Merge pull request #125115 from serathius/progress-notify-timer

Improve progress notify to have more correct and predictable period of triggering

staging/src/k8s.io/apiserver/pkg/storage/cacher/watch_cache_test.go

@@ -140,30 +140,41 @@ func newTestWatchCache(capacity int, indexers *cache.Indexers) *testWatchCache {
 
 type immediateTickerFactory struct{}
 
-func (t *immediateTickerFactory) NewTicker(d time.Duration) clock.Ticker {
+func (t *immediateTickerFactory) NewTimer(d time.Duration) clock.Timer {
-	return &immediateTicker{stopCh: make(chan struct{})}
+	timer := immediateTicker{
+		c: make(chan time.Time),
+	}
+	timer.Reset(d)
+	return &timer
 }
 
 type immediateTicker struct {
-	stopCh chan struct{}
+	c chan time.Time
+}
+
+func (t *immediateTicker) Reset(d time.Duration) (active bool) {
+	select {
+	case <-t.c:
+		active = true
+	default:
+	}
+	go func() {
+		t.c <- time.Now()
+	}()
+	return active
 }
 
 func (t *immediateTicker) C() <-chan time.Time {
-	ch := make(chan time.Time)
+	return t.c
-	go func() {
-		for {
-			select {
-			case ch <- time.Now():
-			case <-t.stopCh:
-				return
-			}
-		}
-	}()
-	return ch
 }
 
-func (t *immediateTicker) Stop() {
+func (t *immediateTicker) Stop() bool {
-	close(t.stopCh)
+	select {
+	case <-t.c:
+		return true
+	default:
+		return false
+	}
 }
 
 func (w *testWatchCache) RequestWatchProgress(ctx context.Context) error {

staging/src/k8s.io/apiserver/pkg/storage/cacher/watch_progress.go

@@ -42,14 +42,14 @@ func newConditionalProgressRequester(requestWatchProgress WatchProgressRequester
 		requestWatchProgress: requestWatchProgress,
 		contextMetadata:      contextMetadata,
 	}
-	pr.cond = sync.NewCond(pr.mux.RLocker())
+	pr.cond = sync.NewCond(&pr.mux)
 	return pr
 }
 
 type WatchProgressRequester func(ctx context.Context) error
 
 type TickerFactory interface {
-	NewTicker(time.Duration) clock.Ticker
+	NewTimer(time.Duration) clock.Timer
 }
 
 // conditionalProgressRequester will request progress notification if there
@@ -59,7 +59,7 @@ type conditionalProgressRequester struct {
 	requestWatchProgress WatchProgressRequester
 	contextMetadata      metadata.MD
 
-	mux     sync.RWMutex
+	mux     sync.Mutex
 	cond    *sync.Cond
 	waiting int
 	stopped bool
@@ -78,12 +78,12 @@ func (pr *conditionalProgressRequester) Run(stopCh <-chan struct{}) {
 		pr.stopped = true
 		pr.cond.Signal()
 	}()
-	ticker := pr.clock.NewTicker(progressRequestPeriod)
+	timer := pr.clock.NewTimer(progressRequestPeriod)
-	defer ticker.Stop()
+	defer timer.Stop()
 	for {
 		stopped := func() bool {
-			pr.mux.RLock()
+			pr.mux.Lock()
-			defer pr.mux.RUnlock()
+			defer pr.mux.Unlock()
 			for pr.waiting == 0 && !pr.stopped {
 				pr.cond.Wait()
 			}
@@ -94,15 +94,17 @@ func (pr *conditionalProgressRequester) Run(stopCh <-chan struct{}) {
 		}
 
 		select {
-		case <-ticker.C():
+		case <-timer.C():
 			shouldRequest := func() bool {
-				pr.mux.RLock()
+				pr.mux.Lock()
-				defer pr.mux.RUnlock()
+				defer pr.mux.Unlock()
 				return pr.waiting > 0 && !pr.stopped
 			}()
 			if !shouldRequest {
+				timer.Reset(0)
 				continue
 			}
+			timer.Reset(progressRequestPeriod)
 			err := pr.requestWatchProgress(ctx)
 			if err != nil {
 				klog.V(4).InfoS("Error requesting bookmark", "err", err)
@@ -124,5 +126,4 @@ func (pr *conditionalProgressRequester) Remove() {
 	pr.mux.Lock()
 	defer pr.mux.Unlock()
 	pr.waiting -= 1
-	pr.cond.Signal()
 }