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Bugfix: damn, no idea how many problems this 5 month old bug caused

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Scott Lystig Fritchie 2015-09-10 01:33:55 +09:00
parent 5943494d54
commit 329a5e0682
1 changed files with 21 additions and 3 deletions
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24
src/machi_chain_manager1.erl
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@ -578,9 +578,26 @@ rank_and_sort_projections_with_extra(All_queried_list, FLUsRs, ProjectionType,
{needs_repair, FLUsRs, [flarfus], S};
true ->
[{_Rank, BestProj}|_] = rank_and_sort_projections(Ps, CurrentProj),
BestEpoch = BestProj#projection_v1.epoch_number,
NotBestPs = [Proj || Proj <- Ps, Proj /= BestProj],
UnanimousTag = if NotBestPs == [] -> unanimous;
true -> not_unanimous
NotBestPsEpochFilt =
[Proj || Proj <- Ps, Proj /= BestProj,
Proj#projection_v1.epoch_number == BestEpoch],
%% Wow, I'm not sure how long this bug has been here, but it's
%% likely 5 months old (April 2015). I just now noticed a problem
%% where BestProj was epoch 1194, but NotBestPs contained a
%% projection at smaller epoch 1192. The test for nonempty
%% NotBestPs list caused the 1194 BestProj to be marked
%% not_unanimous incorrectly. (This can happen in asymmetric
%% partition cases, hooray for crazy corner cases.)
%%
%% We correct the bug by filtering NotBestPs further to include
%% only not-equal projections that also share BestProj's epoch.
%% We'll get the correct answer we seek using this list == []
%% method, as long as rank_and_sort_projections() will always pick
%% a proj with the highest visible epoch.
UnanimousTag = if NotBestPsEpochFilt == [] -> unanimous;
true -> not_unanimous
end,
Extra = [{all_members_replied, length(FLUsRs) == length(All_queried_list)}],
Best_FLUs = [FLU || {FLU, Projx} <- FLUsRs, Projx == BestProj],
@ -590,7 +607,8 @@ rank_and_sort_projections_with_extra(All_queried_list, FLUsRs, ProjectionType,
{not_unanimous_flus, All_queried_list --
(Best_FLUs ++ BadAnswerFLUs)},
{bad_answer_flus, BadAnswerFLUs},
{not_unanimous_answers, NotBestPs}|Extra],
{not_best_ps, NotBestPs},
{not_best_ps_epoch_filt, NotBestPsEpochFilt}|Extra],
{UnanimousTag, BestProj, Extra2, S}
end.