storage: Send snapshot messages with the correct term

[bdarnell]

This fixes a regression in #12686, which meant that a replica that
fell too far behind would be unable to ever catch up because it would
think that it was receiving out-of-date snapshots.

Fixes #13506

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This change is 

[tamird]

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Reviewed 4 of 4 files at r1.
Review status: all files reviewed at latest revision, 4 unresolved discussions, all commit checks successful.

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pkg/storage/client_raft_test.go, line 641 at r1 (raw file):

	for _, changeTerm := range []bool{false, true} {
		name := "same term"

FYI spaces don't render nicely in subtest names, so you may want to use CamelCase.

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pkg/storage/client_raft_test.go, line 698 at r1 (raw file):

				for i := range mtc.stores {
					if i != stoppedStore {
						// Stop and restart all the stores, which guarantees that

not all the stores. "live stores" is the term you use below.

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pkg/storage/client_raft_test.go, line 750 at r1 (raw file):

					}
				}
			} else { // !changeTerm

+1 on this comment

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pkg/storage/helpers_test.go, line 156 at r1 (raw file):

}

// SetRaftSnapshotQueueActive enables or disables the raft snapshotqueue.

raft snapshot queue

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Comments from Reviewable

[bdarnell]

Review status: 2 of 4 files reviewed at latest revision, 3 unresolved discussions.

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pkg/storage/client_raft_test.go, line 641 at r1 (raw file):

Previously, tamird (Tamir Duberstein) wrote…

FYI spaces don't render nicely in subtest names, so you may want to use CamelCase.

In what context? It looks to me like they get replaced with underscores. Changed anyway.

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pkg/storage/client_raft_test.go, line 698 at r1 (raw file):

Previously, tamird (Tamir Duberstein) wrote…

not all the stores. "live stores" is the term you use below.

Done.

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pkg/storage/helpers_test.go, line 156 at r1 (raw file):

Previously, tamird (Tamir Duberstein) wrote…

raft snapshot queue

Done.

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Comments from Reviewable

[petermattis]

Review status: 2 of 4 files reviewed at latest revision, 4 unresolved discussions, some commit checks pending.

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pkg/storage/replica_command.go, line 3345 at r2 (raw file):

	status := r.RaftStatus()
	if status == nil {
		return errors.New("raft status not initialized")

I'm pretty sure this scenario can't happen.

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Comments from Reviewable

[petermattis]

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Review status: 2 of 4 files reviewed at latest revision, 4 unresolved discussions, some commit checks pending.

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Comments from Reviewable

[bdarnell]

Review status: 2 of 4 files reviewed at latest revision, 4 unresolved discussions, some commit checks failed.

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pkg/storage/replica_command.go, line 3345 at r2 (raw file):

Previously, petermattis (Peter Mattis) wrote…

I'm pretty sure this scenario can't happen.

Yeah, me too. But I'd rather have this check than a bare panic if it turns out I'm wrong.

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Comments from Reviewable

[tamird]

Reviewed 2 of 2 files at r2.
Review status: all files reviewed at latest revision, 1 unresolved discussion, all commit checks successful.

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Comments from Reviewable