Function waitForExtSnapshotArmed

worker/import.go:47–66

waitForExtSnapshotArmed blocks until import mode is armed, the context is cancelled, or a bounded deadline elapses. Import mode is armed cluster-wide by an authorized UpdateExtSnapshotStreamingState(Start) proposal, which every group member applies via Raft (node.applyCommitted), so the flag is set

(ctx context.Context)

// covers a follower's async-apply lag. It polls rather than sleeping for a fixed duration so it
// returns as soon as the flag flips.
func waitForExtSnapshotArmed(ctx context.Context) error {
	if x.IsExtSnapshotStreamingStateTrue() {
		return nil
	}

	ctx, cancel := context.WithTimeout(ctx, extSnapshotArmWait)
	defer cancel()
	ticker := time.NewTicker(50 * time.Millisecond)
	defer ticker.Stop()
	for {
		select {
		case <-ctx.Done():
			return errExtSnapshotNotArmed
		case <-ticker.C:
			if x.IsExtSnapshotStreamingStateTrue() {
				return nil
			}
		}
	}
}

type pubSub struct {
	sync.RWMutex