Function waitStability

ring/util.go:76–106

(ctx context.Context, r ReadRing, op Operation, minStability, maxWaiting time.Duration, isChanged func(ReplicationSet, ReplicationSet) bool)

}

func waitStability(ctx context.Context, r ReadRing, op Operation, minStability, maxWaiting time.Duration, isChanged func(ReplicationSet, ReplicationSet) bool) error {
	// Configure the max waiting time as a context deadline.
	ctx, cancel := context.WithTimeout(ctx, maxWaiting)
	defer cancel()

	// Get the initial ring state.
	ringLastState, _ := r.GetAllHealthy(op) // nolint:errcheck
	ringLastStateTs := time.Now()

	const pollingFrequency = time.Second
	pollingTicker := time.NewTicker(pollingFrequency)
	defer pollingTicker.Stop()

	for {
		select {
		case <-ctx.Done():
			return ctx.Err()
		case <-pollingTicker.C:
			// We ignore the error because in case of error it will return an empty
			// replication set which we use to compare with the previous state.
			currRingState, _ := r.GetAllHealthy(op) // nolint:errcheck

			if isChanged(ringLastState, currRingState) {
				ringLastState = currRingState
				ringLastStateTs = time.Now()
			} else if time.Since(ringLastStateTs) >= minStability {
				return nil
			}
		}
	}
}

// MakeBuffersForGet returns buffers to use with Ring.Get().
func MakeBuffersForGet() (bufDescs []InstanceDesc, bufHosts, bufZones []string) {