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Merge pull request #10230 from manishrjain/master 

raft: Explain ReportSnapshot and Propose behavior
release-3.4
Xiang Li 2018-11-01 06:48:45 +08:00 committed by GitHub
parent 8e907e48f9 4aa72ca1d3
commit c0e04700cf
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1 changed files with 12 additions and 2 deletions
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14
raft/node.go
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@ -129,7 +129,8 @@ type Node interface {
Tick()
// Campaign causes the Node to transition to candidate state and start campaigning to become leader.
Campaign(ctx context.Context) error
// Propose proposes that data be appended to the log.
// Propose proposes that data be appended to the log. Note that proposals can be lost without
// notice, therefore it is user's job to ensure proposal retries.
Propose(ctx context.Context, data []byte) error
// ProposeConfChange proposes config change.
// At most one ConfChange can be in the process of going through consensus.
@ -174,7 +175,16 @@ type Node interface {
Status() Status
// ReportUnreachable reports the given node is not reachable for the last send.
ReportUnreachable(id uint64)
// ReportSnapshot reports the status of the sent snapshot.
// ReportSnapshot reports the status of the sent snapshot. The id is the raft ID of the follower
// who is meant to receive the snapshot, and the status is SnapshotFinish or SnapshotFailure.
// Calling ReportSnapshot with SnapshotFinish is a no-op. But, any failure in applying a
// snapshot (for e.g., while streaming it from leader to follower), should be reported to the
// leader with SnapshotFailure. When leader sends a snapshot to a follower, it pauses any raft
// log probes until the follower can apply the snapshot and advance its state. If the follower
// can't do that, for e.g., due to a crash, it could end up in a limbo, never getting any
// updates from the leader. Therefore, it is crucial that the application ensures that any
// failure in snapshot sending is caught and reported back to the leader; so it can resume raft
// log probing in the follower.
ReportSnapshot(id uint64, status SnapshotStatus)
// Stop performs any necessary termination of the Node.
Stop()