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4 commits

Author SHA1 Message Date
Greg Burd
b2f92b8461 Update to 2018 edition of Rust (1.42). Fix and format code. Update dependencies. Fix tests. 2020-01-16 10:58:21 -05:00
Conrad Dean
f4002f34f4 fix empty param type inference with macro and update for rusqlite Result api 2019-07-22 08:54:51 -04:00
Grisha Kruglov
b22b29679b
Basic sync support (#563) r=nalexander
* Pre: remove remnants of 'open_empty'

* Pre: Cleanup 'datoms' table after a timeline move

Since timeline move operations use a transactor, they generate a
"phantom" 'tx' and a 'txInstant' assertion. It is "phantom" in a sense
that it was never present in the 'transactions' table, and is entirely
synthetic as far as our database is concerned.
It's an implementational artifact, and we were not cleaning it up.

It becomes a problem when we start inserting transactions after a move.
Once the transactor clashes with the phantom 'tx', it will retract the
phantom 'txInstant' value, leaving the transactions log in an incorrect state.

This patch adds a test for this scenario and elects the easy way out: simply
remove the offending 'txInstant' datom.

* Part 1: Sync without support for side-effects

A "side-effect" is defined here as a mutation of a remote state as part
of the sync.

If, during a sync we determine that a remote state needs to be changed, bail out.

This generally supports different variations of "baton-passing" syncing, where clients
will succeed syncing if each change is non-conflicting.

* Part 2: Support basic "side-effects" syncing

This patch introduces a concept of a follow-up sync. If a sync generated
a "merge transaction" (a regular transaction that contains assertions
necessary for local and remote transaction logs to converge), then
this transaction needs to be uploaded in a follow-up sync.

Generated SyncReport indicates if a follow-up sync is required.

Follow-up sync itself is just a regular sync. If remote state did not change,
it will result in a simple RemoteFastForward. Otherwise, we'll continue
merging and requesting a follow-up.

Schema alterations are explicitly not supported.

As local transactions are rebased on top of remote, following changes happen:
- entids are changed into tempids, letting transactor upsert :db/unique values
- entids for retractions are changed into lookup-refs if we're confident they'll succeed
-- otherwise, retractions are dropped on the floor

* Post: use a macro for more readable tests

* Tolstoy README
2018-09-07 19:18:20 -07:00
Grisha Kruglov
22b17a6779 Split "mentat transaction" logic away from the main crate
Sync needs to operate over a "mentat transaction", not just a "db transaction".
This shuffle allows internal mentat crates to consume InProgress, which models
the concept of a "mentat transaction".
2018-08-20 18:23:46 -07:00