}

// Until loops until stop channel is closed, running f every period.
//
// Until is syntactic sugar on top of JitterUntil with zero jitter factor and
// with sliding = true (which means the timer for period starts after the f
// completes).
func Until(f func(), period time.Duration, stopCh <-chan struct{}) {
	JitterUntil(f, period, 0.0, true, stopCh)
}

// UntilWithContext loops until context is done, running f every period.
//

func TestJitterUntil(t *testing.T) {
	ch := make(chan struct{})
	// if a channel is closed JitterUntil never calls function f
	// and returns immediately
	close(ch)
	JitterUntil(func() {
		t.Fatal("should not have been invoked")
	}, 0, 1.0, true, ch)

	ch = make(chan struct{})
	called := make(chan struct{})
	go func() {
		JitterUntil(func() {
			called <- struct{}{}
		}, 0, 1.0, true, ch)
		close(called)
	}()

	}
}

// StartOnce starts pod volume calc that will occur periodically in the background until s.StopOnce is called
func (s *volumeStatCalculator) StartOnce() *volumeStatCalculator {
	s.startO.Do(func() {
		go wait.JitterUntil(func() {
			s.calcAndStoreStats()
		}, s.jitterPeriod, 1.0, true, s.stopChannel)
	})
	return s
}

// StopOnce stops background pod volume calculation.  Will not stop a currently executing calculations until

	if err != nil {
		return fmt.Errorf("couldn't create client: %v", err)
	}

	ctx, cancel := context.WithTimeout(ctx, deadline)
	defer cancel()

	var connected bool
	wait.JitterUntil(func() {
		if _, err := cli.Get().AbsPath("/healthz").Do(ctx).Raw(); err != nil {
			klog.InfoS("Failed to connect to apiserver", "err", err)
			return
		}
		cancel()
		connected = true

	ctx, cancel := context.WithCancel(ctx)
	defer cancel()
	succeeded := false
	desc := le.config.Lock.Describe()
	klog.Infof("attempting to acquire leader lease %v...", desc)
	wait.JitterUntil(func() {
		succeeded = le.tryAcquireOrRenew(ctx)
		le.maybeReportTransition()
		if !succeeded {
			klog.V(4).Infof("failed to acquire lease %v", desc)
			return
		}

	resourceName := e.DefaultQualifiedResource.String()
	klog.V(2).InfoS("Monitoring resource count at path", "resource", resourceName, "path", "<storage-prefix>/"+prefix)
	stopCh := make(chan struct{})
	go wait.JitterUntil(func() {
		count, err := e.Storage.Count(prefix)
		if err != nil {
			klog.V(5).InfoS("Failed to update storage count metric", "err", err)
			count = -1
		}

		//
		// Introduce some small jittering to ensure that over time the requests won't start
		// accumulating at approximately the same time from the set of nodes due to priority and
		// fairness effect.
		go wait.JitterUntil(kl.syncNodeStatus, kl.nodeStatusUpdateFrequency, 0.04, true, wait.NeverStop)
		go kl.fastStatusUpdateOnce()

		// start syncing lease
		go kl.nodeLeaseController.Run(context.Background())
	}