C1, <<"pre.G6C116EA.3">>, 1024, 12).
{ok,<<"Hello, world">>}
27> machi_cr_client:read_chunk(C1, <<"pre.G6C116EA.3">>, 1024, 777).
{error,partial_read}
28> machi_cr_client:read_chunk(C1, <<"pre.G6C116EA.3">>, 889323, 12).
{error,not_written}
29> machi_cr_client:read_chunk(C1, <<"no-such-file">>, 1024, 12).
{error,not_written}
### 4. Use the `machi_proxy_flu1_client.erl` client
The `machi_proxy_flu1_client` module implements a simpler client that
only uses a single Machi FLU file server. This client is **not**
aware of chain replication in any way.
Let's use this client to verify that the `<<"Hello, world!">> data
that we wrote in step #3 was truly written to both FLU servers by the
`machi_cr_client` library. We start proxy processes for each of the
FLUs, then we'll query each ... but first we also need to ask (at
least one of) the servers for the current Machi cluster's Epoch ID.
{ok, Pa} = machi_proxy_flu1_client:start_link(orddict:fetch(a, D)).
{ok, Pb} = machi_proxy_flu1_client:start_link(orddict:fetch(b, D)).
{ok, EpochID0} = machi_proxy_flu1_client:get_epoch_id(Pa).
machi_proxy_flu1_client:read_chunk(Pa, EpochID0, <<"pre.G6C116EA.3">>, 1024, 12).
machi_proxy_flu1_client:read_chunk(Pb, EpochID0, <<"pre.G6C116EA.3">>, 1024, 12).
### 5. Checking how Chain Replication "read repair" works
Now, let's cause some trouble: we will write some data only to the
head of the chain. By default, all read operations go to the tail of
the chain. But, if a value is not written at the tail, then "read
repair" ought to verify:
* Perhaps the value truly is not written at any server in the chain.
* Perhaps the value was partially written, i.e. by a buggy or
crashed-in-the-middle-of-the-writing-procedure client.
So, first, let's double-check that the chain is in the order that we
expect it to be.
rr("include/machi_projection.hrl"). % In case you didn't do this earlier.
machi_proxy_flu1_client:read_latest_projection(Pa, private).
The part of the `#projection_v1` record that we're interested in is
the `upi`. This is the list of servers that preserve the Update
Propagation Invariant property of the Chain Replication algorithm.
The output should look something like:
{ok,#projection_v1{
epoch_number = 1119,
[...]
author_server = b,
all_members = [a,b],
creation_time = {1432,189599,85392},
mode = ap_mode,
upi = [a,b],
repairing = [],down = [],
[...]
}
So, we see `upi=[a,b]`, which means that FLU `a` is the head of the
chain and that `b` is the tail.
Let's append to `a` using the `machi_proxy_flu1_client` to the head
and then read from both the head and tail. (If your chain order is
different, then please exchange `Pa` and `Pb` in all of the commands
below.)
16> {ok, {Off1,Size1,File1}} = machi_proxy_flu1_client:append_chunk(Pa, EpochID0, <<"foo">>, <<"Hi, again">>).
{ok,{1024,9,<<"foo.K63D16M4.1">>}}
17> machi_proxy_flu1_client:read_chunk(Pa, EpochID0, File1, Off1, Size1). {ok,<<"Hi, again">>}
18> machi_proxy_flu1_client:read_chunk(Pb, EpochID0, File1, Off1, Size1).
{error,not_written}
That is correct! Now, let's read the same file & offset using the
client that understands chain replication. Then we will try reading
directly from FLU `b` again ... we should see something different.
19> {ok, C2} = machi_cr_client:start_link([P || {_,P} <- orddict:to_list(D)]).
{ok,<0.113.0>}
20> machi_cr_client:read_chunk(C2, File1, Off1, Size1).
{ok,<<"Hi, again">>}
21> machi_proxy_flu1_client:read_chunk(Pb, EpochID0, File1, Off1, Size1).
{ok,<<"Hi, again">>}
That is correct! The command at prompt #20 automatically performed
"read repair" on FLU `b`.
### 6. Exploring what happens when a server is stopped, data written, and server restarted
Cut-and-paste the following into your CLI. We assume that your CLI
still remembers the value of the `D` dictionary from the previous
steps above. We will stop FLU `a`, write one thousand small
chunks, then restart FLU `a`, then see what happens.
{ok, C3} = machi_cr_client:start_link([P || {_,P} <- orddict:to_list(D)]).
machi_flu_psup:stop_flu_package(a).
[machi_cr_client:append_chunk(C3, <<"foo">>, <<"Lots of stuff">>) || _ <- lists:seq(1,1000)].
machi_flu_psup:start_flu_package(a, 4444, "./data.a", []).
About 10 seconds after we restarting `a` with the
`machi_flu_psup:start_flu_package()` function, this appears on the
console:
=INFO REPORT==== 21-May-2015::15:53:46 ===
Repair start: tail b of [b] -> [a], ap_mode ID {b,{1432,191226,707262}}
MissingFileSummary [{<<"foo.CYLJ16ZT.1">>,{14024,[a]}}]
Make repair directives: . done
Out-of-sync data for FLU a: 0.1 MBytes
Out-of-sync data for FLU b: 0.0 MBytes
Execute repair directives: .......... done
=INFO REPORT==== 21-May-2015::15:53:47 ===
Repair success: tail b of [b] finished ap_mode repair ID {b,{1432,191226,707262}}: ok
Stats [{t_in_files,0},{t_in_chunks,1000},{t_in_bytes,13000},{t_out_files,0},{t_out_chunks,1000},{t_out_bytes,13000},{t_bad_chunks,0},{t_elapsed_seconds,0.647}]
The data repair process, executed by `b`'s chain manager, found 1000
chunks that were out of sync and copied them to `a` successfully.
### 7. Exploring the rest of the client APIs
Please see the EDoc documentation for the client APIs. Feel free to
explore!
* [Erlang type definitions for the client APIs](http://basho.github.io/machi/edoc/machi_flu1_client.html)
* [EDoc for machi_cr_client.erl](http://basho.github.io/machi/edoc/machi_cr_client.html)
* [EDoc for machi_proxy_flu1_client.erl](http://basho.github.io/machi/edoc/machi_proxy_flu1_client.html)
* [Top level EDoc collection](http://basho.github.io/machi/edoc/)

178
LICENSE
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@ -1,178 +0,0 @@
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View file

@ -1,94 +0,0 @@
REPO ?= machi
PKG_REVISION ?= $(shell git describe --tags)
PKG_BUILD = 1
BASE_DIR = $(shell pwd)
ERLANG_BIN = $(shell dirname $(shell which erl))
REBAR := $(shell which rebar)
ifeq ($(REBAR),)
REBAR = $(BASE_DIR)/rebar
endif
OVERLAY_VARS ?=
EUNIT_OPTS = -v
.PHONY: rel stagedevrel deps package pkgclean edoc
all: deps compile
compile:
$(REBAR) compile
## Make reltool happy by creating a fake entry in the deps dir for
## machi, because reltool really wants to have a path with
## "machi/ebin" at the end, but we also don't want infinite recursion
## if we just symlink "deps/machi" -> ".."
generate:
rm -rf deps/machi
mkdir deps/machi
ln -s ../../ebin deps/machi
ln -s ../../src deps/machi
$(REBAR) generate $(OVERLAY_VARS) 2>&1 | grep -v 'command does not apply to directory'
deps:
$(REBAR) get-deps
clean:
$(REBAR) -r clean
edoc: edoc-clean
$(REBAR) skip_deps=true doc
edoc-clean:
rm -f edoc/*.png edoc/*.html edoc/*.css edoc/edoc-info
pulse: compile
@echo Sorry, PULSE test needs maintenance. -SLF
#env USE_PULSE=1 $(REBAR) skip_deps=true clean compile
#env USE_PULSE=1 $(REBAR) skip_deps=true -D PULSE eunit -v
##
## Release targets
##
rel: deps compile generate
relclean:
rm -rf rel/$(REPO)
stage : rel
$(foreach dep,$(wildcard deps/*), rm -rf rel/$(REPO)/lib/$(shell basename $(dep))* && ln -sf $(abspath $(dep)) rel/$(REPO)/lib;)
##
## Developer targets
##
## devN - Make a dev build for node N
## stagedevN - Make a stage dev build for node N (symlink libraries)
## devrel - Make a dev build for 1..$DEVNODES
## stagedevrel Make a stagedev build for 1..$DEVNODES
##
## Example, make a 68 node devrel cluster
## make stagedevrel DEVNODES=68
.PHONY : stagedevrel devrel
DEVNODES ?= 3
# 'seq' is not available on all *BSD, so using an alternate in awk
SEQ = $(shell awk 'BEGIN { for (i = 1; i < '$(DEVNODES)'; i++) printf("%i ", i); print i ;exit(0);}')
$(eval stagedevrel : $(foreach n,$(SEQ),stagedev$(n)))
$(eval devrel : $(foreach n,$(SEQ),dev$(n)))
dev% : all
mkdir -p dev
rel/gen_dev $@ rel/vars/dev_vars.config.src rel/vars/$@_vars.config
(cd rel && ../rebar generate target_dir=../dev/$@ overlay_vars=vars/$@_vars.config)
stagedev% : dev%
$(foreach dep,$(wildcard deps/*), rm -rf dev/$^/lib/$(shell basename $(dep))* && ln -sf $(abspath $(dep)) dev/$^/lib;)
devclean: clean
rm -rf dev
DIALYZER_APPS = kernel stdlib sasl erts ssl compiler eunit crypto public_key syntax_tools
PLT = $(HOME)/.machi_dialyzer_plt
include tools.mk

6
NOTICE
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@ -1,6 +0,0 @@
Machi
Copyright 2007-2015 Basho Technologies
This product contains code developed at Basho Technologies.
(http://www.basho.com/)

174
README.md
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@ -1,174 +0,0 @@
# Machi: a distributed, decentralized blob/large file store
[Travis-CI](http://travis-ci.org/basho/machi) :: ![Travis-CI](https://secure.travis-ci.org/basho/machi.png)
Outline
1. [Why another blob/file store?](#sec1)
2. [Where to learn more about Machi](#sec2)
3. [Development status summary](#sec3)
4. [Contributing to Machi's development](#sec4)
<a name="sec1">
## 1. Why another blob/file store?
Our goal is a robust & reliable, distributed, highly available, large
file and blob store. Such stores already exist, both in the open source world
and in the commercial world. Why reinvent the wheel? We believe
there are three reasons, ordered by decreasing rarity.
1. We want end-to-end checksums for all file data, from the initial
file writer to every file reader, anywhere, all the time.
2. We need flexibility to trade consistency for availability:
e.g. weak consistency in exchange for being available in cases
of partial system failure.
3. We want to manage file replicas in a way that's provably correct
and also easy to test.
Criteria #3 is difficult to find in the open source world but perhaps
not impossible.
If we have app use cases where availability is more important than
consistency, then systems that meet criteria #2 are also rare.
Most file stores provide only strong consistency and therefore
have unavoidable, unavailable behavior when parts of the system
fail.
What if we want a file store that is always available to write new
file data and attempts best-effort file reads?
If we really do care about data loss and/or data corruption, then we
really want both #3 and #1. Unfortunately, systems that meet
criteria #1 are _very rare_. (Nonexistant?)
Why? This is 2015. We have decades of research that shows
that computer hardware can (and
indeed does) corrupt data at nearly every level of the modern
client/server application stack. Systems with end-to-end data
corruption detection should be ubiquitous today. Alas, they are not.
Machi is an effort to change the deplorable state of the world, one
Erlang function at a time.
<a name="sec2">
## 2. Where to learn more about Machi
The two major design documents for Machi are now mostly stable.
Please see the [doc](./doc) directory's [README](./doc) for details.
We also have a
[Frequently Asked Questions (FAQ) list](./FAQ.md).
Scott recently (November 2015) gave a presentation at the
[RICON 2015 conference](http://ricon.io) about one of the techniques
used by Machi; "Managing Chain Replication Metadata with
Humming Consensus" is available online now.
* [slides (PDF format)](http://ricon.io/speakers/slides/Scott_Fritchie_Ricon_2015.pdf)
* [video](https://www.youtube.com/watch?v=yR5kHL1bu1Q)
See later in this document for how to run the Humming Consensus demos,
including the network partition simulator.
<a name="sec3">
## 3. Development status summary
Mid-March 2016: The Machi development team has been downsized in
recent months, and the pace of development has slowed. Here is a
summary of the status of Machi's major components.
* Humming Consensus and the chain manager
* No new safety bugs have been found by model-checking tests.
* A new document,
[Hands-on experiments with Machi and Humming Consensus](doc/humming-consensus-demo.md)
is now available. It is a tutorial for setting up a 3 virtual
machine Machi cluster and how to demonstrate the chain manager's
reactions to server stops & starts, crashes & restarts, and pauses
(simulated by `SIGSTOP` and `SIGCONT`).
* The chain manager can still make suboptimal-but-safe choices for
chain transitions when a server hangs/pauses temporarily.
* Recent chain manager changes have made the instability window
much shorter when the slow/paused server resumes execution.
* Scott believes that a modest change to the chain manager's
calculation of a new projection can reduce flapping in this (and
many other cases) less likely. Currently, the new local
projection is calculated using only local state (i.e., the chain
manager's internal state + the fitness server's state).
However, if the "latest" projection read from the public
projection stores were also input to the new projection
calculation function, then many obviously bad projections can be
avoided without needing rounds of Humming Consensus to
demonstrate that a bad projection is bad.
* FLU/data server process
* All known correctness bugs have been fixed.
* Performance has not yet been measured. Performance measurement
and enhancements are scheduled to start in the middle of March 2016.
(This will include a much-needed update to the `basho_bench` driver.)
* Access protocols and client libraries
* The protocol used by both external clients and internally (instead
of using Erlang's native message passing mechanisms) is based on
Protocol Buffers.
* (Machi PB protocol specification: ./src/machi.proto)[./src/machi.proto]
* At the moment, the PB specification contains two protocols.
Sometime in the near future, the spec will be split to separate
the external client API (the "high" protocol) from the internal
communication API (the "low" protocol).
* Recent conference talks about Machi
* Erlang Factory San Francisco 2016
[the slides and video recording](http://www.erlang-factory.com/sfbay2016/scott-lystig-fritchie)
will be available a few weeks after the conference ends on March
11, 2016.
* Ricon 2015
* [The slides](http://ricon.io/archive/2015/slides/Scott_Fritchie_Ricon_2015.pdf)
* and the [video recording](https://www.youtube.com/watch?v=yR5kHL1bu1Q&index=13&list=PL9Jh2HsAWHxIc7Tt2M6xez_TOP21GBH6M)
are now available.
* If you would like to run the Humming Consensus code (with or without
the network partition simulator) as described in the RICON 2015
presentation, please see the
[Humming Consensus demo doc](./doc/humming_consensus_demo.md).
<a name="sec4">
## 4. Contributing to Machi's development
### 4.1 License
Basho Technologies, Inc. as committed to licensing all work for Machi
under the
[Apache Public License version 2](./LICENSE). All authors of source code
and documentation who agree with these licensing terms are welcome to
contribute their ideas in any form: suggested design or features,
documentation, and source code.
Machi is still a very young project within Basho, with a small team of
developers; please bear with us as we grow out of "toddler" stage into
a more mature open source software project.
We invite all contributors to review the
[CONTRIBUTING.md](./CONTRIBUTING.md) document for guidelines for
working with the Basho development team.
### 4.2 Development environment requirements
All development to date has been done with Erlang/OTP version 17 on OS
X. The only known limitations for using R16 are minor type
specification difference between R16 and 17, but we strongly suggest
continuing development using version 17.
We also assume that you have the standard UNIX/Linux developer
tool chain for C and C++ applications. Also, we assume
that Git and GNU Make are available.
The utility used to compile the Machi source code,
`rebar`, is pre-compiled and included in the repo.
For more details, please see the
[Machi development environment prerequisites doc](./doc/dev-prerequisites.md).
Machi has a dependency on the
[ELevelDB](https://github.com/basho/eleveldb) library. ELevelDB only
supports UNIX/Linux OSes and 64-bit versions of Erlang/OTP only; we
apologize to Windows-based and 32-bit-based Erlang developers for this
restriction.
### 4.3 New protocols and features
If you'd like to work on a protocol such as Thrift, UBF,
msgpack over UDP, or some other protocol, let us know by
[opening an issue to discuss it](./issues/new).

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@ -1,114 +0,0 @@
* To Do list
** DONE remove the escript* stuff from machi_util.erl
** DONE Add functions to manipulate 1-chain projections
- Add epoch ID = epoch number + checksum of projection!
Done via compare() func.
** DONE Change all protocol ops to add epoch ID
** DONE Add projection store to each FLU.
*** DONE What should the API look like? (borrow from chain mgr PoC?)
Yeah, I think that's pretty complete. Steal it now, worry later.
*** DONE Choose protocol & TCP port. Share with get/put? Separate?
Hrm, I like the idea of having a single TCP port to talk to any single
FLU.
To make the protocol "easy" to hack, how about using the same basic
method as append/write where there's a variable size blob. But we'll
format that blob as a term_to_binary(). Then dispatch to a single
func, and pattern match Erlang style in that func.
*** DONE Do it.
** DONE Finish OTP'izing the Chain Manager with FLU & proj store processes
** DONE Eliminate the timeout exception for the client: just {error,timeout} ret
** DONE Move prototype/chain-manager code to "top" of source tree
*** DONE Preserve current test code (leave as-is? tiny changes?)
*** DONE Make chain manager code flexible enough to run "real world" or "sim"
** DONE Add projection wedging logic to each FLU.
** DONE Implement real data repair, orchestrated by the chain manager
** DONE Change all protocol ops to enforce the epoch ID
- Add no-wedging state to make testing easier?
** DONE Adapt the projection-aware, CR-implementing client from demo-day
** DONE Add major comment sections to the CR-impl client
** DONE Simple basho_bench driver, put some unscientific chalk on the benchtop
** TODO Create parallel PULSE test for basic API plus chain manager repair
** DONE Add client-side vs. server-side checksum type, expand client API?
** TODO Add gproc and get rid of registered name rendezvous
*** TODO Fixes the atom table leak
*** TODO Fixes the problem of having active sequencer for the same prefix
on two FLUS in the same VM
** TODO Fix all known bugs/cruft with Chain Manager (list below)
*** DONE Fix known bugs
*** DONE Clean up crufty TODO comments and other obvious cruft
*** TODO Re-add verification step of stable epochs, including inner projections!
*** TODO Attempt to remove cruft items in flapping_i?
** TODO Move the FLU server to gen_server behavior?
* DONE Chain manager CP mode, Plan B
** SKIP Maybe? Change ch_mgr to use middleworker
**** DONE Is it worthwhile? Is the parallelism so important? No, probably.
**** SKIP Move middleworker func to utility module?
** DONE Add new proc to psup group
*** DONE Name: machi_fitness
** DONE ch_mgr keeps its current proc struct: i.e. same 1 proc as today
** NO chmgr asks hosed mgr for hosed list @ start of react_to_env
** DONE For all hosed, do *async*: try to read latest proj.
*** NO If OK, inform hosed mgr: status change will be used by next HC iter.
*** NO If fail, no change, because that server is already known to be hosed
*** DONE For all non-hosed, continue as the chain manager code does today
*** DONE Any new errors are added to UpNodes/DownNodes tracking as used today
*** DONE At end of react loop, if UpNodes list differs, inform hosed mgr.
* DONE fitness_mon, the fitness monitor
** DONE Map key & val sketch
Logical sketch:
Map key: ObservingServerName::atom()
Map val: { ObservingServerLastModTime::now(),
UnfitList::list(ServerName::atom()),
AdminDownList::list(ServerName::atom()),
Props::proplist() }
Implementation sketch:
1. Use CRDT map.
2. If map key is not atom, then atom->string or atom->binary is fine.
3. For map value, is it possible CRDT LWW type?
** DONE Investigate riak_dt data structure definition, manipulating, etc.
** DONE Add dependency on riak_dt
** DONE Update is an entire dict from Observer O
*** DONE Merge my pending map + update map + my last mod time + my unfit list
*** DONE if merged /= pending:
**** DONE Schedule async tick (more)
Tick message contains list of servers with differing state as of this
instant in time... we want to avoid triggering decisions about
fitness/unfitness for other servers where we might have received less
than a full time period's worth of waiting.
**** DONE Spam merged map to All_list -- [Me]
**** DONE Set pending <- merged
*** DONE When we receive an async tick
**** DONE set active map <- pending map for all servers in ticks list
**** DONE Send ch_mgr a react_to_env tick trigger
*** DONE react_to_env tick trigger actions
**** DONE Filter active map to remove stale entries (i.e. no update in 1 hour)
**** DONE If time since last map spam is too long, spam our *pending* map
**** DONE Proceed with normal react processing, using *active* map for AllHosed!

View file

@ -1,15 +0,0 @@
### The auto-generated code of machi_pb.beam has some complaints, not fixed yet.
machi_pb.erl:0:
##################################################
######## Specific types #####################
##################################################
Unknown types:
basho_bench_config:get/2
machi_partition_simulator:get/1
hamcrest:matchspec/0
##################################################
######## Specific messages #####################
##################################################
machi_chain_manager1.erl:2473: The created fun has no local return
machi_chain_manager1.erl:2184: The pattern <_P1, P2, Else = {'expected_author2', UPI1_tail, _}> can never match the type <#projection_v1{epoch_number::'undefined' | non_neg_integer(),epoch_csum::'undefined' | binary(),author_server::atom(),chain_name::atom(),all_members::'undefined' | [atom()],witnesses::[atom()],creation_time::'undefined' | {non_neg_integer(),non_neg_integer(),non_neg_integer()},mode::'ap_mode' | 'cp_mode',upi::'undefined' | [atom()],repairing::'undefined' | [atom()],down::'undefined' | [atom()],dbg::'undefined' | [any()],dbg2::'undefined' | [any()],members_dict::'undefined' | [{_,_}]},#projection_v1{epoch_number::'undefined' | non_neg_integer(),epoch_csum::binary(),author_server::atom(),chain_name::atom(),all_members::'undefined' | [atom()],witnesses::[atom()],creation_time::'undefined' | {non_neg_integer(),non_neg_integer(),non_neg_integer()},mode::'ap_mode' | 'cp_mode',upi::'undefined' | [atom()],repairing::'undefined' | [atom()],down::'undefined' | [atom()],dbg::'undefined' | [any()],dbg2::'undefined' | [any()],members_dict::'undefined' | [{_,_}]},'true'>
machi_chain_manager1.erl:2233: The pattern <_P1 = {'projection_v1', _, _, _, _, _, _, _, 'cp_mode', UPI1, Repairing1, _, _, _, _}, _P2 = {'projection_v1', _, _, _, _, _, _, _, 'cp_mode', UPI2, Repairing2, _, _, _, _}, Else = {'epoch_not_si', EpochX, 'not_gt', EpochY}> can never match the type <#projection_v1{epoch_number::'undefined' | non_neg_integer(),epoch_csum::'undefined' | binary(),author_server::atom(),chain_name::atom(),all_members::'undefined' | [atom()],witnesses::[atom()],creation_time::'undefined' | {non_neg_integer(),non_neg_integer(),non_neg_integer()},mode::'ap_mode' | 'cp_mode',upi::'undefined' | [atom()],repairing::'undefined' | [atom()],down::'undefined' | [atom()],dbg::'undefined' | [any()],dbg2::'undefined' | [any()],members_dict::'undefined' | [{_,_}]},#projection_v1{epoch_number::'undefined' | non_neg_integer(),epoch_csum::binary(),author_server::atom(),chain_name::atom(),all_members::'undefined' | [atom()],witnesses::[atom()],creation_time::'undefined' | {non_neg_integer(),non_neg_integer(),non_neg_integer()},mode::'ap_mode' | 'cp_mode',upi::'undefined' | [atom()],repairing::'undefined' | [atom()],down::'undefined' | [atom()],dbg::'undefined' | [any()],dbg2::'undefined' | [any()],members_dict::'undefined' | [{_,_}]},'true'>

View file

@ -1,74 +0,0 @@
## Machi Documentation Overview
For a Web-browsable version of a snapshot of the source doc "EDoc"
Erlang documentation, please use this link:
[Machi EDoc snapshot](https://basho.github.io/machi/edoc/).
## Documents in this directory
### high-level-machi.pdf
[high-level-machi.pdf](high-level-machi.pdf)
is an overview of the high level design for
Machi. Its abstract:
> Our goal is a robust & reliable, distributed, highly available large
> file store based upon write-once registers, append-only files, Chain
> Replication, and client-server style architecture. All members of
> the cluster store all of the files. Distributed load
> balancing/sharding of files is outside of the scope of this system.
> However, it is a high priority that this system be able to integrate
> easily into systems that do provide distributed load balancing,
> e.g., Riak Core. Although strong consistency is a major feature of
> Chain Replication, this document will focus mainly on eventual
> consistency features --- strong consistency design will be discussed
> in a separate document.
### high-level-chain-mgr.pdf
[high-level-chain-mgr.pdf](high-level-chain-mgr.pdf)
is an overview of the techniques used by
Machi to manage Chain Replication metadata state. It also provides an
introduction to the Humming Consensus algorithm. Its abstract:
> Machi is an immutable file store, now in active development by Basho
> Japan KK. Machi uses Chain Replication to maintain strong consistency
> of file updates to all replica servers in a Machi cluster. Chain
> Replication is a variation of primary/backup replication where the
> order of updates between the primary server and each of the backup
> servers is strictly ordered into a single "chain". Management of
> Chain Replication's metadata, e.g., "What is the current order of
> servers in the chain?", remains an open research problem. The
> current state of the art for Chain Replication metadata management
> relies on an external oracle (e.g., ZooKeeper) or the Elastic
> Replication algorithm.
>
> This document describes the Machi chain manager, the component
> responsible for managing Chain Replication metadata state. The chain
> manager uses a new technique, based on a variation of CORFU, called
> "humming consensus".
> Humming consensus does not require active participation by all or even
> a majority of participants to make decisions. Machi's chain manager
> bases its logic on humming consensus to make decisions about how to
> react to changes in its environment, e.g. server crashes, network
> partitions, and changes by Machi cluster admnistrators. Once a
> decision is made during a virtual time epoch, humming consensus will
> eventually discover if other participants have made a different
> decision during that epoch. When a differing decision is discovered,
> new time epochs are proposed in which a new consensus is reached and
> disseminated to all available participants.
### chain-self-management-sketch.org
[chain-self-management-sketch.org](chain-self-management-sketch.org)
is a mostly-deprecated draft of
an introduction to the
self-management algorithm proposed for Machi. Most material has been
moved to the [high-level-chain-mgr.pdf](high-level-chain-mgr.pdf) document.
### cluster (directory)
This directory contains the sketch of the cluster design
strawman for partitioning/distributing/sharding files across a large
number of independent Machi chains.

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@ -1,258 +0,0 @@
# Using basho_bench to twiddle with Machi
"Twiddle"? Really, is that a word? (Yes, it is a real English word.)
## Benchmarking Machi's performance ... no, don't do it.
Machi isn't ready for benchmark testing. Its public-facing API isn't
finished yet. Its internal APIs aren't quite finished yet either. So
any results of "benchmarking" effort is something that has even less
value **N** months from now than the usual benchmarking effort.
However, there are uses for a benchmark tool. For example, one of my
favorites is to put **stress** on a system. I don't care about
average or 99th-percentile latencies, but I **might** care very much
about behavior.
* What happens if a Machi system is under moderate load, and then I
stop one of the servers? What happens?
* How quickly do the chain managers react?
* How quickly do the client libraries within Machi react?
* How quickly do the external client API libraries react?
* What happens if a Machi system is under heavy load, for example,
100% CPU load. Not all 100% might be the Machi services. Some CPU
consumption might be from the load generator, like `basho_bench`
itself that is running on the same machine as a Machi server. Or
perhaps it's a tiny C program that I wrote:
main()
{ while (1) { ; } }
## An example of how adding moderate stress can find weird bugs
The driver/plug-in module for `basho_bench` is only a few hours old.
(I'm writing on Wednesday, 2015-05-20.) But just now, I configured my
basho_bench config file to try to contact a Machi cluster of three
nodes ... but really, only one was running. The client library,
`machi_cr_client.erl`, has **an extremely simple** method for dealing
with failed servers. I know it's simple and dumb, but that's OK in
many cases.
However, `basho_bench` and the `machi_cr_client.erl` were acting very,
very badly. I couldn't figure it out until I took a peek at my OS's
`dmesg` output, namely: `dmesg | tail`. It said things like this:
Limiting closed port RST response from 690 to 50 packets per second
Limiting closed port RST response from 367 to 50 packets per second
Limiting closed port RST response from 101 to 50 packets per second
Limiting closed port RST response from 682 to 50 packets per second
Limiting closed port RST response from 467 to 50 packets per second
Well, isn't that interesting?
This system was running on a single OS X machine: my MacBook Pro
laptop, running OS X 10.10 (Yosemite). I have seen that error
before. And I know how to fix it.
* **Option 1**: Change the client library config to ignore the Machi
servers that I know will always be down during my experiment.
* ** Option 2**: Use the following to change my OS's TCP stack RST
behavior. (If a TCP port is not being listened to, the OS will
send a RST packet to signal "connection refused".)
On OS X, the limit for RST packets is 50/second. The
`machi_cr_client.erl` client can generate far more than 50/second, as
the `Limiting closed port RST response...` messages above show. So, I
used some brute-force to change the environment:
sudo sysctl -w net.inet.icmp.icmplim=20000
... and the problem disappeared.
## Starting with basho_bench: a step-by-step tutorial
First, clone the `basho_bench` source code, then compile it. You will
need Erlang/OTP version R16B or later to compile. I recommend using
Erlang/OTP 17.x, because I've been doing my Machi development using
17.x.
cd /some/nice/dev/place
git clone https://github.com/basho/basho_bench.git
cd basho_bench
make
In order to create graphs of `basho_bench` output, you'll need
installed one of the following:
* R (the statistics package)
* gnuplot
If you don't have either available on the machine(s) you're testing,
but you do have R (or gnuplot) on some other machine **Y**, then you can
copy the output files to machine **Y** and generate the graphs there.
## Compiling the Machi source
First, clone the Machi source code, then compile it. You will
need Erlang/OTP version 17.x to compile.
cd /some/nice/dev/place
git clone https://github.com/basho/machi.git
cd machi
make
## Creating a basho_bench test configuration file.
There are a couple of example `basho_bench` configuration files in the
Machi `priv` directory.
* [basho_bench.append-example.config](priv/basho_bench.append-example.config),
an example for writing Machi files.
* [basho_bench.read-example.config](priv/basho_bench.read-example.config),
an example for reading Machi files.
If you want a test to do both reading & writing ... well, the
driver/plug-in is not mature enough to do it **well**. If you really
want to, refer to the `basho_bench` docs for how to use the
`operations` config option.
The `basho_bench` config file is configured in Erlang term format.
Each configuration item is a 2-tuple followed by a period. Comments
begin with a `%` character and continue to the end-of-line.
%% Mandatory: adjust this code path to top of your compiled Machi source distro
{code_paths, ["/Users/fritchie/b/src/machi"]}.
{driver, machi_basho_bench_driver}.
%% Chose your maximum rate (per worker proc, see 'concurrent' below)
{mode, {rate, 25}}.
%% Runtime & reporting interval
{duration, 10}. % minutes
{report_interval, 1}. % seconds
%% Choose your number of worker procs
{concurrent, 5}.
%% Here's a chain of (up to) length 3, all on localhost
{machi_server_info,
[
{p_srvr,a,machi_flu1_client,"localhost",4444,[]},
{p_srvr,b,machi_flu1_client,"localhost",4445,[]},
{p_srvr,c,machi_flu1_client,"localhost",4446,[]}
]}.
{machi_ets_key_tab_type, set}. % 'set' or 'ordered_set'
%% Workload-specific definitions follow....
%% 10 parts 'append' operation + 0 parts anything else = 100% 'append' ops
{operations, [{append, 10}]}.
%% For append, key = Machi file prefix name
{key_generator, {concat_binary, <<"prefix">>,
{to_binstr, "~w", {uniform_int, 30}}}}.
%% Increase size of value_generator_source_size if value_generator is big!!
{value_generator_source_size, 2111000}.
{value_generator, {fixed_bin, 32768}}. % 32 KB
In summary:
* Yes, you really need to change `code_paths` to be the same as your
`/some/nice/dev/place/basho_bench` directory ... and that directory
must be on the same machine(s) that you intend to run `basho_bench`.
* Each worker process will have a rate limit of 25 ops/sec.
* The test will run for 10 minutes and report stats every 1 second.
* There are 5 concurrent worker processes. Each worker will
concurrently issue commands from the `operations` list, within the
workload throttle limit.
* The Machi cluster is a collection of three servers, all on
"localhost", and using TCP ports 4444-4446.
* Don't change the `machi_ets_key_tab_type`
* Our workload operation mix is 100% `append` operations.
* The key generator for the `append` operation specifies the file
prefix that will be chosen (at pseudo-random). In this case, we'll
choose uniformly randomly between file prefix `prefix0` and
`prefix29`.
* The values that we append will be fixed 32KB length, but they will
be chosen from a random byte string of 2,111,000 bytes.
There are many other options for `basho_bench`, especially for the
`key_generator` and `value_generator` options. Please see the
`basho_bench` docs for further information.
## Running basho_bench
You can run `basho_bench` using the command:
/some/nice/dev/place/basho_bench/basho_bench /path/to/config/file
... where `/path/to/config/file` is the path to your config file. (If
you use an example from the `priv` dir, we recommend that you make a
copy elsewhere, edit the copy, and then use the copy to run
`basho_bench`.)
You'll create a stats output directory, called `tests`, in the current
working directory. (Add `{results_dir, "/some/output/dir"}.` to change
the default!)
Each time `basho_bench` is run, a new output stats directory is
created in the `tests` directory. The symbolic link `tests/current`
will always point to the last `basho_bench` run's output. But all
prior results are always accessible! Take a look in this directory
for all of the output.
## Generating some pretty graphs
If you are using R, then the following command will create a graph:
Rscript --vanilla /some/nice/dev/place/basho_bench/basho_bench/priv/summary.r -i $CWD/tests/current
If the `tests` directory is not in your current working dir (i.e. not
in `$CWD`), then please alter the command accordingly.
R will create the final results graph in `$CWD/tests/current/summary.png`.
If you are using gnuplot, please look at
`/some/nice/dev/place/basho_bench/basho_bench/Makefile` to see how to
use gnuplot to create the final results graph.
## An example graph
So, without a lot of context about the **Machi system** or about the
**basho_bench system** or about the ops being performed, here is an
example graph that was created by R:
![](https://basho.github.io/machi/images/basho_bench.example0.png)
**Without context??* How do I remember the context?
My recommendation is: always keep the `.config` file together with the
graph file. In the `tests` directory, `basho_bench` will always make
a copy of the config file used to generate the test data.
This config tells you very little about the environment of the load
generator machine or the Machi cluster, but ... you need to maintain
that documentation yourself, please! You'll thank me for that advice,
someday, 11 months from now when you can't remember the details of
that important test that you ran so very long ago.
## Conclusion
Really, we don't recommend using `basho_bench` for any serious
performance measurement of Machi yet: Machi needs more maturity before
it's reasonable to measure & judge its performance. But stress
testing is indeed useful for reasons other than measuring
Nth-percentile latency of operation `flarfbnitz`. We hope that this
tutorial has been helpful!
If you encounter any difficulty with this tutorial or with Machi,
please open an issue/ticket at [GH Issues for
Machi](https://github.com/basho/machi/issues) ... use the green "New
issue" button. There are bugs and misfeatures in the `basho_bench`
plugin, sorry, but please help us fix them.
> -Scott Lystig Fritchie,
> Machi Team @ Basho

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@ -4,11 +4,21 @@
#+STARTUP: lognotedone hidestars indent showall inlineimages
#+SEQ_TODO: TODO WORKING WAITING DONE
* 1. Abstract
The high level design of the Machi "chain manager" has moved to the
[[high-level-chain-manager.pdf][Machi chain manager high level design]] document.
* Abstract
Yo, this is the first draft of a document that attempts to describe a
proposed self-management algorithm for Machi's chain replication.
Welcome! Sit back and enjoy the disjointed prose.
We try to discuss the network partition simulator that the
We attempt to describe first the self-management and self-reliance
goals of the algorithm. Then we make a side trip to talk about
write-once registers and how they're used by Machi, but we don't
really fully explain exactly why write-once is so critical (why not
general purpose registers?) ... but they are indeed critical. Then we
sketch the algorithm by providing detailed annotation of a flowchart,
then let the flowchart speak for itself, because writing good prose is
prose is damn hard, but flowcharts are very specific and concise.
Finally, we try to discuss the network partition simulator that the
algorithm runs in and how the algorithm behaves in both symmetric and
asymmetric network partition scenarios. The symmetric partition cases
are all working well (surprising in a good way), and the asymmetric
@ -16,9 +26,7 @@ partition cases are working well (in a damn mystifying kind of way).
It'd be really, *really* great to get more review of the algorithm and
the simulator.
* 2. Copyright
#+BEGIN_SRC
* Copyright
%% Copyright (c) 2015 Basho Technologies, Inc. All Rights Reserved.
%%
%% This file is provided to you under the Apache License,
@ -34,38 +42,442 @@ the simulator.
%% KIND, either express or implied. See the License for the
%% specific language governing permissions and limitations
%% under the License.
* TODO Naming: possible ideas
** Humming consensus?
See [[https://tools.ietf.org/html/rfc7282][On Consensus and Humming in the IETF]], RFC 7282.
** Tunesmith?
A mix of orchestral conducting, music composition, humming?
** Foggy consensus?
CORFU-like consensus between mist-shrouded islands of network
partitions
** Rough consensus
This is my favorite, but it might be too close to handwavy/vagueness
of English language, even with a precise definition and proof
sketching?
** Let the bikeshed continue!
I agree with Chris: there may already be a definition that's close
enough to "rough consensus" to continue using that existing tag than
to invent a new one. TODO: more research required
* What does "self-management" mean in this context?
For the purposes of this document, chain replication self-management
is the ability for the N nodes in an N-length chain replication chain
to manage the state of the chain without requiring an external party
to participate. Chain state includes:
1. Preserve data integrity of all data stored within the chain. Data
loss is not an option.
2. Stably preserve knowledge of chain membership (i.e. all nodes in
the chain, regardless of operational status). A systems
administrators is expected to make "permanent" decisions about
chain membership.
3. Use passive and/or active techniques to track operational
state/status, e.g., up, down, restarting, full data sync, partial
data sync, etc.
4. Choose the run-time replica ordering/state of the chain, based on
current member status and past operational history. All chain
state transitions must be done safely and without data loss or
corruption.
5. As a new node is added to the chain administratively or old node is
restarted, add the node to the chain safely and perform any data
synchronization/"repair" required to bring the node's data into
full synchronization with the other nodes.
* Goals
** Better than state-of-the-art: Chain Replication self-management
We hope/believe that this new self-management algorithem can improve
the current state-of-the-art by eliminating all external management
entities. Current state-of-the-art for management of chain
replication chains is discussed below, to provide historical context.
*** "Leveraging Sharding in the Design of Scalable Replication Protocols" by Abu-Libdeh, van Renesse, and Vigfusson.
Multiple chains are arranged in a ring (called a "band" in the paper).
The responsibility for managing the chain at position N is delegated
to chain N-1. As long as at least one chain is running, that is
sufficient to start/bootstrap the next chain, and so on until all
chains are running. (The paper then estimates mean-time-to-failure
(MTTF) and suggests a "band of bands" topology to handle very large
clusters while maintaining an MTTF that is as good or better than
other management techniques.)
If the chain self-management method proposed for Machi does not
succeed, this paper's technique is our best fallback recommendation.
*** An external management oracle, implemented by ZooKeeper
This is not a recommendation for Machi: we wish to avoid using ZooKeeper.
However, many other open and closed source software products use
ZooKeeper for exactly this kind of data replica management problem.
*** An external management oracle, implemented by Riak Ensemble
This is a much more palatable choice than option #2 above. We also
wish to avoid an external dependency on something as big as Riak
Ensemble. However, if it comes between choosing Riak Ensemble or
choosing ZooKeeper, the choice feels quite clear: Riak Ensemble will
win, unless there is some critical feature missing from Riak
Ensemble. If such an unforseen missing feature is discovered, it
would probably be preferable to add the feature to Riak Ensemble
rather than to use ZooKeeper (and document it and provide product
support for it and so on...).
** Support both eventually consistent & strongly consistent modes of operation
Machi's first use case is for Riak CS, as an eventually consistent
store for CS's "block" storage. Today, Riak KV is used for "block"
storage. Riak KV is an AP-style key-value store; using Machi in an
AP-style mode would match CS's current behavior from points of view of
both code/execution and human administrator exectations.
Later, we wish the option of using CP support to replace other data
store services that Riak KV provides today. (Scope and timing of such
replacement TBD.)
We believe this algorithm allows a Machi cluster to fragment into
arbitrary islands of network partition, all the way down to 100% of
members running in complete network isolation from each other.
Furthermore, it provides enough agreement to allow
formerly-partitioned members to coordinate the reintegration &
reconciliation of their data when partitions are healed.
** Preserve data integrity of Chain Replicated data
While listed last in this section, preservation of data integrity is
paramount to any chain state management technique for Machi.
** Anti-goal: minimize churn
This algorithm's focus is data safety and not availability. If
participants have differing notions of time, e.g., running on
extremely fast or extremely slow hardware, then this algorithm will
"churn" in different states where the chain's data would be
effectively unavailable.
In practice, however, any series of network partition changes that
case this algorithm to churn will cause other management techniques
(such as an external "oracle") similar problems. [Proof by handwaving
assertion.] See also: "time model" assumptions (below).
* Assumptions
** Introduction to assumptions, why they differ from other consensus algorithms
Given a long history of consensus algorithms (viewstamped replication,
Paxos, Raft, et al.), why bother with a slightly different set of
assumptions and a slightly different protocol?
The answer lies in one of our explicit goals: to have an option of
running in an "eventually consistent" manner. We wish to be able to
make progress, i.e., remain available in the CAP sense, even if we are
partitioned down to a single isolated node. VR, Paxos, and Raft
alone are not sufficient to coordinate service availability at such
small scale.
** The CORFU protocol is correct
This work relies tremendously on the correctness of the CORFU
protocol, a cousin of the Paxos protocol. If the implementation of
this self-management protocol breaks an assumption or prerequisite of
CORFU, then we expect that the implementation will be flawed.
** Communication model: Asyncronous message passing
*** Unreliable network: messages may be arbitrarily dropped and/or reordered
**** Network partitions may occur at any time
**** Network partitions may be asymmetric: msg A->B is ok but B->A fails
*** Messages may be corrupted in-transit
**** Assume that message MAC/checksums are sufficient to detect corruption
**** Receiver informs sender of message corruption
**** Sender may resend, if/when desired
*** System particpants may be buggy but not actively malicious/Byzantine
** Time model: per-node clocks, loosely synchronized (e.g. NTP)
The protocol & algorithm presented here do not specify or require any
timestamps, physical or logical. Any mention of time inside of data
structures are for human/historic/diagnostic purposes only.
Having said that, some notion of physical time is suggested for
purposes of efficiency. It's recommended that there be some "sleep
time" between iterations of the algorithm: there is no need to "busy
wait" by executing the algorithm as quickly as possible. See below,
"sleep intervals between executions".
** Failure detector model: weak, fallible, boolean
We assume that the failure detector that the algorithm uses is weak,
it's fallible, and it informs the algorithm in boolean status
updates/toggles as a node becomes available or not.
If the failure detector is fallible and tells us a mistaken status
change, then the algorithm will "churn" the operational state of the
chain, e.g. by removing the failed node from the chain or adding a
(re)started node (that may not be alive) to the end of the chain.
Such extra churn is regrettable and will cause periods of delay as the
"rough consensus" (decribed below) decision is made. However, the
churn cannot (we assert/believe) cause data loss.
** The "wedge state", as described by the Machi RFC & CORFU
A chain member enters "wedge state" when it receives information that
a newer projection (i.e., run-time chain state reconfiguration) is
available. The new projection may be created by a system
administrator or calculated by the self-management algorithm.
Notification may arrive via the projection store API or via the file
I/O API.
When in wedge state, the server/FLU will refuse all file write I/O API
requests until the self-management algorithm has determined that
"rough consensus" has been decided (see next bullet item). The server
may also refuse file read I/O API requests, depending on its CP/AP
operation mode.
See the Machi RFC for more detail of the wedge state and also the
CORFU papers.
** "Rough consensus": consensus built upon data that is *visible now*
CS literature uses the word "consensus" in the context of the problem
description at
[[http://en.wikipedia.org/wiki/Consensus_(computer_science)#Problem_description]].
This traditional definition differs from what is described in this
document.
The phrase "rough consensus" will be used to describe
consensus derived only from data that is visible/known at the current
time. This implies that a network partition may be in effect and that
not all chain members are reachable. The algorithm will calculate
"rough consensus" despite not having input from all/majority/minority
of chain members. "Rough consensus" may proceed to make a
decision based on data from only a single participant, i.e., the local
node alone.
When operating in AP mode, i.e., in eventual consistency mode, "rough
consensus" could mean that an chain of length N could split into N
independent chains of length 1. When a network partition heals, the
rough consensus is sufficient to manage the chain so that each
replica's data can be repaired/merged/reconciled safely.
(Other features of the Machi system are designed to assist such
repair safely.)
When operating in CP mode, i.e., in strong consistency mode, "rough
consensus" would require additional supplements. For example, any
chain that didn't have a minimum length of the quorum majority size of
all members would be invalid and therefore would not move itself out
of wedged state. In very general terms, this requirement for a quorum
majority of surviving participants is also a requirement for Paxos,
Raft, and ZAB.
(Aside: The Machi RFC also proposes using "witness" chain members to
make service more available, e.g. quorum majority of "real" plus
"witness" nodes *and* at least one member must be a "real" node. See
the Machi RFC for more details.)
** Heavy reliance on a key-value store that maps write-once registers
The projection store is implemented using "write-once registers"
inside a key-value store: for every key in the store, the value must
be either of:
- The special 'unwritten' value
- An application-specific binary blob that is immutable thereafter
* The projection store, built with write-once registers
- NOTE to the reader: The notion of "public" vs. "private" projection
stores does not appear in the Machi RFC.
Each participating chain node has its own "projection store", which is
a specialized key-value store. As a whole, a node's projection store
is implemented using two different key-value stores:
- A publicly-writable KV store of write-once registers
- A privately-writable KV store of write-once registers
Both stores may be read by any cluster member.
The store's key is a positive integer; the integer represents the
epoch number of the projection. The store's value is an opaque
binary blob whose meaning is meaningful only to the store's clients.
See the Machi RFC for more detail on projections and epoch numbers.
** The publicly-writable half of the projection store
The publicly-writable projection store is used to share information
during the first half of the self-management algorithm. Any chain
member may write a projection to this store.
** The privately-writable half of the projection store
The privately-writable projection store is used to store the "rough
consensus" result that has been calculated by the local node. Only
the local server/FLU may write values into this store.
The private projection store serves multiple purposes, including:
- remove/clear the local server from "wedge state"
- act as the store of record for chain state transitions
- communicate to remote nodes the past states and current operational
state of the local node
* Modification of CORFU-style epoch numbering and "wedge state" triggers
According to the CORFU research papers, if a server node N or client
node C believes that epoch E is the latest epoch, then any information
that N or C receives from any source that an epoch E+delta (where
delta > 0) exists will push N into the "wedge" state and C into a mode
of searching for the projection definition for the newest epoch.
In the algorithm sketch below, it should become clear that it's
possible to have a race where two nodes may attempt to make proposals
for a single epoch number. In the simplest case, assume a chain of
nodes A & B. Assume that a symmetric network partition between A & B
happens, and assume we're operating in AP/eventually consistent mode.
On A's network partitioned island, A can choose a UPI list of `[A]'.
Similarly B can choose a UPI list of `[B]'. Both might choose the
epoch for their proposal to be #42. Because each are separated by
network partition, neither can realize the conflict. However, when
the network partition heals, it can become obvious that there are
conflicting values for epoch #42 ... but if we use CORFU's protocol
design, which identifies the epoch identifier as an integer only, then
the integer 42 alone is not sufficient to discern the differences
between the two projections.
The proposal modifies all use of CORFU's projection identifier
to use the identifier below instead. (A later section of this
document presents a detailed example.)
#+BEGIN_SRC
{epoch #, hash of the entire projection (minus hash field itself)}
#+END_SRC
* Sketch of the self-management algorithm
** Introduction
See also, the diagram (((Diagram1.eps))), a flowchart of the
algorithm. The code is structured as a state machine where function
executing for the flowchart's state is named by the approximate
location of the state within the flowchart. The flowchart has three
columns:
* 3. Document restructuring
1. Column A: Any reason to change?
2. Column B: Do I act?
3. Column C: How do I act?
Much of the text previously appearing in this document has moved to the
[[high-level-chain-manager.pdf][Machi chain manager high level design]] document.
States in each column are numbered in increasing order, top-to-bottom.
* 4. Diagram of the self-management algorithm
** Flowchart notation
- Author: a function that returns the author of a projection, i.e.,
the node name of the server that proposed the projection.
** WARNING: This section is now deprecated
- Rank: assigns a numeric score to a projection. Rank is based on the
epoch number (higher wins), chain length (larger wins), number &
state of any repairing members of the chain (larger wins), and node
name of the author server (as a tie-breaking criteria).
The definitive text for this section has moved to the [[high-level-chain-manager.pdf][Machi chain
manager high level design]] document.
- E: the epoch number of a projection.
- UPI: "Update Propagation Invariant". The UPI part of the projection
is the ordered list of chain members where the UPI is preserved,
i.e., all UPI list members have their data fully synchronized
(except for updates in-process at the current instant in time).
- Repairing: the ordered list of nodes that are in "repair mode",
i.e., synchronizing their data with the UPI members of the chain.
- Down: the list of chain members believed to be down, from the
perspective of the author. This list may be constructed from
information from the failure detector and/or by status of recent
attempts to read/write to other nodes' public projection store(s).
- P_current: local node's projection that is actively used. By
definition, P_current is the latest projection (i.e. with largest
epoch #) in the local node's private projection store.
- P_newprop: the new projection proposal that is calculated locally,
based on local failure detector info & other data (e.g.,
success/failure status when reading from/writing to remote nodes'
projection stores).
- P_latest: this is the highest-ranked projection with the largest
single epoch # that has been read from all available public
projection stores, including the local node's public store.
- Unanimous: The P_latest projections are unanimous if they are
effectively identical. Minor differences such as creation time may
be ignored, but elements such as the UPI list must not be ignored.
NOTE: "unanimous" has nothing to do with the number of projections
compared, "unanimous" is *not* the same as a "quorum majority".
- P_current -> P_latest transition safe?: A predicate function to
check the sanity & safety of the transition from the local node's
P_current to the P_newprop, which must be unanimous at state C100.
- Stop state: one iteration of the self-management algorithm has
finished on the local node. The local node may execute a new
iteration at any time.
** Column A: Any reason to change?
*** A10: Set retry counter to 0
*** A20: Create a new proposed projection based on the current projection
*** A30: Read copies of the latest/largest epoch # from all nodes
*** A40: Decide if the local proposal P_newprop is "better" than P_latest
** Column B: Do I act?
*** B10: 1. Is the latest proposal unanimous for the largest epoch #?
*** B10: 2. Is the retry counter too big?
*** B10: 3. Is another node's proposal "ranked" equal or higher to mine?
** Column C: How to act?
*** C1xx: Save latest proposal to local private store, unwedge, stop.
*** C2xx: Ping author of latest to try again, then wait, then repeat alg.
*** C3xx: My new proposal appears best: write @ all public stores, repeat alg
** Flowchart notes
*** Algorithm execution rates / sleep intervals between executions
Due to the ranking algorithm's preference for author node names that
are large (lexicographically), nodes with larger node names should
are small (lexicographically), nodes with smaller node names should
execute the algorithm more frequently than other nodes. The reason
for this is to try to avoid churn: a proposal by a "small" node may
propose a UPI list of L at epoch 10, and a few moments later a "big"
for this is to try to avoid churn: a proposal by a "big" node may
propose a UPI list of L at epoch 10, and a few moments later a "small"
node may propose the same UPI list L at epoch 11. In this case, there
would be two chain state transitions: the epoch 11 projection would be
ranked higher than epoch 10's projection. If the "big" node
executed more frequently than the "small" node, then it's more likely
that epoch 10 would be written by the "big" node, which would then
cause the "small" node to stop at state A40 and avoid any
ranked higher than epoch 10's projeciton. If the "small" node
executed more frequently than the "big" node, then it's more likely
that epoch 10 would be written by the "small" node, which would then
cause the "big" node to stop at state A40 and avoid any
externally-visible action.
*** Transition safety checking
In state C100, the transition from P_current -> P_latest is checked
for safety and sanity. The conditions used for the check include:
1. The Erlang data types of all record members are correct.
2. UPI, down, & repairing lists contain no duplicates and are in fact
mutually disjoint.
3. The author node is not down (as far as we can tell).
4. Any additions in P_latest in the UPI list must appear in the tail
of the UPI list and were formerly in P_current's repairing list.
5. No re-ordering of the UPI list members: P_latest's UPI list prefix
must be exactly equal to P_current's UPI prefix, and any P_latest's
UPI list suffix must in the same order as they appeared in
P_current's repairing list.
The safety check may be performed pair-wise once or pair-wise across
the entire history sequence of a server/FLU's private projection
store.
*** A simple example race between two participants noting a 3rd's failure
Assume a chain of three nodes, A, B, and C. In a projection at epoch
@ -145,7 +557,7 @@ look like this:
| E+2 | UPI=[A,B] | UPI=[A,B] | UPI=[C] |
| | Repairing=[] | Repairing=[] | Repairing=[] |
| | Down=[C] | Down=[C] | Down=[A,B] |
| | Author=A | Author=A | Author=C |
| | Author=A | Author=A | |
|-----+--------------+--------------+--------------|
Now we're in a pickle where a client C could read the latest
@ -164,7 +576,7 @@ use of quorum majority for UPI members is out of scope of this
document. Also out of scope is the use of "witness servers" to
augment the quorum majority UPI scheme.)
* 5. The Network Partition Simulator
* The Simulator
** Overview
The function machi_chain_manager1_test:convergence_demo_test()
executes the following in a simulated network environment within a
@ -210,42 +622,51 @@ self-management algorithm and verify its correctness.
** Behavior in asymmetric network partitions
Text has moved to the [[high-level-chain-manager.pdf][Machi chain manager high level design]] document.
The simulator's behavior during stable periods where at least one node
is the victim of an asymmetric network partition is ... weird,
wonderful, and something I don't completely understand yet. This is
another place where we need more eyes reviewing and trying to poke
holes in the algorithm.
* Prototype notes
In cases where any node is a victim of an asymmetric network
partition, the algorithm oscillates in a very predictable way: each
node X makes the same P_newprop projection at epoch E that X made
during a previous recent epoch E-delta (where delta is small, usually
much less than 10). However, at least one node makes a proposal that
makes unanimous results impossible. When any epoch E is not
unanimous, the result is one or more new rounds of proposals.
However, because any node N's proposal doesn't change, the system
spirals into an infinite loop of never-fully-unanimous proposals.
** Mid-April 2015
From the sole perspective of any single participant node, the pattern
of this infinite loop is easy to detect. When detected, the local
node moves to a slightly different mode of operation: it starts
suspecting that a "proposal flapping" series of events is happening.
(The name "flap" is taken from IP network routing, where a "flapping
route" is an oscillating state of churn within the routing fabric
where one or more routes change, usually in a rapid & very disruptive
manner.)
I've finished moving the chain manager plus the inner/nested
projection code into the top-level 'src' dir of this repo. The idea
is working very well under simulation, more than well enough to gamble
on for initial use.
If flapping is suspected, then the count of number of flap cycles is
counted. If the local node sees all participants (including itself)
flappign with the same relative proposed projection for 5 times in a
row, then the local node has firm evidence that there is an asymmetric
network partition somewhere in the system. The pattern of proposals
is analyzed, and the local node makes a decision:
Stronger validation work will continue through 2015, ideally using a
tool like TLA+.
1. The local node is directly affected by the network partition. The
result: stop making new projection proposals until the failure
detector belives that a new status change has taken place.
** Mid-March 2015
2. The local node is not directly affected by the network partition.
The result: continue participating in the system by continuing new
self-management algorithm iterations.
I've come to realize that the property that causes the nice property
of "Were my last 2L proposals identical?" also requires that the
proposals be *stable*. If a participant notices, "Hey, there's
flapping happening, so I'll propose a different projection
P_different", then the very act of proposing P_different disrupts the
"last 2L proposals identical" cycle the enables us to detect
flapping. We kill the goose that's laying our golden egg.
After the asymmetric partition victims have "taken themselves out of
the game" temporarily, then the remaining participants rapidly
converge to rough consensus and then a visibly unanimous proposal.
For as long as the network remains partitioned but stable, any new
iteration of the self-management algorithm stops without
externally-visible effects. (I.e., it stops at the bottom of the
flowchart's Column A.)
I've been working on the idea of "nested" projections, namely an
"outer" and "inner" projection. Only the "outer projection" is used
for cycle detection. The "inner projection" is the same as the outer
projection when flapping is not detected. When flapping is detected,
then the inner projection is one that excludes all nodes that the
outer projection has identified as victims of asymmetric partition.
This inner projection technique may or may not work well enough to
use? It would require constant flapping of the outer proposal, which
is going to consume CPU and also chew up projection store keys with
the flapping churn. That churn would continue as long as an
asymmetric partition exists. The simplest way to cope with this would
be to reduce proposal rates significantly, say 10x or 50x slower, to
slow churn down to proposals from several-per-second to perhaps
several-per-minute?

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@ -1,103 +0,0 @@
#FIG 3.2 Produced by xfig version 3.2.5b
Landscape
Center
Inches
Letter
94.00
Single
-2
1200 2
6 7425 2700 8700 3300
4 0 0 50 -1 2 18 0.0000 4 195 645 7425 2895 After\001
4 0 0 50 -1 2 18 0.0000 4 255 1215 7425 3210 Migration\001
-6
6 7425 450 8700 1050
4 0 0 50 -1 2 18 0.0000 4 195 780 7425 675 Before\001
4 0 0 50 -1 2 18 0.0000 4 255 1215 7425 990 Migration\001
-6
6 75 1425 6900 2325
6 4875 1425 6900 2325
6 5400 1575 6375 2175
4 0 0 50 -1 2 14 0.0000 4 165 390 5400 1800 Not\001
4 0 0 50 -1 2 14 0.0000 4 225 945 5400 2100 migrated\001
-6
2 2 1 2 0 7 50 -1 -1 6.000 0 0 -1 0 0 5
4950 1500 6825 1500 6825 2250 4950 2250 4950 1500
-6
6 2475 1425 4500 2325
6 3000 1575 3975 2175
4 0 0 50 -1 2 14 0.0000 4 165 390 3000 1800 Not\001
4 0 0 50 -1 2 14 0.0000 4 225 945 3000 2100 migrated\001
-6
2 2 1 2 0 7 50 -1 -1 6.000 0 0 -1 0 0 5
2550 1500 4425 1500 4425 2250 2550 2250 2550 1500
-6
6 75 1425 2100 2325
6 600 1575 1575 2175
4 0 0 50 -1 2 14 0.0000 4 165 390 600 1800 Not\001
4 0 0 50 -1 2 14 0.0000 4 225 945 600 2100 migrated\001
-6
2 2 1 2 0 7 50 -1 -1 6.000 0 0 -1 0 0 5
150 1500 2025 1500 2025 2250 150 2250 150 1500
-6
-6
2 1 0 2 0 7 50 -1 -1 6.000 0 0 -1 1 0 2
1 1 3.00 60.00 120.00
150 4200 150 3750
2 1 0 2 0 7 50 -1 -1 6.000 0 0 -1 1 0 2
1 1 3.00 60.00 120.00
3750 4200 3750 3750
2 1 0 2 0 7 50 -1 -1 6.000 0 0 -1 1 0 2
1 1 3.00 60.00 120.00
2025 4200 2025 3750
2 1 0 2 0 7 50 -1 -1 6.000 0 0 -1 1 0 2
1 1 3.00 60.00 120.00
7350 4200 7350 3750
2 1 0 2 0 7 50 -1 -1 6.000 0 0 -1 1 0 2
1 1 3.00 60.00 120.00
5550 4200 5550 3750
2 2 0 3 0 7 50 -1 -1 0.000 0 0 -1 0 0 5
2550 0 2550 1500 150 1500 150 0 2550 0
2 2 0 3 0 7 50 -1 -1 0.000 0 0 -1 0 0 5
4950 0 4950 1500 2550 1500 2550 0 4950 0
2 2 0 3 0 7 50 -1 -1 0.000 0 0 -1 0 0 5
7350 0 7350 1500 4950 1500 4950 0 7350 0
2 2 0 3 0 7 50 -1 -1 0.000 0 0 -1 0 0 5
150 2250 2025 2250 2025 3750 150 3750 150 2250
2 2 0 3 0 7 50 -1 -1 0.000 0 0 -1 0 0 5
4425 2250 4950 2250 4950 3750 4425 3750 4425 2250
2 2 0 3 0 7 50 -1 -1 0.000 0 0 -1 0 0 5
4950 2250 6825 2250 6825 3750 4950 3750 4950 2250
2 2 0 3 0 7 50 -1 -1 0.000 0 0 -1 0 0 5
6825 2250 7350 2250 7350 3750 6825 3750 6825 2250
2 2 0 3 0 7 50 -1 -1 0.000 0 0 -1 0 0 5
2025 2250 2550 2250 2550 3750 2025 3750 2025 2250
2 2 0 3 0 7 50 -1 -1 0.000 0 0 -1 0 0 5
2550 2250 4425 2250 4425 3750 2550 3750 2550 2250
4 0 0 50 -1 2 18 0.0000 4 195 480 75 4500 0.00\001
4 0 0 50 -1 2 18 0.0000 4 195 480 6825 4500 1.00\001
4 0 0 50 -1 2 18 0.0000 4 195 480 1725 4500 0.25\001
4 0 0 50 -1 2 18 0.0000 4 195 480 3525 4500 0.50\001
4 0 0 50 -1 2 18 0.0000 4 195 480 5250 4500 0.75\001
4 0 0 50 -1 2 14 0.0000 4 240 1710 450 1275 ~33% total keys\001
4 0 0 50 -1 2 14 0.0000 4 240 1710 2925 1275 ~33% total keys\001
4 0 0 50 -1 2 14 0.0000 4 240 1710 5250 1275 ~33% total keys\001
4 0 0 50 -1 2 14 0.0000 4 180 495 2025 3525 ~8%\001
4 0 0 50 -1 2 14 0.0000 4 240 1710 300 3525 ~25% total keys\001
4 0 0 50 -1 2 14 0.0000 4 240 1710 2625 3525 ~25% total keys\001
4 0 0 50 -1 2 14 0.0000 4 180 495 4425 3525 ~8%\001
4 0 0 50 -1 2 14 0.0000 4 240 1710 5025 3525 ~25% total keys\001
4 0 0 50 -1 2 14 0.0000 4 180 495 6825 3525 ~8%\001
4 0 0 50 -1 2 24 0.0000 4 270 195 2175 3075 4\001
4 0 0 50 -1 2 24 0.0000 4 270 195 4575 3075 4\001
4 0 0 50 -1 2 24 0.0000 4 270 195 6975 3075 4\001
4 0 0 50 -1 2 24 0.0000 4 270 1245 600 600 Chain1\001
4 0 0 50 -1 2 24 0.0000 4 270 1245 3000 600 Chain2\001
4 0 0 50 -1 2 24 0.0000 4 270 1245 5400 600 Chain3\001
4 0 0 50 -1 2 24 0.0000 4 270 285 2100 2625 C\001
4 0 0 50 -1 2 24 0.0000 4 270 285 4500 2625 C\001
4 0 0 50 -1 2 24 0.0000 4 270 285 6900 2625 C\001
4 0 0 50 -1 2 24 0.0000 4 270 1245 525 2850 Chain1\001
4 0 0 50 -1 2 24 0.0000 4 270 1245 2925 2850 Chain2\001
4 0 0 50 -1 2 24 0.0000 4 270 1245 5325 2850 Chain3\001
4 0 0 50 -1 2 18 0.0000 4 240 4350 1350 4875 Cluster locator, on the unit interval\001

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-*- mode: org; -*-
#+TITLE: Machi cluster "name game" sketch
#+AUTHOR: Scott
#+STARTUP: lognotedone hidestars indent showall inlineimages
#+SEQ_TODO: TODO WORKING WAITING DONE
#+COMMENT: M-x visual-line-mode
#+COMMENT: Also, disable auto-fill-mode
* 1. "Name Games" with random-slicing style consistent hashing
Our goal: to distribute lots of files very evenly across a large
collection of individual, small Machi chains.
* 2. Assumptions
** Basic familiarity with Machi high level design and Machi's "projection"
The [[https://github.com/basho/machi/blob/master/doc/high-level-machi.pdf][Machi high level design document]] contains all of the basic
background assumed by the rest of this document.
** Analogy: "neighborhood : city :: Machi chain : Machi cluster"
Analogy: The word "machi" in Japanese means small town or
neighborhood. As the Tokyo Metropolitan Area is built from many
machis and smaller cities, therefore a big, partitioned file store can
be built out of many small Machi chains.
** Familiarity with the Machi chain concept
It's clear (I hope!) from
the [[https://github.com/basho/machi/blob/master/doc/high-level-machi.pdf][Machi high level design document]] that Machi alone does not support
any kind of file partitioning/distribution/sharding across multiple
small Machi chains. There must be another layer above a Machi chain to
provide such partitioning services.
Using the [[https://github.com/basho/machi/tree/master/prototype/demo-day-hack][cluster quick-and-dirty prototype]] as an
architecture sketch, let's now assume that we have ~n~ independent Machi
chains. We assume that each of these chains has the same
chain length in the nominal case, e.g. chain length of 3.
We wish to provide partitioned/distributed file storage
across all ~n~ chains. We call the entire collection of ~n~ Machi
chains a "cluster".
We may wish to have several types of Machi clusters. For example:
+ Chain length of 1 for "don't care if it gets lost,
store stuff very very cheaply" data.
+ Chain length of 2 for normal data.
+ Equivalent to quorum replication's reliability with 3 copies.
+ Chain length of 7 for critical, unreplaceable data.
+ Equivalent to quorum replication's reliability with 15 copies.
Each of these types of chains will have a name ~N~ in the
namespace. The role of the cluster namespace will be demonstrated in
Section 3 below.
** Continue an early assumption: a Machi chain is unaware of clustering
Let's continue with an assumption that an individual Machi chain
inside of a cluster is completely unaware of the cluster layer.
** The reader is familiar with the random slicing technique
I'd done something very-very-nearly-like-this for the Hibari database
6 years ago. But the Hibari technique was based on stuff I did at
Sendmail, Inc, in 2000, so this technique feels like old news to me.
{shrug}
The following section provides an illustrated example.
Very quickly, the random slicing algorithm is:
- Hash a string onto the unit interval [0.0, 1.0)
- Calculate h(unit interval point, Map) -> bin, where ~Map~ divides
the unit interval into bins (or partitions or shards).
Machi's adaptation is in step 1: we do not hash any strings. Instead, we
simply choose a number on the unit interval. This number is called
the "cluster locator number".
As described later in this doc, Machi file names are structured into
several components. One component of the file name contains the cluster
locator number; we use the number as-is for step 2 above.
*** For more information about Random Slicing
For a comprehensive description of random slicing, please see the
first two papers. For a quicker summary, please see the third
reference.
#+BEGIN_QUOTE
Reliable and Randomized Data Distribution Strategies for Large Scale Storage Systems
Alberto Miranda et al.
http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.226.5609
(short version, HIPC'11)
Random Slicing: Efficient and Scalable Data Placement for Large-Scale
Storage Systems
Alberto Miranda et al.
DOI: http://dx.doi.org/10.1145/2632230 (long version, ACM Transactions
on Storage, Vol. 10, No. 3, Article 9, 2014)
[[http://hibari.github.io/hibari-doc/hibari-sysadmin-guide.en.html#chain-migration][Hibari Sysadmin Guide, chain migration section]].
http://hibari.github.io/hibari-doc/hibari-sysadmin-guide.en.html#chain-migration
#+END_QUOTE
* 3. A simple illustration
We use a variation of the Random Slicing hash that we will call
~rs_hash_with_float()~. The Erlang-style function type is shown
below.
#+BEGIN_SRC erlang
%% type specs, Erlang-style
-spec rs_hash_with_float(float(), rs_hash:map()) -> rs_hash:chain_id().
#+END_SRC
I'm borrowing an illustration from the HibariDB documentation here,
but it fits my purposes quite well. (I am the original creator of that
image, and also the use license is compatible.)
#+CAPTION: Illustration of 'Map', using four Machi chains
[[./migration-4.png]]
Assume that we have a random slicing map called ~Map~. This particular
~Map~ maps the unit interval onto 4 Machi chains:
| Hash range | Chain ID |
|-------------+----------|
| 0.00 - 0.25 | Chain1 |
| 0.25 - 0.33 | Chain4 |
| 0.33 - 0.58 | Chain2 |
| 0.58 - 0.66 | Chain4 |
| 0.66 - 0.91 | Chain3 |
| 0.91 - 1.00 | Chain4 |
Assume that the system chooses a cluster locator of 0.05.
According to ~Map~, the value of
~rs_hash_with_float(0.05,Map) = Chain1~.
Similarly, ~rs_hash_with_float(0.26,Map) = Chain4~.
This example should look very similar to Hibari's technique.
The Hibari documentation has a brief photo illustration of how random
slicing works, see [[http://hibari.github.io/hibari-doc/hibari-sysadmin-guide.en.html#chain-migration][Hibari Sysadmin Guide, chain migration]].
* 4. Use of the cluster namespace: name separation plus chain type
Let us assume that the cluster framework provides several different types
of chains:
| Chain length | Namespace | Consistency Mode | Comment |
|--------------+--------------+------------------+----------------------------------|
| 3 | ~normal~ | eventual | Normal storage redundancy & cost |
| 2 | ~reduced~ | eventual | Reduced cost storage |
| 1 | ~risky~ | eventual | Really, really cheap storage |
| 7 | ~paranoid~ | eventual | Safety-critical storage |
| 3 | ~sequential~ | strong | Strong consistency |
|--------------+--------------+------------------+----------------------------------|
The client may want to choose the amount of redundancy that its
application requires: normal, reduced cost, or perhaps even a single
copy. The cluster namespace is used by the client to signal this
intention.
Further, the cluster administrators may wish to use the namespace to
provide separate storage for different applications. Jane's
application may use the namespace "jane-normal" and Bob's app uses
"bob-reduced". Administrators may definine separate groups of
chains on separate servers to serve these two applications.
* 5. In its lifetime, a file may be moved to different chains
The cluster management scheme may decide that files need to migrate to
other chains -- i.e., file that is initially created on chain ID ~X~
has been moved to chain ID ~Y~.
+ For storage load or I/O load balancing reasons.
+ Because a chain is being decommissioned by the sysadmin.
* 6. Floating point is not required ... it is merely convenient for explanation
NOTE: Use of floating point terms is not required. For example,
integer arithmetic could be used, if using a sufficiently large
interval to create an even & smooth distribution of hashes across the
expected maximum number of chains.
For example, if the maximum cluster size would be 4,000 individual
Machi chains, then a minimum of 12 bits of integer space is required
to assign one integer per Machi chain. However, for load balancing
purposes, a finer grain of (for example) 100 integers per Machi
chain would permit file migration to move increments of
approximately 1% of single Machi chain's storage capacity. A
minimum of 12+7=19 bits of hash space would be necessary to accommodate
these constraints.
It is likely that Machi's final implementation will choose a 24 bit
integer (or perhaps 32 bits) to represent the cluster locator.
* 7. Proposal: Break the opacity of Machi file names, slightly.
Machi assigns file names based on:
~ClientSuppliedPrefix ++ "^" ++ SomeOpaqueFileNameSuffix~
What if some parts of the system could peek inside of the opaque file name
suffix in order to look at the cluster location information that we might
code in the filename suffix?
We break the system into parts that speak two levels of protocols,
"high" and "low".
+ The high level protocol is used outside of the Machi cluster
+ The low level protocol is used inside of the Machi cluster
Both protocols are based on a Protocol Buffers specification and
implementation. Other protocols, such as HTTP, will be added later.
#+BEGIN_SRC
+-----------------------+
| Machi external client |
| e.g. Riak CS |
+-----------------------+
^
| Machi "high" API
| ProtoBuffs protocol Machi cluster boundary: outside
.........................................................................
| Machi cluster boundary: inside
v
+--------------------------+ +------------------------+
| Machi "high" API service | | Machi HTTP API service |
+--------------------------+ +------------------------+
^ |
| +------------------------+
v v
+------------------------+
| Cluster bridge service |
+------------------------+
^
| Machi "low" API
| ProtoBuffs protocol
+----------------------------------------+----+----+
| | | |
v v v v
+-------------------------+ ... other chains...
| Chain C1 (logical view) |
| +--------------+ |
| | FLU server 1 | |
| | +--------------+ |
| +--| FLU server 2 | |
| +--------------+ | In reality, API bridge talks directly
+-------------------------+ to each FLU server in a chain.
#+END_SRC
** The notation we use
- ~N~ = the cluster namespace, chosen by the client.
- ~p~ = file prefix, chosen by the client.
- ~L~ = the cluster locator (a number, type is implementation-dependent)
- ~Map~ = a mapping of cluster locators to chains
- ~T~ = the target chain ID/name
- ~u~ = a unique opaque file name suffix, e.g. a GUID string
- ~F~ = a Machi file name, i.e., a concatenation of ~p^L^N^u~
** The details: cluster file append
0. Cluster client chooses ~N~ and ~p~ (i.e., cluster namespace and
file prefix) and sends the append request to a Machi cluster member
via the Protocol Buffers "high" API.
1. Cluster bridge chooses ~T~ (i.e., target chain), based on criteria
such as disk utilization percentage.
2. Cluster bridge knows the cluster ~Map~ for namespace ~N~.
3. Cluster bridge choose some cluster locator value ~L~ such that
~rs_hash_with_float(L,Map) = T~ (see algorithm below).
4. Cluster bridge sends its request to chain
~T~: ~append_chunk(p,L,N,...) -> {ok,p^L^N^u,ByteOffset}~
5. Cluster bridge forwards the reply tuple to the client.
6. Client stores/uses the file name ~F = p^L^N^u~.
** The details: Cluster file read
0. Cluster client sends the read request to a Machi cluster member via
the Protocol Buffers "high" API.
1. Cluster bridge parses the file name ~F~ to find
the values of ~L~ and ~N~ (recall, ~F = p^L^N^u~).
2. Cluster bridge knows the Cluster ~Map~ for type ~N~.
3. Cluster bridge calculates ~rs_hash_with_float(L,Map) = T~
4. Cluster bridge sends request to chain ~T~:
~read_chunk(F,...) ->~ ... reply
5. Cluster bridge forwards the reply to the client.
** The details: calculating 'L' (the cluster locator number) to match a desired target chain
1. We know ~Map~, the current cluster mapping for a cluster namespace ~N~.
2. We look inside of ~Map~, and we find all of the unit interval ranges
that map to our desired target chain ~T~. Let's call this list
~MapList = [Range1=(start,end],Range2=(start,end],...]~.
3. In our example, ~T=Chain2~. The example ~Map~ contains a single
unit interval range for ~Chain2~, ~[(0.33,0.58]]~.
4. Choose a uniformly random number ~r~ on the unit interval.
5. Calculate the cluster locator ~L~ by mapping ~r~ onto the concatenation
of the cluster hash space range intervals in ~MapList~. For example,
if ~r=0.5~, then ~L = 0.33 + 0.5*(0.58-0.33) = 0.455~, which is
exactly in the middle of the ~(0.33,0.58]~ interval.
** A bit more about the cluster namespaces's meaning and use
For use by Riak CS, for example, we'd likely start with the following
namespaces ... working our way down the list as we add new features
and/or re-implement existing CS features.
- "standard" = Chain length = 3, eventually consistency mode
- "reduced" = Chain length = 2, eventually consistency mode.
- "stanchion7" = Chain length = 7, strong consistency mode. Perhaps
use this namespace for the metadata required to re-implement the
operations that are performed by today's Stanchion application.
We want the cluster framework to:
- provide means of creating and managing
chains of different types, e.g., chain length, consistency mode.
- manage the mapping of cluster namespace
names to the chains in the system.
- provide query functions to map a cluster
namespace name to a cluster map,
e.g. ~get_cluster_latest_map("reduced") -> Map{generation=7,...}~.
* 8. File migration (a.k.a. rebalancing/reparitioning/resharding/redistribution)
** What is "migration"?
This section describes Machi's file migration. Other storage systems
call this process as "rebalancing", "repartitioning", "resharding" or
"redistribution".
For Riak Core applications, it is called "handoff" and "ring resizing"
(depending on the context).
See also the [[http://hadoop.apache.org/docs/current/hadoop-project-dist/hadoop-hdfs/HdfsUserGuide.html#Balancer][Hadoop file balancer]] for another example of a data
migration process.
As discussed in section 5, the client can have good reason for wanting
to have some control of the initial location of the file within the
chain. However, the chain manager has an ongoing interest in
balancing resources throughout the lifetime of the file. Disks will
get full, hardware will change, read workload will fluctuate,
etc etc.
This document uses the word "migration" to describe moving data from
one Machi chain to another chain within a cluster system.
A simple variation of the Random Slicing hash algorithm can easily
accommodate Machi's need to migrate files without interfering with
availability. Machi's migration task is much simpler due to the
immutable nature of Machi file data.
** Change to Random Slicing
The map used by the Random Slicing hash algorithm needs a few simple
changes to make file migration straightforward.
- Add a "generation number", a strictly increasing number (similar to
a Machi chain's "epoch number") that reflects the history of
changes made to the Random Slicing map
- Use a list of Random Slicing maps instead of a single map, one map
per chance that files may not have been migrated yet out of
that map.
As an example:
#+CAPTION: Illustration of 'Map', using four Machi chains
[[./migration-3to4.png]]
And the new Random Slicing map for some cluster namespace ~N~ might look
like this:
| Generation number / Namespace | 7 / reduced |
|-------------------------------+-------------|
| SubMap | 1 |
|-------------------------------+-------------|
| Hash range | Chain ID |
|-------------------------------+-------------|
| 0.00 - 0.33 | Chain1 |
| 0.33 - 0.66 | Chain2 |
| 0.66 - 1.00 | Chain3 |
|-------------------------------+-------------|
| SubMap | 2 |
|-------------------------------+-------------|
| Hash range | Chain ID |
|-------------------------------+-------------|
| 0.00 - 0.25 | Chain1 |
| 0.25 - 0.33 | Chain4 |
| 0.33 - 0.58 | Chain2 |
| 0.58 - 0.66 | Chain4 |
| 0.66 - 0.91 | Chain3 |
| 0.91 - 1.00 | Chain4 |
When a new Random Slicing map contains a single submap, then its use
is identical to the original Random Slicing algorithm. If the map
contains multiple submaps, then the access rules change a bit:
- Write operations always go to the newest/largest submap.
- Read operations attempt to read from all unique submaps.
- Skip searching submaps that refer to the same chain ID.
- In this example, unit interval value 0.10 is mapped to Chain1
by both submaps.
- Read from newest/largest submap to oldest/smallest submap.
- If not found in any submap, search a second time (to handle races
with file copying between submaps).
- If the requested data is found, optionally copy it directly to the
newest submap. (This is a variation of read repair (RR). RR here
accelerates the migration process and can reduce the number of
operations required to query servers in multiple submaps).
The cluster manager is responsible for:
- Managing the various generations of the cluster Random Slicing maps for
all namespaces.
- Distributing namespace maps to cluster bridges.
- Managing the processes that are responsible for copying "cold" data,
i.e., files data that is not regularly accessed, to its new submap
location.
- When migration of a file to its new chain is confirmed successful,
delete it from the old chain.
In example map #7, the cluster manager will copy files with unit interval
assignments in ~(0.25,0.33]~, ~(0.58,0.66]~, and ~(0.91,1.00]~ from their
old locations in chain IDs Chain1/2/3 to their new chain,
Chain4. When the cluster manager is satisfied that all such files have
been copied to Chain4, then the cluster manager can create and
distribute a new map, such as:
| Generation number / Namespace | 8 / reduced |
|-------------------------------+-------------|
| SubMap | 1 |
|-------------------------------+-------------|
| Hash range | Chain ID |
|-------------------------------+-------------|
| 0.00 - 0.25 | Chain1 |
| 0.25 - 0.33 | Chain4 |
| 0.33 - 0.58 | Chain2 |
| 0.58 - 0.66 | Chain4 |
| 0.66 - 0.91 | Chain3 |
| 0.91 - 1.00 | Chain4 |
The HibariDB system performs data migrations in almost exactly this
manner. However, one important
limitation of HibariDB is not being able to
perform more than one migration at a time. HibariDB's data is
mutable. Mutation causes many problems when migrating data
across two submaps; three or more submaps was too complex to implement
quickly and correctly.
Fortunately for Machi, its file data is immutable and therefore can
easily manage many migrations in parallel, i.e., its submap list may
be several maps long, each one for an in-progress file migration.
* 9. Other considerations for FLU/sequencer implementations
** Append to existing file when possible
The sequencer should always assign new offsets to the latest/newest
file for any prefix, as long as all prerequisites are also true,
- The epoch has not changed. (In AP mode, epoch change -> mandatory
file name suffix change.)
- The cluster locator number is stable.
- The latest file for prefix ~p~ is smaller than maximum file size for
a FLU's configuration.
The stability of the cluster locator number is an implementation detail that
must be managed by the cluster bridge.
Reuse of the same file is not possible if the bridge always chooses a
different cluster locator number ~L~ or if the client always uses a unique
file prefix ~p~. The latter is a sign of a misbehaved client; the
former is a poorly-implemented bridge.
* 10. Acknowledgments
The original source for the "migration-4.png" and "migration-3to4.png" images
come from the [[http://hibari.github.io/hibari-doc/images/migration-3to4.png][HibariDB documentation]].

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# Clone and compile Machi
Clone the Machi source repo and compile the source and test code. Run
the following commands at your login shell:
cd /tmp
git clone https://github.com/basho/machi.git
cd machi
git checkout master
make # or 'gmake' if GNU make uses an alternate name
Then run the unit test suite. This may take up to two minutes or so
to finish.
make test
At the end, the test suite should report that all tests passed. The
actual number of tests shown in the "All `X` tests passed" line may be
different than the example below.
[... many lines omitted ...]
module 'event_logger'
module 'chain_mgr_legacy'
=======================================================
All 90 tests passed.
If you had a test failure, a likely cause may be a limit on the number
of file descriptors available to your user process. (Recent releases
of OS X have a limit of 1024 file descriptors, which may be too slow.)
The output of the `limit -n` will tell you your file descriptor limit.

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@ -1,38 +0,0 @@
## Machi developer environment prerequisites
1. Machi requires an 64-bit variant of UNIX: OS X, FreeBSD, Linux, or
Solaris machine is a standard developer environment for C and C++
applications (64-bit versions).
2. You'll need the `git` source management utility.
3. You'll need the 64-bit Erlang/OTP 17 runtime environment. Please
don't use earlier or later versions until we have a chance to fix
the compilation warnings that versions R16B and 18 will trigger.
Also, please verify that you are not using a 32-bit Erlang/OTP
runtime package.
For `git` and the Erlang runtime, please use your OS-specific
package manager to install these. If your package manager doesn't
have 64-bit Erlang/OTP version 17 available, then we recommend using the
[precompiled packages available at Erlang Solutions](https://www.erlang-solutions.com/resources/download.html).
Also, please verify that you have enough file descriptors available to
your user processes. The output of `ulimit -n` should report at least
4,000 file descriptors available. If your limit is lower (a frequent
problem for OS X users), please increase it to at least 4,000.
# Using Vagrant to set up a developer environment for Machi
The Machi source directory contains a `Vagrantfile` for creating an
Ubuntu Linux-based virtual machine for compiling and running Machi.
This file is in the
[$SRC_TOP/priv/humming-consensus-demo.vagrant](../priv/humming-consensus-demo.vagrant)
directory.
If used as-is, the virtual machine specification is modest.
* 1 virtual CPU
* 512MB virtual memory
* 768MB swap space
* 79GB sparse virtual disk image. After installing prerequisites and
compiling Machi, the root file system uses approximately 2.7 GBytes.

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@ -1,617 +0,0 @@
FLU and Chain Life Cycle Management -*- mode: org; -*-
#+STARTUP: lognotedone hidestars indent showall inlineimages
#+COMMENT: To generate the outline section: egrep '^\*[*]* ' doc/flu-and-chain-lifecycle.org | egrep -v '^\* Outline' | sed -e 's/^\*\*\* / + /' -e 's/^\*\* / + /' -e 's/^\* /+ /'
* FLU and Chain Life Cycle Management
In an ideal world, we (the Machi development team) would have a full
vision of how Machi would be managed, down to the last detail of
beautiful CLI character and network protocol bit. Our vision isn't
complete yet, so we are working one small step at a time.
* Outline
+ FLU and Chain Life Cycle Management
+ Terminology review
+ Terminology: Machi run-time components/services/thingies
+ Terminology: Machi chain data structures
+ Terminology: Machi cluster data structures
+ Overview of administrative life cycles
+ Cluster administrative life cycle
+ Chain administrative life cycle
+ FLU server administrative life cycle
+ Quick admin: declarative management of Machi FLU and chain life cycles
+ Quick admin uses the "rc.d" config scheme for life cycle management
+ Quick admin's declarative "language": an Erlang-flavored AST
+ Term 'host': define a new host for FLU services
+ Term 'flu': define a new FLU
+ Term 'chain': define or reconfigure a chain
+ Executing quick admin AST files via the 'machi-admin' utility
+ Checking the syntax of an AST file
+ Executing an AST file
+ Using quick admin to manage multiple machines
+ The "rc.d" style configuration file scheme
+ Riak had a similar configuration file editing problem (and its solution)
+ Machi's "rc.d" file scheme.
+ FLU life cycle management using "rc.d" style files
+ The key configuration components of a FLU
+ Chain life cycle management using "rc.d" style files
+ The key configuration components of a chain
* Terminology review
** Terminology: Machi run-time components/services/thingies
+ FLU: a basic Machi server, responsible for managing a collection of
files.
+ Chain: a small collection of FLUs that maintain replicas of the same
collection of files. A chain is usually small, 1-3 servers, where
more than 3 would be used only in cases when availability of
certain data is critical despite failures of several machines.
+ The length of a chain is directly proportional to its
replication factor, e.g., a chain length=3 will maintain
(nominally) 3 replicas of each file.
+ To maintain file availability when ~F~ failures have occurred, a
chain must be at least ~F+1~ members long. (In comparison, the
quorum replication technique requires ~2F+1~ members in the
general case.)
+ Cluster: A collection of Machi chains that are used to store files
in a horizontally partitioned/sharded/distributed manner.
** Terminology: Machi data structures
+ Projection: used to define a single chain: the chain's consistency
mode (strong or eventual consistency), all members (from an
administrative point of view), all active members (from a runtime,
automatically-managed point of view), repairing/file-syncing members
(also runtime, auto-managed), and so on
+ Epoch: A version number of a projection. The epoch number is used
by both clients & servers to manage transitions from one projection
to another, e.g., when the chain is temporarily shortened by the
failure of a member FLU server.
** Terminology: Machi cluster data structures
+ Namespace: A collection of human-friendly names that are mapped to
groups of Machi chains that provide the same type of storage
service: consistency mode, replication policy, etc.
+ A single namespace name, e.g. ~normal-ec~, is paired with a single
cluster map (see below).
+ Example: ~normal-ec~ might be a collection of Machi chains in
eventually-consistent mode that are of length=3.
+ Example: ~risky-ec~ might be a collection of Machi chains in
eventually-consistent mode that are of length=1.
+ Example: ~mgmt-critical~ might be a collection of Machi chains in
strongly-consistent mode that are of length=7.
+ Cluster map: Encodes the rules which partition/shard/distribute
the files stored in a particular namespace across a group of chains
that collectively store the namespace's files.
+ Chain weight: A value assigned to each chain within a cluster map
structure that defines the relative storage capacity of a chain
within the namespace. For example, a chain weight=150 has 50% more
capacity than a chain weight=100.
+ Cluster map epoch: The version number assigned to a cluster map.
* Overview of administrative life cycles
** Cluster administrative life cycle
+ Cluster is first created
+ Adds namespaces (e.g. consistency policy + chain length policy) to
the cluster
+ Chains are added to/removed from a namespace to increase/decrease the
namespace's storage capacity.
+ Adjust chain weights within a namespace, e.g., to shift files
within the namespace to chains with greater storage capacity
resources and/or runtime I/O resources.
A cluster "file migration" is the process of moving files from one
namespace member chain to another for purposes of shifting &
re-balancing storage capacity and/or runtime I/O capacity.
** Chain administrative life cycle
+ A chain is created with an initial FLU membership list.
+ Chain may be administratively modified zero or more times to
add/remove member FLU servers.
+ A chain may be decommissioned.
See also: http://basho.github.io/machi/edoc/machi_lifecycle_mgr.html
** FLU server administrative life cycle
+ A FLU is created after an administrator chooses the FLU's runtime
location is selected by the administrator: which machine/virtual
machine, IP address and TCP port allocation, etc.
+ An unassigned FLU may be added to a chain by chain administrative
policy.
+ A FLU that is assigned to a chain may be removed from that chain by
chain administrative policy.
+ In the current implementation, the FLU's Erlang processes will be
halted. Then the FLU's data and metadata files will be moved to
another area of the disk for safekeeping. Later, a "garbage
collection" process can be used for reclaiming disk space used by
halted FLU servers.
See also: http://basho.github.io/machi/edoc/machi_lifecycle_mgr.html
* Quick admin: declarative management of Machi FLU and chain life cycles
The "quick admin" scheme is a temporary (?) tool for managing Machi
FLU server and chain life cycles in a declarative manner. The API is
described in this section.
** Quick admin uses the "rc.d" config scheme for life cycle management
As described at the top of
http://basho.github.io/machi/edoc/machi_lifecycle_mgr.html, the "rc.d"
config files do not manage "policy". "Policy" is doing the right
thing with a Machi cluster from a systems administrator's
point of view. The "rc.d" config files can only implement decisions
made according to policy.
The "quick admin" tool is a first attempt at automating policy
decisions in a safe way (we hope) that is also easy to implement (we
hope) with a variety of systems management tools, e.g. Chef, Puppet,
Ansible, Saltstack, or plain-old-human-at-a-keyboard.
** Quick admin's declarative "language": an Erlang-flavored AST
The "language" that an administrator uses to express desired policy
changes is not (yet) a true language. As a quick implementation hack,
the current language is an Erlang-flavored abstract syntax tree
(AST). The tree isn't very deep, either, frequently just one
element tall. (Not much of a tree, is it?)
There are three terms in the language currently:
+ ~host~, define a new host that can execute FLU servers
+ ~flu~, define a new FLU
+ ~chain~, define a new chain or re-configure an existing chain with
the same name
*** Term 'host': define a new host for FLU services
In this context, a host is a machine, virtual machine, or container
that can execute the Machi application and can therefore provide FLU
services, i.e. file service, Humming Consensus management.
Two formats may be used to define a new host:
#+BEGIN_SRC
{host, Name, Props}.
{host, Name, AdminI, ClientI, Props}.
#+END_SRC
The shorter tuple is shorthand notation for the latter. If the
shorthand form is used, then it will be converted automatically to the
long form as:
#+BEGIN_SRC
{host, Name, AdminI=Name, ClientI=Name, Props}.
#+END_SRC
Type information, description, and restrictions:
+ ~Name::string()~ The ~Name~ attribute must be unique. Note that it
is possible to define two different hosts, one using a DNS hostname
and one using an IP address. The user must avoid this
double-definition because it is not enforced by quick admin.
+ The ~Name~ field is used for cross-reference purposes with other
terms, e.g., ~flu~ and ~chain~.
+ There is no syntax yet for removing a host definition.
+ ~AdminI::string()~ A DNS hostname or IP address for cluster
administration purposes, e.g. SSH access.
+ This field is unused at the present time.
+ ~ClientI::string()~ A DNS hostname or IP address for Machi's client
protocol access, e.g., Protocol Buffers network API service.
+ This field is unused at the present time.
+ ~props::proplist()~ is an Erlang-style property list for specifying
additional configuration options, debugging information, sysadmin
comments, etc.
+ A full-featured admin tool should also include managing several
other aspects of configuration related to a "host". For example,
for any single IP address, quick admin assumes that there will be
exactly one Erlang VM that is running the Machi application. Of
course, it is possible to have dozens of Erlang VMs on the same
(let's assume for clarity) hardware machine and all running Machi
... but there are additional aspects of such a machine that quick
admin does not account for
+ multiple IP addresses per machine
+ multiple Machi package installation paths
+ multiple Machi config files (e.g. cuttlefish config, ~etc.conf~,
~vm.args~)
+ multiple data directories/file system mount points
+ This is also a management problem for quick admin for a single
Machi package on a machine to take advantage of bulk data
storage using multiple multiple file system mount points.
+ multiple Erlang VM host names, required for distributed Erlang,
which is used for communication with ~machi~ and ~machi-admin~
command line utilities.
+ and others....
*** Term 'flu': define a new FLU
A new FLU is defined relative to a previously-defined ~host~ entities;
an exception will be thrown if the ~host~ cannot be cross-referenced.
#+BEGIN_SRC
{flu, Name, HostName, Port, Props}
#+END_SRC
Type information, description, and restrictions:
+ ~Name::atom()~ The name of the FLU, as a human-friendly name and
also for internal management use; please note the ~atom()~ type.
This name must be unique.
+ The ~Name~ field is used for cross-reference purposes with the
~chain~ term.
+ There is no syntax yet for removing a FLU definition.
+ ~Hostname::string()~ The cross-reference name of the ~host~ that
this FLU should run on.
+ ~Port::non_neg_integer()~ The TCP port used by this FLU server's
Protocol Buffers network API listener service
+ ~props::proplist()~ is an Erlang-style property list for specifying
additional configuration options, debugging information, sysadmin
comments, etc.
*** Term 'chain': define or reconfigure a chain
A chain is defined relative to zero or more previously-defined ~flu~
entities; an exception will be thrown if any ~flu~ cannot be
cross-referenced.
Two formats may be used to define/reconfigure a chain:
#+BEGIN_SRC
{chain, Name, FullList, Props}.
{chain, Name, CMode, FullList, Witnesses, Props}.
#+END_SRC
The shorter tuple is shorthand notation for the latter. If the
shorthand form is used, then it will be converted automatically to the
long form as:
#+BEGIN_SRC
{chain, Name, ap_mode, FullList, [], Props}.
#+END_SRC
Type information, description, and restrictions:
+ ~Name::atom()~ The name of the chain, as a human-friendly name and
also for internal management use; please note the ~atom()~ type.
This name must be unique.
+ There is no syntax yet for removing a chain definition.
+ ~CMode::'ap_mode'|'cp_mode'~ Defines the consistency mode of the
chain, either eventual consistency or strong consistency,
respectively.
+ A chain cannot change consistency mode, e.g., from
strong~->~eventual consistency.
+ ~FullList::list(atom())~ Specifies the list of full-service FLU
servers, i.e. servers that provide file data & metadata services as
well as Humming Consensus. Each atom in the list must
cross-reference with a previously defined ~chain~; an exception will
be thrown if any ~flu~ cannot be cross-referenced.
+ ~Witnesses::list(atom())~ Specifies the list of witness-only
servers, i.e. servers that only participate in Humming Consensus.
Each atom in the list must cross-reference with a previously defined
~chain~; an exception will be thrown if any ~flu~ cannot be
cross-referenced.
+ This list must be empty for eventual consistency chains.
+ ~props::proplist()~ is an Erlang-style property list for specifying
additional configuration options, debugging information, sysadmin
comments, etc.
+ If this term specifies a new ~chain~ name, then all of the member
FLU servers (full & witness types) will be bootstrapped to a
starting configuration.
+ If this term specifies a previously-defined ~chain~ name, then all
of the member FLU servers (full & witness types, respectively) will
be adjusted to add or remove members, as appropriate.
+ Any FLU servers added to either list must not be assigned to any
other chain, or they must be a member of this specific chain.
+ Any FLU servers removed from either list will be halted.
(See the "FLU server administrative life cycle" section above.)
** Executing quick admin AST files via the 'machi-admin' utility
Examples of quick admin AST files can be found in the
~priv/quick-admin/examples~ directory. Below is an example that will
define a new host ( ~"localhost"~ ), three new FLU servers ( ~f1~ & ~f2~
and ~f3~ ), and an eventually consistent chain ( ~c1~ ) that uses the new
FLU servers:
#+BEGIN_SRC
{host, "localhost", []}.
{flu,f1,"localhost",20401,[]}.
{flu,f2,"localhost",20402,[]}.
{flu,f3,"localhost",20403,[]}.
{chain,c1,[f1,f2,f3],[]}.
#+END_SRC
*** Checking the syntax of an AST file
Given an AST config file, ~/path/to/ast/file~, its basic syntax and
correctness can be checked without executing it.
#+BEGIN_SRC
./rel/machi/bin/machi-admin quick-admin-check /path/to/ast/file
#+END_SRC
+ The utility will exit with status zero and output ~ok~ if the syntax
and proposed configuration appears to be correct.
+ If there is an error, the utility will exit with status one, and an
error message will be printed.
*** Executing an AST file
Given an AST config file, ~/path/to/ast/file~, it can be executed
using the command:
#+BEGIN_SRC
./rel/machi/bin/machi-admin quick-admin-apply /path/to/ast/file RelativeHost
#+END_SRC
... where the last argument, ~RelativeHost~, should be the exact
spelling of one of the previously defined AST ~host~ entities,
*and also* is the same host that the ~machi-admin~ utility is being
executed on.
Restrictions and warnings:
+ This is alpha quality software.
+ There is no "undo".
+ Of course there is, but you need to resort to doing things like
using ~machi attach~ to attach to the server's CLI to then execute
magic Erlang incantations to stop FLUs, unconfigure chains, etc.
+ Oh, and delete some files with magic paths, also.
** Using quick admin to manage multiple machines
A quick sketch follows:
1. Create the AST file to specify all of the changes that you wish to
make to all hosts, FLUs, and/or chains, e.g., ~/tmp/ast.txt~.
2. Check the basic syntax with the ~quick-admin-check~ argument to
~machi-admin~.
3. If the syntax is good, then copy ~/tmp/ast.txt~ to all hosts in the
cluster, using the same path, ~/tmp/ast.txt~.
4. For each machine in the cluster, run:
#+BEGIN_SRC
./rel/machi/bin/machi-admin quick-admin-apply /tmp/ast.txt RelativeHost
#+END_SRC
... where RelativeHost is the AST ~host~ name of the machine that you
are executing the ~machi-admin~ command on. The command should be
successful, with exit status 0 and outputting the string ~ok~.
Finally, for each machine in the cluster, a listing of all files in
the directory ~rel/machi/etc/quick-admin-archive~ should show exactly
the same files, one for each time that ~quick-admin-apply~ has been
run successfully on that machine.
* The "rc.d" style configuration file scheme
This configuration scheme is inspired by BSD UNIX's ~init(8)~ process
manager's configuration style, called "rc.d" after the name of the
directory where these files are stored, ~/etc/rc.d~. The ~init~
process is responsible for (among other things) starting UNIX
processes at machine boot time and stopping them when the machine is
shut down.
The original scheme used by ~init~ to start processes at boot time was
a single Bourne shell script called ~/etc/rc~. When a new software
package was installed that required a daemon to be started at boot
time, text was added to the ~/etc/rc~ file. Uninstalling packages was
much trickier, because it meant removing lines from a file that
*is a computer program (run by the Bourne shell, a Turing-complete
programming language)*. Error-free editing of the ~/etc/rc~ script
was impossible in all cases.
Later, ~init~'s configuration was split into a few master Bourne shell
scripts and a subdirectory, ~/etc/rc.d~. The subdirectory contained
shell scripts that were responsible for boot time starting of a single
daemon or service, e.g. NFS or an HTTP server. When a new software
package was added, a new file was added to the ~rc.d~ subdirectory.
When a package was removed, the corresponding file in ~rc.d~ was
removed. With this simple scheme, addition & removal of boot time
scripts was vastly simplified.
** Riak had a similar configuration file editing problem (and its solution)
Another software product from Basho Technologies, Riak, had a similar
configuration file editing problem. One file in particular,
~app.config~, had a syntax that made it difficult both for human
systems administrators and also computer programs to edit the file in
a syntactically correct manner.
Later releases of Riak switched to an alternative configuration file
format, one inspired by the BSD UNIX ~sysctl(8)~ utility and
~sysctl.conf(5)~ file syntax. The ~sysctl.conf~ format is much easier
to manage by computer programs to add items. Removing items is not
100% simple, however: the correct lines must be identified and then
removed (e.g. with Perl or a text editor or combination of ~grep -v~
and ~mv~), but removing any comment lines that "belong" to the removed
config item(s) is not any easy for a 1-line shell script to do 100%
correctly.
Machi will use the ~sysctl.conf~ style configuration for some
application configuration variables. However, adding & removing FLUs
and chains will be managed using the "rc.d" style because of the
"rc.d" scheme's simplicity and tolerance of mistakes by administrators
(human or computer).
** Machi's "rc.d" file scheme.
Machi will use a single subdirectory that will contain configuration
files for some life cycle management task, e.g. a single FLU or a
single chain.
The contents of the file should be a single Erlang term, serialized in
ASCII form as Erlang source code statement, i.e. a single Erlang term
~T~ that is formatted by ~io:format("~w.",[T]).~. This file must be
parseable by the Erlang function ~file:consult()~.
Later versions of Machi may change the file format to be more familiar
to administrators who are unaccustomed to Erlang language syntax.
** FLU life cycle management using "rc.d" style files
*** The key configuration components of a FLU
1. The machine (or virtual machine) to run it on.
2. The Machi software package's artifacts to execute.
3. The disk device(s) used to store Machi file data & metadata, "rc.d"
style config files, etc.
4. The name, IP address and TCP port assigned to the FLU service.
5. Its chain assignment.
Notes:
+ Items 1-3 are currently outside of the scope of this life cycle
document. We assume that human administrators know how to do these
things.
+ Item 4's properties are explicitly managed by a FLU-defining "rc.d"
style config file.
+ Item 5 is managed by the chain life cycle management system.
Here is an example of a properly formatted FLU config file:
#+BEGIN_SRC
{p_srvr,f1,machi_flu1_client,"192.168.72.23",20401,[]}.
#+END_SRC
... which corresponds to the following Erlang record definition:
#+BEGIN_SRC
-record(p_srvr, {
name :: atom(),
proto_mod = 'machi_flu1_client' :: atom(), % Module name
address :: term(), % Protocol-specific
port :: term(), % Protocol-specific
props = [] :: list() % proplist for other related info
}).
#+END_SRC
+ ~name~ is ~f1~. This is name of the FLU. This name should be
unique over the lifetime of the administrative domain and thus
managed by external policy. This name must be the same as the name
of the config file that defines the FLU.
+ ~proto_mod~ is used for internal management purposes and should be
considered a mandatory constant.
+ ~address~ is "192.168.72.23". The DNS hostname or IP address used
by other servers to communicate with this FLU. This must be a valid
IP address, previously assigned to this machine/VM using the
appropriate operating system-specific procedure.
+ ~port~ is TCP port 20401. The TCP port number that the FLU listens
to for incoming Protocol Buffers-serialized communication. This TCP
port must not be in use (now or in the future) by another Machi FLU
or any other process running on this machine/VM.
+ ~props~ is an Erlang-style property list for specifying additional
configuration options, debugging information, sysadmin comments,
etc.
** Chain life cycle management using "rc.d" style files
Unlike FLUs, chains have a self-management aspect that makes a chain
life cycle different from a single FLU server. Machi's chains are
self-managing, via Humming Consensus; see the
https://github.com/basho/machi/tree/master/doc/ directory for much
more detail about Humming Consensus. After FLUs have received their
initial chain configuration for Humming Consensus, the FLUs will
manage the chain (and each other) by themselves.
However, Humming Consensus does not handle three chain management
problems:
1. Specifying the very first chain configuration,
2. Altering the membership of the chain (i.e. adding/removing FLUs
from the chain),
3. Stopping the chain permanently.
A chain "rc.d" file will only be used to bootstrap a newly-defined FLU
server. It's like a piece of glue information to introduce the new
FLU to the Humming Consensus group that is managing the chain's
dynamic state (e.g. which members are up or down). In all other
respects, chain config files are ignored by life cycle management code.
However, to mimic the life cycle of the FLU server's "rc.d" config
files, a chain "rc.d" files is not deleted until the chain has been
decommissioned (i.e. defined with length=0).
*** The key configuration components of a chain
1. The name of the chain.
2. Consistency mode: eventually consistent or strongly consistent.
3. The membership list of all FLU servers in the chain.
+ Remember, all servers in a single chain will manage full replicas
of the same collection of Machi files.
4. If the chain is defined to use strongly consistent mode, then a
list of "witness servers" may also be defined. See the
[https://github.com/basho/machi/tree/master/doc/] documentation for
more information on witness servers.
+ The witness list must be empty for all chains in eventual
consistency mode.
Here is an example of a properly formatted chain config file:
#+BEGIN_SRC
{chain_def_v1,c1,ap_mode,
[{p_srvr,f1,machi_flu1_client,"localhost",20401,[]},
{p_srvr,f2,machi_flu1_client,"localhost",20402,[]},
{p_srvr,f3,machi_flu1_client,"localhost",20403,[]}],
[],[],[],
[f1,f2,f3],
[],[]}.
#+END_SRC
... which corresponds to the following Erlang record definition:
#+BEGIN_SRC
-record(chain_def_v1, {
name :: atom(), % chain name
mode :: 'ap_mode' | 'cp_mode',
full = [] :: [p_srvr()],
witnesses = [] :: [p_srvr()],
old_full = [] :: [atom()], % guard against some races
old_witnesses=[] :: [atom()], % guard against some races
local_run = [] :: [atom()], % must be tailored to each machine!
local_stop = [] :: [atom()], % must be tailored to each machine!
props = [] :: list() % proplist for other related info
}).
#+END_SRC
+ ~name~ is ~c1~, the name of the chain. This name should be unique
over the lifetime of the administrative domain and thus managed by
external policy. This name must be the same as the name of the
config file that defines the chain.
+ ~mode~ is ~ap_mode~, an internal code symbol for eventual
consistency mode.
+ ~full~ is a list of Erlang ~#p_srvr{}~ records for full-service
members of the chain, i.e., providing Machi file data & metadata
storage services.
+ ~witnesses~ is a list of Erlang ~#p_srvr{}~ records for witness-only
FLU servers, i.e., providing only Humming Consensus service.
+ The next four fields are used for internal management only.
+ ~props~ is an Erlang-style property list for specifying additional
configuration options, debugging information, sysadmin comments,
etc.

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# Table of contents
* [Hands-on experiments with Machi and Humming Consensus](#hands-on)
* [Using the network partition simulator and convergence demo test code](#partition-simulator)
<a name="hands-on">
# Hands-on experiments with Machi and Humming Consensus
## Prerequisites
Please refer to the
[Machi development environment prerequisites doc](./dev-prerequisites.md)
for Machi developer environment prerequisites.
If you do not have an Erlang/OTP runtime system available, but you do
have [the Vagrant virtual machine](https://www.vagrantup.com/) manager
available, then please refer to the instructions in the prerequisites
doc for using Vagrant.
<a name="clone-compile">
## Clone and compile the code
Please see the
[Machi 'clone and compile' doc](./dev-clone-compile.md)
for the short list of steps required to fetch the Machi source code
from GitHub and to compile &amp; test Machi.
## Running three Machi instances on a single machine
All of the commands that should be run at your login shell (e.g. Bash,
c-shell) can be cut-and-pasted from this document directly to your
login shell prompt.
Run the following command:
make stagedevrel
This will create a directory structure like this:
|-dev1-|... stand-alone Machi app + subdirectories
|-dev-|-dev2-|... stand-alone Machi app + directories
|-dev3-|... stand-alone Machi app + directories
Each of the `dev/dev1`, `dev/dev2`, and `dev/dev3` are stand-alone
application instances of Machi and can be run independently of each
other on the same machine. This demo will use all three.
The lifecycle management utilities for Machi are a bit immature,
currently. They assume that each Machi server runs on a host with a
unique hostname -- there is no flexibility built-in yet to easily run
multiple Machi instances on the same machine. To continue with the
demo, we need to use `sudo` or `su` to obtain superuser privileges to
edit the `/etc/hosts` file.
Please add the following line to `/etc/hosts`, using this command:
sudo sh -c 'echo "127.0.0.1 machi1 machi2 machi3" >> /etc/hosts'
Next, we will use a shell script to finish setting up our cluster. It
will do the following for us:
* Verify that the new line that was added to `/etc/hosts` is correct.
* Modify the `etc/app.config` files to configure the Humming Consensus
chain manager's actions logged to the `log/console.log` file.
* Start the three application instances.
* Verify that the three instances are running correctly.
* Configure a single chain, with one FLU server per application
instance.
Please run this script using this command:
./priv/humming-consensus-demo.setup.sh
If the output looks like this (and exits with status zero), then the
script was successful.
Step: Verify that the required entries in /etc/hosts are present
Step: add a verbose logging option to app.config
Step: start three three Machi application instances
pong
pong
pong
Step: configure one chain to start a Humming Consensus group with three members
Result: ok
Result: ok
Result: ok
We have now created a single replica chain, called `c1`, that has
three file servers participating in the chain. Thanks to the
hostnames that we added to `/etc/hosts`, all are using the localhost
network interface.
| App instance | Pseudo | FLU name | TCP port |
| directory | Hostname | | number |
|--------------+----------+----------+----------|
| dev1 | machi1 | flu1 | 20401 |
| dev2 | machi2 | flu2 | 20402 |
| dev3 | machi3 | flu3 | 20403 |
The log files for each application instance can be found in the
`./dev/devN/log/console.log` file, where the `N` is the instance
number: 1, 2, or 3.
## Understanding the chain manager's log file output
After running the `./priv/humming-consensus-demo.setup.sh` script,
let's look at the last few lines of the `./dev/dev1/log/console.log`
log file for Erlang VM process #1.
2016-03-09 10:16:35.676 [info] <0.105.0>@machi_lifecycle_mgr:process_pending_flu:422 Started FLU f1 with supervisor pid <0.128.0>
2016-03-09 10:16:35.676 [info] <0.105.0>@machi_lifecycle_mgr:move_to_flu_config:540 Creating FLU config file f1
2016-03-09 10:16:35.790 [info] <0.105.0>@machi_lifecycle_mgr:bootstrap_chain2:312 Configured chain c1 via FLU f1 to mode=ap_mode all=[f1,f2,f3] witnesses=[]
2016-03-09 10:16:35.790 [info] <0.105.0>@machi_lifecycle_mgr:move_to_chain_config:546 Creating chain config file c1
2016-03-09 10:16:44.139 [info] <0.132.0> CONFIRM epoch 1141 <<155,42,7,221>> upi [] rep [] auth f1 by f1
2016-03-09 10:16:44.271 [info] <0.132.0> CONFIRM epoch 1148 <<57,213,154,16>> upi [f1] rep [] auth f1 by f1
2016-03-09 10:16:44.864 [info] <0.132.0> CONFIRM epoch 1151 <<239,29,39,70>> upi [f1] rep [f3] auth f1 by f1
2016-03-09 10:16:45.235 [info] <0.132.0> CONFIRM epoch 1152 <<173,17,66,225>> upi [f2] rep [f1,f3] auth f2 by f1
2016-03-09 10:16:47.343 [info] <0.132.0> CONFIRM epoch 1154 <<154,231,224,149>> upi [f2,f1,f3] rep [] auth f2 by f1
Let's pick apart some of these lines. We have started all three
servers at about the same time. We see some race conditions happen,
and some jostling and readjustment happens pretty quickly in the first
few seconds.
* `Started FLU f1 with supervisor pid <0.128.0>`
* This VM, #1,
started a FLU (Machi data server) with the name `f1`. In the Erlang
process supervisor hierarchy, the process ID of the top supervisor
is `<0.128.0>`.
* `Configured chain c1 via FLU f1 to mode=ap_mode all=[f1,f2,f3] witnesses=[]`
* A bootstrap configuration for a chain named `c1` has been created.
* The FLUs/data servers that are eligible for participation in the
chain have names `f1`, `f2`, and `f3`.
* The chain will operate in eventual consistency mode (`ap_mode`)
* The witness server list is empty. Witness servers are never used
in eventual consistency mode.
* `CONFIRM epoch 1141 <<155,42,7,221>> upi [] rep [] auth f1 by f1`
* All participants in epoch 1141 are unanimous in adopting epoch
1141's projection. All active membership lists are empty, so
there is no functional chain replication yet, at least as far as
server `f1` knows
* The epoch's abbreviated checksum is `<<155,42,7,221>>`.
* The UPI list, i.e. the replicas whose data is 100% in sync is
`[]`, the empty list. (UPI = Update Propagation Invariant)
* The list of servers that are under data repair (`rep`) is also
empty, `[]`.
* This projection was authored by server `f1`.
* The log message was generated by server `f1`.
* `CONFIRM epoch 1148 <<57,213,154,16>> upi [f1] rep [] auth f1 by f1`
* Now the server `f1` has created a chain of length 1, `[f1]`.
* Chain repair/file re-sync is not required when the UPI server list
changes from length 0 -> 1.
* `CONFIRM epoch 1151 <<239,29,39,70>> upi [f1] rep [f3] auth f1 by f1`
* Server `f1` has noticed that server `f3` is alive. Apparently it
has not yet noticed that server `f2` is also running.
* Server `f3` is in the repair list.
* `CONFIRM epoch 1152 <<173,17,66,225>> upi [f2] rep [f1,f3] auth f2 by f1`
* Server `f2` is apparently now aware that all three servers are running.
* The previous configuration used by `f2` was `upi [f2]`, i.e., `f2`
was running in a chain of one. `f2` noticed that `f1` and `f3`
were now available and has started adding them to the chain.
* All new servers are always added to the tail of the chain in the
repair list.
* In eventual consistency mode, a UPI change like this is OK.
* When performing a read, a client must read from both tail of the
UPI list and also from all repairing servers.
* When performing a write, the client writes to both the UPI
server list and also the repairing list, in that order.
* I.e., the client concatenates both lists,
`UPI ++ Repairing`, for its chain configuration for the write.
* Server `f2` will trigger file repair/re-sync shortly.
* The waiting time for starting repair has been configured to be
extremely short, 1 second. The default waiting time is 10
seconds, in case Humming Consensus remains unstable.
* `CONFIRM epoch 1154 <<154,231,224,149>> upi [f2,f1,f3] rep [] auth f2 by f1`
* File repair/re-sync has finished. All file data on all servers
are now in sync.
* The UPI/in-sync part of the chain is now `[f2,f1,f3]`, and there
are no servers under repair.
## Let's create some failures
Here are some suggestions for creating failures.
* Use the `./dev/devN/bin/machi stop` and `./dev/devN/bin/machi start`
commands to stop & start VM #`N`.
* Stop a VM abnormally by using `kill`. The OS process name to look
for is `beam.smp`.
* Suspend and resume a VM, using the `SIGSTOP` and `SIGCONT` signals.
* E.g. `kill -STOP 9823` and `kill -CONT 9823`
The network partition simulator is not (yet) available when running
Machi in this mode. Please see the next section for instructions on
how to use partition simulator.
<a name="partition-simulator">
# Using the network partition simulator and convergence demo test code
This is the demo code mentioned in the presentation that Scott Lystig
Fritchie gave at the
[RICON 2015 conference](http://ricon.io).
* [slides (PDF format)](http://ricon.io/speakers/slides/Scott_Fritchie_Ricon_2015.pdf)
* [video](https://www.youtube.com/watch?v=yR5kHL1bu1Q)
## A complete example of all input and output
If you don't have an Erlang/OTP 17 runtime environment available,
please see this file for full input and output of a strong consistency
length=3 chain test:
https://gist.github.com/slfritchie/8352efc88cc18e62c72c
This file contains all commands input and all simulator output from a
sample run of the simulator.
To help interpret the output of the test, please skip ahead to the
"The test output is very verbose" section.
## Prerequisites
If you don't have `git` and/or the Erlang 17 runtime system available
on your OS X, FreeBSD, Linux, or Solaris machine, please take a look
at the [Prerequisites section](#prerequisites) first. When you have
installed the prerequisite software, please return back here.
## Clone and compile the code
Please briefly visit the [Clone and compile the code](#clone-compile)
section. When finished, please return back here.
## Run an interactive Erlang CLI shell
Run the following command at your login shell:
erl -pz .eunit ebin deps/*/ebin
If you are using Erlang/OTP version 17, you should see some CLI output
that looks like this:
Erlang/OTP 17 [erts-6.4] [source] [64-bit] [smp:8:8] [async-threads:10] [hipe] [kernel-poll:false] [dtrace]
Eshell V6.4 (abort with ^G)
1>
## The test output is very verbose ... what are the important parts?
The output of the Erlang command
`machi_chain_manager1_converge_demo:help()` will display the following
guide to the output of the tests.
A visualization of the convergence behavior of the chain self-management
algorithm for Machi.
1. Set up some server and chain manager pairs.
2. Create a number of different network partition scenarios, where
(simulated) partitions may be symmetric or asymmetric. Then stop changing
the partitions and keep the simulated network stable (and perhaps broken).
3. Run a number of iterations of the algorithm in parallel by poking each
of the manager processes on a random'ish basis.
4. Afterward, fetch the chain transition changes made by each FLU and
verify that no transition was unsafe.
During the iteration periods, the following is a cheatsheet for the output.
See the internal source for interpreting the rest of the output.
'SET partitions = '
A pair-wise list of actors which cannot send messages. The
list is uni-directional. If there are three servers (a,b,c),
and if the partitions list is '[{a,b},{b,c}]' then all
messages from a->b and b->c will be dropped, but any other
sender->recipient messages will be delivered successfully.
'x uses:'
The FLU x has made an internal state transition and is using
this epoch's projection as operating chain configuration. The
rest of the line is a summary of the projection.
'CONFIRM epoch {N}'
This message confirms that all of the servers listed in the
UPI and repairing lists of the projection at epoch {N} have
agreed to use this projection because they all have written
this projection to their respective private projection stores.
The chain is now usable by/available to all clients.
'Sweet, private projections are stable'
This report announces that this iteration of the test cycle
has passed successfully. The report that follows briefly
summarizes the latest private projection used by each
participating server. For example, when in strong consistency
mode with 'a' as a witness and 'b' and 'c' as real servers:
%% Legend:
%% server name, epoch ID, UPI list, repairing list, down list, ...
%% ... witness list, 'false' (a constant value)
[{a,{{1116,<<23,143,246,55>>},[a,b],[],[c],[a],false}},
{b,{{1116,<<23,143,246,55>>},[a,b],[],[c],[a],false}}]
Both servers 'a' and 'b' agree on epoch 1116 with epoch ID
{1116,<<23,143,246,55>>} where UPI=[a,b], repairing=[],
down=[c], and witnesses=[a].
Server 'c' is not shown because 'c' has wedged itself OOS (out
of service) by configuring a chain length of zero.
If no servers are listed in the report (i.e. only '[]' is
displayed), then all servers have wedged themselves OOS, and
the chain is unavailable.
'DoIt,'
This marks a group of tick events which trigger the manager
processes to evaluate their environment and perhaps make a
state transition.
A long chain of 'DoIt,DoIt,DoIt,' means that the chain state has
(probably) settled to a stable configuration, which is the goal of the
algorithm.
Press control-c to interrupt the test....".
## Run a test in eventual consistency mode
Run the following command at the Erlang CLI prompt:
machi_chain_manager1_converge_demo:t(3, [{private_write_verbose,true}]).
The first argument, `3`, is the number of servers to participate in
the chain. Please note:
* Chain lengths as short as 1 or 2 are valid, but the results are a
bit boring.
* Chain lengths as long as 7 or 9 can be used, but they may
suffer from longer periods of churn/instability before all chain
managers reach agreement via humming consensus. (It is future work
to shorten the worst of the unstable churn latencies.)
* In eventual consistency mode, chain lengths may be even numbers,
e.g. 2, 4, or 6.
* The simulator will choose partition events from the permutations of
all 1, 2, and 3 node partition pairs. The total runtime will
increase *dramatically* with chain length.
* Chain length 2: about 3 partition cases
* Chain length 3: about 35 partition cases
* Chain length 4: about 230 partition cases
* Chain length 5: about 1100 partition cases
## Run a test in strong consistency mode (with witnesses):
*NOTE:* Due to a bug in the test code, please do not try to run the
convergence test in strong consistency mode and also without the
correct minority number of witness servers! If in doubt, please run
the commands shown below exactly.
Run the following command at the Erlang CLI prompt:
machi_chain_manager1_converge_demo:t(3, [{private_write_verbose,true}, {consistency_mode, cp_mode}, {witnesses, [a]}]).
The first argument, `3`, is the number of servers to participate in
the chain. Chain lengths as long as 7 or 9 can be used, but they may
suffer from longer periods of churn/instability before all chain
managers reach agreement via humming consensus.
Due to the bug mentioned above, please use the following
commands when running with chain lengths of 5 or 7, respectively.
machi_chain_manager1_converge_demo:t(5, [{private_write_verbose,true}, {consistency_mode, cp_mode}, {witnesses, [a,b]}]).
machi_chain_manager1_converge_demo:t(7, [{private_write_verbose,true}, {consistency_mode, cp_mode}, {witnesses, [a,b,c]}]).

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machi:
latex high-level-machi.tex
dvipdfm high-level-machi.dvi
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pop dup dup newpath 525 -17 moveto 2 div neg 0 rmoveto 0 rlineto 0 11 rlineto neg 0 rlineto closepath fill
0.000000 0.000000 0.000000 setrgbcolor
525 -15 moveto dup stringwidth pop 2 div neg 0 rmoveto show
newpath 75 -22 moveto 75 -49 lineto stroke
newpath 225 -22 moveto 225 -49 lineto stroke
newpath 375 -22 moveto 375 -49 lineto stroke
newpath 525 -22 moveto 525 -49 lineto stroke
newpath 75 -35 moveto 225 -35 lineto stroke
newpath 225 -35 moveto 215 -41 lineto stroke
(get current) dup stringwidth
1.000000 1.000000 1.000000 setrgbcolor
pop dup newpath 122 -33 moveto 0 rlineto 0 11 rlineto neg 0 rlineto closepath fill
0.000000 0.000000 0.000000 setrgbcolor
122 -33 moveto show
newpath 75 -49 moveto 75 -76 lineto stroke
newpath 225 -49 moveto 225 -76 lineto stroke
newpath 375 -49 moveto 375 -76 lineto stroke
newpath 525 -49 moveto 525 -76 lineto stroke
newpath 225 -62 moveto 75 -62 lineto stroke
newpath 75 -62 moveto 85 -68 lineto stroke
(ok, #12...) dup stringwidth
1.000000 1.000000 1.000000 setrgbcolor
pop dup newpath 126 -60 moveto 0 rlineto 0 11 rlineto neg 0 rlineto closepath fill
0.000000 0.000000 0.000000 setrgbcolor
126 -60 moveto show
newpath 75 -76 moveto 75 -103 lineto stroke
newpath 225 -76 moveto 225 -103 lineto stroke
newpath 375 -76 moveto 375 -103 lineto stroke
newpath 525 -76 moveto 525 -103 lineto stroke
newpath 75 -89 moveto 525 -89 lineto stroke
newpath 525 -89 moveto 515 -95 lineto stroke
(read "foo.seq_a.009" offset=447 bytes=123 epoch=12) dup stringwidth
1.000000 1.000000 1.000000 setrgbcolor
pop dup newpath 157 -87 moveto 0 rlineto 0 11 rlineto neg 0 rlineto closepath fill
0.000000 0.000000 0.000000 setrgbcolor
157 -87 moveto show
newpath 75 -103 moveto 75 -130 lineto stroke
newpath 225 -103 moveto 225 -130 lineto stroke
newpath 375 -103 moveto 375 -130 lineto stroke
newpath 525 -103 moveto 525 -130 lineto stroke
newpath 525 -116 moveto 75 -116 lineto stroke
newpath 75 -116 moveto 85 -122 lineto stroke
1.000000 0.000000 0.000000 setrgbcolor
(bad_epoch, 13) dup stringwidth
1.000000 1.000000 1.000000 setrgbcolor
pop dup newpath 261 -114 moveto 0 rlineto 0 11 rlineto neg 0 rlineto closepath fill
1.000000 0.000000 0.000000 setrgbcolor
261 -114 moveto show
0.000000 0.000000 0.000000 setrgbcolor
newpath 75 -130 moveto 75 -157 lineto stroke
newpath 225 -130 moveto 225 -157 lineto stroke
newpath 375 -130 moveto 375 -157 lineto stroke
newpath 525 -130 moveto 525 -157 lineto stroke
newpath 75 -143 moveto 375 -143 lineto stroke
newpath 375 -143 moveto 365 -149 lineto stroke
(get epoch #13) dup stringwidth
1.000000 1.000000 1.000000 setrgbcolor
pop dup newpath 187 -141 moveto 0 rlineto 0 11 rlineto neg 0 rlineto closepath fill
0.000000 0.000000 0.000000 setrgbcolor
187 -141 moveto show
newpath 75 -157 moveto 75 -184 lineto stroke
newpath 225 -157 moveto 225 -184 lineto stroke
newpath 375 -157 moveto 375 -184 lineto stroke
newpath 525 -157 moveto 525 -184 lineto stroke
newpath 375 -170 moveto 75 -170 lineto stroke
newpath 75 -170 moveto 85 -176 lineto stroke
(ok, #13...) dup stringwidth
1.000000 1.000000 1.000000 setrgbcolor
pop dup newpath 201 -168 moveto 0 rlineto 0 11 rlineto neg 0 rlineto closepath fill
0.000000 0.000000 0.000000 setrgbcolor
201 -168 moveto show
newpath 75 -184 moveto 75 -211 lineto stroke
newpath 225 -184 moveto 225 -211 lineto stroke
newpath 375 -184 moveto 375 -211 lineto stroke
newpath 525 -184 moveto 525 -211 lineto stroke
newpath 75 -197 moveto 525 -197 lineto stroke
newpath 525 -197 moveto 515 -203 lineto stroke
(read "foo.seq_a.009" offset=447 bytes=123 epoch=13) dup stringwidth
1.000000 1.000000 1.000000 setrgbcolor
pop dup newpath 157 -195 moveto 0 rlineto 0 11 rlineto neg 0 rlineto closepath fill
0.000000 0.000000 0.000000 setrgbcolor
157 -195 moveto show
newpath 75 -211 moveto 75 -238 lineto stroke
newpath 225 -211 moveto 225 -238 lineto stroke
newpath 375 -211 moveto 375 -238 lineto stroke
newpath 525 -211 moveto 525 -238 lineto stroke
newpath 525 -224 moveto 75 -224 lineto stroke
newpath 75 -224 moveto 85 -230 lineto stroke
(ok, <<...123...>>) dup stringwidth
1.000000 1.000000 1.000000 setrgbcolor
pop dup newpath 257 -222 moveto 0 rlineto 0 11 rlineto neg 0 rlineto closepath fill
0.000000 0.000000 0.000000 setrgbcolor
257 -222 moveto show

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2
ebin/.gitignore vendored
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*.beam
*.app

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@ -1,63 +0,0 @@
%% -------------------------------------------------------------------
%%
%% Copyright (c) 2007-2015 Basho Technologies, Inc. All Rights Reserved.
%%
%% This file is provided to you under the Apache License,
%% Version 2.0 (the "License"); you may not use this file
%% except in compliance with the License. You may obtain
%% a copy of the License at
%%
%% http://www.apache.org/licenses/LICENSE-2.0
%%
%% Unless required by applicable law or agreed to in writing,
%% software distributed under the License is distributed on an
%% "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
%% KIND, either express or implied. See the License for the
%% specific language governing permissions and limitations
%% under the License.
%%
%% -------------------------------------------------------------------
%% @doc Now 4GiBytes, could be up to 64bit due to PB message limit of
%% chunk size
-define(DEFAULT_MAX_FILE_SIZE, ((1 bsl 32) - 1)).
-define(MINIMUM_OFFSET, 1024).
%% 0th draft of checksum typing with 1st byte.
-define(CSUM_TAG_NONE, 0). % No csum provided by client
-define(CSUM_TAG_CLIENT_SHA, 1). % Client-generated SHA1
-define(CSUM_TAG_SERVER_SHA, 2). % Server-genereated SHA1
-define(CSUM_TAG_SERVER_REGEN_SHA, 3). % Server-regenerated SHA1
-define(CSUM_TAG_NONE_ATOM, none).
-define(CSUM_TAG_CLIENT_SHA_ATOM, client_sha).
-define(CSUM_TAG_SERVER_SHA_ATOM, server_sha).
-define(CSUM_TAG_SERVER_REGEN_SHA_ATOM, server_regen_sha).
%% Protocol Buffers goop
-define(PB_MAX_MSG_SIZE, (33*1024*1024)).
-define(PB_PACKET_OPTS, [{packet, 4}, {packet_size, ?PB_MAX_MSG_SIZE}]).
%% TODO: it's used in flu_sup and elsewhere, change this to suitable name
-define(TEST_ETS_TABLE, test_ets_table).
-define(DEFAULT_COC_NAMESPACE, "").
-define(DEFAULT_COC_LOCATOR, 0).
-record(ns_info, {
version = 0 :: machi_dt:namespace_version(),
name = <<>> :: machi_dt:namespace(),
locator = 0 :: machi_dt:locator()
}).
-record(append_opts, {
chunk_extra = 0 :: machi_dt:chunk_size(),
preferred_file_name :: 'undefined' | machi_dt:file_name_s(),
flag_fail_preferred = false :: boolean()
}).
-record(read_opts, {
no_checksum = false :: boolean(),
no_chunk = false :: boolean(),
needs_trimmed = false :: boolean()
}).

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@ -1,26 +0,0 @@
%% -------------------------------------------------------------------
%%
%% Copyright (c) 2007-2015 Basho Technologies, Inc. All Rights Reserved.
%%
%% This file is provided to you under the Apache License,
%% Version 2.0 (the "License"); you may not use this file
%% except in compliance with the License. You may obtain
%% a copy of the License at
%%
%% http://www.apache.org/licenses/LICENSE-2.0
%%
%% Unless required by applicable law or agreed to in writing,
%% software distributed under the License is distributed on an
%% "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
%% KIND, either express or implied. See the License for the
%% specific language governing permissions and limitations
%% under the License.
%%
%% -------------------------------------------------------------------
-include("machi_projection.hrl").
-define(NOT_FLAPPING, {0,0,0}).
-type projection() :: #projection_v1{}.

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@ -1,20 +0,0 @@
%% machi merkle tree records
-record(naive, {
chunk_size = 1048576 :: pos_integer(), %% default 1 MB
recalc = true :: boolean(),
root :: 'undefined' | binary(),
lvl1 = [] :: [ binary() ],
lvl2 = [] :: [ binary() ],
lvl3 = [] :: [ binary() ],
leaves = [] :: [ { Offset :: pos_integer(),
Size :: pos_integer(),
Csum :: binary()} ]
}).
-record(mt, {
filename :: string(),
tree :: #naive{},
backend = 'naive' :: 'naive'
}).

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@ -1,92 +0,0 @@
%% -------------------------------------------------------------------
%%
%% Copyright (c) 2007-2015 Basho Technologies, Inc. All Rights Reserved.
%%
%% This file is provided to you under the Apache License,
%% Version 2.0 (the "License"); you may not use this file
%% except in compliance with the License. You may obtain
%% a copy of the License at
%%
%% http://www.apache.org/licenses/LICENSE-2.0
%%
%% Unless required by applicable law or agreed to in writing,
%% software distributed under the License is distributed on an
%% "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
%% KIND, either express or implied. See the License for the
%% specific language governing permissions and limitations
%% under the License.
%%
%% -------------------------------------------------------------------
-ifndef(MACHI_PROJECTION_HRL).
-define(MACHI_PROJECTION_HRL, true).
-type pv1_consistency_mode() :: 'ap_mode' | 'cp_mode'.
-type pv1_chain_name():: atom().
-type pv1_csum() :: binary().
-type pv1_epoch() :: {pv1_epoch_n(), pv1_csum()}.
-type pv1_epoch_n() :: non_neg_integer().
-type pv1_server() :: atom().
-type pv1_timestamp() :: {non_neg_integer(), non_neg_integer(), non_neg_integer()}.
-record(p_srvr, {
name :: pv1_server(),
proto_mod = 'machi_flu1_client' :: atom(), % Module name
address :: term(), % Protocol-specific
port :: term(), % Protocol-specific
props = [] :: list() % proplist for other related info
}).
-record(flap_i, {
flap_count :: {term(), term()},
all_hosed :: list(),
all_flap_counts :: list(),
my_unique_prop_count :: non_neg_integer()
}).
-type p_srvr() :: #p_srvr{}.
-type p_srvr_dict() :: orddict:orddict().
-define(DUMMY_PV1_EPOCH, {0,<<0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0>>}).
%% Kludge for spam gossip. TODO: replace me
-define(SPAM_PROJ_EPOCH, ((1 bsl 32) - 7)).
-record(projection_v1, {
epoch_number :: pv1_epoch_n() | ?SPAM_PROJ_EPOCH,
epoch_csum :: pv1_csum(),
author_server :: pv1_server(),
chain_name = ch_not_def_yet :: pv1_chain_name(),
all_members :: [pv1_server()],
witnesses = [] :: [pv1_server()],
creation_time :: pv1_timestamp(),
mode = ap_mode :: pv1_consistency_mode(),
upi :: [pv1_server()],
repairing :: [pv1_server()],
down :: [pv1_server()],
dbg :: list(), %proplist(), is checksummed
dbg2 :: list(), %proplist(), is not checksummed
members_dict :: p_srvr_dict()
}).
-define(MACHI_DEFAULT_TCP_PORT, 50000).
-define(SHA_MAX, (1 bsl (20*8))).
%% Set a limit to the maximum chain length, so that it's easier to
%% create a consistent projection ranking score.
-define(MAX_CHAIN_LENGTH, 64).
-record(chain_def_v1, {
name :: atom(), % chain name
mode :: pv1_consistency_mode(),
full = [] :: [p_srvr()],
witnesses = [] :: [p_srvr()],
old_full = [] :: [pv1_server()], % guard against some races
old_witnesses=[] :: [pv1_server()], % guard against some races
local_run = [] :: [pv1_server()], % must be tailored to each machine!
local_stop = [] :: [pv1_server()], % must be tailored to each machine!
props = [] :: list() % proplist for other related info
}).
-endif. % !MACHI_PROJECTION_HRL

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@ -1,31 +0,0 @@
%% -------------------------------------------------------------------
%%
%% Machi: a small village of replicated files
%%
%% Copyright (c) 2014-2015 Basho Technologies, Inc. All Rights Reserved.
%%
%% This file is provided to you under the Apache License,
%% Version 2.0 (the "License"); you may not use this file
%% except in compliance with the License. You may obtain
%% a copy of the License at
%%
%% http://www.apache.org/licenses/LICENSE-2.0
%%
%% Unless required by applicable law or agreed to in writing,
%% software distributed under the License is distributed on an
%% "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
%% KIND, either express or implied. See the License for the
%% specific language governing permissions and limitations
%% under the License.
%%
%% -------------------------------------------------------------------
-ifdef(PULSE).
-define(V(Fmt, Args), pulse:format(Fmt, Args)).
-else. % PULSE
-define(V(Fmt, Args), io:format(user, Fmt, Args)).
-endif. % PULSE
-define(D(X), ?V("~s ~p\n", [??X, X])).
-define(Dw(X), ?V("~s ~w\n", [??X, X])).

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@ -1,45 +0,0 @@
%% Mandatory: adjust this code path to top of your compiled Machi source distro
{code_paths, ["/Users/fritchie/b/src/machi"]}.
{driver, machi_basho_bench_driver}.
%% Chose your maximum rate (per worker proc, see 'concurrent' below)
%{mode, {rate,10}}.
%{mode, {rate,20}}.
{mode, max}.
%% Runtime & reporting interval
{duration, 10}. % minutes
{report_interval, 1}. % seconds
%% Choose your number of worker procs
%{concurrent, 1}.
{concurrent, 5}.
%{concurrent, 10}.
%% Here's a chain of (up to) length 3, all on localhost
%% Note: if any servers are down, and your OS/TCP stack has an
%% ICMP response limit such as OS X's "net.inet.icmp.icmplim" setting,
%% then if that setting is very low (e.g., OS X's limit is 50), then
%% you can have big problems with ICMP/RST responses being delayed and
%% interactive *very* badly with your test.
%% For OS X, fix using "sudo sysctl -w net.inet.icmp.icmplim=9999"
{machi_server_info,
[
{p_srvr,a,machi_flu1_client,"localhost",4444,[]},
{p_srvr,b,machi_flu1_client,"localhost",4445,[]},
{p_srvr,c,machi_flu1_client,"localhost",4446,[]}
]}.
{machi_ets_key_tab_type, set}. % set | ordered_set
%% Workload-specific definitions follow....
%% 10 parts 'append' operation + 0 parts anything else = 100% 'append' ops
{operations, [{append, 10}]}.
%% For append, key = Machi file prefix name
{key_generator, {to_binstr, "prefix~w", {uniform_int, 30}}}.
%% Increase size of value_generator_source_size if value_generator is big!!
{value_generator_source_size, 2111000}.
{value_generator, {fixed_bin, 32768}}. % 32 KB

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@ -1,47 +0,0 @@
%% Mandatory: adjust this code path to top of your compiled Machi source distro
{code_paths, ["/Users/fritchie/b/src/machi"]}.
{driver, machi_basho_bench_driver}.
%% Chose your maximum rate (per worker proc, see 'concurrent' below)
%{mode, {rate,10}}.
%{mode, {rate,20}}.
{mode, max}.
%% Runtime & reporting interval
{duration, 10}. % minutes
{report_interval, 1}. % seconds
%% Choose your number of worker procs
%{concurrent, 1}.
{concurrent, 5}.
%{concurrent, 10}.
%% Here's a chain of (up to) length 3, all on localhost
%% Note: if any servers are down, and your OS/TCP stack has an
%% ICMP response limit such as OS X's "net.inet.icmp.icmplim" setting,
%% then if that setting is very low (e.g., OS X's limit is 50), then
%% you can have big problems with ICMP/RST responses being delayed and
%% interactive *very* badly with your test.
%% For OS X, fix using "sudo sysctl -w net.inet.icmp.icmplim=9999"
{machi_server_info,
[
{p_srvr,a,machi_flu1_client,"localhost",4444,[]},
{p_srvr,b,machi_flu1_client,"localhost",4445,[]},
{p_srvr,c,machi_flu1_client,"localhost",4446,[]}
]}.
{machi_ets_key_tab_type, set}. % set | ordered_set
%% Workload-specific definitions follow....
%% 10 parts 'read' operation + 0 parts anything else = 100% 'read' ops
{operations, [{read, 10}]}.
%% For read, key = integer index into Machi's chunk ETS table, modulo the
%% ETS table size, so a huge number here is OK.
{key_generator, {uniform_int, 999999999999}}.
%% For read, value_generator_* isn't used, so leave these defaults as-is.
{value_generator_source_size, 2111000}.
{value_generator, {fixed_bin, 32768}}. % 32 KB

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@ -1,56 +0,0 @@
#!/bin/sh
echo "Step: Verify that the required entries in /etc/hosts are present"
for i in 1 2 3; do
grep machi$i /etc/hosts | egrep -s '^127.0.0.1' > /dev/null 2>&1
if [ $? -ne 0 ]; then
echo ""
echo "'grep -s machi$i' failed. Aborting, sorry."
exit 1
fi
ping -c 1 machi$i > /dev/null 2>&1
if [ $? -ne 0 ]; then
echo ""
echo "Ping attempt on host machi$i failed. Aborting."
echo ""
ping -c 1 machi$i
exit 1
fi
done
echo "Step: add a verbose logging option to app.config"
for i in 1 2 3; do
ed ./dev/dev$i/etc/app.config <<EOF > /dev/null 2>&1
/verbose_confirm
a
{chain_manager_opts, [{private_write_verbose_confirm,true}]},
{stability_time, 1},
.
w
q
EOF
done
echo "Step: start three three Machi application instances"
for i in 1 2 3; do
./dev/dev$i/bin/machi start
./dev/dev$i/bin/machi ping
if [ $? -ne 0 ]; then
echo "Sorry, a 'ping' check for instance dev$i failed. Aborting."
exit 1
fi
done
echo "Step: configure one chain to start a Humming Consensus group with three members"
# Note: $CWD of each Machi proc is two levels below the source code root dir.
LIFECYCLE000=../../priv/quick-admin-examples/demo-000
for i in 3 2 1; do
./dev/dev$i/bin/machi-admin quick-admin-apply $LIFECYCLE000 machi$i
if [ $? -ne 0 ]; then
echo "Sorry, 'machi-admin quick-admin-apply failed' on machi$i. Aborting."
exit 1
fi
done
exit 0

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@ -1,93 +0,0 @@
# -*- mode: ruby -*-
# vi: set ft=ruby :
# All Vagrant configuration is done below. The "2" in Vagrant.configure
# configures the configuration version (we support older styles for
# backwards compatibility). Please don't change it unless you know what
# you're doing.
Vagrant.configure(2) do |config|
# The most common configuration options are documented and commented below.
# For a complete reference, please see the online documentation at
# https://docs.vagrantup.com.
# Every Vagrant development environment requires a box. You can search for
# boxes at https://atlas.hashicorp.com/search.
# If this Vagrant box has not been downloaded before (e.g. using "vagrant box add"),
# then Vagrant will automatically download the VM image from HashiCorp.
config.vm.box = "hashicorp/precise64"
# If using a FreeBSD box, Bash may not be installed.
# Use the config.ssh.shell setting to specify an alternate shell.
# Note, however, that any code in the 'config.vm.provision' section
# would then have to use this shell's syntax!
# config.ssh.shell = "/bin/csh -l"
# Disable automatic box update checking. If you disable this, then
# boxes will only be checked for updates when the user runs
# `vagrant box outdated`. This is not recommended.
# config.vm.box_check_update = false
# Create a forwarded port mapping which allows access to a specific port
# within the machine from a port on the host machine. In the example below,
# accessing "localhost:8080" will access port 80 on the guest machine.
# config.vm.network "forwarded_port", guest: 80, host: 8080
# Create a private network, which allows host-only access to the machine
# using a specific IP.
# config.vm.network "private_network", ip: "192.168.33.10"
# Create a public network, which generally matched to bridged network.
# Bridged networks make the machine appear as another physical device on
# your network.
# config.vm.network "public_network"
# Share an additional folder to the guest VM. The first argument is
# the path on the host to the actual folder. The second argument is
# the path on the guest to mount the folder. And the optional third
# argument is a set of non-required options.
# config.vm.synced_folder "../data", "/vagrant_data"
# Provider-specific configuration so you can fine-tune various
# backing providers for Vagrant. These expose provider-specific options.
# Example for VirtualBox:
#
config.vm.provider "virtualbox" do |vb|
# Display the VirtualBox GUI when booting the machine
# vb.gui = true
# Customize the amount of memory on the VM:
vb.memory = "512"
end
#
# View the documentation for the provider you are using for more
# information on available options.
# Define a Vagrant Push strategy for pushing to Atlas. Other push strategies
# such as FTP and Heroku are also available. See the documentation at
# https://docs.vagrantup.com/v2/push/atlas.html for more information.
# config.push.define "atlas" do |push|
# push.app = "YOUR_ATLAS_USERNAME/YOUR_APPLICATION_NAME"
# end
# Enable provisioning with a shell script. Additional provisioners such as
# Puppet, Chef, Ansible, Salt, and Docker are also available. Please see the
# documentation for more information about their specific syntax and use.
config.vm.provision "shell", inline: <<-SHELL
# Install prerequsites
# Support here for FreeBSD is experimental
apt-get update ; sudo apt-get install -y git sudo rsync ; # Ubuntu Linux
env ASSUME_ALWAYS_YES=yes pkg install -f git sudo rsync ; # FreeBSD 10
# Install dependent packages, using slf-configurator
git clone https://github.com/slfritchie/slf-configurator.git
chown -R vagrant ./slf-configurator
(cd slf-configurator ; sudo sh -x ./ALL.sh)
echo 'export PATH=${PATH}:/usr/local/erlang/17.5/bin' >> ~vagrant/.bashrc
export PATH=${PATH}:/usr/local/erlang/17.5/bin
## echo 'set path = ( $path /usr/local/erlang/17.5/bin )' >> ~vagrant/.cshrc
## setenv PATH /usr/local/erlang/17.5/bin:$PATH
git clone https://github.com/basho/machi.git
(cd machi ; git checkout master ; make && make test )
chown -R vagrant ./machi
SHELL
end

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@ -1,81 +0,0 @@
#!/usr/bin/perl
$input = shift;
$tmp1 = "/tmp/my-tmp.1.$$";
$tmp2 = "/tmp/my-tmp.2.$$";
$l1 = 0;
$l2 = 0;
$l3 = 0;
open(I, $input);
open(T1, "> $tmp1");
open(T2, "> $tmp2");
while (<I>) {
if (/^##*/) {
$line = $_;
chomp;
@a = split;
$count = length($a[0]) - 2;
if ($count >= 0) {
if ($count == 0) {
$l1++;
$l2 = 0;
$l3 = 0;
$label = "$l1"
}
if ($count == 1) {
$l2++;
$l3 = 0;
$label = "$l1.$l2"
}
if ($count == 2) {
$l3++;
$label = "$l1.$l2.$l3"
}
$indent = " " x ($count * 4);
s/^#*\s*[0-9. ]*//;
$anchor = "n$label";
printf T1 "%s+ [%s. %s](#%s)\n", $indent, $label, $_, $anchor;
printf T2 "<a name=\"%s\">\n", $anchor;
$line =~ s/(#+)\s*[0-9. ]*/$1 $label. /;
print T2 $line;
} else {
print T2 $_, "\n";
}
} else {
next if /^<a name="n[0-9.]+">/;
print T2 $_;
}
}
close(I);
close(T1);
close(T2);
open(T2, $tmp2);
while (<T2>) {
if (/<!\-\- OUTLINE \-\->/) {
print;
print "\n";
open(T1, $tmp1);
while (<T1>) {
print;
}
close(T1);
while (<T2>) {
if (/<!\-\- ENDOUTLINE \-\->/) {
print "\n";
print;
last;
}
}
} else {
print;
}
}
close(T2);
unlink($tmp1);
unlink($tmp2);
exit(0);

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@ -1 +0,0 @@
{host, "localhost", []}.

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@ -1,4 +0,0 @@
{flu,f1,"localhost",20401,[]}.
{flu,f2,"localhost",20402,[]}.
{flu,f3,"localhost",20403,[]}.
{chain,c1,[f1,f2,f3],[]}.

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@ -1,4 +0,0 @@
{flu,f4,"localhost",20404,[]}.
{flu,f5,"localhost",20405,[]}.
{flu,f6,"localhost",20406,[]}.
{chain,c2,[f4,f5,f6],[]}.

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@ -1,7 +0,0 @@
{host, "machi1", []}.
{host, "machi2", []}.
{host, "machi3", []}.
{flu,f1,"machi1",20401,[]}.
{flu,f2,"machi2",20402,[]}.
{flu,f3,"machi3",20403,[]}.
{chain,c1,[f1,f2,f3],[]}.

View file

@ -1,10 +0,0 @@
#!/bin/sh
if [ "${TRAVIS_PULL_REQUEST}" = "false" ]; then
echo '$TRAVIS_PULL_REQUEST is false, skipping tests'
exit 0
else
echo '$TRAVIS_PULL_REQUEST is not false ($TRAVIS_PULL_REQUEST), running tests'
make test
make dialyzer
fi

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@ -1,64 +0,0 @@
# Prototype directory
The contents of the `prototype` directory is the result of
consolidating several small & independent repos. Originally, each
small was a separate prototype/quick hack for experimentation
purposes. The code is preserved here for use as:
* Examples of what not to do ... the code **is** a bit ugly, after
all. <tt>^_^</tt>
* Some examples of what to do when prototyping in Erlang. For
example, "Let it crash" style coding is so nice to hack on quickly.
* Some code might actually be reusable, as-is or after some
refactoring.
The prototype code here is not meant for long-term use or
maintenance. We are unlikely to accept changes/pull requests for adding
large new features or to build full Erlang/OTP applications using this
code only.
However, pull requests for small changes, such as support for
newer Erlang versions (e.g., Erlang 17), will be gladly accepted.
We will also accept fixes for bugs in the test code.
## The corfurl prototype
The `corfurl` code is a mostly-complete complete implementation of the
CORFU server & client specification. More details on the papers about
CORFU are mentioned in the `corfurl/docs/corfurl.md` file.
This code contains a QuickCheck + PULSE test. If you wish to use it,
please note the usage instructions and restrictions mentioned in the
`README.md` file.
## The demo-day-hack prototype
This code in the `demo-day-hack` is expected to remain static,
as an archive of past "Demo Day" work.
See the top-level README.md file for details on work to move
much of this code out of the `prototype` directory and into real
use elsewhere in the repo.
## The tango prototype
A quick & dirty prototype of Tango on top of the `prototype/corfurl`
CORFU implementation. The implementation is powerful enough (barely)
to run concurrently on multiple Erlang nodes. See its `README.md`
file for limitations, TODO items, etc.
## The chain-manager prototype
This is a very early experiment to try to create a distributed "rough
consensus" algorithm that is sufficient & safe for managing the order
of a Chain Replication chain, its members, and its chain order.
Unlike the other code projects in this repository's `prototype`
directory, the chain management code is still under active
development. However, the chain manager code here in the `prototype`
subdirectory will remain frozen in time.
Efforts in April 2015 have moved the chain manager code to the "top level"
of the repository. All new work is being merged weekly into the `master`
branch, see `src/machi_chain_manager1.erl` and related source at the top of
the repo.

View file

@ -6,4 +6,3 @@ deps
ebin/*.beam
ebin/*.app
erl_crash.dump
RUNLOG*

View file

@ -14,7 +14,7 @@ deps:
$(REBAR_BIN) get-deps
clean:
$(REBAR_BIN) -r clean
$(REBAR_BIN) clean
test: deps compile eunit
@ -23,7 +23,7 @@ eunit:
pulse: compile
env USE_PULSE=1 $(REBAR_BIN) skip_deps=true clean compile
env USE_PULSE=1 $(REBAR_BIN) skip_deps=true -D PULSE -v eunit
env USE_PULSE=1 $(REBAR_BIN) -v skip_deps=true -D PULSE eunit
CONC_ARGS = --pz ./.eunit --treat_as_normal shutdown --after_timeout 1000
@ -41,15 +41,3 @@ concuerror: deps compile
concuerror -m machi_flu0_test -t proj_store_test $(CONC_ARGS)
concuerror -m machi_flu0_test -t wedge_test $(CONC_ARGS)
concuerror -m machi_flu0_test -t proj0_test $(CONC_ARGS)
APPS = kernel stdlib sasl erts ssl compiler eunit
PLT = $(HOME)/.chmgr_dialyzer_plt
build_plt: deps compile
dialyzer --build_plt --output_plt $(PLT) --apps $(APPS) deps/*/ebin
dialyzer: deps compile
dialyzer -Wno_return --plt $(PLT) ebin
clean_plt:
rm $(PLT)

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@ -1,202 +0,0 @@
# The chain manager prototype
This is a very early experiment to try to create a distributed "rough
consensus" algorithm that is sufficient & safe for managing the order
of a Chain Replication chain, its members, and its chain order. A
name hasn't been chosen yet, though the following are contenders:
* chain self-management
* rough consensus
* humming consensus
* foggy consensus
## Code status: active!
Unlike the other code projects in this repository's `prototype`
directory, the chain management code is still under active
development. It is quite likely (as of early March 2015) that this
code will be robust enough to move to the "real" Machi code base soon.
The most up-to-date documentation for this prototype will **not** be
found in this subdirectory. Rather, please see the `doc` directory at
the top of the Machi source repository.
## Testing, testing, testing
It's important to implement any Chain Replication chain manager as
close to 100% bug-free as possible. Any bug can introduce the
possibility of data loss, which is something we must avoid.
Therefore, we will spend a large amount of effort to use as many
robust testing tools and methods as feasible to test this code.
* [Concuerror](http://concuerror.com), a DPOR-based full state space
exploration tool. Some preliminary Concuerror tests can be found in the
`test/machi_flu0_test.erl` module.
* [QuickCheck](http://www.quviq.com/products/erlang-quickcheck/), a
property-based testing tool for Erlang. QuickCheck doesn't provide
the reassurance of 100% state exploration, but it proven quite
effective at Basho for finding numerous subtle bugs.
* Automatic simulation of arbitrary network partition failures. This
code is already in progress and is used, for example, by the
`test/machi_chain_manager1_test.erl` module.
* TLA+ (future work), to try to create a rigorous model of the
algorithm and its behavior
If you'd like to work on additional testing of this component, please
[open a new GitHub Issue ticket](https://github.com/basho/machi) with
any questions you have. Or just open a GitHub pull request. <tt>^_^</tt>
## Compilation & unit testing
Use `make` and `make test`. Note that the Makefile assumes that the
`rebar` utility is available somewhere in your path.
Tested using Erlang/OTP R16B and Erlang/OTP 17, both on OS X.
If you wish to run the PULSE test in
`test/machi_chain_manager1_pulse.erl` module, you must use Erlang
R16B and Quviq QuickCheck 1.30.2 -- there is a known problem with
QuickCheck 1.33.2, sorry! Also, please note that a single iteration
of a PULSE test case in this model can run for 10s of seconds!
Otherwise, it ought to "just work" on other versions of Erlang and on other OS
platforms, but sorry, I haven't tested it.
### Testing with simulated network partitions
See the `doc/chain-self-management-sketch.org` file for details of how
the simulator works.
In summary, the simulator tries to emulate the effect of arbitrary
asymmetric network partitions. For example, for two simulated nodes A
and B, it's possible to have node A send messages to B, but B cannot
send messages to A.
This kind of one-way message passing is nearly impossible do with
distributed Erlang, because disterl uses TCP. If a network partition
happens at ISO Layer 2 (for example, due to a bad Ethernet cable that
has a faulty receive wire), the entire TCP connection will hang rather
than deliver disterl messages in only one direction.
### Testing simulated data "repair"
In the Machi documentation, "repair" is a re-syncronization of data
between the UPI members of the chain (see below) and members which
have been down/partitioned/gone-to-Hawaii-for-vacation for some period
of time and may have state which is out-of-sync with the rest of the
active-and-running-and-fully-in-sync chain members.
A rough-and-inaccurate-but-useful summary of state transitions are:
down -> repair eligible -> repairing started -> repairing finished -> upi
* Any state can transition back to 'down'
* Repair interruptions might trigger a transition to
'repair eligible instead of 'down'.
* UPI = Update Propagation Invariant (per the original
Chain Replication paper) preserving members.
I.e., The state stored by any UPI member is fully
in sync with all other UPI chain members, except
for new updates which are being processed by Chain
Replication at a particular instant in time.
In both the PULSE and `convergence_demo*()` tests, there is a
simulated time when a FLU's repair state goes from "repair started" to
"repair finished", which means that the FLU-under-repair is now
eligible to join the UPI portion of the chain as a fully-sync'ed
member of the chain. The simulation is based on a simple "coin
flip"-style random choice.
The simulator framework is simulating repair failures when a network
partition is detected with the repair destination FLU. In the "real
world", other kinds of failure could also interrupt the repair
process.
### The PULSE test in machi_chain_manager1_test.erl
As mentioned above, this test is quite slow: it can take many dozens
of seconds to execute a single test case. However, the test really is using
PULSE to play strange games with Erlang process scheduling.
Unfortnately, the PULSE framework is very slow for this test. We'd
like something better, so I wrote the
`machi_chain_manager1_test:convergence_demo_test()` test to use most
of the network partition simulator to try to run many more partition
scenarios in the same amount of time.
### machi_chain_manager1_test:convergence_demo1()
This function is intended both as a demo and as a possible
fully-automated sanity checking function (it will throw an exception
when a model failure happens). It's purpose is to "go faster" than
the PULSE test describe above. It meets this purpose handily.
However, it doesn't give quite as much confidence as PULSE does that
Erlang process scheduling cannot somehow break algorithm running
inside the simulator.
To execute:
make test
erl -pz ./.eunit deps/*/ebin
ok = machi_chain_manager1_test:convergence_demo1().
In summary:
* Set up four FLUs, `[a,b,c,d]`, to be used for the test
* Set up a set of random asymmetric network partitions, based on a
'seed' for a pseudo-random number generator. Each call to the
partition simulator may yield a different partition scenario ... so
the simulated environment is very unstable.
* Run the algorithm for a while so that it has witnessed the partition
instability for a long time.
* Set the partitions definition to a fixed `[{a,b}]`, meaning that FLU `a`
cannot send messages to FLU `b`, but all other communication
(including messages from `b -> a`) works correctly.
* Run the algorithm, wait for everyone to settle on rough consensus.
* Set the partition definition to wildly random again.
* Run the algorithm for a while so that it has witnessed the partition
instability for a long time.
* Set the partitions definition to a fixed `[{a,c}]`.
* Run the algorithm, wait for everyone to settle on rough consensus.
* Set the partitions definition to a fixed `[]`, i.e., there are no
network partitions at all.
* Run the algorithm, wait for everyone to settle on a **unanimous value**
of some ordering of all four FLUs.
To try to understand the simulator's output, let's look at some examples:
20:12:59.120 c uses: [{epoch,1023},{author,d},{upi,[c,b,d,a]},{repair,[]},{down,[]},{d,[{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[[a,b,c,d]]},{hooray,{v2,{2015,3,3},{20,12,59}}}]}]
So, server C has decided the following, as far as it can tell:
* Epoch 1023 is the latest epoch
* There's already a projection written to the "public" projection stores by author server D.
* C has decided that D's proposal is the best out of all that C can see in the "public" projection stores plus its own calculation
* The UPI/active chain order is: C (head), B, D, A (tail).
* No servers are under repair
* No servers are down.
* Then there's some other debugging/status info in the 'd' and 'd2' data attributes
* The 'react' to outside stimulus triggered the author's action
* The 'ps' says that there are no network partitions *inside the simulator* (yes, that's cheating, but sooo useful for debugging)
* All 4 nodes are believed up
* (aside) The 'ps' partition list describes nodes that cannot talk to each other.
* For easier debugging/visualization, the 'network_islands' converts 'ps' into lists of "islands" where nodes can talk to each other.
* So 'network_islands' says that A&B&C&D can all message each other, as far as author D understands at the moment.
* Hooray, the decision was made at 20:12:59 on 2015-03-03.
So, let's see a tiny bit of what happens when there's an asymmetric
network partition. Note that no consensus has yet been reached:
participants are still churning/uncertain.
20:12:48.420 a uses: [{epoch,1011},{author,a},{upi,[a,b]},{repair,[d]},{down,[c]},{d,[{author_proc,react},{ps,[{a,c}]},{nodes_up,[a,b,d]}]},{d2,[{network_islands,[na_reset_by_always]},{hooray,{v2,{2015,3,3},{20,12,48}}}]}]
20:12:48.811 d uses: [{epoch,1012},{author,d},{upi,[a]},{repair,[b,c,d]},{down,[]},{d,[{author_proc,react},{ps,[{a,c}]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[na_reset_by_always]},{hooray,{v2,{2015,3,3},{20,12,48}}}]}]
{FLAP: a flaps 5}!
* The simulator says that the one-way partition definition is `{ps,[{a,c}]}`. This is authoritative info from the simulator. The algorithm *does not* use this source of info, however!
* Server A believes that `{nodes_up,[a,b,d]}`. A is a victim of the simulator's partitioning, so this belief is correct relative to A.
* Server D believes that `{nodes_up,[a,b,c,d]}`. D doesn't have any simulator partition, so this belief is also correct relative to D.
* A participant has now noticed that server A has "flapped": it has
proposed the same proposal at least 5 times in a row. This kind of
pattern is indicative of an asymmetric partition ... which is indeed
what is happening at this moment.

View file

@ -0,0 +1,431 @@
/Users/fritchie/b/src/rebar/rebar get-deps
==> goldrush (get-deps)
==> lager (get-deps)
==> chain-manager (get-deps)
/Users/fritchie/b/src/rebar/rebar compile
==> goldrush (compile)
Compiled src/gre.erl
Compiled src/gr_param_sup.erl
Compiled src/gr_sup.erl
Compiled src/gr_manager_sup.erl
Compiled src/gr_counter_sup.erl
Compiled src/gr_manager.erl
Compiled src/gr_context.erl
Compiled src/gr_app.erl
Compiled src/gr_param.erl
Compiled src/glc_ops.erl
Compiled src/gr_counter.erl
Compiled src/glc.erl
Compiled src/glc_lib.erl
Compiled src/glc_code.erl
==> lager (compile)
Compiled src/lager_util.erl
Compiled src/lager_transform.erl
Compiled src/lager_sup.erl
Compiled src/lager_msg.erl
Compiled src/lager_handler_watcher_sup.erl
Compiled src/lager_handler_watcher.erl
Compiled src/lager_stdlib.erl
Compiled src/lager_trunc_io.erl
Compiled src/lager_default_formatter.erl
Compiled src/lager_format.erl
Compiled src/lager_crash_log.erl
Compiled src/lager_console_backend.erl
Compiled src/lager_file_backend.erl
Compiled src/lager_config.erl
Compiled src/lager_backend_throttle.erl
Compiled src/lager_app.erl
Compiled src/lager.erl
Compiled src/error_logger_lager_h.erl
==> chain-manager (compile)
Compiled src/machi_util.erl
Compiled src/machi_flu0.erl
Compiled src/machi_chain_manager0.erl
Compiled src/machi_chain_manager1.erl
/Users/fritchie/b/src/rebar/rebar -v skip_deps=true eunit
INFO: Looking for lager-2.0.1 ; found lager-2.0.1 at /Users/fritchie/b/src/machi/prototype/chain-manager/deps/lager
INFO: Looking for lager-2.0.1 ; found lager-2.0.1 at /Users/fritchie/b/src/machi/prototype/chain-manager/deps/lager
INFO: Looking for goldrush-.* ; found goldrush-0.1.5 at /Users/fritchie/b/src/machi/prototype/chain-manager/deps/goldrush
INFO: Looking for goldrush-.* ; found goldrush-0.1.5 at /Users/fritchie/b/src/machi/prototype/chain-manager/deps/goldrush
==> chain-manager (eunit)
INFO: sh info:
cwd: "/Users/fritchie/b/src/machi/prototype/chain-manager"
cmd: cp -R src/machi_util.erl src/machi_flu0.erl src/machi_chain_manager1.erl src/machi_chain_manager0.erl test/pulse_util/lamport_clock.erl test/pulse_util/handle_errors.erl test/pulse_util/event_logger.erl test/machi_util_test.erl test/machi_partition_simulator.erl test/machi_flu0_test.erl test/machi_chain_manager1_test.erl test/machi_chain_manager1_pulse.erl test/machi_chain_manager0_test.erl ".eunit"
Compiled src/machi_flu0.erl
Compiled src/machi_util.erl
Compiled test/pulse_util/lamport_clock.erl
Compiled test/pulse_util/handle_errors.erl
Compiled src/machi_chain_manager0.erl
Compiled test/pulse_util/event_logger.erl
Compiled test/machi_partition_simulator.erl
Compiled test/machi_util_test.erl
Compiled test/machi_flu0_test.erl
Compiled test/machi_chain_manager1_pulse.erl
Compiled test/machi_chain_manager1_test.erl
Compiled src/machi_chain_manager1.erl
Compiled test/machi_chain_manager0_test.erl
======================== EUnit ========================
machi_util_test: repair_merge_test_ (module 'machi_util_test')...............................................................................................................................................................................................................................................................................................................
OK, passed 300 tests
[1.733 s] ok
module 'machi_util'
module 'machi_partition_simulator'
module 'machi_flu0_test'
machi_flu0_test: repair_status_test...[0.002 s] ok
machi_flu0_test: concuerror1_test...ok
machi_flu0_test: concuerror2_test...ok
machi_flu0_test: concuerror3_test...ok
machi_flu0_test: concuerror4_test...ok
machi_flu0_test: proj_store_test...ok
machi_flu0_test: wedge_test...ok
machi_flu0_test: proj0_test...[0.001 s] ok
[done in 0.026 s]
module 'machi_flu0'
module 'machi_chain_manager1_test'
machi_chain_manager1_test: smoke0_test...[{epoch,1},{author,a},{upi,[a,b,c]},{repair,[]},{down,[]},{d,[{author_proc,call},{ps,[]},{nodes_up,[a,b,c]}]},{d2,[]}]
[{epoch,1},{author,a},{upi,[a]},{repair,[]},{down,[b,c]},{d,[{author_proc,call},{ps,[{a,b},{c,a},{b,c},{c,b}]},{nodes_up,[a]}]},{d2,[]}]
[{epoch,1},{author,a},{upi,[a,b]},{repair,[]},{down,[c]},{d,[{author_proc,call},{ps,[{c,a},{b,c}]},{nodes_up,[a,b]}]},{d2,[]}]
[{epoch,1},{author,a},{upi,[a,b]},{repair,[]},{down,[c]},{d,[{author_proc,call},{ps,[{c,a},{b,c}]},{nodes_up,[a,b]}]},{d2,[]}]
[{epoch,1},{author,a},{upi,[a]},{repair,[]},{down,[b,c]},{d,[{author_proc,call},{ps,[{a,b},{b,a},{a,c},{c,a},{b,c}]},{nodes_up,[a]}]},{d2,[]}]
[0.003 s] ok
machi_chain_manager1_test: smoke1_test...[0.001 s] ok
machi_chain_manager1_test: nonunanimous_setup_and_fix_test...x x
_XX {not_unanimous,{projection,1,<<110,253,187,8,20,172,231,72,56,72,97,162,22,0,234,37,105,166,11,10>>,[a,b],[a],{1425,368983,392344},b,[b],[],[{hackhack,103}],[]},[{unanimous_flus,[b]},{not_unanimous_flus,[{projection,1,<<125,66,48,143,209,3,150,235,225,93,216,21,70,165,243,106,106,243,105,176>>,[a,b],[b],{1425,368983,392326},a,[a],[],[{hackhack,100}],[]}]},{all_members_replied,true}]}
[0.001 s] ok
machi_chain_manager1_test: convergence_demo_test_...16:49:43.396 a uses: [{epoch,1},{author,a},{upi,[a,b,c,d]},{repair,[]},{down,[]},{d,[{author_proc,call},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[[a,b,c,d]]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
XX1 1
16:49:43.396 b uses: [{epoch,1},{author,a},{upi,[a,b,c,d]},{repair,[]},{down,[]},{d,[{author_proc,call},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[[a,b,c,d]]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.396 c uses: [{epoch,1},{author,a},{upi,[a,b,c,d]},{repair,[]},{down,[]},{d,[{author_proc,call},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[[a,b,c,d]]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
QQ unanimous
? MGR : make_projection_summary ( QQP2 ) [{epoch,1},{author,a},{upi,[a,b,c,d]},{repair,[]},{down,[]},{d,[{author_proc,call},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[]}]
QQE2 [{unanimous_flus,[a,b,c,d]},
{not_unanimous_flus,[]},
{all_members_replied,true}]
16:49:43.397 d uses: [{epoch,1},{author,a},{upi,[a,b,c,d]},{repair,[]},{down,[]},{d,[{author_proc,call},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[[a,b,c,d]]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.398 c uses: [{epoch,4},{author,c},{upi,[c]},{repair,[]},{down,[a,b,d]},{d,[{author_proc,react},{ps,[{a,b},{b,a},{a,c},{c,b},{b,d},{d,b},{c,d},{d,c}]},{nodes_up,[c]}]},{d2,[{network_islands,[islands_not_supported]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.399 d uses: [{epoch,10},{author,d},{upi,[d]},{repair,[]},{down,[a,b,c]},{d,[{author_proc,react},{ps,[{d,a},{b,c},{b,d},{d,b},{c,d}]},{nodes_up,[d]}]},{d2,[{network_islands,[islands_not_supported]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.401 d uses: [{epoch,19},{author,d},{upi,[d]},{repair,[a,b,c]},{down,[]},{d,[{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[[a,b,c,d]]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.403 d uses: [{epoch,26},{author,d},{upi,[d]},{repair,[a,b,c]},{down,[]},{d,[{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[[a,b,c,d]]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.404 d uses: [{epoch,28},{author,d},{upi,[d]},{repair,[a,b,c]},{down,[]},{d,[{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[[a,b,c,d]]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.405 d uses: [{epoch,34},{author,d},{upi,[d]},{repair,[]},{down,[a,b,c]},{d,[{author_proc,react},{ps,[{b,a},{a,c},{c,a},{a,d},{b,c},{c,b},{d,b},{c,d},{d,c}]},{nodes_up,[d]}]},{d2,[{network_islands,[islands_not_supported]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.406 d uses: [{epoch,38},{author,d},{upi,[d]},{repair,[a,b,c]},{down,[]},{d,[{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[[a,b,c,d]]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.408 d uses: [{epoch,45},{author,d},{upi,[d]},{repair,[]},{down,[a,b,c]},{d,[{author_proc,react},{ps,[{a,b},{b,a},{a,c},{c,a},{a,d},{d,a},{b,c},{c,b},{b,d},{d,b},{c,d},{d,c}]},{nodes_up,[d]}]},{d2,[{network_islands,[islands_not_supported]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.411 d uses: [{epoch,63},{author,d},{upi,[d]},{repair,[]},{down,[a,b,c]},{d,[{author_proc,react},{ps,[{b,a},{a,c},{c,a},{a,d},{d,a},{b,c},{c,b},{b,d},{d,b},{c,d},{d,c}]},{nodes_up,[d]}]},{d2,[{network_islands,[islands_not_supported]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.412 d uses: [{epoch,65},{author,d},{upi,[d]},{repair,[]},{down,[a,b,c]},{d,[{author_proc,react},{ps,[{a,b},{b,a},{a,c},{c,a},{a,d},{d,a},{b,c},{c,b},{b,d},{d,b},{d,c}]},{nodes_up,[d]}]},{d2,[{network_islands,[islands_not_supported]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.414 d uses: [{epoch,71},{author,d},{upi,[d]},{repair,[a,b,c]},{down,[]},{d,[{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[[a,b,c,d]]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.417 d uses: [{epoch,85},{author,d},{upi,[d]},{repair,[a,c]},{down,[b]},{d,[{author_proc,react},{ps,[{d,b}]},{nodes_up,[a,c,d]}]},{d2,[{network_islands,[islands_not_supported]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.418 d uses: [{epoch,87},{author,d},{upi,[d]},{repair,[a,c,b]},{down,[]},{d,[{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[[a,b,c,d]]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.421 d uses: [{epoch,98},{author,d},{upi,[d]},{repair,[]},{down,[a,b,c]},{d,[{author_proc,react},{ps,[{a,b},{b,a},{a,c},{c,a},{a,d},{d,a},{b,c},{c,b},{b,d},{d,b},{c,d},{d,c}]},{nodes_up,[d]}]},{d2,[{network_islands,[islands_not_supported]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.423 d uses: [{epoch,104},{author,d},{upi,[d]},{repair,[]},{down,[a,b,c]},{d,[{author_proc,react},{ps,[{a,b},{b,a},{a,d},{d,a},{b,c},{c,b},{b,d},{d,b},{c,d},{d,c}]},{nodes_up,[d]}]},{d2,[{network_islands,[islands_not_supported]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.424 d uses: [{epoch,107},{author,d},{upi,[d]},{repair,[a,b,c]},{down,[]},{d,[{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[[a,b,c,d]]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.425 d uses: [{epoch,110},{author,d},{upi,[d]},{repair,[a,b,c]},{down,[]},{d,[{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[islands_not_supported]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.426 d uses: [{epoch,113},{author,d},{upi,[d]},{repair,[]},{down,[a,b,c]},{d,[{author_proc,react},{ps,[{a,b},{b,a},{a,c},{c,a},{a,d},{b,c},{c,b},{d,b},{c,d},{d,c}]},{nodes_up,[d]}]},{d2,[{network_islands,[islands_not_supported]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.426 d uses: [{epoch,116},{author,d},{upi,[d]},{repair,[]},{down,[a,b,c]},{d,[{author_proc,react},{ps,[{a,b},{a,c},{a,d},{c,b},{b,d},{d,b},{d,c}]},{nodes_up,[d]}]},{d2,[{network_islands,[islands_not_supported]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.427 d uses: [{epoch,118},{author,d},{upi,[d]},{repair,[]},{down,[a,b,c]},{d,[{author_proc,react},{ps,[{a,b},{b,a},{c,a},{a,d},{d,a},{b,c},{b,d},{d,b},{c,d},{d,c}]},{nodes_up,[d]}]},{d2,[{network_islands,[islands_not_supported]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.428 d uses: [{epoch,121},{author,d},{upi,[d]},{repair,[a,b,c]},{down,[]},{d,[{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[[a,b,c,d]]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.428 d uses: [{epoch,123},{author,d},{upi,[d]},{repair,[]},{down,[a,b,c]},{d,[{author_proc,react},{ps,[{b,a},{a,d},{b,d},{d,c}]},{nodes_up,[d]}]},{d2,[{network_islands,[islands_not_supported]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.430 d uses: [{epoch,129},{author,d},{upi,[d]},{repair,[a,b,c]},{down,[]},{d,[{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[[a,b,c,d]]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.433 d uses: [{epoch,139},{author,d},{upi,[d]},{repair,[a,b,c]},{down,[]},{d,[{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[islands_not_supported]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.436 d uses: [{epoch,149},{author,d},{upi,[d]},{repair,[a,b,c]},{down,[]},{d,[{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[[a,b,c,d]]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.503 c uses: [{epoch,149},{author,d},{upi,[d]},{repair,[a,b,c]},{down,[]},{d,[{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[[a,b,c,d]]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.506 b uses: [{epoch,153},{author,b},{upi,[a,b,c,d]},{repair,[]},{down,[]},{d,[{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[[a,b,c,d]]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.507 b uses: [{epoch,157},{author,b},{upi,[a,b,c,d]},{repair,[]},{down,[]},{d,[{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[[a,b,c,d]]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.508 b uses: [{epoch,161},{author,b},{upi,[b]},{repair,[]},{down,[a,c,d]},{d,[{author_proc,react},{ps,[{a,b},{b,a},{a,c},{c,a},{a,d},{d,a},{b,c},{c,b},{b,d},{d,b},{c,d},{d,c}]},{nodes_up,[b]}]},{d2,[{network_islands,[islands_not_supported]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.509 b uses: [{epoch,166},{author,b},{upi,[b]},{repair,[a,c,d]},{down,[]},{d,[{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[[a,b,c,d]]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.510 b uses: [{epoch,170},{author,b},{upi,[b]},{repair,[]},{down,[a,c,d]},{d,[{author_proc,react},{ps,[{a,b},{b,a},{c,a},{a,d},{d,a},{b,c},{c,b},{d,b},{c,d},{d,c}]},{nodes_up,[b]}]},{d2,[{network_islands,[islands_not_supported]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.513 b uses: [{epoch,181},{author,b},{upi,[b]},{repair,[a,c,d]},{down,[]},{d,[{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[[a,b,c,d]]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.515 b uses: [{epoch,184},{author,b},{upi,[b]},{repair,[a,c,d]},{down,[]},{d,[{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[[a,b,c,d]]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.516 b uses: [{epoch,187},{author,b},{upi,[b]},{repair,[a,c,d]},{down,[]},{d,[{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[[a,b,c,d]]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.516 b uses: [{epoch,189},{author,b},{upi,[b]},{repair,[]},{down,[a,c,d]},{d,[{author_proc,react},{ps,[{b,a},{c,a},{a,d},{d,a},{c,b},{b,d},{d,b},{c,d},{d,c}]},{nodes_up,[b]}]},{d2,[{network_islands,[islands_not_supported]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.517 b uses: [{epoch,192},{author,b},{upi,[b]},{repair,[a,c,d]},{down,[]},{d,[{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[[a,b,c,d]]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.518 b uses: [{epoch,196},{author,b},{upi,[b]},{repair,[a,c,d]},{down,[]},{d,[{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[[a,b,c,d]]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.520 b uses: [{epoch,200},{author,b},{upi,[b]},{repair,[a,c,d]},{down,[]},{d,[{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[[a,b,c,d]]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.521 b uses: [{epoch,202},{author,b},{upi,[b]},{repair,[a,c,d]},{down,[]},{d,[{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[[a,b,c,d]]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.523 b uses: [{epoch,209},{author,b},{upi,[b]},{repair,[a,c,d]},{down,[]},{d,[{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[[a,b,c,d]]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.524 b uses: [{epoch,211},{author,b},{upi,[b]},{repair,[a,c,d]},{down,[]},{d,[{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[[a,b,c,d]]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.526 b uses: [{epoch,220},{author,b},{upi,[b]},{repair,[a,c,d]},{down,[]},{d,[{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[[a,b,c,d]]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.528 b uses: [{epoch,225},{author,b},{upi,[b]},{repair,[c]},{down,[a,d]},{d,[{author_proc,react},{ps,[{a,b},{a,c},{a,d},{d,a},{b,d},{d,b},{c,d}]},{nodes_up,[b,c]}]},{d2,[{network_islands,[islands_not_supported]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.529 b uses: [{epoch,228},{author,b},{upi,[b]},{repair,[]},{down,[a,c,d]},{d,[{author_proc,react},{ps,[{a,b},{b,a},{a,c},{a,d},{b,c},{b,d},{d,b},{c,d},{d,c}]},{nodes_up,[b]}]},{d2,[{network_islands,[islands_not_supported]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.530 b uses: [{epoch,232},{author,b},{upi,[b]},{repair,[]},{down,[a,c,d]},{d,[{author_proc,react},{ps,[{a,b},{b,a},{c,a},{a,d},{d,a},{c,b},{b,d},{d,b}]},{nodes_up,[b]}]},{d2,[{network_islands,[islands_not_supported]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.531 b uses: [{epoch,235},{author,b},{upi,[b]},{repair,[a,c,d]},{down,[]},{d,[{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[[a,b,c,d]]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.534 b uses: [{epoch,243},{author,b},{upi,[b]},{repair,[a,c,d]},{down,[]},{d,[{author_proc,react},{ps,[{d,c}]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[[a,b,c,d]]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.563 c uses: [{epoch,243},{author,b},{upi,[b]},{repair,[a,c,d]},{down,[]},{d,[{author_proc,react},{ps,[{d,c}]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[[a,b,c,d]]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.563 c uses: [{epoch,245},{author,c},{upi,[b]},{repair,[a,c,d]},{down,[]},{d,[{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[[a,b,c,d]]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.567 c uses: [{epoch,261},{author,c},{upi,[c]},{repair,[]},{down,[a,b,d]},{d,[{author_proc,react},{ps,[{a,b},{a,c},{c,a},{a,d},{d,a},{b,c},{c,b},{b,d},{d,b},{c,d},{d,c}]},{nodes_up,[c]}]},{d2,[{network_islands,[islands_not_supported]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.567 c uses: [{epoch,263},{author,c},{upi,[c]},{repair,[a,b,d]},{down,[]},{d,[{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[[a,b,c,d]]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.568 c uses: [{epoch,266},{author,c},{upi,[c]},{repair,[]},{down,[a,b,d]},{d,[{author_proc,react},{ps,[{a,b},{a,c},{c,a},{a,d},{b,c},{d,b},{c,d},{d,c}]},{nodes_up,[c]}]},{d2,[{network_islands,[islands_not_supported]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.570 c uses: [{epoch,273},{author,c},{upi,[c]},{repair,[a,b,d]},{down,[]},{d,[{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[[a,b,c,d]]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.571 c uses: [{epoch,279},{author,c},{upi,[c]},{repair,[a,b,d]},{down,[]},{d,[{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[[a,b,c,d]]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.573 c uses: [{epoch,284},{author,c},{upi,[c]},{repair,[a,b,d]},{down,[]},{d,[{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[[a,b,c,d]]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.573 c uses: [{epoch,286},{author,c},{upi,[c]},{repair,[a,b,d]},{down,[]},{d,[{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[islands_not_supported]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.575 c uses: [{epoch,294},{author,c},{upi,[c]},{repair,[a,b,d]},{down,[]},{d,[{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[[a,b,c,d]]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.576 c uses: [{epoch,296},{author,c},{upi,[c]},{repair,[]},{down,[a,b,d]},{d,[{author_proc,react},{ps,[{b,a},{a,c},{c,a},{d,a},{b,c},{c,b},{d,b},{c,d},{d,c}]},{nodes_up,[c]}]},{d2,[{network_islands,[islands_not_supported]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.576 c uses: [{epoch,299},{author,c},{upi,[c]},{repair,[a,b,d]},{down,[]},{d,[{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[[a,b,c,d]]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.579 c uses: [{epoch,311},{author,c},{upi,[c]},{repair,[a,b,d]},{down,[]},{d,[{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[[a,b,c,d]]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.580 c uses: [{epoch,314},{author,c},{upi,[c]},{repair,[a,b,d]},{down,[]},{d,[{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[[a,b,c,d]]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.582 c uses: [{epoch,322},{author,c},{upi,[c]},{repair,[]},{down,[a,b,d]},{d,[{author_proc,react},{ps,[{b,a},{c,a},{a,d},{d,a},{b,c},{c,b},{d,b},{d,c}]},{nodes_up,[c]}]},{d2,[{network_islands,[islands_not_supported]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.583 c uses: [{epoch,325},{author,c},{upi,[c]},{repair,[a,b,d]},{down,[]},{d,[{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[[a,b,c,d]]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.583 c uses: [{epoch,327},{author,c},{upi,[c]},{repair,[]},{down,[a,b,d]},{d,[{author_proc,react},{ps,[{a,b},{c,a},{c,b},{c,d}]},{nodes_up,[c]}]},{d2,[{network_islands,[islands_not_supported]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.631 a uses: [{epoch,329},{author,a},{upi,[a,b,c,d]},{repair,[]},{down,[]},{d,[{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[[a,b,c,d]]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.633 a uses: [{epoch,338},{author,a},{upi,[a]},{repair,[]},{down,[b,c,d]},{d,[{author_proc,react},{ps,[{a,b},{a,c},{c,a},{a,d},{d,a},{c,b},{b,d},{c,d},{d,c}]},{nodes_up,[a]}]},{d2,[{network_islands,[islands_not_supported]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.635 a uses: [{epoch,344},{author,a},{upi,[a]},{repair,[b,c,d]},{down,[]},{d,[{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[[a,b,c,d]]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.635 a uses: [{epoch,347},{author,a},{upi,[a]},{repair,[]},{down,[b,c,d]},{d,[{author_proc,react},{ps,[{a,b},{b,a},{a,c},{c,a},{a,d},{d,a},{b,c},{c,b},{b,d},{c,d},{d,c}]},{nodes_up,[a]}]},{d2,[{network_islands,[islands_not_supported]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.636 a uses: [{epoch,349},{author,a},{upi,[a]},{repair,[b,c,d]},{down,[]},{d,[{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[[a,b,c,d]]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.636 a uses: [{epoch,351},{author,a},{upi,[a]},{repair,[]},{down,[b,c,d]},{d,[{author_proc,react},{ps,[{a,b},{b,a},{c,a},{a,d},{d,b},{c,d},{d,c}]},{nodes_up,[a]}]},{d2,[{network_islands,[islands_not_supported]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.637 a uses: [{epoch,354},{author,a},{upi,[a]},{repair,[b,c,d]},{down,[]},{d,[{author_proc,react},{ps,[{c,b}]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[[a,b,c,d]]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.639 a uses: [{epoch,362},{author,a},{upi,[a]},{repair,[]},{down,[b,c,d]},{d,[{author_proc,react},{ps,[{a,b},{b,a},{a,c},{c,a},{a,d},{d,a},{b,c},{c,b},{c,d},{d,c}]},{nodes_up,[a]}]},{d2,[{network_islands,[islands_not_supported]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.640 a uses: [{epoch,365},{author,a},{upi,[a]},{repair,[b,c,d]},{down,[]},{d,[{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[[a,b,c,d]]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.641 a uses: [{epoch,368},{author,a},{upi,[a]},{repair,[]},{down,[b,c,d]},{d,[{author_proc,react},{ps,[{a,b},{a,c},{c,a},{a,d},{d,a},{b,d},{d,b},{d,c}]},{nodes_up,[a]}]},{d2,[{network_islands,[islands_not_supported]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.642 a uses: [{epoch,372},{author,a},{upi,[a]},{repair,[b,c,d]},{down,[]},{d,[{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[[a,b,c,d]]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.642 a uses: [{epoch,374},{author,a},{upi,[a]},{repair,[b,c,d]},{down,[]},{d,[{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[[a,b,c,d]]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.643 a uses: [{epoch,376},{author,a},{upi,[a]},{repair,[]},{down,[b,c,d]},{d,[{author_proc,react},{ps,[{a,b},{b,a},{a,c},{c,a},{a,d},{b,c},{c,b},{b,d},{d,b},{d,c}]},{nodes_up,[a]}]},{d2,[{network_islands,[islands_not_supported]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.644 a uses: [{epoch,380},{author,a},{upi,[a]},{repair,[]},{down,[b,c,d]},{d,[{author_proc,react},{ps,[{b,a},{c,a},{d,a},{d,c}]},{nodes_up,[a]}]},{d2,[{network_islands,[islands_not_supported]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.644 a uses: [{epoch,382},{author,a},{upi,[a]},{repair,[]},{down,[b,c,d]},{d,[{author_proc,react},{ps,[{a,b},{c,a},{a,d},{c,b}]},{nodes_up,[a]}]},{d2,[{network_islands,[islands_not_supported]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.647 a uses: [{epoch,394},{author,a},{upi,[a]},{repair,[b,c,d]},{down,[]},{d,[{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[[a,b,c,d]]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.648 a uses: [{epoch,398},{author,a},{upi,[a]},{repair,[b,c,d]},{down,[]},{d,[{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[[a,b,c,d]]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.649 a uses: [{epoch,402},{author,a},{upi,[a]},{repair,[b,c,d]},{down,[]},{d,[{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[[a,b,c,d]]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.650 a uses: [{epoch,404},{author,a},{upi,[a]},{repair,[b,c,d]},{down,[]},{d,[{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[[a,b,c,d]]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.651 a uses: [{epoch,409},{author,a},{upi,[a]},{repair,[b,c,d]},{down,[]},{d,[{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[[a,b,c,d]]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.652 a uses: [{epoch,414},{author,a},{upi,[a]},{repair,[b,c,d]},{down,[]},{d,[{author_proc,react},{ps,[{b,d},{d,b}]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[[a,b,c,d]]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.654 a uses: [{epoch,420},{author,a},{upi,[a]},{repair,[]},{down,[b,c,d]},{d,[{author_proc,react},{ps,[{a,b},{b,a},{a,c},{c,a},{a,d},{c,b},{d,b},{d,c}]},{nodes_up,[a]}]},{d2,[{network_islands,[islands_not_supported]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.656 a uses: [{epoch,427},{author,a},{upi,[a]},{repair,[b,c,d]},{down,[]},{d,[{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[[a,b,c,d]]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.657 a uses: [{epoch,431},{author,a},{upi,[a]},{repair,[]},{down,[b,c,d]},{d,[{author_proc,react},{ps,[{a,b},{b,a},{a,c},{c,a},{a,d},{d,a},{b,c},{c,b},{b,d},{d,b},{c,d},{d,c}]},{nodes_up,[a]}]},{d2,[{network_islands,[islands_not_supported]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.658 a uses: [{epoch,434},{author,a},{upi,[a]},{repair,[b,c,d]},{down,[]},{d,[{author_proc,react},{ps,[{b,c},{c,b},{d,b},{c,d},{d,c}]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[islands_not_supported]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
SET always_last_partitions ON ... we should see convergence to correct chains.
16:49:43.701 d uses: [{epoch,434},{author,a},{upi,[a]},{repair,[b,c,d]},{down,[]},{d,[{author_proc,react},{ps,[{b,c},{c,b},{d,b},{c,d},{d,c}]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[na_reset_by_always]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.799 c uses: [{epoch,434},{author,a},{upi,[a]},{repair,[b,c,d]},{down,[]},{d,[{author_proc,react},{ps,[{b,c},{c,b},{d,b},{c,d},{d,c}]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[na_reset_by_always]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:43.999 a uses: [{epoch,436},{author,a},{upi,[a,c]},{repair,[d]},{down,[b]},{d,[{repair_airquote_done,{we_agree,434}},{author_proc,react},{ps,[{a,b}]},{nodes_up,[a,c,d]}]},{d2,[{network_islands,[na_reset_by_always]},{hooray,{v2,{2015,3,3},{16,49,43}}}]}]
16:49:44.143 b uses: [{epoch,437},{author,b},{upi,[b]},{repair,[c,d]},{down,[a]},{d,[{author_proc,react},{ps,[{a,b}]},{nodes_up,[b,c,d]}]},{d2,[{network_islands,[na_reset_by_always]},{hooray,{v2,{2015,3,3},{16,49,44}}}]}]
16:49:44.171 d uses: [{epoch,438},{author,d},{upi,[a]},{repair,[b,c,d]},{down,[]},{d,[{author_proc,react},{ps,[{a,b}]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[na_reset_by_always]},{hooray,{v2,{2015,3,3},{16,49,44}}}]}]
16:49:44.206 c uses: [{epoch,438},{author,d},{upi,[a]},{repair,[b,c,d]},{down,[]},{d,[{author_proc,react},{ps,[{a,b}]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[na_reset_by_always]},{hooray,{v2,{2015,3,3},{16,49,44}}}]}]
16:49:44.403 a uses: [{epoch,439},{author,a},{upi,[a,c]},{repair,[d]},{down,[b]},{d,[{author_proc,react},{ps,[{a,b}]},{nodes_up,[a,c,d]}]},{d2,[{network_islands,[na_reset_by_always]},{hooray,{v2,{2015,3,3},{16,49,44}}}]}]
16:49:44.695 d uses: [{epoch,440},{author,d},{upi,[a]},{repair,[b,c,d]},{down,[]},{d,[{author_proc,react},{ps,[{a,b}]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[na_reset_by_always]},{hooray,{v2,{2015,3,3},{16,49,44}}}]}]
16:49:44.740 c uses: [{epoch,440},{author,d},{upi,[a]},{repair,[b,c,d]},{down,[]},{d,[{author_proc,react},{ps,[{a,b}]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[na_reset_by_always]},{hooray,{v2,{2015,3,3},{16,49,44}}}]}]
16:49:44.808 a uses: [{epoch,441},{author,a},{upi,[a,c]},{repair,[d]},{down,[b]},{d,[{author_proc,react},{ps,[{a,b}]},{nodes_up,[a,c,d]}]},{d2,[{network_islands,[na_reset_by_always]},{hooray,{v2,{2015,3,3},{16,49,44}}}]}]
16:49:44.810 b uses: [{epoch,442},{author,b},{upi,[b]},{repair,[c,d]},{down,[a]},{d,[{author_proc,react},{ps,[{a,b}]},{nodes_up,[b,c,d]}]},{d2,[{network_islands,[na_reset_by_always]},{hooray,{v2,{2015,3,3},{16,49,44}}}]}]
16:49:45.100 d uses: [{epoch,443},{author,d},{upi,[a]},{repair,[b,c,d]},{down,[]},{d,[{author_proc,react},{ps,[{a,b}]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[na_reset_by_always]},{hooray,{v2,{2015,3,3},{16,49,45}}}]}]
16:49:45.144 c uses: [{epoch,443},{author,d},{upi,[a]},{repair,[b,c,d]},{down,[]},{d,[{author_proc,react},{ps,[{a,b}]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[na_reset_by_always]},{hooray,{v2,{2015,3,3},{16,49,45}}}]}]
16:49:45.212 a uses: [{epoch,444},{author,a},{upi,[a,c]},{repair,[d]},{down,[b]},{d,[{author_proc,react},{ps,[{a,b}]},{nodes_up,[a,c,d]}]},{d2,[{network_islands,[na_reset_by_always]},{hooray,{v2,{2015,3,3},{16,49,45}}}]}]
16:49:45.460 b uses: [{epoch,445},{author,b},{upi,[b]},{repair,[c,d]},{down,[a]},{d,[{author_proc,react},{ps,[{a,b}]},{nodes_up,[b,c,d]}]},{d2,[{network_islands,[na_reset_by_always]},{hooray,{v2,{2015,3,3},{16,49,45}}}]}]
16:49:45.502 d uses: [{epoch,446},{author,d},{upi,[a]},{repair,[b,c,d]},{down,[]},{d,[{author_proc,react},{ps,[{a,b}]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[na_reset_by_always]},{hooray,{v2,{2015,3,3},{16,49,45}}}]}]
16:49:45.549 c uses: [{epoch,446},{author,d},{upi,[a]},{repair,[b,c,d]},{down,[]},{d,[{author_proc,react},{ps,[{a,b}]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[na_reset_by_always]},{hooray,{v2,{2015,3,3},{16,49,45}}}]}]
16:49:45.618 a uses: [{epoch,447},{author,a},{upi,[a,c]},{repair,[d]},{down,[b]},{d,[{author_proc,react},{ps,[{a,b}]},{nodes_up,[a,c,d]}]},{d2,[{network_islands,[na_reset_by_always]},{hooray,{v2,{2015,3,3},{16,49,45}}}]}]
16:49:46.025 d uses: [{epoch,448},{author,d},{upi,[a]},{repair,[b,c,d]},{down,[]},{d,[{author_proc,react},{ps,[{a,b}]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[na_reset_by_always]},{hooray,{v2,{2015,3,3},{16,49,46}}}]}]
16:49:46.031 c uses: [{epoch,448},{author,d},{upi,[a]},{repair,[b,c,d]},{down,[]},{d,[{author_proc,react},{ps,[{a,b}]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[na_reset_by_always]},{hooray,{v2,{2015,3,3},{16,49,46}}}]}]
16:49:46.117 b uses: [{epoch,449},{author,b},{upi,[b]},{repair,[c,d]},{down,[a]},{d,[{author_proc,react},{ps,[{a,b}]},{nodes_up,[b,c,d]}]},{d2,[{network_islands,[na_reset_by_always]},{hooray,{v2,{2015,3,3},{16,49,46}}}]}]
16:49:46.427 a uses: [{epoch,450},{author,a},{upi,[a,c]},{repair,[d]},{down,[b]},{d,[{author_proc,react},{ps,[{a,b}]},{nodes_up,[a,c,d]}]},{d2,[{network_islands,[na_reset_by_always]},{hooray,{v2,{2015,3,3},{16,49,46}}}]}]
16:49:46.531 d uses: [{epoch,451},{author,d},{upi,[a]},{repair,[b,c,d]},{down,[]},{d,[{author_proc,react},{ps,[{a,b}]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[na_reset_by_always]},{hooray,{v2,{2015,3,3},{16,49,46}}}]}]
16:49:46.580 c uses: [{epoch,451},{author,d},{upi,[a]},{repair,[b,c,d]},{down,[]},{d,[{author_proc,react},{ps,[{a,b}]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[na_reset_by_always]},{hooray,{v2,{2015,3,3},{16,49,46}}}]}]
16:49:46.790 b uses: [{epoch,452},{author,b},{upi,[b]},{repair,[c,d]},{down,[a]},{d,[{author_proc,react},{ps,[{a,b}]},{nodes_up,[b,c,d]}]},{d2,[{network_islands,[na_reset_by_always]},{hooray,{v2,{2015,3,3},{16,49,46}}}]}]
16:49:46.833 a uses: [{epoch,453},{author,a},{upi,[a,c]},{repair,[d]},{down,[b]},{d,[{author_proc,react},{ps,[{a,b}]},{nodes_up,[a,c,d]}]},{d2,[{network_islands,[na_reset_by_always]},{hooray,{v2,{2015,3,3},{16,49,46}}}]}]
16:49:47.039 d uses: [{epoch,454},{author,d},{upi,[a]},{repair,[b,c,d]},{down,[]},{d,[{author_proc,react},{ps,[{a,b}]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[na_reset_by_always]},{hooray,{v2,{2015,3,3},{16,49,47}}}]}]
16:49:47.043 c uses: [{epoch,454},{author,d},{upi,[a]},{repair,[b,c,d]},{down,[]},{d,[{author_proc,react},{ps,[{a,b}]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[na_reset_by_always]},{hooray,{v2,{2015,3,3},{16,49,47}}}]}]
16:49:47.237 a uses: [{epoch,455},{author,a},{upi,[a,c]},{repair,[d]},{down,[b]},{d,[{author_proc,react},{ps,[{a,b}]},{nodes_up,[a,c,d]}]},{d2,[{network_islands,[na_reset_by_always]},{hooray,{v2,{2015,3,3},{16,49,47}}}]}]
16:49:47.451 b uses: [{epoch,456},{author,b},{upi,[b]},{repair,[c,d]},{down,[a]},{d,[{author_proc,react},{ps,[{a,b}]},{nodes_up,[b,c,d]}]},{d2,[{network_islands,[na_reset_by_always]},{hooray,{v2,{2015,3,3},{16,49,47}}}]}]
16:49:47.492 d uses: [{epoch,457},{author,d},{upi,[a]},{repair,[b,c,d]},{down,[]},{d,[{author_proc,react},{ps,[{a,b}]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[na_reset_by_always]},{hooray,{v2,{2015,3,3},{16,49,47}}}]}]
16:49:47.538 c uses: [{epoch,457},{author,d},{upi,[a]},{repair,[b,c,d]},{down,[]},{d,[{author_proc,react},{ps,[{a,b}]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[na_reset_by_always]},{hooray,{v2,{2015,3,3},{16,49,47}}}]}]
16:49:47.644 a uses: [{epoch,458},{author,a},{upi,[a,c]},{repair,[d]},{down,[b]},{d,[{author_proc,react},{ps,[{a,b}]},{nodes_up,[a,c,d]}]},{d2,[{network_islands,[na_reset_by_always]},{hooray,{v2,{2015,3,3},{16,49,47}}}]}]
16:49:48.016 d uses: [{epoch,459},{author,d},{upi,[a]},{repair,[b,c,d]},{down,[]},{d,[{author_proc,react},{ps,[{a,b}]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[na_reset_by_always]},{hooray,{v2,{2015,3,3},{16,49,48}}}]}]
16:49:48.022 c uses: [{epoch,459},{author,d},{upi,[a]},{repair,[b,c,d]},{down,[]},{d,[{author_proc,react},{ps,[{a,b}]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[na_reset_by_always]},{hooray,{v2,{2015,3,3},{16,49,48}}}]}]
16:49:48.049 a uses: [{epoch,460},{author,a},{upi,[a,c]},{repair,[d]},{down,[b]},{d,[{author_proc,react},{ps,[{a,b}]},{nodes_up,[a,c,d]}]},{d2,[{network_islands,[na_reset_by_always]},{hooray,{v2,{2015,3,3},{16,49,48}}}]}]
16:49:48.111 b uses: [{epoch,461},{author,b},{upi,[b]},{repair,[c,d]},{down,[a]},{d,[{author_proc,react},{ps,[{a,b}]},{nodes_up,[b,c,d]}]},{d2,[{network_islands,[na_reset_by_always]},{hooray,{v2,{2015,3,3},{16,49,48}}}]}]
{FLAP: c flaps 5}!
{FLAP: a flaps 5}!
{FLAP: c flaps 6}!
{FLAP: a flaps 6}!
SET always_last_partitions OFF ... let loose the dogs of war!
16:49:56.562 a uses: [{epoch,466},{author,a},{upi,[a,c]},{repair,[d,b]},{down,[]},{d,[{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[[a,b,c,d]]},{hooray,{v2,{2015,3,3},{16,49,56}}}]}]
16:49:56.565 a uses: [{epoch,471},{author,a},{upi,[a,c]},{repair,[d,b]},{down,[]},{d,[{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[islands_not_supported]},{hooray,{v2,{2015,3,3},{16,49,56}}}]}]
16:49:56.568 a uses: [{epoch,479},{author,a},{upi,[a,c]},{repair,[d,b]},{down,[]},{d,[{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[[a,b,c,d]]},{hooray,{v2,{2015,3,3},{16,49,56}}}]}]
16:49:56.569 a uses: [{epoch,481},{author,a},{upi,[a]},{repair,[]},{down,[b,c,d]},{d,[{author_proc,react},{ps,[{a,b},{b,a},{a,c},{c,a},{d,a},{b,c},{c,b},{b,d},{d,b},{c,d},{d,c}]},{nodes_up,[a]}]},{d2,[{network_islands,[islands_not_supported]},{hooray,{v2,{2015,3,3},{16,49,56}}}]}]
16:49:56.571 a uses: [{epoch,487},{author,a},{upi,[a]},{repair,[b,c,d]},{down,[]},{d,[{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[[a,b,c,d]]},{hooray,{v2,{2015,3,3},{16,49,56}}}]}]
16:49:56.572 a uses: [{epoch,490},{author,a},{upi,[a]},{repair,[b,c,d]},{down,[]},{d,[{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[[a,b,c,d]]},{hooray,{v2,{2015,3,3},{16,49,56}}}]}]
16:49:56.573 a uses: [{epoch,493},{author,a},{upi,[a]},{repair,[b,c,d]},{down,[]},{d,[{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[[a,b,c,d]]},{hooray,{v2,{2015,3,3},{16,49,56}}}]}]
16:49:56.575 a uses: [{epoch,496},{author,a},{upi,[a]},{repair,[b,c,d]},{down,[]},{d,[{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[[a,b,c,d]]},{hooray,{v2,{2015,3,3},{16,49,56}}}]}]
16:49:56.580 a uses: [{epoch,509},{author,a},{upi,[a]},{repair,[b,c,d]},{down,[]},{d,[{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[islands_not_supported]},{hooray,{v2,{2015,3,3},{16,49,56}}}]}]
16:49:56.582 a uses: [{epoch,513},{author,a},{upi,[a]},{repair,[b,c,d]},{down,[]},{d,[{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[islands_not_supported]},{hooray,{v2,{2015,3,3},{16,49,56}}}]}]
16:49:56.583 a uses: [{epoch,516},{author,a},{upi,[a]},{repair,[]},{down,[b,c,d]},{d,[{author_proc,react},{ps,[{a,b},{a,c},{d,a},{c,b},{b,d},{d,b},{c,d},{d,c}]},{nodes_up,[a]}]},{d2,[{network_islands,[islands_not_supported]},{hooray,{v2,{2015,3,3},{16,49,56}}}]}]
16:49:56.585 a uses: [{epoch,520},{author,a},{upi,[a]},{repair,[b,c,d]},{down,[]},{d,[{author_proc,react},{ps,[{c,d}]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[[a,b,c,d]]},{hooray,{v2,{2015,3,3},{16,49,56}}}]}]
16:49:56.587 a uses: [{epoch,524},{author,a},{upi,[a]},{repair,[b,c,d]},{down,[]},{d,[{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[[a,b,c,d]]},{hooray,{v2,{2015,3,3},{16,49,56}}}]}]
16:49:56.589 a uses: [{epoch,529},{author,a},{upi,[a]},{repair,[b,c,d]},{down,[]},{d,[{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[islands_not_supported]},{hooray,{v2,{2015,3,3},{16,49,56}}}]}]
16:49:56.590 a uses: [{epoch,532},{author,a},{upi,[a]},{repair,[b,c,d]},{down,[]},{d,[{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[[a,b,c,d]]},{hooray,{v2,{2015,3,3},{16,49,56}}}]}]
16:49:56.591 a uses: [{epoch,535},{author,a},{upi,[a]},{repair,[]},{down,[b,c,d]},{d,[{author_proc,react},{ps,[{a,b},{b,a},{a,c},{d,a},{b,c},{c,b},{d,c}]},{nodes_up,[a]}]},{d2,[{network_islands,[islands_not_supported]},{hooray,{v2,{2015,3,3},{16,49,56}}}]}]
16:49:56.592 a uses: [{epoch,537},{author,a},{upi,[a]},{repair,[b,c,d]},{down,[]},{d,[{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[[a,b,c,d]]},{hooray,{v2,{2015,3,3},{16,49,56}}}]}]
16:49:56.594 a uses: [{epoch,540},{author,a},{upi,[a]},{repair,[b,c,d]},{down,[]},{d,[{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[[a,b,c,d]]},{hooray,{v2,{2015,3,3},{16,49,56}}}]}]
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16:49:56.795 b uses: [{epoch,821},{author,b},{upi,[b]},{repair,[a,c,d]},{down,[]},{d,[{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[[a,b,c,d]]},{hooray,{v2,{2015,3,3},{16,49,56}}}]}]
16:49:56.797 b uses: [{epoch,825},{author,b},{upi,[b]},{repair,[a,c,d]},{down,[]},{d,[{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[islands_not_supported]},{hooray,{v2,{2015,3,3},{16,49,56}}}]}]
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16:49:56.894 c uses: [{epoch,925},{author,c},{upi,[c]},{repair,[a,b,d]},{down,[]},{d,[{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[islands_not_supported]},{hooray,{v2,{2015,3,3},{16,49,56}}}]}]
16:49:56.896 c uses: [{epoch,929},{author,c},{upi,[c]},{repair,[a,b,d]},{down,[]},{d,[{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[[a,b,c,d]]},{hooray,{v2,{2015,3,3},{16,49,56}}}]}]
16:49:56.902 c uses: [{epoch,943},{author,c},{upi,[c]},{repair,[a,b,d]},{down,[]},{d,[{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[islands_not_supported]},{hooray,{v2,{2015,3,3},{16,49,56}}}]}]
16:49:56.903 c uses: [{epoch,945},{author,c},{upi,[c]},{repair,[a,b,d]},{down,[]},{d,[{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[[a,b,c,d]]},{hooray,{v2,{2015,3,3},{16,49,56}}}]}]
SET always_last_partitions ON ... we should see convergence to correct chains2.
16:49:56.946 d uses: [{epoch,945},{author,c},{upi,[c]},{repair,[a,b,d]},{down,[]},{d,[{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[na_reset_by_always]},{hooray,{v2,{2015,3,3},{16,49,56}}}]}]
16:49:57.049 c uses: [{epoch,947},{author,c},{upi,[c]},{repair,[b,d]},{down,[a]},{d,[{author_proc,react},{ps,[{a,c}]},{nodes_up,[b,c,d]}]},{d2,[{network_islands,[na_reset_by_always]},{hooray,{v2,{2015,3,3},{16,49,57}}}]}]
16:49:57.147 b uses: [{epoch,948},{author,b},{upi,[b]},{repair,[a,c,d]},{down,[]},{d,[{author_proc,react},{ps,[{a,c}]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[na_reset_by_always]},{hooray,{v2,{2015,3,3},{16,49,57}}}]}]
16:49:57.350 d uses: [{epoch,948},{author,b},{upi,[b]},{repair,[a,c,d]},{down,[]},{d,[{author_proc,react},{ps,[{a,c}]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[na_reset_by_always]},{hooray,{v2,{2015,3,3},{16,49,57}}}]}]
16:49:57.579 a uses: [{epoch,949},{author,a},{upi,[a]},{repair,[b,d]},{down,[c]},{d,[{author_proc,react},{ps,[{a,c}]},{nodes_up,[a,b,d]}]},{d2,[{network_islands,[na_reset_by_always]},{hooray,{v2,{2015,3,3},{16,49,57}}}]}]
16:49:57.625 c uses: [{epoch,950},{author,c},{upi,[c]},{repair,[b,d]},{down,[a]},{d,[{author_proc,react},{ps,[{a,c}]},{nodes_up,[b,c,d]}]},{d2,[{network_islands,[na_reset_by_always]},{hooray,{v2,{2015,3,3},{16,49,57}}}]}]
16:49:57.760 d uses: [{epoch,951},{author,d},{upi,[b]},{repair,[a,c,d]},{down,[]},{d,[{author_proc,react},{ps,[{a,c}]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[na_reset_by_always]},{hooray,{v2,{2015,3,3},{16,49,57}}}]}]
16:49:57.959 b uses: [{epoch,951},{author,d},{upi,[b]},{repair,[a,c,d]},{down,[]},{d,[{author_proc,react},{ps,[{a,c}]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[na_reset_by_always]},{hooray,{v2,{2015,3,3},{16,49,57}}}]}]
16:49:58.200 c uses: [{epoch,952},{author,c},{upi,[c]},{repair,[b,d]},{down,[a]},{d,[{author_proc,react},{ps,[{a,c}]},{nodes_up,[b,c,d]}]},{d2,[{network_islands,[na_reset_by_always]},{hooray,{v2,{2015,3,3},{16,49,58}}}]}]
16:49:58.321 a uses: [{epoch,953},{author,a},{upi,[a]},{repair,[b,d]},{down,[c]},{d,[{author_proc,react},{ps,[{a,c}]},{nodes_up,[a,b,d]}]},{d2,[{network_islands,[na_reset_by_always]},{hooray,{v2,{2015,3,3},{16,49,58}}}]}]
16:49:58.366 b uses: [{epoch,954},{author,b},{upi,[b]},{repair,[a,c,d]},{down,[]},{d,[{author_proc,react},{ps,[{a,c}]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[na_reset_by_always]},{hooray,{v2,{2015,3,3},{16,49,58}}}]}]
16:49:58.572 d uses: [{epoch,954},{author,b},{upi,[b]},{repair,[a,c,d]},{down,[]},{d,[{author_proc,react},{ps,[{a,c}]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[na_reset_by_always]},{hooray,{v2,{2015,3,3},{16,49,58}}}]}]
16:49:58.802 c uses: [{epoch,955},{author,c},{upi,[c]},{repair,[b,d]},{down,[a]},{d,[{author_proc,react},{ps,[{a,c}]},{nodes_up,[b,c,d]}]},{d2,[{network_islands,[na_reset_by_always]},{hooray,{v2,{2015,3,3},{16,49,58}}}]}]
16:49:58.976 d uses: [{epoch,956},{author,d},{upi,[b]},{repair,[a,c,d]},{down,[]},{d,[{author_proc,react},{ps,[{a,c}]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[na_reset_by_always]},{hooray,{v2,{2015,3,3},{16,49,58}}}]}]
16:49:59.047 a uses: [{epoch,957},{author,a},{upi,[a]},{repair,[b,d]},{down,[c]},{d,[{author_proc,react},{ps,[{a,c}]},{nodes_up,[a,b,d]}]},{d2,[{network_islands,[na_reset_by_always]},{hooray,{v2,{2015,3,3},{16,49,59}}}]}]
16:49:59.173 b uses: [{epoch,958},{author,b},{upi,[b]},{repair,[a,c,d]},{down,[]},{d,[{author_proc,react},{ps,[{a,c}]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[na_reset_by_always]},{hooray,{v2,{2015,3,3},{16,49,59}}}]}]
16:49:59.382 d uses: [{epoch,958},{author,b},{upi,[b]},{repair,[a,c,d]},{down,[]},{d,[{author_proc,react},{ps,[{a,c}]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[na_reset_by_always]},{hooray,{v2,{2015,3,3},{16,49,59}}}]}]
16:49:59.383 c uses: [{epoch,959},{author,c},{upi,[c]},{repair,[b,d]},{down,[a]},{d,[{author_proc,react},{ps,[{a,c}]},{nodes_up,[b,c,d]}]},{d2,[{network_islands,[na_reset_by_always]},{hooray,{v2,{2015,3,3},{16,49,59}}}]}]
16:49:59.576 b uses: [{epoch,960},{author,b},{upi,[b]},{repair,[a,c,d]},{down,[]},{d,[{author_proc,react},{ps,[{a,c}]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[na_reset_by_always]},{hooray,{v2,{2015,3,3},{16,49,59}}}]}]
16:49:59.778 a uses: [{epoch,961},{author,a},{upi,[a]},{repair,[b,d]},{down,[c]},{d,[{author_proc,react},{ps,[{a,c}]},{nodes_up,[a,b,d]}]},{d2,[{network_islands,[na_reset_by_always]},{hooray,{v2,{2015,3,3},{16,49,59}}}]}]
16:49:59.784 d uses: [{epoch,962},{author,d},{upi,[b]},{repair,[a,c,d]},{down,[]},{d,[{author_proc,react},{ps,[{a,c}]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[na_reset_by_always]},{hooray,{v2,{2015,3,3},{16,49,59}}}]}]
16:49:59.957 c uses: [{epoch,963},{author,c},{upi,[c]},{repair,[b,d]},{down,[a]},{d,[{author_proc,react},{ps,[{a,c}]},{nodes_up,[b,c,d]}]},{d2,[{network_islands,[na_reset_by_always]},{hooray,{v2,{2015,3,3},{16,49,59}}}]}]
16:49:59.980 b uses: [{epoch,964},{author,b},{upi,[b]},{repair,[a,c,d]},{down,[]},{d,[{author_proc,react},{ps,[{a,c}]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[na_reset_by_always]},{hooray,{v2,{2015,3,3},{16,49,59}}}]}]
16:50:00.187 d uses: [{epoch,964},{author,b},{upi,[b]},{repair,[a,c,d]},{down,[]},{d,[{author_proc,react},{ps,[{a,c}]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[na_reset_by_always]},{hooray,{v2,{2015,3,3},{16,50,0}}}]}]
16:50:00.532 a uses: [{epoch,965},{author,a},{upi,[a]},{repair,[b,d]},{down,[c]},{d,[{author_proc,react},{ps,[{a,c}]},{nodes_up,[a,b,d]}]},{d2,[{network_islands,[na_reset_by_always]},{hooray,{v2,{2015,3,3},{16,50,0}}}]}]
16:50:00.552 c uses: [{epoch,966},{author,c},{upi,[c]},{repair,[b,d]},{down,[a]},{d,[{author_proc,react},{ps,[{a,c}]},{nodes_up,[b,c,d]}]},{d2,[{network_islands,[na_reset_by_always]},{hooray,{v2,{2015,3,3},{16,50,0}}}]}]
16:50:00.590 d uses: [{epoch,967},{author,d},{upi,[b]},{repair,[a,c,d]},{down,[]},{d,[{author_proc,react},{ps,[{a,c}]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[na_reset_by_always]},{hooray,{v2,{2015,3,3},{16,50,0}}}]}]
16:50:00.788 b uses: [{epoch,967},{author,d},{upi,[b]},{repair,[a,c,d]},{down,[]},{d,[{author_proc,react},{ps,[{a,c}]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[na_reset_by_always]},{hooray,{v2,{2015,3,3},{16,50,0}}}]}]
16:50:01.136 c uses: [{epoch,968},{author,c},{upi,[c]},{repair,[b,d]},{down,[a]},{d,[{author_proc,react},{ps,[{a,c}]},{nodes_up,[b,c,d]}]},{d2,[{network_islands,[na_reset_by_always]},{hooray,{v2,{2015,3,3},{16,50,1}}}]}]
16:50:01.194 b uses: [{epoch,969},{author,b},{upi,[b]},{repair,[a,c,d]},{down,[]},{d,[{author_proc,react},{ps,[{a,c}]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[na_reset_by_always]},{hooray,{v2,{2015,3,3},{16,50,1}}}]}]
16:50:01.263 a uses: [{epoch,970},{author,a},{upi,[a]},{repair,[b,d]},{down,[c]},{d,[{author_proc,react},{ps,[{a,c}]},{nodes_up,[a,b,d]}]},{d2,[{network_islands,[na_reset_by_always]},{hooray,{v2,{2015,3,3},{16,50,1}}}]}]
16:50:01.398 d uses: [{epoch,971},{author,d},{upi,[b]},{repair,[a,c,d]},{down,[]},{d,[{author_proc,react},{ps,[{a,c}]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[na_reset_by_always]},{hooray,{v2,{2015,3,3},{16,50,1}}}]}]
16:50:01.600 b uses: [{epoch,971},{author,d},{upi,[b]},{repair,[a,c,d]},{down,[]},{d,[{author_proc,react},{ps,[{a,c}]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[na_reset_by_always]},{hooray,{v2,{2015,3,3},{16,50,1}}}]}]
16:50:01.716 c uses: [{epoch,972},{author,c},{upi,[c]},{repair,[b,d]},{down,[a]},{d,[{author_proc,react},{ps,[{a,c}]},{nodes_up,[b,c,d]}]},{d2,[{network_islands,[na_reset_by_always]},{hooray,{v2,{2015,3,3},{16,50,1}}}]}]
16:50:01.803 d uses: [{epoch,973},{author,d},{upi,[b]},{repair,[a,c,d]},{down,[]},{d,[{author_proc,react},{ps,[{a,c}]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[na_reset_by_always]},{hooray,{v2,{2015,3,3},{16,50,1}}}]}]
16:50:02.002 a uses: [{epoch,974},{author,a},{upi,[a]},{repair,[b,d]},{down,[c]},{d,[{author_proc,react},{ps,[{a,c}]},{nodes_up,[a,b,d]}]},{d2,[{network_islands,[na_reset_by_always]},{hooray,{v2,{2015,3,3},{16,50,2}}}]}]
16:50:02.003 b uses: [{epoch,975},{author,b},{upi,[b]},{repair,[a,c,d]},{down,[]},{d,[{author_proc,react},{ps,[{a,c}]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[na_reset_by_always]},{hooray,{v2,{2015,3,3},{16,50,2}}}]}]
16:50:02.209 d uses: [{epoch,975},{author,b},{upi,[b]},{repair,[a,c,d]},{down,[]},{d,[{author_proc,react},{ps,[{a,c}]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[na_reset_by_always]},{hooray,{v2,{2015,3,3},{16,50,2}}}]}]
16:50:02.291 c uses: [{epoch,976},{author,c},{upi,[c]},{repair,[b,d]},{down,[a]},{d,[{author_proc,react},{ps,[{a,c}]},{nodes_up,[b,c,d]}]},{d2,[{network_islands,[na_reset_by_always]},{hooray,{v2,{2015,3,3},{16,50,2}}}]}]
{FLAP: b flaps 4}!
{FLAP: b flaps 5}!
{FLAP: d flaps 6}!
{FLAP: b flaps 6}!
16:50:02.761 a uses: [{epoch,977},{author,a},{upi,[a]},{repair,[b,d]},{down,[c]},{d,[{author_proc,react},{ps,[{a,c}]},{nodes_up,[a,b,d]}]},{d2,[{network_islands,[na_reset_by_always]},{hooray,{v2,{2015,3,3},{16,50,2}}}]}]
SET always_last_partitions ON ... we should see convergence to correct chains3.
16:50:12.096 c uses: [{epoch,978},{author,c},{upi,[c]},{repair,[b,d,a]},{down,[]},{d,[{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[[a,b,c,d]]},{hooray,{v2,{2015,3,3},{16,50,12}}}]}]
16:50:12.196 b uses: [{epoch,978},{author,c},{upi,[c]},{repair,[b,d,a]},{down,[]},{d,[{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[[a,b,c,d]]},{hooray,{v2,{2015,3,3},{16,50,12}}}]}]
16:50:12.294 a uses: [{epoch,978},{author,c},{upi,[c]},{repair,[b,d,a]},{down,[]},{d,[{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[[a,b,c,d]]},{hooray,{v2,{2015,3,3},{16,50,12}}}]}]
16:50:12.464 d uses: [{epoch,978},{author,c},{upi,[c]},{repair,[b,d,a]},{down,[]},{d,[{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[[a,b,c,d]]},{hooray,{v2,{2015,3,3},{16,50,12}}}]}]
16:50:12.503 c uses: [{epoch,980},{author,c},{upi,[c,b]},{repair,[d,a]},{down,[]},{d,[{repair_airquote_done,{we_agree,978}},{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[[a,b,c,d]]},{hooray,{v2,{2015,3,3},{16,50,12}}}]}]
16:50:12.601 b uses: [{epoch,980},{author,c},{upi,[c,b]},{repair,[d,a]},{down,[]},{d,[{repair_airquote_done,{we_agree,978}},{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[[a,b,c,d]]},{hooray,{v2,{2015,3,3},{16,50,12}}}]}]
16:50:12.700 a uses: [{epoch,980},{author,c},{upi,[c,b]},{repair,[d,a]},{down,[]},{d,[{repair_airquote_done,{we_agree,978}},{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[[a,b,c,d]]},{hooray,{v2,{2015,3,3},{16,50,12}}}]}]
16:50:12.871 d uses: [{epoch,980},{author,c},{upi,[c,b]},{repair,[d,a]},{down,[]},{d,[{repair_airquote_done,{we_agree,978}},{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[[a,b,c,d]]},{hooray,{v2,{2015,3,3},{16,50,12}}}]}]
16:50:12.910 c uses: [{epoch,982},{author,c},{upi,[c,b,d]},{repair,[a]},{down,[]},{d,[{repair_airquote_done,{we_agree,980}},{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[[a,b,c,d]]},{hooray,{v2,{2015,3,3},{16,50,12}}}]}]
16:50:13.008 b uses: [{epoch,982},{author,c},{upi,[c,b,d]},{repair,[a]},{down,[]},{d,[{repair_airquote_done,{we_agree,980}},{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[[a,b,c,d]]},{hooray,{v2,{2015,3,3},{16,50,13}}}]}]
16:50:13.106 a uses: [{epoch,982},{author,c},{upi,[c,b,d]},{repair,[a]},{down,[]},{d,[{repair_airquote_done,{we_agree,980}},{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[[a,b,c,d]]},{hooray,{v2,{2015,3,3},{16,50,13}}}]}]
16:50:13.278 d uses: [{epoch,982},{author,c},{upi,[c,b,d]},{repair,[a]},{down,[]},{d,[{repair_airquote_done,{we_agree,980}},{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[[a,b,c,d]]},{hooray,{v2,{2015,3,3},{16,50,13}}}]}]
16:50:13.316 c uses: [{epoch,984},{author,c},{upi,[c,b,d,a]},{repair,[]},{down,[]},{d,[{repair_airquote_done,{we_agree,982}},{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[[a,b,c,d]]},{hooray,{v2,{2015,3,3},{16,50,13}}}]}]
16:50:13.414 b uses: [{epoch,984},{author,c},{upi,[c,b,d,a]},{repair,[]},{down,[]},{d,[{repair_airquote_done,{we_agree,982}},{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[[a,b,c,d]]},{hooray,{v2,{2015,3,3},{16,50,13}}}]}]
16:50:13.513 a uses: [{epoch,984},{author,c},{upi,[c,b,d,a]},{repair,[]},{down,[]},{d,[{repair_airquote_done,{we_agree,982}},{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[[a,b,c,d]]},{hooray,{v2,{2015,3,3},{16,50,13}}}]}]
16:50:13.684 d uses: [{epoch,984},{author,c},{upi,[c,b,d,a]},{repair,[]},{down,[]},{d,[{repair_airquote_done,{we_agree,982}},{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[[a,b,c,d]]},{hooray,{v2,{2015,3,3},{16,50,13}}}]}]
16:50:14.088 d uses: [{epoch,986},{author,d},{upi,[c,b,d,a]},{repair,[]},{down,[]},{d,[{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[[a,b,c,d]]},{hooray,{v2,{2015,3,3},{16,50,14}}}]}]
16:50:14.128 c uses: [{epoch,986},{author,d},{upi,[c,b,d,a]},{repair,[]},{down,[]},{d,[{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[[a,b,c,d]]},{hooray,{v2,{2015,3,3},{16,50,14}}}]}]
16:50:14.224 b uses: [{epoch,986},{author,d},{upi,[c,b,d,a]},{repair,[]},{down,[]},{d,[{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[[a,b,c,d]]},{hooray,{v2,{2015,3,3},{16,50,14}}}]}]
16:50:14.326 a uses: [{epoch,986},{author,d},{upi,[c,b,d,a]},{repair,[]},{down,[]},{d,[{author_proc,react},{ps,[]},{nodes_up,[a,b,c,d]}]},{d2,[{network_islands,[[a,b,c,d]]},{hooray,{v2,{2015,3,3},{16,50,14}}}]}]
Tue Mar 3 16:50:20 JST 2015
[36.758 s] ok
[done in 36.773 s]
module 'machi_chain_manager1_pulse'
module 'machi_chain_manager1'
module 'machi_chain_manager0_test'
machi_chain_manager0_test: smoke0_test...[0.001 s] ok
machi_chain_manager0_test: calc_projection_test_...
{ time ( ) , Hack } {{16,50,20},0}
.......................
NotCounted list was written to /tmp/manager-test.16.50.22
OKs length = 135
Transitions hit = 109
NotCounted length = 26
Least-counted transition = {{[a,c,b],[b]},1}
Most-counted transition = {{[b],[b]},21051}
[2.626 s] ok
machi_chain_manager0_test: pass1_smoke_test...ok
machi_chain_manager0_test: fail1_smoke_test...ok
machi_chain_manager0_test: fail2_smoke_test...ok
machi_chain_manager0_test: fail3_smoke_test...ok
machi_chain_manager0_test: fail4_smoke_test...ok
[done in 2.647 s]
module 'machi_chain_manager0'
module 'lamport_clock'
module 'handle_errors'
module 'event_logger'
=======================================================
All 20 tests passed.
=INFO REPORT==== 3-Mar-2015::16:50:22 ===
application: pulse
exited: stopped
type: temporary
=INFO REPORT==== 3-Mar-2015::16:50:22 ===
application: inets
exited: killed
type: temporary

View file

@ -1,2 +0,0 @@
Please see the `doc` directory at the top of the Machi repo.

View file

@ -0,0 +1,191 @@
## CORFU papers
I recommend the "5 pages" paper below first, to give a flavor of
what the CORFU is about. When Scott first read the CORFU paper
back in 2011 (and the Hyder paper), he thought it was insanity.
He recommends waiting before judging quite so hastily. :-)
After that, then perhaps take a step back are skim over the
Hyder paper. Hyder started before CORFU, but since CORFU, the
Hyder folks at Microsoft have rewritten Hyder to use CORFU as
the shared log underneath it. But the Hyder paper has lots of
interesting bits about how you'd go about creating a distributed
DB where the transaction log *is* the DB.
### "CORFU: A Distributed Shared LogCORFU: A Distributed Shared Log"
MAHESH BALAKRISHNAN, DAHLIA MALKHI, JOHN D. DAVIS, and VIJAYAN
PRABHAKARAN, Microsoft Research Silicon Valley, MICHAEL WEI,
University of California, San Diego, TED WOBBER, Microsoft Research
Silicon Valley
Long version of introduction to CORFU (~30 pages)
http://www.snookles.com/scottmp/corfu/corfu.a10-balakrishnan.pdf
### "CORFU: A Shared Log Design for Flash Clusters"
Same authors as above
Short version of introduction to CORFU paper above (~12 pages)
http://www.snookles.com/scottmp/corfu/corfu-shared-log-design.nsdi12-final30.pdf
### "From Paxos to CORFU: A Flash-Speed Shared Log"
Same authors as above
5 pages, a short summary of CORFU basics and some trial applications
that have been implemented on top of it.
http://www.snookles.com/scottmp/corfu/paxos-to-corfu.malki-acmstyle.pdf
### "Beyond Block I/O: Implementing a Distributed Shared Log in Hardware"
Wei, Davis, Wobber, Balakrishnan, Malkhi
Summary report of implmementing the CORFU server-side in
FPGA-style hardware. (~11 pages)
http://www.snookles.com/scottmp/corfu/beyond-block-io.CameraReady.pdf
### "Tango: Distributed Data Structures over a Shared Log"
Balakrishnan, Malkhi, Wobber, Wu, Brabhakaran, Wei, Davis, Rao, Zou, Zuck
Describes a framework for developing data structures that reside
persistently within a CORFU log: the log *is* the database/data
structure store.
http://www.snookles.com/scottmp/corfu/Tango.pdf
### "Dynamically Scalable, Fault-Tolerant Coordination on a Shared Logging Service"
Wei, Balakrishnan, Davis, Malkhi, Prabhakaran, Wobber
The ZooKeeper inter-server communication is replaced with CORFU.
Faster, fewer lines of code than ZK, and more features than the
original ZK code base.
http://www.snookles.com/scottmp/corfu/zookeeper-techreport.pdf
### "Hyder A Transactional Record Manager for Shared Flash"
Bernstein, Reid, Das
Describes a distributed log-based DB system where the txn log is
treated quite oddly: a "txn intent" record is written to a
shared common log All participants read the shared log in
parallel and make commit/abort decisions in parallel, based on
what conflicts (or not) that they see in the log. Scott's first
reading was "No way, wacky" ... and has since changed his mind.
http://www.snookles.com/scottmp/corfu/CIDR2011Proceedings.pdf
pages 9-20
## Fiddling with PULSE
Do the following:
make clean
make
make pulse
... then watch the dots go across the screen for 60 seconds. If you
wish, you can press `Control-c` to interrupt the test. We're really
interested in the build artifacts.
erl -pz .eunit deps/*/ebin
eqc:quickcheck(eqc:testing_time(5, corfurl_pulse:prop_pulse())).
This will run the PULSE test for 5 seconds. Feel free to adjust for
as many seconds as you wish.
Erlang R16B02-basho4 (erts-5.10.3) [source] [64-bit] [smp:8:8] [async-threads:10] [hipe] [kernel-poll:false] [dtrace]
Eshell V5.10.3 (abort with ^G)
1> eqc:quickcheck(eqc:testing_time(5, corfurl_pulse:prop_pulse())).
Starting Quviq QuickCheck version 1.30.4
(compiled at {{2014,2,7},{9,19,50}})
Licence for Basho reserved until {{2014,2,17},{1,41,39}}
......................................................................................
OK, passed 86 tests
schedule: Count: 86 Min: 2 Max: 1974 Avg: 3.2e+2 Total: 27260
true
2>
REPL interactive work can be done via:
1. Edit code, e.g. `corfurl_pulse.erl`.
2. Run `env BITCASK_PULSE=1 ./rebar skip_deps=true -D PULSE eunit suites=SKIP`
to compile.
3. Reload any recompiled modules, e.g. `l(corfurl_pulse).`
4. Resume QuickCheck activities.
## Seeing an PULSE scheduler interleaving failure in action
1. Edit `corfurl_pulse:check_trace()` to uncomment the
use of `conjunction()` that mentions `bogus_order_check_do_not_use_me`
and comment out the real `conjunction()` call below it.
2. Recompile & reload.
3. Check.
For example:
9> eqc:quickcheck(eqc:testing_time(5, corfurl_pulse:prop_pulse())).
.........Failed! After 9 tests.
Sweet! The first tuple below are the first `?FORALL()` values,
and the 2nd is the list of commands,
`{SequentialCommands, ListofParallelCommandLists}`. The 3rd is the
seed used to perturb the PULSE scheduler.
In this case, `SequentialCommands` has two calls (to `setup()` then
`append()`) and there are two parallel procs: one makes 1 call
call to `append()` and the other makes 2 calls to `append()`.
{2,2,9}
{{[{set,{var,1},{call,corfurl_pulse,setup,[2,2,9]}}],
[[{set,{var,3},
{call,corfurl_pulse,append,
[{var,1},<<231,149,226,203,10,105,54,223,147>>]}}],
[{set,{var,2},
{call,corfurl_pulse,append,
[{var,1},<<7,206,146,75,249,13,154,238,110>>]}},
{set,{var,4},
{call,corfurl_pulse,append,
[{var,1},<<224,121,129,78,207,23,79,216,36>>]}}]]},
{27492,46961,4884}}
Here are our results:
simple_result: passed
errors: passed
events: failed
identity: passed
bogus_order_check_do_not_use_me: failed
[{ok,1},{ok,3},{ok,2}] /= [{ok,1},{ok,2},{ok,3}]
Our (bogus!) order expectation was violated. Shrinking!
simple_result: passed
errors: passed
events: failed
identity: passed
bogus_order_check_do_not_use_me: failed
[{ok,1},{ok,3},{ok,2}] /= [{ok,1},{ok,2},{ok,3}]
Shrinking was able to remove two `append()` calls and to shrink the
size of the pages down from 9 bytes down to 1 byte.
Shrinking........(8 times)
{1,1,1}
{{[{set,{var,1},{call,corfurl_pulse,setup,[1,1,1]}}],
[[{set,{var,3},{call,corfurl_pulse,append,[{var,1},<<0>>]}}],
[{set,{var,4},{call,corfurl_pulse,append,[{var,1},<<0>>]}}]]},
{27492,46961,4884}}
events: failed
bogus_order_check_do_not_use_me: failed
[{ok,2},{ok,1}] /= [{ok,1},{ok,2}]
false

View file

@ -1,16 +1,3 @@
## NOTE
The Git commit numbers used below refer to a private Git
repository and not to the https://github.com/basho/machi repo. My
apologies for any confusion.
## Generating diagrams of the race/bug scenarios
Each of the scenario notes includes an MSC diagram
(Message Sequence Chart) specification file
to help illustrate the race, each with an `.mscgen` suffix. Use the
`mscgen` utility to render the diagrams into PNG, Encapsulated Postscript,
or other graphic file formats.
## read-repair-race.1.
@ -23,15 +10,7 @@ Chart (MSC) for a race found at commit 087c2605ab.
Second attempt. This is almost exactly the trace that is
generated by this failing test case at commit 087c2605ab:
C2 = [{1,2,1},
{{[{set,{var,1},{call,corfurl_pulse,setup,[1,2,1,standard]}}],
[[{set,{var,3},{call,corfurl_pulse,append,[{var,1},<<0>>]}}],
[{set,{var,2},{call,corfurl_pulse,read_approx,[{var,1},6201864198]}},
{set,{var,5},{call,corfurl_pulse,append,[{var,1},<<0>>]}}],
[{set,{var,4},{call,corfurl_pulse,append,[{var,1},<<0>>]}},
{set,{var,6},{call,corfurl_pulse,trim,[{var,1},510442857]}}]]},
{25152,1387,78241}},
[{events,[[{no_bad_reads,[]}]]}]]
C2 = [{1,2,1},{{[{set,{var,1},{call,corfurl_pulse,setup,[1,2,1,standard]}}],[[{set,{var,3},{call,corfurl_pulse,append,[{var,1},<<0>>]}}],[{set,{var,2},{call,corfurl_pulse,read_approx,[{var,1},6201864198]}},{set,{var,5},{call,corfurl_pulse,append,[{var,1},<<0>>]}}],[{set,{var,4},{call,corfurl_pulse,append,[{var,1},<<0>>]}},{set,{var,6},{call,corfurl_pulse,trim,[{var,1},510442857]}}]]},{25152,1387,78241}},[{events,[[{no_bad_reads,[]}]]}]].
eqc:check(corfurl_pulse:prop_pulse(), C2).
## read-repair-race.2b.*

File diff suppressed because it is too large Load diff

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@ -0,0 +1,109 @@
digraph {
compound=true
label="Machi chain management flowchart (sample)";
node[shape="box", style="rounded"]
start;
node[shape="box", style="rounded", label="stop1"]
stop1;
node[shape="box", style="rounded", label="stop2"]
stop2;
node[shape="box", style="rounded"]
crash;
subgraph clustera {
node[shape="parallelogram", style="", label="Set retry counter = 0"]
a05_retry;
node[shape="parallelogram", style="", label="Create P_newprop @ epoch E+1\nbased on P_current @ epoch E"]
a10_create;
node[shape="parallelogram", style="", label="Get latest public projection, P_latest"]
a20_get;
node[shape="diamond", style="", label="Epoch(P_latest) > Epoch(P_current)\norelse\nP_latest was not unanimous"]
a30_epoch;
node[shape="diamond", style="", label="Epoch(P_latest) == Epoch(P_current)"]
a40_epochequal;
node[shape="diamond", style="", label="P_latest == P_current"]
a50_equal;
}
subgraph clustera100 {
node[shape="diamond", style="", label="Write P_newprop to everyone"]
a100_write;
}
subgraph clusterb {
node[shape="diamond", style="", label="P_latest was unanimous?"]
b10_unanimous;
node[shape="diamond", style="", label="Retry counter too big?"]
b20_counter;
node[shape="diamond", style="", label="Rank(P_latest) >= Rank(P_newprop)"]
b30_rank;
node[shape="diamond", style="", label="P_latest.upi == P_newprop.upi\nand also\nPlatest.repairing == P_newprop.repairing"]
b40_condc;
node[shape="square", style="", label="P_latest author is\ntoo slow, let's try!"]
b45_lets;
node[shape="parallelogram", style="", label="P_newprop is better than P_latest.\nSet P_newprop.epoch = P_latest.epoch + 1."]
b50_better;
}
subgraph clusterc {
node[shape="diamond", style="", label="Is Move(P_current, P_latest) ok?"]
c10_move;
node[shape="parallelogram", style="", label="Tell Author(P_latest) to rewrite\nwith a bigger epoch number"]
c20_tell;
}
subgraph clusterd {
node[shape="diamond", style="", label="Use P_latest as the\nnew P_current"]
d10_use;
}
start -> a05_retry;
a05_retry -> a10_create;
a10_create -> a20_get;
a20_get -> a30_epoch;
a30_epoch -> a40_epochequal[label="false"];
a30_epoch -> b10_unanimous[label="true"];
a40_epochequal -> a50_equal[label="true"];
a40_epochequal -> crash[label="falseXX"];
a50_equal -> stop1[label="true"];
a50_equal -> b20_counter[label="false"];
a100_write -> a10_create;
b10_unanimous -> c10_move[label="yes"];
b10_unanimous -> b20_counter[label="no"];
b20_counter -> b45_lets[label="true"];
b20_counter -> b30_rank[label="false"];
b30_rank -> b40_condc[label="false"];
b30_rank -> c20_tell[label="true"];
b40_condc -> b50_better[label="false"];
b40_condc -> c20_tell[label="true"];
b45_lets -> b50_better;
b50_better -> a100_write;
c10_move -> d10_use[label="yes"];
c10_move -> a100_write[label="no"];
c20_tell -> b50_better;
d10_use -> stop2;
{rank=same; clustera clusterb clusterc clusterd};
// {rank=same; a10_create b10_unanimous c10_move d10_use stop2};
// {rank=same; a20_get b20_counter c20_tell};
// {rank=same; a30_epoch b40_condc};
// {rank=same; a40_epochequal b40_condc crash};
// {rank=same; stop1 a50_equal b50_better};
// if_valid;
//
// start -> input;
// input -> if_valid;
// if_valid -> message[label="no"];
// if_valid -> end[label="yes"];
// message -> input;
// {rank=same; message input}
}

View file

@ -45,16 +45,19 @@
dbg2 :: list() %proplist(), is not checksummed
}).
-define(NOT_FLAPPING, {0,0,0}).
-record(ch_mgr, {
init_finished :: boolean(),
name :: m_server(),
proj :: #projection{},
proj_history :: queue(),
myflu :: pid() | atom(),
flap_limit :: non_neg_integer(),
%%
runenv :: list(), %proplist()
opts :: list(), %proplist()
flaps=0 :: integer(),
flaps=0 :: integer(),
%% Deprecated ... TODO: remove when old test unit test code is removed
proj_proposed :: 'none' | #projection{}

View file

@ -1,6 +0,0 @@
%%% {erl_opts, [warnings_as_errors, {parse_transform, lager_transform}, debug_info]}.
{erl_opts, [{parse_transform, lager_transform}, debug_info]}.
{deps, [
{lager, "2.0.1", {git, "git://github.com/basho/lager.git", {tag, "2.0.1"}}}
]}.

View file

@ -1,5 +1,7 @@
%% -------------------------------------------------------------------
%%
%% Machi: a small village of replicated files
%%
%% Copyright (c) 2014 Basho Technologies, Inc. All Rights Reserved.
%%
%% This file is provided to you under the Apache License,
@ -17,7 +19,6 @@
%% under the License.
%%
%% -------------------------------------------------------------------
-module(corfurl).
-export([new_simple_projection/5,
@ -261,7 +262,6 @@ trim_page(#proj{epoch=Epoch} = P, LPN) ->
fill_or_trim_page([], _Epoch, _LPN, _Func) ->
ok;
fill_or_trim_page([H|T], Epoch, LPN, Func) ->
%% io:format(user, "~s.erl line ~w: TODO: this 'fill or trim' logic is probably stupid, due to mis-remembering the CORFU paper, sorry! Commenting out this warning line is OK, if you wish to proceed with testing Corfurl. This code can change a fill into a trim. Those things are supposed to be separate, silly me, a fill should never automagically change to a trim.\n", [?MODULE, ?LINE]),
case corfurl_flu:Func(flu_pid(H), Epoch, LPN) of
Res when Res == ok; Res == error_trimmed ->
%% Detecting a race here between fills and trims is too crazy,

View file

@ -1,5 +1,7 @@
%% -------------------------------------------------------------------
%%
%% Machi: a small village of replicated files
%%
%% Copyright (c) 2014 Basho Technologies, Inc. All Rights Reserved.
%%
%% This file is provided to you under the Apache License,
@ -17,7 +19,6 @@
%% under the License.
%%
%% -------------------------------------------------------------------
-module(corfurl_client).
-export([append_page/2, read_page/2, fill_page/2, trim_page/2, scan_forward/3]).

View file

@ -1,5 +1,7 @@
%% -------------------------------------------------------------------
%%
%% Machi: a small village of replicated files
%%
%% Copyright (c) 2014 Basho Technologies, Inc. All Rights Reserved.
%%
%% This file is provided to you under the Apache License,
@ -17,7 +19,6 @@
%% under the License.
%%
%% -------------------------------------------------------------------
-module(corfurl_flu).
-behaviour(gen_server).
@ -123,7 +124,7 @@ init({Dir, ExpPageSize, ExpMaxMem}) ->
lclock_init(),
MemFile = memfile_path(Dir),
ok = filelib:ensure_dir(MemFile),
filelib:ensure_dir(MemFile),
{ok, FH} = file:open(MemFile, [read, write, raw, binary]),
{_Version, MinEpoch, PageSize, MaxMem, TrimWatermark} =
@ -324,7 +325,7 @@ check_write(LogicalPN, PageBin,
error_overwritten
end;
true ->
{bummer, ?MODULE, ?LINE, lpn, LogicalPN, offset, Offset, max_mem, MaxMem, page_size, PageSize, bin_size, byte_size(PageBin)}
{bummer, ?MODULE, ?LINE, lpn, LogicalPN, offset, Offset, max_mem, MaxMem, page_size, PageSize}
end.
check_is_written(Offset, _PhysicalPN, #state{mem_fh=FH}) ->

View file

@ -1,5 +1,7 @@
%% -------------------------------------------------------------------
%%
%% Machi: a small village of replicated files
%%
%% Copyright (c) 2014 Basho Technologies, Inc. All Rights Reserved.
%%
%% This file is provided to you under the Apache License,
@ -17,7 +19,6 @@
%% under the License.
%%
%% -------------------------------------------------------------------
-module(corfurl_sequencer).
-behaviour(gen_server).

View file

@ -1,5 +1,7 @@
%% -------------------------------------------------------------------
%%
%% Machi: a small village of replicated files
%%
%% Copyright (c) 2014 Basho Technologies, Inc. All Rights Reserved.
%%
%% This file is provided to you under the Apache License,
@ -17,7 +19,6 @@
%% under the License.
%%
%% -------------------------------------------------------------------
-module(corfurl_util).
-export([delete_dir/1]).

View file

@ -1,9 +0,0 @@
{application, foo, [
{description, "Prototype of Machi chain manager."},
{vsn, "0.0.0"},
{applications, [kernel, stdlib, lager]},
{mod,{foo_unfinished_app,[]}},
{registered, []},
{env, [
]}
]}.

View file

@ -2,7 +2,7 @@
%%
%% Machi: a small village of replicated files
%%
%% Copyright (c) 2014 Basho Technologies, Inc. All Rights Reserved.
%% Copyright (c) 2014-2015 Basho Technologies, Inc. All Rights Reserved.
%%
%% This file is provided to you under the Apache License,
%% Version 2.0 (the "License"); you may not use this file
@ -50,7 +50,8 @@
test_calc_proposed_projection/1,
test_write_proposed_projection/1,
test_read_latest_public_projection/2,
test_react_to_env/1]).
test_react_to_env/1,
get_all_hosed/1]).
-ifdef(EQC).
-include_lib("eqc/include/eqc.hrl").
@ -113,16 +114,22 @@ init({MyName, All_list, MyFLUPid, MgrOpts}) ->
{seed, now()},
{network_partitions, []},
{network_islands, []},
{flapping_i, []},
{up_nodes, not_init_yet}],
BestProj = make_initial_projection(MyName, All_list, All_list,
[], [{author_proc, init_best}]),
[], []),
NoneProj = make_initial_projection(MyName, All_list, [],
[], [{author_proc, init_none}]),
[], []),
S = #ch_mgr{init_finished=false,
name=MyName,
proj=NoneProj,
proj_history=queue:new(),
myflu=MyFLUPid, % pid or atom local name
%% TODO 2015-03-04: revisit, should this constant be bigger?
%% Yes, this should be bigger, but it's a hack. There is
%% no guarantee that all parties will advance to a minimum
%% flap awareness in the amount of time that this mgr will.
flap_limit=length(All_list) + 50,
runenv=RunEnv,
opts=MgrOpts},
@ -145,7 +152,7 @@ handle_call(_Call, _From, #ch_mgr{init_finished=false} = S) ->
handle_call({calculate_projection_internal_old}, _From,
#ch_mgr{name=MyName}=S) ->
RelativeToServer = MyName,
{Reply, S2} = calc_projection(S, RelativeToServer, [{author_proc, call}]),
{Reply, S2} = calc_projection(S, RelativeToServer),
{reply, Reply, S2};
handle_call({test_write_proposed_projection}, _From, S) ->
if S#ch_mgr.proj_proposed == none ->
@ -161,7 +168,7 @@ handle_call({stop}, _From, S) ->
handle_call({test_calc_projection, KeepRunenvP}, _From,
#ch_mgr{name=MyName}=S) ->
RelativeToServer = MyName,
{P, S2} = calc_projection(S, RelativeToServer, [{author_proc, call}]),
{P, S2} = calc_projection(S, RelativeToServer),
{reply, {ok, P}, if KeepRunenvP -> S2;
true -> S
end};
@ -180,7 +187,7 @@ handle_cast(_Cast, #ch_mgr{init_finished=false} = S) ->
{noreply, S};
handle_cast({test_calc_proposed_projection}, #ch_mgr{name=MyName}=S) ->
RelativeToServer = MyName,
{Proj, S2} = calc_projection(S, RelativeToServer, [{author_proc, cast}]),
{Proj, S2} = calc_projection(S, RelativeToServer),
{noreply, S2#ch_mgr{proj_proposed=Proj}};
handle_cast(_Cast, S) ->
?D({cast_whaaaaaaaaaaa, _Cast}),
@ -256,9 +263,13 @@ cl_write_public_proj_local(Epoch, Proj, SkipLocalWriteErrorP,
end,
case Res0 of
ok ->
Continue();
{XX, SS} = Continue(),
{{qqq_local_write, ok, XX}, SS};
%% Continue();
_Else when SkipLocalWriteErrorP ->
Continue();
{XX, SS} = Continue(),
{{qqq_local_write, _Else, XX}, SS};
%% Continue();
Else when Else == error_written; Else == timeout; Else == t_timeout ->
{Else, S2}
end.
@ -274,7 +285,7 @@ cl_write_public_proj_remote(FLUs, Partitions, Epoch, Proj, S) ->
do_cl_read_latest_public_projection(ReadRepairP,
#ch_mgr{proj=Proj1, myflu=_MyFLU} = S) ->
_Epoch1 = Proj1#projection.epoch_number,
case cl_read_latest_public_projection(S) of
case cl_read_latest_projection(public, S) of
{needs_repair, FLUsRs, Extra, S3} ->
if not ReadRepairP ->
{not_unanimous, todoxyz, [{results, FLUsRs}|Extra], S3};
@ -286,11 +297,11 @@ do_cl_read_latest_public_projection(ReadRepairP,
{UnanimousTag, Proj2, Extra, S3}
end.
cl_read_latest_public_projection(#ch_mgr{proj=CurrentProj}=S) ->
cl_read_latest_projection(ProjectionType, #ch_mgr{proj=CurrentProj}=S) ->
#projection{all_members=All_list} = CurrentProj,
{_UpNodes, Partitions, S2} = calc_up_nodes(S),
DoIt = fun(X) ->
case machi_flu0:proj_read_latest(X, public) of
case machi_flu0:proj_read_latest(X, ProjectionType) of
{ok, P} -> P;
Else -> Else
end
@ -300,6 +311,11 @@ cl_read_latest_public_projection(#ch_mgr{proj=CurrentProj}=S) ->
FLUsRs = lists:zip(All_list, Rs),
UnwrittenRs = [x || error_unwritten <- Rs],
Ps = [Proj || {_FLU, Proj} <- FLUsRs, is_record(Proj, projection)],
%% debug only:
%% BadAnswerFLUs = [{FLU,bad_answer,Answer} || {FLU, Answer} <- FLUsRs,
%% not is_record(Answer, projection)],
BadAnswerFLUs = [FLU || {FLU, Answer} <- FLUsRs,
not is_record(Answer, projection)],
if length(UnwrittenRs) == length(Rs) ->
{error_unwritten, FLUsRs, [todo_fix_caller_perhaps], S2};
UnwrittenRs /= [] ->
@ -312,8 +328,17 @@ cl_read_latest_public_projection(#ch_mgr{proj=CurrentProj}=S) ->
end,
Extra = [{all_members_replied, length(Rs) == length(All_list)}],
Best_FLUs = [FLU || {FLU, Projx} <- FLUsRs, Projx == BestProj],
AllHosed = lists:usort(
lists:flatten([get_all_hosed(P) || P <- Ps])),
AllFlapCounts = merge_flap_counts([get_all_flap_counts(P) ||
P <- Ps]),
Extra2 = [{unanimous_flus,Best_FLUs},
{not_unanimous_flus, NotBestPs}|Extra],
{not_unanimous_flus, All_list --
(Best_FLUs ++ BadAnswerFLUs)},
{bad_answer_flus, BadAnswerFLUs},
{not_unanimous_answers, NotBestPs},
{trans_all_hosed, AllHosed},
{trans_all_flap_counts, AllFlapCounts}|Extra],
{UnanimousTag, BestProj, Extra2, S2}
end.
@ -364,26 +389,31 @@ make_projection(EpochNum,
P2 = update_projection_checksum(P),
P2#projection{dbg2=Dbg2}.
update_projection_checksum(P) ->
CSum = crypto:hash(sha, term_to_binary(P)),
P#projection{epoch_csum=CSum}.
update_projection_checksum(#projection{dbg2=Dbg2} = P) ->
CSum = crypto:hash(sha, term_to_binary(P#projection{dbg2=[]})),
P#projection{epoch_csum=CSum, dbg2=Dbg2}.
update_projection_dbg2(P, Dbg2) when is_list(Dbg2) ->
P#projection{dbg2=Dbg2}.
calc_projection(S, RelativeToServer) ->
AllHosed = [],
calc_projection(S, RelativeToServer, AllHosed).
calc_projection(#ch_mgr{proj=LastProj, runenv=RunEnv} = S, RelativeToServer,
Dbg) ->
AllHosed) ->
Dbg = [],
OldThreshold = proplists:get_value(old_threshold, RunEnv),
NoPartitionThreshold = proplists:get_value(no_partition_threshold, RunEnv),
calc_projection(OldThreshold, NoPartitionThreshold, LastProj,
RelativeToServer, Dbg, S).
RelativeToServer, AllHosed, Dbg, S).
%% OldThreshold: Percent chance of using the old/previous network partition list
%% NoPartitionThreshold: If the network partition changes, what percent chance
%% that there are no partitions at all?
calc_projection(_OldThreshold, _NoPartitionThreshold, LastProj,
RelativeToServer, Dbg,
RelativeToServer, _____TODO_delme_I_think__AllHosed, Dbg,
#ch_mgr{name=MyName, runenv=RunEnv1}=S) ->
#projection{epoch_number=OldEpochNum,
all_members=All_list,
@ -403,7 +433,7 @@ calc_projection(_OldThreshold, _NoPartitionThreshold, LastProj,
{NewUPI_list3, Repairing_list3, RunEnv3} =
case {NewUp, Repairing_list2} of
{[], []} ->
D_foo=[],
D_foo=[],
{NewUPI_list, [], RunEnv2};
{[], [H|T]} when RelativeToServer == hd(NewUPI_list) ->
%% The author is head of the UPI list. Let's see if
@ -417,16 +447,19 @@ D_foo=[],
tl(NewUPI_list) ++ Repairing_list2,
S#ch_mgr.proj, Partitions, S),
if not SameEpoch_p ->
D_foo=[],
D_foo=[],
{NewUPI_list, OldRepairing_list, RunEnv2};
true ->
D_foo=[{repair_airquote_done, {we_agree, (S#ch_mgr.proj)#projection.epoch_number}}],
D_foo=[{repair_airquote_done,
{we_agree,
(S#ch_mgr.proj)#projection.epoch_number}}],
{NewUPI_list ++ [H], T, RunEnv2}
end;
{_, _} ->
D_foo=[],
D_foo=[],
{NewUPI_list, OldRepairing_list, RunEnv2}
end,
Repairing_list4 = case NewUp of
[] -> Repairing_list3;
NewUp -> Repairing_list3 ++ NewUp
@ -446,7 +479,7 @@ D_foo=[],
P = make_projection(OldEpochNum + 1,
MyName, All_list, Down, NewUPI, NewRepairing,
D_foo ++
[da_hd] ++ D_foo ++
Dbg ++ [{ps, Partitions},{nodes_up, Up}]),
{P, S#ch_mgr{runenv=RunEnv3}}.
@ -529,6 +562,8 @@ rank_projections(Projs, CurrentProj) ->
N = length(All_list),
[{rank_projection(Proj, MemberRank, N), Proj} || Proj <- Projs].
rank_projection(#projection{upi=[]}, _MemberRank, _N) ->
-100;
rank_projection(#projection{author_server=Author,
upi=UPI_list,
repairing=Repairing_list}, MemberRank, N) ->
@ -546,15 +581,8 @@ react_to_env_A10(S) ->
?REACT(a10),
react_to_env_A20(0, S).
react_to_env_A20(Retries, #ch_mgr{name=MyName} = S) ->
react_to_env_A20(Retries, S) ->
?REACT(a20),
RelativeToServer = MyName,
{P_newprop, S2} = calc_projection(S, RelativeToServer,
[{author_proc, react}]),
react_to_env_A30(Retries, P_newprop, S2).
react_to_env_A30(Retries, P_newprop, S) ->
?REACT(a30),
{UnanimousTag, P_latest, ReadExtra, S2} =
do_cl_read_latest_public_projection(true, S),
@ -562,29 +590,58 @@ react_to_env_A30(Retries, P_newprop, S) ->
%% to determine if *all* of the UPI+Repairing FLUs are members of
%% the unanimous server replies.
UnanimousFLUs = lists:sort(proplists:get_value(unanimous_flus, ReadExtra)),
UPI_Repairing_FLUs = lists:sort(P_latest#projection.upi ++
P_latest#projection.repairing),
?REACT({a20,?LINE,latest_epoch,P_latest#projection.epoch_number}),
?REACT({a20,?LINE,latest_upi,P_latest#projection.upi}),
?REACT({a20,?LINE,latest_repairing,P_latest#projection.repairing}),
?REACT({a20,?LINE,flapping_i,get_raw_flapping_i(P_latest)}),
%% Reach into hosed compensation, if necessary, to find effective
%% UPI and Repairing lists.
{E_UPI, E_Repairing} = case get_flapping_hosed_compensation(P_latest) of
undefined ->
{P_latest#projection.upi,
P_latest#projection.repairing};
Answer ->
Answer
end,
UPI_Repairing_FLUs = lists:sort(E_UPI ++ E_Repairing),
All_UPI_Repairing_were_unanimous = UPI_Repairing_FLUs == UnanimousFLUs,
%% TODO: investigate if the condition below is more correct?
%% All_UPI_Repairing_were_unanimous = (UPI_Repairing_FLUs -- UnanimousFLUs) == [],
%% TODO: or:
%% All_UPI_Repairing_were_unanimous =
%% ordsets:is_subset(ordsets:from_list(UPI_Repairing_FLUs),
%% ordsets:from_list(UnanimousFLUs)),
LatestUnanimousP =
if UnanimousTag == unanimous
andalso
All_UPI_Repairing_were_unanimous ->
?REACT({a30,?LINE}),
?REACT({a20,?LINE}),
true;
UnanimousTag == unanimous ->
?REACT({a30,?LINE,UPI_Repairing_FLUs,UnanimousFLUs}),
?REACT({a20,?LINE,UPI_Repairing_FLUs,UnanimousFLUs}),
false;
UnanimousTag == not_unanimous ->
?REACT({a30,?LINE}),
?REACT({a20,?LINE}),
false;
true ->
exit({badbad, UnanimousTag})
end,
react_to_env_A40(Retries, P_newprop, P_latest,
react_to_env_A30(Retries, P_latest,
LatestUnanimousP, S2).
react_to_env_A30(Retries, P_latest, LatestUnanimousP,
#ch_mgr{name=MyName, flap_limit=FlapLimit} = S) ->
?REACT(a30),
RelativeToServer = MyName,
AllHosed = get_all_hosed(S),
{P_newprop1, S2} = calc_projection(S, RelativeToServer, AllHosed),
{P_newprop2, S3} = calculate_flaps(P_newprop1, FlapLimit, S2),
react_to_env_A40(Retries, P_newprop2, P_latest,
LatestUnanimousP, S3).
react_to_env_A40(Retries, P_newprop, P_latest, LatestUnanimousP,
#ch_mgr{name=MyName, proj=P_current}=S) ->
?REACT(a40),
@ -690,33 +747,81 @@ react_to_env_A50(P_latest, S) ->
{{no_change, P_latest#projection.epoch_number}, S}.
react_to_env_B10(Retries, P_newprop, P_latest, LatestUnanimousP,
Rank_newprop, Rank_latest, #ch_mgr{name=MyName}=S0) ->
Rank_newprop, Rank_latest,
#ch_mgr{name=MyName, flap_limit=FlapLimit}=S) ->
?REACT(b10),
S = calculate_flaps(P_newprop, S0),
FlapLimit = 3, % todo tweak
{_P_newprop_flap_time, P_newprop_flap_count} = get_flap_count(P_newprop),
LatestAllFlapCounts = get_all_flap_counts_counts(P_latest),
P_latest_trans_flap_count = my_find_minmost(LatestAllFlapCounts),
if
LatestUnanimousP ->
?REACT({b10, ?LINE}),
put(b10_hack, false),
react_to_env_C100(P_newprop, P_latest, S);
S#ch_mgr.flaps > FlapLimit
andalso
Rank_latest =< Rank_newprop ->
if S#ch_mgr.flaps - FlapLimit - 3 =< 0 -> io:format(user, "{FLAP: ~w flaps ~w}!\n", [S#ch_mgr.name, S#ch_mgr.flaps]); true -> ok end,
{_, _, USec} = os:timestamp(),
%% If we always go to C200, then we can deadlock sometimes.
%% So we roll the dice.
%% TODO: make this PULSE-friendly!
if USec rem 3 == 0 ->
P_newprop_flap_count >= FlapLimit ->
%% I am flapping ... what else do I do?
B10Hack = get(b10_hack),
if B10Hack == false andalso P_newprop_flap_count - FlapLimit - 3 =< 0 -> io:format(user, "{FLAP: ~w flaps ~w}!\n", [S#ch_mgr.name, P_newprop_flap_count]), put(b10_hack, true); true -> ok end,
if
%% So, if we noticed a flap count by some FLU X with a
%% count below FlapLimit, then X crashes so that X's
%% flap count remains below FlapLimit, then we could get
%% stuck forever? Hrm, except that 'crashes' ought to be
%% detected by our own failure detector and get us out of
%% this current flapping situation, right? TODO
%%
%% 2015-04-05: If we add 'orelse AllSettled' to this 'if'
%% clause, then we can end up short-circuiting too
%% early. (Where AllSettled comes from the runenv's
%% flapping_i prop.) So, I believe that we need to
%% rely on the failure detector to rescue us.
%%
%% TODO About the above ^^ I think that was based on buggy
%% calculation of AllSettled. Recheck!
%%
%% TODO Yay, another magic constant below, added to
%% FlapLimit, that needs thorough examination and
%% hopefully elimination. I'm adding it to try to
%% make it more likely that someone's private proj
%% will include all_flap_counts_settled,true 100%
%% of the time. But I'm not sure how important that
%% really is.
%% That settled flag can lag behind after a change in
%% network conditions, so I'm not sure how big its
%% value is, if any.
P_latest_trans_flap_count >= FlapLimit + 20 ->
%% Everyone that's flapping together now has flap_count
%% that's larger than the limit. So it's safe and good
%% to stop here, so we can break the cycle of flapping.
react_to_env_A50(P_latest, S);
true ->
react_to_env_C200(Retries, P_latest, S)
true ->
%% It is our moral imperative to write so that the flap
%% cycle continues enough times so that everyone notices
%% and thus the earlier clause above fires.
P_newprop2 = trim_proj_with_all_hosed(P_newprop, S),
io:format(user, "GEE ~w\n", [self()]),
io:format(user, "GEE1 ~w ~w\n", [self(), make_projection_summary(P_newprop)]),
if P_newprop2#projection.upi == [] ->
io:format(user, "GEE1-50 ~w ~w\n", [self(), make_projection_summary(P_newprop)]),
?REACT({b10, ?LINE}),
react_to_env_A50(P_latest, S);
true ->
io:format(user, "GEE1-300 newprop ~w ~w\n", [self(), make_projection_summary(P_newprop)]),
io:format(user, "GEE1-300 latest ~w ~w\n", [self(), make_projection_summary(P_latest)]),
?REACT({b10, ?LINE}),
react_to_env_C300(P_newprop2, P_latest, S)
end
end;
Retries > 2 ->
?REACT({b10, ?LINE}),
put(b10_hack, false),
%% The author of P_latest is too slow or crashed.
%% Let's try to write P_newprop and see what happens!
@ -726,6 +831,7 @@ react_to_env_B10(Retries, P_newprop, P_latest, LatestUnanimousP,
andalso
P_latest#projection.author_server /= MyName ->
?REACT({b10, ?LINE}),
put(b10_hack, false),
%% Give the author of P_latest an opportunite to write a
%% new projection in a new epoch to resolve this mixed
@ -734,6 +840,7 @@ react_to_env_B10(Retries, P_newprop, P_latest, LatestUnanimousP,
true ->
?REACT({b10, ?LINE}),
put(b10_hack, false),
%% P_newprop is best, so let's write it.
react_to_env_C300(P_newprop, P_latest, S)
@ -781,8 +888,10 @@ react_to_env_C110(P_latest, #ch_mgr{myflu=MyFLU} = S) ->
Islands = proplists:get_value(network_islands, RunEnv),
P_latest2 = update_projection_dbg2(
P_latest,
[{network_islands, Islands},
{hooray, {v2, date(), time()}}|Extra_todo]),
[%% {network_islands, Islands},
%% {hooray, {v2, date(), time()}}
Islands--Islands
|Extra_todo]),
Epoch = P_latest2#projection.epoch_number,
ok = machi_flu0:proj_write(MyFLU, Epoch, private, P_latest2),
case proplists:get_value(private_write_verbose, S#ch_mgr.opts) of
@ -790,7 +899,7 @@ react_to_env_C110(P_latest, #ch_mgr{myflu=MyFLU} = S) ->
{_,_,C} = os:timestamp(),
MSec = trunc(C / 1000),
{HH,MM,SS} = time(),
io:format(user, "~2..0w:~2..0w:~2..0w.~3..0w ~p uses: ~w\n",
io:format(user, "\n~2..0w:~2..0w:~2..0w.~3..0w ~p uses: ~w\n",
[HH,MM,SS,MSec, S#ch_mgr.name,
make_projection_summary(P_latest2)]);
_ ->
@ -802,6 +911,10 @@ react_to_env_C120(P_latest, #ch_mgr{proj_history=H} = S) ->
?REACT(c120),
H2 = queue:in(P_latest, H),
H3 = case queue:len(H2) of
%% TODO: revisit this constant? Is this too long as a base?
%% My hunch is that it's fine and that the flap_limit needs to
%% be raised much higher (because it can increase several ticks
%% without a newer public epoch proposed anywhere).
X when X > length(P_latest#projection.all_members) * 2 ->
{_V, Hxx} = queue:out(H2),
Hxx;
@ -842,29 +955,183 @@ react_to_env_C310(P_newprop, S) ->
?REACT(c310),
Epoch = P_newprop#projection.epoch_number,
{_Res, S2} = cl_write_public_proj_skip_local_error(Epoch, P_newprop, S),
io:format(user, "GEE3 ~w ~w epoch ~w ~w\n", [self(), S#ch_mgr.name, P_newprop#projection.epoch_number, _Res]),
io:format(user, "GEE3 ~w ~w\n", [self(), make_projection_summary(P_newprop)]),
HH = lists:sublist(get(react), 90),
io:format(user, "GEE3 ~w ~p\n", [self(), lists:reverse(HH)]),
?REACT({c310,make_projection_summary(P_newprop)}),
?REACT({c310,_Res}),
react_to_env_A10(S2).
calculate_flaps(P_newprop, #ch_mgr{name=_MyName,
proj_history=H, flaps=Flaps} = S) ->
Ps = queue:to_list(H) ++ [P_newprop],
UPI_Repairing_combos =
lists:usort([{P#projection.upi, P#projection.repairing} || P <- Ps]),
Down_combos = lists:usort([P#projection.down || P <- Ps]),
case {queue:len(H), length(UPI_Repairing_combos), length(Down_combos)} of
{N, _, _} when N < length(P_newprop#projection.all_members) ->
S#ch_mgr{flaps=0};
%% {_, URs=_URs, 1=_Ds} when URs < 3 ->
{_, 1=_URs, 1=_Ds} ->
%%%%%% io:format(user, "F{~w,~w,~w..~w}!", [_MyName, _URs, _Ds, Flaps]),
S#ch_mgr{flaps=Flaps + 1};
%% todo_flapping;
_ ->
S#ch_mgr{flaps=0}
proposals_are_flapping(Ps) ->
%% This works:
%% UniqueProposalSummaries = lists:usort([{P#projection.upi,
%% P#projection.repairing,
%% P#projection.down} || P <- Ps]),
%% length(UniqueProposalSummaries).
%% ... but refactor to use a fold, for later refactoring ease.
[First|Rest] = Ps,
case lists:foldl(
fun(#projection{upi=UPI,repairing=Repairing,down=Down}=NewP,
#projection{upi=UPI,repairing=Repairing,down=Down}) ->
NewP;
(#projection{}=NewP,
#projection{upi=UPIo,repairing=Repairingo}=_OldP) ->
case get_flapping_hosed_compensation(NewP) of
{NewUnadjUPI, NewUnadjRepairing} ->
OK = case get_flapping_hosed_compensation(NewP) of
{OldUnadjUPI, OldUnadjRepairing} ->
OldUnadjUPI == NewUnadjUPI
andalso
OldUnadjRepairing == NewUnadjRepairing;
_Else9 ->
UPIo == NewUnadjUPI
andalso
Repairingo == NewUnadjRepairing
end,
if not OK ->
bummer4;
true ->
NewP
end;
undefined ->
bummer2;
_Else ->
bummer3
end;
(_, _Else) ->
bummer
end, First, Rest) of
LastProj when is_record(LastProj, projection) ->
1;
_Else ->
-1 % arbitrary, anything but 1
end.
calculate_flaps(P_newprop, FlapLimit,
#ch_mgr{name=MyName, proj_history=H,
flaps=Flaps, runenv=RunEnv0} = S) ->
Now = os:timestamp(),
RunEnv1 = replace(RunEnv0, [{flapping_i, []}]),
HistoryPs = queue:to_list(H),
Ps = HistoryPs ++ [P_newprop],
UniqueProposalSummaries = proposals_are_flapping(Ps),
{_WhateverUnanimous, BestP, Props, _S} =
cl_read_latest_projection(private, S),
NotBestPs = proplists:get_value(not_unanimous_answers, Props),
DownUnion = lists:usort(
lists:flatten(
[P#projection.down ||
P <- [BestP|NotBestPs]])),
HosedTransUnion = proplists:get_value(trans_all_hosed, Props),
TransFlapCounts0 = proplists:get_value(trans_all_flap_counts, Props),
_Unanimous = proplists:get_value(unanimous_flus, Props),
_NotUnanimous = proplists:get_value(not_unanimous_flus, Props),
%% NOTE: bad_answer_flus are probably due to timeout or some other network
%% glitch, i.e., anything other than {ok, P::projection()}
%% response from machi_flu0:proj_read_latest().
BadFLUs = proplists:get_value(bad_answer_flus, Props),
RemoteTransFlapCounts1 = lists:keydelete(MyName, 1, TransFlapCounts0),
RemoteTransFlapCounts =
[X || {_FLU, {FlTime, _FlapCount}}=X <- RemoteTransFlapCounts1,
FlTime /= ?NOT_FLAPPING],
TempNewFlaps = Flaps + 1,
TempAllFlapCounts = lists:sort([{MyName, {Now, TempNewFlaps}}|
RemoteTransFlapCounts]),
%% Sanity check.
true = lists:all(fun({_,{_,_}}) -> true;
(_) -> false end, TempAllFlapCounts),
%% H is the bounded history of all of this manager's private
%% projection store writes. If we've proposed the *same*
%% {UPI+Repairing, Down} combination for the entire length of our
%% bounded size of H, then we're flapping.
%%
%% If we're flapping, then we use our own flap counter and that of
%% all of our peer managers to see if we've all got flap counters
%% that exceed the flap_limit. If that global condition appears
%% true, then we "blow the circuit breaker" by stopping our
%% participation in the flapping store (via the shortcut to A50).
%%
%% We reset our flap counter on any of several conditions:
%%
%% 1. If our bounded history H contains more than one proposal,
%% then by definition we are not flapping.
%% 2. If a remote manager is flapping and has re-started a new
%% flapping episode.
%% 3. If one of the remote managers that we saw earlier has
%% stopped flapping.
case {queue:len(H), UniqueProposalSummaries} of
{N, 1} when N >= length(P_newprop#projection.all_members) ->
NewFlaps = TempNewFlaps,
%% Wow, this behavior is almost spooky.
%%
%% For an example partition map [{c,a}], on the very first
%% time this 'if' clause is hit by FLU b, AllHosed=[a,c].
%% How the heck does B know that??
%%
%% If I use:
%% DownUnionQQQ = [{P#projection.epoch_number, P#projection.author_server, P#projection.down} || P <- [BestP|NotBestPs]],
%% AllHosed = [x_1] ++ DownUnion ++ [x_2] ++ HosedTransUnion ++ [x_3] ++ BadFLUs ++ [{downunionqqq, DownUnionQQQ}];
%%
%% ... then b sees this when proposing epoch 451:
%%
%% {all_hosed,
%% [x_1,a,c,x_2,x_3,
%% {downunionqqq,
%% [{450,a,[c]},{449,b,[]},{448,c,[a]},{441,d,[]}]}]},
%%
%% So b's working on epoch 451 at the same time that d's latest
%% public projection is only epoch 441. But there's enough
%% lag so that b can "see" that a's bad=[c] (due to t_timeout!)
%% and c's bad=[a]. So voila, b magically knows about both
%% problem FLUs. Weird/cool.
AllFlapCounts = TempAllFlapCounts,
AllHosed = lists:usort(DownUnion ++ HosedTransUnion ++ BadFLUs);
{_N, _} ->
NewFlaps = 0,
AllFlapCounts = [],
AllHosed = []
end,
%% If there's at least one count in AllFlapCounts that isn't my
%% flap count, and if it's over the flap limit, then consider them
%% settled.
AllFlapCountsSettled = lists:keydelete(MyName, 1, AllFlapCounts) /= []
andalso
my_find_minmost(AllFlapCounts) >= FlapLimit,
FlappingI = {flapping_i, [{flap_count, {Now, NewFlaps}},
{all_hosed, AllHosed},
{all_flap_counts, lists:sort(AllFlapCounts)},
{all_flap_counts_settled, AllFlapCountsSettled},
{bad,BadFLUs},
{da_downu, DownUnion}, % debugging aid
{da_hosedtu, HosedTransUnion}, % debugging aid
{da_downreports, [{P#projection.epoch_number, P#projection.author_server, P#projection.down} || P <- [BestP|NotBestPs]]} % debugging aid
]},
Dbg2 = [FlappingI|P_newprop#projection.dbg],
%% SLF TODO: 2015-03-04: I'm growing increasingly suspicious of
%% the 'runenv' variable that's threaded through all this code.
%% It isn't doing what I'd originally intended. And I think that
%% the flapping information that we've just constructed here is
%% going to get lost, and that's a shame. Fix it.
RunEnv2 = replace(RunEnv1, [FlappingI]),
%% NOTE: If we'd increment of flaps here, that doesn't mean that
%% someone's public proj store has been updated. For example,
%% if we loop through states C2xx a few times, we would incr
%% flaps each time ... but the C2xx path doesn't write a new
%% proposal to everyone's public proj stores, and there's no
%% guarantee that anyone else as written a new public proj either.
{update_projection_checksum(P_newprop#projection{dbg=Dbg2}),
S#ch_mgr{flaps=NewFlaps, runenv=RunEnv2}}.
projection_transitions_are_sane(Ps, RelativeToServer) ->
projection_transitions_are_sane(Ps, RelativeToServer, false).
@ -1134,6 +1401,82 @@ sleep_ranked_order(MinSleep, MaxSleep, FLU, FLU_list) ->
timer:sleep(SleepTime),
SleepTime.
my_find_minmost([]) ->
0;
my_find_minmost([{_,_}|_] = TransFlapCounts0) ->
lists:min([FlapCount || {_T, {_FlTime, FlapCount}} <- TransFlapCounts0]);
my_find_minmost(TransFlapCounts0) ->
lists:min(TransFlapCounts0).
get_raw_flapping_i(#projection{dbg=Dbg}) ->
proplists:get_value(flapping_i, Dbg, []).
get_flap_count(P) ->
proplists:get_value(flap_count, get_raw_flapping_i(P), 0).
get_all_flap_counts(P) ->
proplists:get_value(all_flap_counts, get_raw_flapping_i(P), []).
get_all_flap_counts_counts(P) ->
case get_all_flap_counts(P) of
[] ->
[];
[{_,{_,_}}|_] = Cs ->
[Count || {_FLU, {_Time, Count}} <- Cs]
end.
get_all_hosed(P) when is_record(P, projection)->
proplists:get_value(all_hosed, get_raw_flapping_i(P), []);
get_all_hosed(S) when is_record(S, ch_mgr) ->
proplists:get_value(all_hosed,
proplists:get_value(flapping_i, S#ch_mgr.runenv, []),
[]).
get_flapping_hosed_compensation(P) ->
proplists:get_value(hosed_compensation, get_raw_flapping_i(P),
undefined).
merge_flap_counts(FlapCounts) ->
merge_flap_counts(FlapCounts, orddict:new()).
merge_flap_counts([], D) ->
orddict:to_list(D);
merge_flap_counts([FlapCount|Rest], D1) ->
%% We know that FlapCount is list({Actor, {FlapStartTime,NumFlaps}}).
D2 = orddict:from_list(FlapCount),
%% If the FlapStartTimes differ, then pick the larger start time tuple.
D3 = orddict:merge(fun(_Key, {T1,_NF1}= V1, {T2,_NF2}=_V2)
when T1 > T2 ->
V1;
(_Key, {_T1,_NF1}=_V1, {_T2,_NF2}= V2) ->
V2;
(_Key, V1, V2) ->
exit({bad_merge_2tuples,mod,?MODULE,line,?LINE,
_Key, V1, V2})
end, D1, D2),
merge_flap_counts(Rest, D3).
trim_proj_with_all_hosed(#projection{upi=UPI, repairing=Repairing,
dbg=Dbg}=P, S) ->
AllHosed = get_all_hosed(S),
HosedComp = get_flapping_hosed_compensation(P),
if AllHosed == [] orelse HosedComp /= undefined ->
P;
true ->
UPI2 = UPI -- AllHosed,
Repairing2 = Repairing -- AllHosed,
X = if AllHosed /= [] ->
Compensation = {hosed_compensation, {UPI, Repairing}},
[Compensation, {now_all_hosed, AllHosed}];
true ->
[no_comp]
end,
FI = get_raw_flapping_i(P),
Replace = [{flapping_i, X ++ FI}],
DbgB = replace(Dbg, Replace),
P#projection{upi=UPI2, repairing=Repairing2, dbg=DbgB}
end.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
perhaps_call_t(S, Partitions, FLU, DoIt) ->

View file

@ -1,5 +1,7 @@
%% -------------------------------------------------------------------
%%
%% Machi: a small village of replicated files
%%
%% Copyright (c) 2014 Basho Technologies, Inc. All Rights Reserved.
%%
%% This file is provided to you under the Apache License,
@ -17,7 +19,6 @@
%% under the License.
%%
%% -------------------------------------------------------------------
-module(corfurl_flu_test).
-ifdef(TEST).

View file

@ -1,5 +1,7 @@
%% -------------------------------------------------------------------
%%
%% Machi: a small village of replicated files
%%
%% Copyright (c) 2014 Basho Technologies, Inc. All Rights Reserved.
%%
%% This file is provided to you under the Apache License,
@ -17,7 +19,6 @@
%% under the License.
%%
%% -------------------------------------------------------------------
-module(corfurl_pulse).
-ifdef(TEST).
@ -477,9 +478,7 @@ check_trace(Trace0, _Cmds, _Seed) ->
fun(x)-> [] end,
Events),
{_, _, Perhaps} = lists:last(eqc_temporal:all_future(PerhapsR)),
%% ?QC_FMT("*Perhaps: ~p\n", [Perhaps]),
_PerhapsLPNs = lists:sort([LPN || {perhaps, LPN, _} <- Perhaps]),
%% ?QC_FMT("*_PerhapsLPNs: ~p\n", [_PerhapsLPNs]),
%%?QC_FMT("*Perhaps: ~p\n", [Perhaps]),
Reads = eqc_temporal:stateful(
fun({call, Pid, {read, LPN, _, _}}) ->
{read, Pid, LPN, []}
@ -557,12 +556,13 @@ check_trace(Trace0, _Cmds, _Seed) ->
InvalidTransitions == []},
{no_bad_reads,
eqc_temporal:is_false(eqc_temporal:all_future(BadReads))},
%% If you want to see PULSE causing crazy scheduling, then
%% change one of the "true orelse" -> "false orelse" below.
%% {bogus_no_gaps,
%% (_PerhapsLPNs == [] orelse length(range_ify(_PerhapsLPNs)) == 1)},
%% true orelse
%% (AppendLPNs == [] orelse length(range_ify(AppendLPNs)) == 1)},
%% {bogus_exactly_1_to_N,
%% (_PerhapsLPNs == lists:seq(1, length(_PerhapsLPNs)))},
%% Do not remove the {true, true}, please. It should always be the
%% last conjunction test.
%% true orelse (AppendLPNs == lists:seq(1, length(AppendLPNs)))},
{true, true}
])).

View file

@ -1,5 +1,7 @@
%% -------------------------------------------------------------------
%%
%% Machi: a small village of replicated files
%%
%% Copyright (c) 2014 Basho Technologies, Inc. All Rights Reserved.
%%
%% This file is provided to you under the Apache License,
@ -17,7 +19,6 @@
%% under the License.
%%
%% -------------------------------------------------------------------
-module(corfurl_sequencer_test).
-compile(export_all).

View file

@ -1,5 +1,7 @@
%% -------------------------------------------------------------------
%%
%% Machi: a small village of replicated files
%%
%% Copyright (c) 2014 Basho Technologies, Inc. All Rights Reserved.
%%
%% This file is provided to you under the Apache License,
@ -17,7 +19,6 @@
%% under the License.
%%
%% -------------------------------------------------------------------
-module(corfurl_test).
-include("corfurl.hrl").

View file

@ -29,7 +29,6 @@
-export([]).
-ifdef(TEST).
-ifndef(PULSE).
-ifdef(EQC).
-include_lib("eqc/include/eqc.hrl").
@ -459,5 +458,4 @@ combinations(L) ->
perms([]) -> [[]];
perms(L) -> [[H|T] || H <- L, T <- perms(L--[H])].
-endif. % ! PULSE
-endif.

View file

@ -134,6 +134,19 @@ change_partitions(OldThreshold, NoPartitionThreshold) ->
machi_partition_simulator:reset_thresholds(OldThreshold,
NoPartitionThreshold).
always_last_partitions() ->
machi_partition_simulator:always_last_partitions().
private_stable_check(FLUs) ->
{_FLU_pids, Mgr_pids} = get(manager_pids_hack),
Res = private_projections_are_stable_check(FLUs, Mgr_pids),
if not Res ->
io:format(user, "BUMMER: private stable check failed!\n", []);
true ->
ok
end,
Res.
do_ticks(Num, PidsMaybe, OldThreshold, NoPartitionThreshold) ->
io:format(user, "~p,~p,~p|", [Num, OldThreshold, NoPartitionThreshold]),
{_FLU_pids, Mgr_pids} = case PidsMaybe of
@ -229,34 +242,38 @@ prop_pulse() ->
%% doesn't always allow unanimous private projection store values:
%% FLU a might need one more tick to write its private projection, but
%% it isn't given a chance at the end of the PULSE run. So we cheat
Stabilize1 = [{set,{var,99999995},
{call, ?MODULE, always_last_partitions, []}}],
Stabilize2 = [{set,{var,99999996},
{call, ?MODULE, private_stable_check, [all_list()]}}],
LastTriggerTicks = {set,{var,99999997},
{call, ?MODULE, do_ticks, [25, undefined, no, no]}},
Cmds1 = lists:duplicate(2, LastTriggerTicks),
%% Cmds1 = lists:duplicate(length(all_list())*2, LastTriggerTicks),
Cmds = Cmds0 ++
Cmds1 ++ [{set,{var,99999999},
{call, ?MODULE, dump_state, []}}],
Stabilize1 ++
Cmds1 ++
Stabilize2 ++
[{set,{var,99999999}, {call, ?MODULE, dump_state, []}}],
{_H2, S2, Res} = pulse:run(
fun() ->
{_H, _S, _R} = run_commands(?MODULE, Cmds)
end, [{seed, Seed},
{strategy, unfair}]),
%% {FLU_pids, Mgr_pids} = S2#state.pids,
%% [ok = machi_flu0:stop(FLU) || FLU <- FLU_pids],
%% [ok = ?MGR:stop(Mgr) || Mgr <- Mgr_pids],
ok = shutdown_hard(),
%% ?QC_FMT("Cmds ~p\n", [Cmds]),
%% ?QC_FMT("H2 ~p\n", [_H2]),
%% ?QC_FMT("S2 ~p\n", [S2]),
{Report, Diag} = S2#state.dump_state,
%% ?QC_FMT("\nLast report = ~p\n", [lists:last(Report)]),
%% Report is ordered by Epoch. For each private projection
%% written during any given epoch, confirm that all chain
%% members appear in only one unique chain, i.e., the sets of
%% unique chains are disjoint.
AllDisjointP = ?MGRTEST:all_reports_are_disjoint(Report),
%% Given the report, we flip it around so that we observe the
%% sets of chain transitions relative to each FLU.
R_Chains = [?MGRTEST:extract_chains_relative_to_flu(FLU, Report) ||
FLU <- all_list()],
%% ?D(R_Chains),
R_Projs = [{FLU, [?MGRTEST:chain_to_projection(
FLU, Epoch, UPI, Repairing, all_list()) ||
{Epoch, UPI, Repairing} <- E_Chains]} ||
@ -268,16 +285,11 @@ prop_pulse() ->
[{FLU,_SaneRes} = {FLU,?MGR:projection_transitions_are_sane_retrospective(
Ps, FLU)} ||
{FLU, Ps} <- R_Projs],
%% ?QC_FMT("Sane ~p\n", [Sane]),
SaneP = lists:all(fun({_FLU, SaneRes}) -> SaneRes == true end, Sane),
%% The final report item should say that all are agreed_membership.
{_LastEpoch, {ok_disjoint, LastRepXs}} = lists:last(Report),
%% ?QC_FMT("LastEpoch=~p,", [_LastEpoch]),
%% ?QC_FMT("Report ~P\n", [Report, 5000]),
%% ?QC_FMT("Diag ~s\n", [Diag]),
AgreedOrNot = lists:usort([element(1, X) || X <- LastRepXs]),
%% ?QC_FMT("LastRepXs ~p", [LastRepXs]),
%% TODO: Check that we've converged to a single chain with no repairs.
SingleChainNoRepair = case LastRepXs of
@ -296,7 +308,7 @@ prop_pulse() ->
?QC_FMT("SingleChainNoRepair failure =\n ~p\n", [SingleChainNoRepair])
end,
conjunction([{res, Res == true orelse Res == ok},
{all_disjoint, ?MGRTEST:all_reports_are_disjoint(Report)},
{all_disjoint, AllDisjointP},
{sane, SaneP},
{all_agreed_at_end, AgreedOrNot == [agreed_membership]},
{single_chain_no_repair, SingleChainNoRepair}
@ -329,7 +341,7 @@ shutdown_hard() ->
exec_ticks(Num, Mgr_pids) ->
Parent = self(),
Pids = [spawn(fun() ->
Pids = [spawn_link(fun() ->
[begin
erlang:yield(),
Max = 10,
@ -349,4 +361,19 @@ exec_ticks(Num, Mgr_pids) ->
end || _ <- Pids],
ok.
private_projections_are_stable_check(All_list, Mgr_pids) ->
%% TODO: extend the check to look not only for latest num, but
%% also check for flapping, and if yes, to see if all_hosed are
%% all exactly equal.
_ = exec_ticks(40, Mgr_pids),
Private1 = [machi_flu0:proj_get_latest_num(FLU, private) ||
FLU <- All_list],
_ = exec_ticks(5, Mgr_pids),
Private2 = [machi_flu0:proj_get_latest_num(FLU, private) ||
FLU <- All_list],
(Private1 == Private2).
-endif. % PULSE

View file

@ -28,7 +28,7 @@
-define(D(X), io:format(user, "~s ~p\n", [??X, X])).
-define(Dw(X), io:format(user, "~s ~w\n", [??X, X])).
-export([unanimous_report/1, unanimous_report/2]).
-export([]).
-ifdef(TEST).
@ -42,243 +42,6 @@
-include_lib("eunit/include/eunit.hrl").
-compile(export_all).
-ifndef(PULSE).
smoke0_test() ->
machi_partition_simulator:start_link({1,2,3}, 50, 50),
{ok, FLUa} = machi_flu0:start_link(a),
{ok, M0} = ?MGR:start_link(a, [a,b,c], a),
try
pong = ?MGR:ping(M0),
%% If/when calculate_projection_internal_old() disappears, then
%% get rid of the comprehension below ... start/ping/stop is
%% good enough for smoke0.
io:format(user, "\n\nBegin 5 lines of verbose stuff, check manually for differences\n", []),
[begin
Proj = ?MGR:calculate_projection_internal_old(M0),
io:format(user, "~w\n", [?MGR:make_projection_summary(Proj)])
end || _ <- lists:seq(1,5)],
io:format(user, "\n", [])
after
ok = ?MGR:stop(M0),
ok = machi_flu0:stop(FLUa),
ok = machi_partition_simulator:stop()
end.
smoke1_test() ->
machi_partition_simulator:start_link({1,2,3}, 100, 0),
{ok, FLUa} = machi_flu0:start_link(a),
{ok, FLUb} = machi_flu0:start_link(b),
{ok, FLUc} = machi_flu0:start_link(c),
I_represent = I_am = a,
{ok, M0} = ?MGR:start_link(I_represent, [a,b,c], I_am),
try
{ok, _P1} = ?MGR:test_calc_projection(M0, false),
_ = ?MGR:test_calc_proposed_projection(M0),
{remote_write_results,
[{b,ok},{c,ok}]} = ?MGR:test_write_proposed_projection(M0),
{unanimous, P1, Extra1} = ?MGR:test_read_latest_public_projection(M0, false),
ok
after
ok = ?MGR:stop(M0),
ok = machi_flu0:stop(FLUa),
ok = machi_flu0:stop(FLUb),
ok = machi_flu0:stop(FLUc),
ok = machi_partition_simulator:stop()
end.
nonunanimous_setup_and_fix_test() ->
machi_partition_simulator:start_link({1,2,3}, 100, 0),
{ok, FLUa} = machi_flu0:start_link(a),
{ok, FLUb} = machi_flu0:start_link(b),
I_represent = I_am = a,
{ok, Ma} = ?MGR:start_link(I_represent, [a,b], I_am),
{ok, Mb} = ?MGR:start_link(b, [a,b], b),
try
{ok, P1} = ?MGR:test_calc_projection(Ma, false),
P1a = ?MGR:update_projection_checksum(
P1#projection{down=[b], upi=[a], dbg=[{hackhack, ?LINE}]}),
P1b = ?MGR:update_projection_checksum(
P1#projection{author_server=b, creation_time=now(),
down=[a], upi=[b], dbg=[{hackhack, ?LINE}]}),
P1Epoch = P1#projection.epoch_number,
ok = machi_flu0:proj_write(FLUa, P1Epoch, public, P1a),
ok = machi_flu0:proj_write(FLUb, P1Epoch, public, P1b),
%% ?D(x),
{not_unanimous,_,_}=_XX = ?MGR:test_read_latest_public_projection(Ma, false),
%% ?Dw(_XX),
{not_unanimous,_,_}=_YY = ?MGR:test_read_latest_public_projection(Ma, true),
%% The read repair here doesn't automatically trigger the creation of
%% a new projection (to try to create a unanimous projection). So
%% we expect nothing to change when called again.
{not_unanimous,_,_}=_YY = ?MGR:test_read_latest_public_projection(Ma, true),
{now_using, _} = ?MGR:test_react_to_env(Ma),
{unanimous,P2,E2} = ?MGR:test_read_latest_public_projection(Ma, false),
{ok, P2pa} = machi_flu0:proj_read_latest(FLUa, private),
P2 = P2pa#projection{dbg2=[]},
%% FLUb should still be using proj #0 for its private use
{ok, P0pb} = machi_flu0:proj_read_latest(FLUb, private),
0 = P0pb#projection.epoch_number,
%% Poke FLUb to react ... should be using the same private proj
%% as FLUa.
{now_using, _} = ?MGR:test_react_to_env(Mb),
{ok, P2pb} = machi_flu0:proj_read_latest(FLUb, private),
P2 = P2pb#projection{dbg2=[]},
ok
after
ok = ?MGR:stop(Ma),
ok = ?MGR:stop(Mb),
ok = machi_flu0:stop(FLUa),
ok = machi_flu0:stop(FLUb),
ok = machi_partition_simulator:stop()
end.
%% This test takes a long time and spits out a huge amount of logging
%% cruft to the console. Comment out the EUnit fixture and run manually.
%% convergence_demo_test_() ->
%% {timeout, 300, fun() -> convergence_demo1() end}.
convergence_demo1() ->
All_list = [a,b,c,d],
%% machi_partition_simulator:start_link({111,222,33}, 0, 100),
Seed = erlang:now(),
machi_partition_simulator:start_link(Seed, 0, 100),
io:format(user, "convergence_demo seed = ~p\n", [Seed]),
_ = machi_partition_simulator:get(All_list),
{ok, FLUa} = machi_flu0:start_link(a),
{ok, FLUb} = machi_flu0:start_link(b),
{ok, FLUc} = machi_flu0:start_link(c),
{ok, FLUd} = machi_flu0:start_link(d),
Namez = [{a, FLUa}, {b, FLUb}, {c, FLUc}, {d, FLUd}],
I_represent = I_am = a,
MgrOpts = [private_write_verbose],
{ok, Ma} = ?MGR:start_link(I_represent, All_list, I_am, MgrOpts),
{ok, Mb} = ?MGR:start_link(b, All_list, b, MgrOpts),
{ok, Mc} = ?MGR:start_link(c, All_list, c, MgrOpts),
{ok, Md} = ?MGR:start_link(d, All_list, d, MgrOpts),
try
{ok, P1} = ?MGR:test_calc_projection(Ma, false),
P1Epoch = P1#projection.epoch_number,
ok = machi_flu0:proj_write(FLUa, P1Epoch, public, P1),
ok = machi_flu0:proj_write(FLUb, P1Epoch, public, P1),
ok = machi_flu0:proj_write(FLUc, P1Epoch, public, P1),
ok = machi_flu0:proj_write(FLUd, P1Epoch, public, P1),
{now_using, XX1} = ?MGR:test_react_to_env(Ma),
?D(XX1),
{now_using, _} = ?MGR:test_react_to_env(Mb),
{now_using, _} = ?MGR:test_react_to_env(Mc),
{QQ,QQP2,QQE2} = ?MGR:test_read_latest_public_projection(Ma, false),
?D(QQ),
?Dw(?MGR:make_projection_summary(QQP2)),
?D(QQE2),
%% {unanimous,P2,E2} = test_read_latest_public_projection(Ma, false),
machi_partition_simulator:reset_thresholds(10, 50),
_ = machi_partition_simulator:get(All_list),
Parent = self(),
DoIt = fun(Iters, S_min, S_max) ->
Pids = [spawn(fun() ->
[begin
erlang:yield(),
Elapsed =
?MGR:sleep_ranked_order(S_min, S_max, M_name, All_list),
Res = ?MGR:test_react_to_env(MMM),
timer:sleep(S_max - Elapsed),
Res=Res %% ?D({self(), Res})
end || _ <- lists:seq(1, Iters)],
Parent ! done
end) || {M_name, MMM} <- [{a, Ma},
{b, Mb},
{c, Mc},
{d, Md}] ],
[receive
done ->
ok
after 995000 ->
exit(icky_timeout)
end || _ <- Pids]
end,
DoIt(30, 0, 0),
io:format(user, "\nSET always_last_partitions ON ... we should see convergence to correct chains.\n", []),
%% machi_partition_simulator:always_these_partitions([{b,a}]),
machi_partition_simulator:always_these_partitions([{a,b}]),
%% machi_partition_simulator:always_these_partitions([{b,c}]),
%% machi_partition_simulator:always_these_partitions([{a,c},{c,b}]),
%% machi_partition_simulator:always_last_partitions(),
[DoIt(25, 40, 400) || _ <- [1]],
%% TODO: We should be stable now ... analyze it.
io:format(user, "\nSET always_last_partitions OFF ... let loose the dogs of war!\n", []),
machi_partition_simulator:reset_thresholds(10, 50),
DoIt(30, 0, 0),
io:format(user, "\nSET always_last_partitions ON ... we should see convergence to correct chains2.\n", []),
%% machi_partition_simulator:always_last_partitions(),
machi_partition_simulator:always_these_partitions([{a,c}]),
[DoIt(25, 40, 400) || _ <- [1]],
io:format(user, "\nSET always_last_partitions ON ... we should see convergence to correct chains3.\n", []),
machi_partition_simulator:no_partitions(),
[DoIt(20, 40, 400) || _ <- [1]],
%% TODO: We should be stable now ... analyze it.
io:format(user, "~s\n", [os:cmd("date")]),
%% Create a report where at least one FLU has written a
%% private projection.
Report = unanimous_report(Namez),
%% ?D(Report),
%% Report is ordered by Epoch. For each private projection
%% written during any given epoch, confirm that all chain
%% members appear in only one unique chain, i.e., the sets of
%% unique chains are disjoint.
true = all_reports_are_disjoint(Report),
%% Given the report, we flip it around so that we observe the
%% sets of chain transitions relative to each FLU.
R_Chains = [extract_chains_relative_to_flu(FLU, Report) ||
FLU <- All_list],
%% ?D(R_Chains),
R_Projs = [{FLU, [chain_to_projection(FLU, Epoch, UPI, Repairing,
All_list) ||
{Epoch, UPI, Repairing} <- E_Chains]} ||
{FLU, E_Chains} <- R_Chains],
%% For each chain transition experienced by a particular FLU,
%% confirm that each state transition is OK.
try
[{FLU, true} = {FLU, ?MGR:projection_transitions_are_sane(Ps, FLU)} ||
{FLU, Ps} <- R_Projs]
catch _Err:_What ->
io:format(user, "Report ~p\n", [Report]),
exit({line, ?LINE, _Err, _What})
end,
%% ?D(R_Projs),
ok
after
ok = ?MGR:stop(Ma),
ok = ?MGR:stop(Mb),
ok = machi_flu0:stop(FLUa),
ok = machi_flu0:stop(FLUb),
ok = machi_partition_simulator:stop()
end.
-endif. % not PULSE
unanimous_report(Namez) ->
UniquePrivateEs =
lists:usort(lists:flatten(
@ -366,4 +129,382 @@ chain_to_projection(MyName, Epoch, UPI_list, Repairing_list, All_list) ->
All_list -- (UPI_list ++ Repairing_list),
UPI_list, Repairing_list, []).
-ifndef(PULSE).
smoke0_test() ->
machi_partition_simulator:start_link({1,2,3}, 50, 50),
{ok, FLUa} = machi_flu0:start_link(a),
{ok, M0} = ?MGR:start_link(a, [a,b,c], a),
try
pong = ?MGR:ping(M0),
%% If/when calculate_projection_internal_old() disappears, then
%% get rid of the comprehension below ... start/ping/stop is
%% good enough for smoke0.
[begin
Proj = ?MGR:calculate_projection_internal_old(M0),
io:format(user, "~w\n", [?MGR:make_projection_summary(Proj)])
end || _ <- lists:seq(1,5)]
after
ok = ?MGR:stop(M0),
ok = machi_flu0:stop(FLUa),
ok = machi_partition_simulator:stop()
end.
smoke1_test() ->
machi_partition_simulator:start_link({1,2,3}, 100, 0),
{ok, FLUa} = machi_flu0:start_link(a),
{ok, FLUb} = machi_flu0:start_link(b),
{ok, FLUc} = machi_flu0:start_link(c),
I_represent = I_am = a,
{ok, M0} = ?MGR:start_link(I_represent, [a,b,c], I_am),
try
{ok, _P1} = ?MGR:test_calc_projection(M0, false),
_ = ?MGR:test_calc_proposed_projection(M0),
{remote_write_results,
[{b,ok},{c,ok}]} = ?MGR:test_write_proposed_projection(M0),
{unanimous, P1, Extra1} = ?MGR:test_read_latest_public_projection(M0, false),
ok
after
ok = ?MGR:stop(M0),
ok = machi_flu0:stop(FLUa),
ok = machi_flu0:stop(FLUb),
ok = machi_flu0:stop(FLUc),
ok = machi_partition_simulator:stop()
end.
nonunanimous_setup_and_fix_test() ->
machi_partition_simulator:start_link({1,2,3}, 100, 0),
{ok, FLUa} = machi_flu0:start_link(a),
{ok, FLUb} = machi_flu0:start_link(b),
I_represent = I_am = a,
{ok, Ma} = ?MGR:start_link(I_represent, [a,b], I_am),
{ok, Mb} = ?MGR:start_link(b, [a,b], b),
try
{ok, P1} = ?MGR:test_calc_projection(Ma, false),
P1a = ?MGR:update_projection_checksum(
P1#projection{down=[b], upi=[a], dbg=[{hackhack, ?LINE}]}),
P1b = ?MGR:update_projection_checksum(
P1#projection{author_server=b, creation_time=now(),
down=[a], upi=[b], dbg=[{hackhack, ?LINE}]}),
P1Epoch = P1#projection.epoch_number,
ok = machi_flu0:proj_write(FLUa, P1Epoch, public, P1a),
ok = machi_flu0:proj_write(FLUb, P1Epoch, public, P1b),
?D(x),
{not_unanimous,_,_}=_XX = ?MGR:test_read_latest_public_projection(Ma, false),
?Dw(_XX),
{not_unanimous,_,_}=_YY = ?MGR:test_read_latest_public_projection(Ma, true),
%% The read repair here doesn't automatically trigger the creation of
%% a new projection (to try to create a unanimous projection). So
%% we expect nothing to change when called again.
{not_unanimous,_,_}=_YY = ?MGR:test_read_latest_public_projection(Ma, true),
{now_using, _} = ?MGR:test_react_to_env(Ma),
{unanimous,P2,E2} = ?MGR:test_read_latest_public_projection(Ma, false),
{ok, P2pa} = machi_flu0:proj_read_latest(FLUa, private),
P2 = P2pa#projection{dbg2=[]},
%% FLUb should still be using proj #0 for its private use
{ok, P0pb} = machi_flu0:proj_read_latest(FLUb, private),
0 = P0pb#projection.epoch_number,
%% Poke FLUb to react ... should be using the same private proj
%% as FLUa.
{now_using, _} = ?MGR:test_react_to_env(Mb),
{ok, P2pb} = machi_flu0:proj_read_latest(FLUb, private),
P2 = P2pb#projection{dbg2=[]},
ok
after
ok = ?MGR:stop(Ma),
ok = ?MGR:stop(Mb),
ok = machi_flu0:stop(FLUa),
ok = machi_flu0:stop(FLUb),
ok = machi_partition_simulator:stop()
end.
short_doc() ->
"
A visualization of the convergence behavior of the chain self-management
algorithm for Machi.
1. Set up 4 FLUs and chain manager pairs.
2. Create a number of different network partition scenarios, where
(simulated) partitions may be symmetric or asymmetric. Then halt changing
the partitions and keep the simulated network stable and broken.
3. Run a number of iterations of the algorithm in parallel by poking each
of the manager processes on a random'ish basis.
4. Afterward, fetch the chain transition changes made by each FLU and
verify that no transition was unsafe.
During the iteration periods, the following is a cheatsheet for the output.
See the internal source for interpreting the rest of the output.
'Let loose the dogs of war!' Network instability
'SET partitions = ' Network stability (but broken)
'x uses:' The FLU x has made an internal state transition. The rest of
the line is a dump of internal state.
'{t}' This is a tick event which triggers one of the manager processes
to evaluate its environment and perhaps make a state transition.
A long chain of '{t}{t}{t}{t}' means that the chain state has settled
to a stable configuration, which is the goal of the algorithm.
Press control-c to interrupt....".
long_doc() ->
"
'Let loose the dogs of war!'
The simulated network is very unstable for a few seconds.
'x uses'
After a single iteration, server x has determined that the chain
should be defined by the upi, repair, and down list in this record.
If all participants reach the same conclusion at the same epoch
number (and checksum, see next item below), then the chain is
stable, fully configured, and can provide full service.
'epoch,E'
The epoch number for this decision is E. The checksum of the full
record is not shown. For purposes of the protocol, a server will
'wedge' itself and refuse service (until a new config is chosen)
whenever: a). it sees a bigger epoch number mentioned somewhere, or
b). it sees the same epoch number but a different checksum. In case
of b), there was a network partition that has healed, and both sides
had chosen to operate with an identical epoch number but different
chain configs.
'upi', 'repair', and 'down'
Members in the chain that are fully in sync and thus preserving the
Update Propagation Invariant, up but under repair (simulated), and
down, respectively.
'ps,[some list]'
The list of asymmetric network partitions. {a,b} means that a
cannot send to b, but b can send to a.
This partition list is recorded for debugging purposes but is *not*
used by the algorithm. The algorithm only 'feels' its effects via
simulated timeout whenever there's a partition in one of the
messaging directions.
'nodes_up,[list]'
The best guess right now of which ndoes are up, relative to the
author node, specified by '{author,X}'
'SET partitions = [some list]'
All subsequent iterations should have a stable list of partitions,
i.e. the 'ps' list described should be stable.
'{FLAP: x flaps n}!'
Server x has detected that it's flapping/oscillating after iteration
n of a naive/1st draft detection algorithm.
".
convergence_demo_test_() ->
{timeout, 98*300, fun() -> convergence_demo_test(x) end}.
convergence_demo_test(_) ->
timer:sleep(100),
io:format(user, short_doc(), []),
timer:sleep(3000),
All_list = [a,b,c,d],
machi_partition_simulator:start_link({111,222,33}, 0, 100),
_ = machi_partition_simulator:get(All_list),
{ok, FLUa} = machi_flu0:start_link(a),
{ok, FLUb} = machi_flu0:start_link(b),
{ok, FLUc} = machi_flu0:start_link(c),
{ok, FLUd} = machi_flu0:start_link(d),
Namez = [{a, FLUa}, {b, FLUb}, {c, FLUc}, {d, FLUd}],
I_represent = I_am = a,
MgrOpts = [private_write_verbose],
{ok, Ma} = ?MGR:start_link(I_represent, All_list, I_am, MgrOpts),
{ok, Mb} = ?MGR:start_link(b, All_list, b, MgrOpts),
{ok, Mc} = ?MGR:start_link(c, All_list, c, MgrOpts),
{ok, Md} = ?MGR:start_link(d, All_list, d, MgrOpts),
try
{ok, P1} = ?MGR:test_calc_projection(Ma, false),
P1Epoch = P1#projection.epoch_number,
ok = machi_flu0:proj_write(FLUa, P1Epoch, public, P1),
ok = machi_flu0:proj_write(FLUb, P1Epoch, public, P1),
ok = machi_flu0:proj_write(FLUc, P1Epoch, public, P1),
ok = machi_flu0:proj_write(FLUd, P1Epoch, public, P1),
machi_partition_simulator:reset_thresholds(10, 50),
_ = machi_partition_simulator:get(All_list),
Parent = self(),
DoIt = fun(Iters, S_min, S_max) ->
io:format(user, "\nDoIt: top\n\n", []),
Pids = [spawn(fun() ->
random:seed(now()),
[begin
erlang:yield(),
S_max_rand = random:uniform(
S_max + 1),
io:format(user, "{t}", []),
Elapsed =
?MGR:sleep_ranked_order(
S_min, S_max_rand,
M_name, All_list),
_ = ?MGR:test_react_to_env(MMM),
%% Be more unfair by not
%% sleeping here.
%% timer:sleep(S_max - Elapsed),
Elapsed
end || _ <- lists:seq(1, Iters)],
Parent ! done
end) || {M_name, MMM} <- [{a, Ma},
{b, Mb},
{c, Mc},
{d, Md}] ],
[receive
done ->
ok
after 995000 ->
exit(icky_timeout)
end || _ <- Pids]
end,
XandYs1 = [[{X,Y}] || X <- All_list, Y <- All_list, X /= Y],
XandYs2 = [[{X,Y}, {A,B}] || X <- All_list, Y <- All_list, X /= Y,
A <- All_list, B <- All_list, A /= B,
X /= A],
%% XandYs3 = [[{X,Y}, {A,B}, {C,D}] || X <- All_list, Y <- All_list, X /= Y,
%% A <- All_list, B <- All_list, A /= B,
%% C <- All_list, D <- All_list, C /= D,
%% X /= A, X /= C, A /= C],
AllPartitionCombinations = XandYs1 ++ XandYs2,
%% AllPartitionCombinations = XandYs3,
?D({?LINE, length(AllPartitionCombinations)}),
machi_partition_simulator:reset_thresholds(10, 50),
io:format(user, "\nLet loose the dogs of war!\n", []),
DoIt(30, 0, 0),
[begin
%% machi_partition_simulator:reset_thresholds(10, 50),
%% io:format(user, "\nLet loose the dogs of war!\n", []),
%% DoIt(30, 0, 0),
machi_partition_simulator:always_these_partitions(Partition),
io:format(user, "\nSET partitions = ~w.\n", [Partition]),
[DoIt(50, 10, 100) || _ <- [1,2,3,4] ],
true = private_projections_are_stable(Namez, DoIt),
true = all_hosed_lists_are_identical(Namez, Partition),
io:format(user, "\nSweet, we converged & all_hosed are unanimous-or-islands-inconclusive.\n", []),
%% PPP =
%% [begin
%% PPPallPubs = machi_flu0:proj_list_all(FLU, public),
%% [begin
%% {ok, Pr} = machi_flu0:proj_read(FLU, PPPepoch, public),
%% {Pr#projection.epoch_number, FLUName, Pr}
%% end || PPPepoch <- PPPallPubs]
%% end || {FLUName, FLU} <- Namez],
%% io:format(user, "PPP ~p\n", [lists:sort(lists:append(PPP))]),
timer:sleep(1000),
ok
end || Partition <- AllPartitionCombinations
%% end || Partition <- [ [{c,a}] ]
%% end || Partition <- [ [{c,a}], [{c,b}, {a, b}] ]
%% end || Partition <- [ [{a,b},{b,a}, {a,c},{c,a}, {a,d},{d,a}],
%% [{a,b},{b,a}, {a,c},{c,a}, {a,d},{d,a}, {b,c}],
%% [{a,b},{b,a}, {a,c},{c,a}, {a,d},{d,a}, {c,d}] ]
],
%% exit(end_experiment),
io:format(user, "\nSET partitions = []\n", []),
io:format(user, "Sweet, finishing early\n", []), exit(yoyoyo_testing_hack),
io:format(user, "We should see convergence to 1 correct chain.\n", []),
machi_partition_simulator:no_partitions(),
[DoIt(50, 10, 100) || _ <- [1]],
true = private_projections_are_stable(Namez, DoIt),
io:format(user, "~s\n", [os:cmd("date")]),
%% We are stable now ... analyze it.
%% Create a report where at least one FLU has written a
%% private projection.
Report = unanimous_report(Namez),
%% ?D(Report),
%% Report is ordered by Epoch. For each private projection
%% written during any given epoch, confirm that all chain
%% members appear in only one unique chain, i.e., the sets of
%% unique chains are disjoint.
true = all_reports_are_disjoint(Report),
%% Given the report, we flip it around so that we observe the
%% sets of chain transitions relative to each FLU.
R_Chains = [extract_chains_relative_to_flu(FLU, Report) ||
FLU <- All_list],
%% ?D(R_Chains),
R_Projs = [{FLU, [chain_to_projection(FLU, Epoch, UPI, Repairing,
All_list) ||
{Epoch, UPI, Repairing} <- E_Chains]} ||
{FLU, E_Chains} <- R_Chains],
%% For each chain transition experienced by a particular FLU,
%% confirm that each state transition is OK.
try
[{FLU, true} = {FLU, ?MGR:projection_transitions_are_sane(Ps, FLU)} ||
{FLU, Ps} <- R_Projs],
io:format(user, "\nAll sanity checks pass, hooray!\n", [])
catch _Err:_What ->
io:format(user, "Report ~p\n", [Report]),
exit({line, ?LINE, _Err, _What})
end,
%% ?D(R_Projs),
ok
after
ok = ?MGR:stop(Ma),
ok = ?MGR:stop(Mb),
ok = machi_flu0:stop(FLUa),
ok = machi_flu0:stop(FLUb),
ok = machi_partition_simulator:stop()
end.
private_projections_are_stable(Namez, PollFunc) ->
Private1 = [machi_flu0:proj_get_latest_num(FLU, private) ||
{_Name, FLU} <- Namez],
PollFunc(5, 1, 10),
Private2 = [machi_flu0:proj_get_latest_num(FLU, private) ||
{_Name, FLU} <- Namez],
true = (Private1 == Private2).
all_hosed_lists_are_identical(Namez, Partition) ->
Ps = [machi_flu0:proj_read_latest(FLU, private) || {_Name, FLU} <- Namez],
Uniques = lists:usort([machi_chain_manager1:get_all_hosed(P) ||
{ok, P} <- Ps]),
Members = [M || {M, _Pid} <- Namez],
Islands = machi_partition_simulator:partitions2num_islands(
Members, Partition),
%% io:format(user, "all_hosed_lists_are_identical:\n", []),
%% io:format(user, " Uniques = ~p Islands ~p\n Partition ~p\n",
%% [Uniques, Islands, Partition]),
case length(Uniques) of
1 ->
true;
_ when Islands == 'many' ->
%% There are at least two partitions, so yes, it's quite
%% possible that the all_hosed lists may differ.
%% TODO Fix this up to be smarter about fully-isolated
%% islands of partition.
true;
_ ->
false
end.
-endif. % not PULSE
-endif. % TEST

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@ -29,7 +29,6 @@
-endif.
-ifdef(TEST).
-ifndef(PULSE).
repair_status_test() ->
{ok, F} = machi_flu0:start_link(one),
@ -42,6 +41,7 @@ repair_status_test() ->
ok = machi_flu0:stop(F)
end.
-ifndef(PULSE).
concuerror1_test() ->
ok.
@ -375,5 +375,5 @@ event_get_all() ->
Tab = ?MODULE,
ets:tab2list(Tab).
-endif. % ! PULSE
-endif.
-endif.

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@ -38,6 +38,8 @@
-export([init/1, handle_call/3, handle_cast/2, handle_info/2,
terminate/2, code_change/3]).
-export([islands2partitions/1, partitions2num_islands/2]).
-define(TAB, ?MODULE).
-record(state, {
@ -178,6 +180,16 @@ islands2partitions([Island|Rest]) ->
++
islands2partitions(Rest).
partitions2num_islands(Members, Partition) ->
Connections0 = [{X,Y} || X <- Members, Y <- Members, X /= Y],
Connections1 = Connections0 -- Partition,
Cs = [lists:member({X,Y}, Connections1)
orelse
lists:member({Y,X}, Connections1) || X <- Members, Y <- Members,
X /= Y],
case lists:usort(Cs) of
[true] -> 1;
[false, true] -> many % TODO too lazy to finish
end.
-endif. % TEST

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@ -26,7 +26,6 @@
-export([]).
-ifdef(TEST).
-ifndef(PULSE).
-ifdef(EQC).
-include_lib("eqc/include/eqc.hrl").
@ -147,6 +146,5 @@ make_canonical_form2([{File, Start, End, Members}|T]) ->
Member <- Members] ++
make_canonical_form2(T).
-endif. % ! PULSE
-endif. % TEST

BIN
prototype/corfurl/.eqc-info Normal file

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@ -1,7 +0,0 @@
.eunit
.eqc-info
current_counterexample.eqc
deps
ebin/*.beam
ebin/*.app
erl_crash.dump

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@ -1,26 +0,0 @@
REBAR_BIN := $(shell which rebar)
ifeq ($(REBAR_BIN),)
REBAR_BIN = /local/path/to/rebar
endif
.PHONY: rel deps package pkgclean
all: deps compile
compile:
$(REBAR_BIN) compile
deps:
$(REBAR_BIN) get-deps
clean:
$(REBAR_BIN) -r clean
test: deps compile eunit
eunit:
$(REBAR_BIN) -v skip_deps=true eunit
pulse: compile
env USE_PULSE=1 $(REBAR_BIN) skip_deps=true clean compile
env USE_PULSE=1 $(REBAR_BIN) skip_deps=true -D PULSE eunit

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@ -1,45 +0,0 @@
# CORFU in Erlang, a prototype
This is a mostly-complete complete prototype implementation of the
CORFU server & client specification. More details on the papers about
CORFU are mentioned in the `docs/corfurl.md` file.
## Compilation & unit testing
Use `make` and `make test`. Note that the Makefile assumes that the
`rebar` utility is available somewhere in your path.
## Testing with QuickCheck + PULSE
This model is a bit exciting because it includes all of the following:
* It uses PULSE
* It uses temporal logic to help verify the model's properties
* It also includes a (manual!) fault injection method to help verify
that the model can catch many bugs. The `eqc_temporal` library uses
a lot of `try/catch` internally, and if your callback code causes an
exception in the "wrong" places, the library will pursue a default
action rather than triggering an error! The fault injection is an
additional sanity check to verify that the model isn't (obviously)
flawed or broken.
* Uses Lamport clocks to help order happens-before and concurrent events.
* Includes stopping the sequencer (either nicely or brutal kill) to verify
that the logic still works without any active sequencer.
* Includes logic to allow the sequencer to give
**faulty sequencer assignments**, including duplicate page numbers and
gaps of unused pages. Even if the sequencer **lies to us**, all other
CORFU operation should remain 100% correct.
If you have a Quviq QuickCheck license, then you can also use the
`make pulse` target.
Please note the following prerequisites:
* Erlang R16B. Perhaps R15B might also work, but it has not been
tested yet.
* Quviq QuickCheck version 1.30.2. There appears to be an
`eqc_statem` change in Quviq EQC 1.33.2 that has broken the
test. We'll try to fix the test to be able to use 1.33.x or later,
but it is a lower priority work item for the team right now.
For more information about the PULSE test and how to use it, see the
`docs/using-pulse.md` file.

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## Notes on developing & debugging this CORFU prototype
I've recorded some notes while developing & debugging this CORFU
prototype. See the `corfurl/notes` subdirectory.
Most of the cases mentioned involve race conditions that were notable
during the development cycle. There is one case that IIRC is not
mentioned in any of the CORFU papers and is probably a case that
cannot be fixed/solved by CORFU itself.
Each of the scenario notes includes an MSC diagram specification file
to help illustrate the race. The diagrams are annotated by hand, both
with text and color, to point out critical points of timing.
## CORFU papers
I recommend the "5 pages" paper below first, to give a flavor of
what the CORFU is about. When Scott first read the CORFU paper
back in 2011 (and the Hyder paper), he thought it was insanity.
He recommends waiting before judging quite so hastily. :-)
After that, then perhaps take a step back are skim over the
Hyder paper. Hyder started before CORFU, but since CORFU, the
Hyder folks at Microsoft have rewritten Hyder to use CORFU as
the shared log underneath it. But the Hyder paper has lots of
interesting bits about how you'd go about creating a distributed
DB where the transaction log *is* the DB.
### "CORFU: A Distributed Shared Log"
MAHESH BALAKRISHNAN, DAHLIA MALKHI, JOHN D. DAVIS, and VIJAYAN
PRABHAKARAN, Microsoft Research Silicon Valley, MICHAEL WEI,
University of California, San Diego, TED WOBBER, Microsoft Research
Silicon Valley
Long version of introduction to CORFU (~30 pages)
http://www.snookles.com/scottmp/corfu/corfu.a10-balakrishnan.pdf
### "CORFU: A Shared Log Design for Flash Clusters"
Same authors as above
Short version of introduction to CORFU paper above (~12 pages)
http://www.snookles.com/scottmp/corfu/corfu-shared-log-design.nsdi12-final30.pdf
### "From Paxos to CORFU: A Flash-Speed Shared Log"
Same authors as above
5 pages, a short summary of CORFU basics and some trial applications
that have been implemented on top of it.
http://www.snookles.com/scottmp/corfu/paxos-to-corfu.malki-acmstyle.pdf
### "Beyond Block I/O: Implementing a Distributed Shared Log in Hardware"
Wei, Davis, Wobber, Balakrishnan, Malkhi
Summary report of implmementing the CORFU server-side in
FPGA-style hardware. (~11 pages)
http://www.snookles.com/scottmp/corfu/beyond-block-io.CameraReady.pdf
### "Tango: Distributed Data Structures over a Shared Log"
Balakrishnan, Malkhi, Wobber, Wu, Brabhakaran, Wei, Davis, Rao, Zou, Zuck
Describes a framework for developing data structures that reside
persistently within a CORFU log: the log *is* the database/data
structure store.
http://www.snookles.com/scottmp/corfu/Tango.pdf
### "Dynamically Scalable, Fault-Tolerant Coordination on a Shared Logging Service"
Wei, Balakrishnan, Davis, Malkhi, Prabhakaran, Wobber
The ZooKeeper inter-server communication is replaced with CORFU.
Faster, fewer lines of code than ZK, and more features than the
original ZK code base.
http://www.snookles.com/scottmp/corfu/zookeeper-techreport.pdf
### "Hyder A Transactional Record Manager for Shared Flash"
Bernstein, Reid, Das
Describes a distributed log-based DB system where the txn log is
treated quite oddly: a "txn intent" record is written to a
shared common log All participants read the shared log in
parallel and make commit/abort decisions in parallel, based on
what conflicts (or not) that they see in the log. Scott's first
reading was "No way, wacky" ... and has since changed his mind.
http://www.snookles.com/scottmp/corfu/CIDR11Proceedings.pdf
pages 9-20

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# Fiddling with PULSE
## About the PULSE test
This test is based on `eqc_statem` QuickCheck model, i.e., a
stateful/state machine style test. Roughly speaking, it does the
following things:
1. Chooses a random number of chains, chain length, and simulated flash
page size.
2. Generates a random set of stateful commands to run.
3. During the test case run, an event trace log is generated.
4. If there are any `postcondition()` checks that fail, of course,
QuickCheck will stop the test and start shrinking.
5. If all of the postcondition checks (and the rest of QuickCheck's
sanity checking) are OK, the event trace log is checked for
sanity.
### The eqc_statem commands used.
See the `corfurl_pulse:command/1` function for full details. In
summary:
* `'setup'`, for configuring the # of chains, chain length, simulated
page size, and whether or not the sequencer is faulty (i.e.,
gives faulty sequencer assignments, including duplicate page numbers and
gaps of unused pages).
* `'append'`, for `corfurl_client:append_page/2`
* '`read_approx'`, for `corfurl_client:read_page/2`
* `'scan_forward'`, for `corfurl_client:scan_forward/3`
* `'fill'`, for `corfurl_client:fill_page/2`
* `'trim'`, for `corfurl_client:trim_page/2'
* `'stop_sequencer'`, for `corfurl_sequencer:stop/2'
### Sanity checks for the event trace log
Checking the event trace log for errors is a bit tricky. The model is
similar to checking a key-value store. In a simple key-value store
model, we know (in advance) the full key. However, in CORFU, the
sequencer tells us the key, i.e., the flash page number that an
"append page" operation will use. So the model must be able to infer
the flash page number from the event trace, then use that page number
as the key for the rest of the key-value-store-like model checks.
This test also uses the `eqc_temporal` library for temporal logic. I
don't claim to be a master of using temporal logic in general or that
library specifically ... so I hope that I haven't introduced a subtle
bug into the model. <tt>^_^</tt>.
Summary of the sanity checks of the event trace:
* Do all calls finish?
* Are there any invalid page transitions? E.g., `written ->
unwritten` is forbidden.
* Are there any bad reads? E.g., reading an `error_unwritten` result
when the page has **definitely** been written/filled/trimmed.
* Note that temporal logic is used to calculate when we definitely
know a page's value vs. when we know that a page's value is
definitely going to change
**but we don't know exactly when the change has taken place**.
### Manual fault injection
TODO: Automate the fault injection testing, via "erl -D" compilation.
There are (at least) five different types of fault injection that can
be implemented by defining certain Erlang preprocessor symbols at
compilation time of `corfurl_pulse.erl`.
TRIP_no_append_duplicates
Will falsely report the LPN (page number) of an append, if the
actual LPN is 3, as page #3.
TRIP_bad_read
Will falsely report the value of a read operation of LPN #3.
TRIP_bad_scan_forward
Will falsely report written/filled pages if the # of requested
pages is equal to 10.
TRIP_bad_fill
Will falsely report the return value of a fill operation if the
requested LPN is between 3 & 5.
TRIP_bad_trim
Will falsely report the return value of a trim operation if the
requested LPN is between 3 & 5.
## Compiling and executing batch-style
Do the following:
make clean ; make ; make pulse
... then watch the dots go across the screen for 60 seconds. If you
wish, you can press `Control-c` to interrupt the test. We're really
interested in the build artifacts.
## Executing interactively at the REPL shell
After running `make pulse`, use the following two commands to start an
Erlang REPL shell and run a test for 5 seconds.
erl -pz .eunit deps/*/ebin
eqc:quickcheck(eqc:testing_time(5, corfurl_pulse:prop_pulse())).
This will run the PULSE test for 5 seconds. Feel free to adjust for
as many seconds as you wish.
Erlang R16B02-basho4 (erts-5.10.3) [source] [64-bit] [smp:8:8] [async-threads:10] [hipe] [kernel-poll:false] [dtrace]
Eshell V5.10.3 (abort with ^G)
1> eqc:quickcheck(eqc:testing_time(5, corfurl_pulse:prop_pulse())).
Starting Quviq QuickCheck version 1.30.4
(compiled at {{2014,2,7},{9,19,50}})
Licence for Basho reserved until {{2014,2,17},{1,41,39}}
......................................................................................
OK, passed 86 tests
schedule: Count: 86 Min: 2 Max: 1974 Avg: 3.2e+2 Total: 27260
true
2>
REPL interactive work can be done via:
1. Edit code, e.g. `corfurl_pulse.erl`.
2. Run `env USE_PULSE=1 rebar skip_deps=true -D PULSE eunit suites=SKIP`
to compile.
3. Reload any recompiled modules, e.g. `l(corfurl_pulse).`
4. Resume QuickCheck activities.
## Seeing an PULSE scheduler interleaving failure in action
1. Edit `corfurl_pulse:check_trace()` to uncomment the
use of `conjunction()` that mentions the `{bogus_no_gaps, ...}` tuple.
2. Recompile & reload.
3. Check.
For example:
9> eqc:quickcheck(eqc:testing_time(5, corfurl_pulse:prop_pulse())).
.........Failed! After 9 tests.
Sweet! The first tuple below are the first `?FORALL()` values,
and the 2nd is the list of commands,
`{SequentialCommands, ListofParallelCommandLists}`. The 3rd is the
seed used to perturb the PULSE scheduler.
In this case, `SequentialCommands` has two calls (to `setup()` then
`append()`) and there are two parallel procs: one makes 1 call
call to `append()` and the other makes 2 calls to `append()`.
{2,2,9}
{{[{set,{var,1},{call,corfurl_pulse,setup,[2,2,9]}}],
[[{set,{var,3},
{call,corfurl_pulse,append,
[{var,1},<<231,149,226,203,10,105,54,223,147>>]}}],
[{set,{var,2},
{call,corfurl_pulse,append,
[{var,1},<<7,206,146,75,249,13,154,238,110>>]}},
{set,{var,4},
{call,corfurl_pulse,append,
[{var,1},<<224,121,129,78,207,23,79,216,36>>]}}]]},
{27492,46961,4884}}
Here are our results:
simple_result: passed
errors: passed
events: failed
identity: passed
bogus_order_check_do_not_use_me: failed
[{ok,1},{ok,3},{ok,2}] /= [{ok,1},{ok,2},{ok,3}]
Our (bogus!) order expectation was violated. Shrinking!
simple_result: passed
errors: passed
events: failed
identity: passed
bogus_order_check_do_not_use_me: failed
[{ok,1},{ok,3},{ok,2}] /= [{ok,1},{ok,2},{ok,3}]
Shrinking was able to remove two `append()` calls and to shrink the
size of the pages down from 9 bytes down to 1 byte.
Shrinking........(8 times)
{1,1,1}
{{[{set,{var,1},{call,corfurl_pulse,setup,[1,1,1]}}],
[[{set,{var,3},{call,corfurl_pulse,append,[{var,1},<<0>>]}}],
[{set,{var,4},{call,corfurl_pulse,append,[{var,1},<<0>>]}}]]},
{27492,46961,4884}}
events: failed
bogus_order_check_do_not_use_me: failed
[{ok,2},{ok,1}] /= [{ok,1},{ok,2}]
false

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@ -0,0 +1,9 @@
{application,corfurl,
[{description,"Quick prototype of CORFU in Erlang."},
{vsn,"0.0.0"},
{applications,[kernel,stdlib,lager]},
{mod,{corfurl_unfinished_app,[]}},
{registered,[]},
{env,[{ring_size,32}]},
{modules,[corfurl,corfurl_client,corfurl_flu,corfurl_sequencer,
corfurl_util]}]}.

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