raft: Fix race when proposal is cancelled and triggered at the same time #1846
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The demotion changes revealed an interesting race. If a proposal is triggered at the same moment that something cancels it, the callback can be called (which commits the transaction to memory), but an error can be returned from ProposeValue, which causes the transaction to be aborted. ProposeValue should return an error if and only if the callback was not called. Add a return value to cancel(). If cancel fails because the proposal was already triggered, avoid returning an error. Also, remove the applyResult type, since it isn't useful. Signed-off-by: Aaron Lehmann <aaron.lehmann@docker.com>
Current coverage is 54.66% (diff: 50.00%)@@ master #1846 diff @@
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- Hits 9325 9315 -10
- Misses 6583 6588 +5
- Partials 1133 1138 +5
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LGTM |
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The demotion changes revealed an interesting race. If a proposal is
triggered at the same moment that something cancels it, the callback can
be called (which commits the transaction to memory), but an error can be
returned from
ProposeValue, which causes the transaction to be aborted.ProposeValue should return an error if and only if the callback was not
called.
Add a return value to
cancel(). Ifcancelfails because the proposal wasalready triggered, avoid returning an error.
Also, remove the
applyResulttype, since it isn't useful.