WIP: Chain manager projection store flowchart goop
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Scott Lystig Fritchie
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109
prototype/poc-machi/docs/machi/chain-mgmt-flowchart.dot
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109
prototype/poc-machi/docs/machi/chain-mgmt-flowchart.dot
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@ -0,0 +1,109 @@
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digraph {
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compound=true
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label="Machi chain management flowchart (sample)";
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node[shape="box", style="rounded"]
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start;
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node[shape="box", style="rounded", label="stop1"]
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stop1;
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node[shape="box", style="rounded", label="stop2"]
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stop2;
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node[shape="box", style="rounded"]
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crash;
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subgraph clustera {
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node[shape="parallelogram", style="", label="Set retry counter = 0"]
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a05_retry;
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node[shape="parallelogram", style="", label="Create P_newprop @ epoch E+1\nbased on P_current @ epoch E"]
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a10_create;
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node[shape="parallelogram", style="", label="Get latest public projection, P_latest"]
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a20_get;
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node[shape="diamond", style="", label="Epoch(P_latest) > Epoch(P_current)\norelse\nP_latest was not unanimous"]
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a30_epoch;
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node[shape="diamond", style="", label="Epoch(P_latest) == Epoch(P_current)"]
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a40_epochequal;
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node[shape="diamond", style="", label="P_latest == P_current"]
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a50_equal;
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}
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subgraph clustera100 {
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node[shape="diamond", style="", label="Write P_newprop to everyone"]
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a100_write;
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}
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subgraph clusterb {
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node[shape="diamond", style="", label="P_latest was unanimous?"]
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b10_unanimous;
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node[shape="diamond", style="", label="Retry counter too big?"]
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b20_counter;
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node[shape="diamond", style="", label="Rank(P_latest) >= Rank(P_newprop)"]
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b30_rank;
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node[shape="diamond", style="", label="P_latest.upi == P_newprop.upi\nand also\nPlatest.repairing == P_newprop.repairing"]
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b40_condc;
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node[shape="square", style="", label="P_latest author is\ntoo slow, let's try!"]
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b45_lets;
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node[shape="parallelogram", style="", label="P_newprop is better than P_latest.\nSet P_newprop.epoch = P_latest.epoch + 1."]
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b50_better;
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}
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subgraph clusterc {
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node[shape="diamond", style="", label="Is Move(P_current, P_latest) ok?"]
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c10_move;
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node[shape="parallelogram", style="", label="Tell Author(P_latest) to rewrite\nwith a bigger epoch number"]
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c20_tell;
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}
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subgraph clusterd {
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node[shape="diamond", style="", label="Use P_latest as the\nnew P_current"]
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d10_use;
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}
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start -> a05_retry;
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a05_retry -> a10_create;
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a10_create -> a20_get;
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a20_get -> a30_epoch;
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a30_epoch -> a40_epochequal[label="false"];
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a30_epoch -> b10_unanimous[label="true"];
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a40_epochequal -> a50_equal[label="true"];
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a40_epochequal -> crash[label="falseXX"];
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a50_equal -> stop1[label="true"];
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a50_equal -> b20_counter[label="false"];
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a100_write -> a10_create;
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b10_unanimous -> c10_move[label="yes"];
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b10_unanimous -> b20_counter[label="no"];
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b20_counter -> b45_lets[label="true"];
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b20_counter -> b30_rank[label="false"];
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b30_rank -> b40_condc[label="false"];
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b30_rank -> c20_tell[label="true"];
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b40_condc -> b50_better[label="false"];
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b40_condc -> c20_tell[label="true"];
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b45_lets -> b50_better;
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b50_better -> a100_write;
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c10_move -> d10_use[label="yes"];
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c10_move -> a100_write[label="no"];
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c20_tell -> b50_better;
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d10_use -> stop2;
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{rank=same; clustera clusterb clusterc clusterd};
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// {rank=same; a10_create b10_unanimous c10_move d10_use stop2};
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// {rank=same; a20_get b20_counter c20_tell};
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// {rank=same; a30_epoch b40_condc};
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// {rank=same; a40_epochequal b40_condc crash};
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// {rank=same; stop1 a50_equal b50_better};
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// if_valid;
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//
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// start -> input;
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// input -> if_valid;
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// if_valid -> message[label="no"];
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// if_valid -> end[label="yes"];
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// message -> input;
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// {rank=same; message input}
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}
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@ -36,6 +36,81 @@
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-export([make_projection_summary/1]).
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-ifdef(TEST).
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%% NOTE NOTE NOTE NOTE NOTE NOTE
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%% The sketch below is old ... the flowchart is newer.
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%% TODO todo delete these comments when the flowchart
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%% and its implementation have been debugged
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%% NOTE NOTE NOTE NOTE NOTE NOTE
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%% Sketch for chain management simulator: the 'monitor'
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%%
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%% Principles:
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%% * Monitor based on only one dimension of the FLU's inherent state:
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%% up or down
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%% * Plus one additional aspect that is experienced by the external
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%% repair coordinator: not_started, in_progress, finished_ok, or
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%% finished_failed
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%% * For simulation purposes, start first with the repair coordinator
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%% happening completely by magic, e.g., an oracle implemented by the
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%% test harness.
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%% - Then add more complexity, slowly, and only when necessary.
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%% * Assumption for ease-of-implementation: assume that the repair
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%% coordinator will be the head of the chain (or some process that
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%% is managed by the head).
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%% - So the simulator need only worry about the head making any
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%% decisions about changes in repair state.
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%%
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%% Implementation:
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%%
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%% A. Calculate a local projection, P_{newprop} @ epoch E+1 that is
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%% based on the current projection P_{current} @ epoch E.
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%% - NOTE: This has side-effects in the current simulator:
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%% e.g., newenv changing perception of up/down state
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%% and other network partition effects.
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%%
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%% B. Get the latest public projection, P_{latest}. Then consider:
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%%
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%% B1a). If Epoch(P_{latest}) == Epoch(P_{current}), then goto step C.
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%%
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%% B1b). If Epoch(P_{latest}) < Epoch(P_{current}), then we have a
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%% serious invariant violation/logic problem. Shouldn't happen,
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%% but keep an eye out for it anyway.
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%%
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%% B1c). If Epoch(P_{latest}) > Epoch(P_{current}), then some other
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%% manager has noticed a change.
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%%
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%% If we haven't stopped yet, then continue:
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%%
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%% B2a). If P_{latest} was read unanimously, then use it as the new
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%% P_{current}. Then stop.
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%%
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%% B2b). If P_{latest} is not unanimous, then compare rank.
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%%
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%% - If Rank(P_{latest}) >= Rank(P_{newprop}), then we encourage
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%% the author to re-write this projection with a bigger epoch
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%% number.
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%% - If the counter has exceeded some # of tries, F=2?, then
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%% goto Step D instead.
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%% - Set a counter of the # of times that we've encouraged
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%% the author to re-write.
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%% - Sleep a while, then goto A.
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%%
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%% - If Rank(P_{latest}) < Rank(P_{newprop}) and also
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%% P_{latest}.upi == P_{newprop}.upi and also
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%% P_{latest}.repairing == P_{newprop}.repairing, then our
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%% proposal P_{newprop} isn't anything substantially new.
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%% - Use the same encouragement & retry loop as described above.
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%%
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%% - If Rank(P_{latest}) < Rank(P_{newprop}) (last case)...
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%% ... our proposal is better. Goto step D.
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%%
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%% C. If P_{latest}.upi == P_{newprop}.upi and also
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%% P_{latest}.repairing == P_{newprop}.repairing, then our proposal
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%% P_{newprop} isn't anything substantially new. Stop.
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%%
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%% D. Write P_{newprop} to everyone. Then goto A.
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-export([test_calc_projection/2,
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test_calc_proposed_projection/1,
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test_write_proposed_projection/1,
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