raft: Remove waitForCallback and centralize re-proposal logic. #3154
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LGTM |
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LGTM. Nice simplification. Reviewed 2 of 2 files at r1. multiraft/multiraft_test.go, line 579 [r1] (raw file): Comments from the review on Reviewable.io |
When a proposal is forwarded from a follower to a leader, waitForCallback is incorrect: what matters is whether the *leader* is waiting for a pending config change callback. Instead, we need to repropose from the follower when the leader has completed its pending config change. This is difficult to observe directly but does have a side effect: when a config change is dropped, it is replaced with an empty entry. When we see such an entry, we know we have to re-propose. Since empty entries are also used to signal leader changes, we can remove the re-proposals in maybeSendLeaderEvent. Fixes cockroachdb#2639
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Review status: 0 of 2 files reviewed at latest revision, 1 unresolved discussion. multiraft/multiraft_test.go, line 579 [r1] (raw file): Comments from the review on Reviewable.io |
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raft: Remove waitForCallback and centralize re-proposal logic.
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When a proposal is forwarded from a follower to a leader,
waitForCallback is incorrect: what matters is whether the leader is
waiting for a pending config change callback. Instead, we need to
repropose from the follower when the leader has completed its pending
config change. This is difficult to observe directly but does have a
side effect: when a config change is dropped, it is replaced with an
empty entry. When we see such an entry, we know we have to re-propose.
Since empty entries are also used to signal leader changes, we can
remove the re-proposals in maybeSendLeaderEvent.
Fixes #2639