// GetSnapshot wraps Snapshot() but does not require the replica lock
// to be held and it will block instead of returning
// ErrSnapshotTemporaryUnavailable.
func (r *Replica) GetSnapshot(ctx context.Context) (raftpb.Snapshot, error) {
retryOptions := retry.Options{
InitialBackoff: 1 * time.Millisecond,
MaxBackoff: 50 * time.Millisecond,
Multiplier: 2,
Closer: r.store.Stopper().ShouldQuiesce(),
}
for retry := retry.Start(retryOptions); retry.Next(); {
log.Tracef(ctx, "snapshot retry loop pass %d", retry.CurrentAttempt())
r.mu.Lock()
snap, err := r.SnapshotWithContext(ctx)
snapshotChan := r.mu.snapshotChan
r.mu.Unlock()
if err == raft.ErrSnapshotTemporarilyUnavailable {
if snapshotChan == nil {
// The call to Snapshot() didn't start an async process due to
// rate limiting. Try again later.
continue
}
var ok bool
snap, ok = <-snapshotChan
if ok {
return snap, nil
}
// Each snapshot worker's output can only be consumed once.
// We could be racing with raft itself, so if we get a closed
// channel loop back and try again.
} else {
return snap, err
}
}
return raftpb.Snapshot{}, &roachpb.NodeUnavailableError{}
}
// GetSnapshot wraps Snapshot() but does not require the replica lock
// to be held and it will block instead of returning
// ErrSnapshotTemporaryUnavailable.
func (r *Replica) GetSnapshot() (raftpb.Snapshot, error) {
retryOptions := retry.Options{
InitialBackoff: 1 * time.Millisecond,
MaxBackoff: 50 * time.Millisecond,
Multiplier: 2,
}
for retry := retry.Start(retryOptions); retry.Next(); {
r.mu.Lock()
snap, err := r.Snapshot()
snapshotChan := r.mu.snapshotChan
r.mu.Unlock()
if err == raft.ErrSnapshotTemporarilyUnavailable {
if snapshotChan == nil {
// The call to Snapshot() didn't start an async process due to
// rate limiting. Try again later.
continue
}
var ok bool
snap, ok = <-snapshotChan
if ok {
return snap, nil
}
// Each snapshot worker's output can only be consumed once.
// We could be racing with raft itself, so if we get a closed
// channel loop back and try again.
} else {
return snap, err
}
}
panic("unreachable") // due to infinite retries
}