import (
	"context"
	"sync"
	"time"

	"k8s.io/utils/clock"
)

// DelayFunc returns the next time interval to wait.
type DelayFunc func() time.Duration

// Timer takes an arbitrary delay function and returns a timer that can handle arbitrary interval changes.
// Use Backoff{...}.Timer() for simple delays and more efficient timers.
func (fn DelayFunc) Timer(c clock.Clock) Timer {
	return &variableTimer{fn: fn, new: c.NewTimer}
}

// zero no backoff will be performed as the same calling DelayFunc with a zero factor
// and steps.
func (b Backoff) DelayWithReset(c clock.Clock, resetInterval time.Duration) DelayFunc {
	if b.Factor <= 0 {
		return b.DelayFunc()
	}
	if resetInterval <= 0 {
		b.Steps = 0
		b.Factor = 0
		return b.DelayFunc()
	}
	return (&backoffManager{
		backoff:        b,
		initialBackoff: b,
		resetInterval:  resetInterval,

func (f *defaultFeatureSupportChecker) checkClient(ctx context.Context, c client) {
	// start with 10 ms, multiply by 2 each step, until 15 s and stays on 15 seconds.
	delayFunc := wait.Backoff{
		Duration: 10 * time.Millisecond,
		Cap:      15 * time.Second,
		Factor:   2.0,
		Steps:    11}.DelayFunc()
	f.lock.Lock()
	defer f.lock.Unlock()
	for _, ep := range c.Endpoints() {
		if _, found := f.checkingEndpoint[ep]; found {
			continue
		}

	// of the behavior of the loop, but tests that we drive the scenario to completion.
	tests := []struct {
		name               string
		delayFn            DelayFunc
		immediate          bool
		sliding            bool
		context            func() (context.Context, context.CancelFunc)
		callback           func(calls int, lastInterval time.Duration) (bool, error)

	close(ch)
	return noopTimer{closedCh: ch}
}

func (t noopTimer) C() <-chan time.Time {
	return t.closedCh
}
func (noopTimer) Next() {}
func (noopTimer) Stop() {}

type variableTimer struct {
	fn  DelayFunc
	t   clock.Timer
	new func(time.Duration) clock.Timer
}

func (t *variableTimer) C() <-chan time.Time {
	if t.t == nil {
		d := t.fn()
		t.t = t.new(d)
	}
	return t.t.C()
}

				t.Fatalf("failed to update PVC %q", getPVCName(scenario.apiPVC))
			}
		}

		if scenario.delayFunc != nil {
			go func(scenario scenarioType) {
				time.Sleep(5 * time.Second)
				// Sleep a while to run after bindAPIUpdate in BindPodVolumes
				logger.V(5).Info("Running delay function")
				scenario.delayFunc(t, ctx, testEnv, pod, scenario.initPVs, scenario.initPVCs)
			}(scenario)
		}

		// Execute