storage/cacher: dispatchEvents use progressRequester

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

@@ -905,7 +905,23 @@ func (c *Cacher) dispatchEvents() {
 	bookmarkTimer := c.clock.NewTimer(wait.Jitter(time.Second, 0.25))
 	defer bookmarkTimer.Stop()
 
+	// The internal informer populates the RV as soon as it conducts
+	// The first successful sync with the underlying store.
+	// The cache must wait until this first sync is completed to be deemed ready.
+	// Since we cannot send a bookmark when the lastProcessedResourceVersion is 0,
+	// we poll aggressively for the first RV before entering the dispatch loop.
 	lastProcessedResourceVersion := uint64(0)
+	if err := wait.PollUntilContextCancel(wait.ContextForChannel(c.stopCh), 10*time.Millisecond, true, func(_ context.Context) (bool, error) {
+		if rv := c.watchCache.getResourceVersion(); rv != 0 {
+			lastProcessedResourceVersion = rv
+			return true, nil
+		}
+		return false, nil
+	}); err != nil {
+		// given the function above never returns error,
+		// the non-empty error means that the stopCh was closed
+		return
+	}
 	for {
 		select {
 		case event, ok := <-c.incoming:
@@ -929,29 +945,6 @@ func (c *Cacher) dispatchEvents() {
 			metrics.EventsCounter.WithLabelValues(c.groupResource.String()).Inc()
 		case <-bookmarkTimer.C():
 			bookmarkTimer.Reset(wait.Jitter(time.Second, 0.25))
-			// Never send a bookmark event if we did not see an event here, this is fine
-			// because we don't provide any guarantees on sending bookmarks.
-			//
-			// Just pop closed watchers and requeue others if needed.
-			//
-			// TODO(#115478): rework the following logic
-			//  in a way that would allow more
-			//  efficient cleanup of closed watchers
-			if lastProcessedResourceVersion == 0 {
-				func() {
-					c.Lock()
-					defer c.Unlock()
-					for _, watchers := range c.bookmarkWatchers.popExpiredWatchersThreadUnsafe() {
-						for _, watcher := range watchers {
-							if watcher.stopped {
-								continue
-							}
-							c.bookmarkWatchers.addWatcherThreadUnsafe(watcher)
-						}
-					}
-				}()
-				continue
-			}
 			bookmarkEvent := &watchCacheEvent{
 				Type:            watch.Bookmark,
 				Object:          c.newFunc(),

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

@@ -1902,16 +1902,13 @@ func BenchmarkCacher_GetList(b *testing.B) {
 	}
 }
 
-// TestDoNotPopExpiredWatchersWhenNoEventsSeen makes sure that
-// a bookmark event will be delivered after the cacher has seen an event.
-// Previously the watchers have been removed from the "want bookmark" queue.
-func TestDoNotPopExpiredWatchersWhenNoEventsSeen(t *testing.T) {
+// TestWatchListIsSynchronisedWhenNoEventsFromStoreReceived makes sure that
+// a bookmark event will be delivered even if the cacher has not received an event.
+func TestWatchListIsSynchronisedWhenNoEventsFromStoreReceived(t *testing.T) {
 	featuregatetesting.SetFeatureGateDuringTest(t, utilfeature.DefaultFeatureGate, features.WatchList, true)
 	backingStorage := &dummyStorage{}
 	cacher, _, err := newTestCacher(backingStorage)
-	if err != nil {
-		t.Fatalf("Couldn't create cacher: %v", err)
-	}
+	require.NoError(t, err, "failed to create cacher")
 	defer cacher.Stop()
 
 	// wait until cacher is initialized.
@@ -1929,29 +1926,10 @@ func TestDoNotPopExpiredWatchersWhenNoEventsSeen(t *testing.T) {
 	require.NoError(t, err, "failed to create watch: %v")
 	defer w.Stop()
 
-	// Ensure that popExpiredWatchers is called to ensure that our watch isn't removed from bookmarkWatchers.
-	// We do that every ~1s, so waiting 2 seconds seems enough.
-	time.Sleep(2 * time.Second)
-
-	// Send an event to ensure that lastProcessedResourceVersion in Cacher will change to non-zero value.
-	makePod := func(rv uint64) *example.Pod {
-		return &example.Pod{
-			ObjectMeta: metav1.ObjectMeta{
-				Name:            fmt.Sprintf("pod-%d", rv),
-				Namespace:       "ns",
-				ResourceVersion: fmt.Sprintf("%d", rv),
-				Annotations:     map[string]string{},
-			},
-		}
-	}
-	err = cacher.watchCache.Add(makePod(102))
-	require.NoError(t, err)
-
 	verifyEvents(t, w, []watch.Event{
-		{Type: watch.Added, Object: makePod(102)},
 		{Type: watch.Bookmark, Object: &example.Pod{
 			ObjectMeta: metav1.ObjectMeta{
-				ResourceVersion: "102",
+				ResourceVersion: "100",
 				Annotations:     map[string]string{metav1.InitialEventsAnnotationKey: "true"},
 			},
 		}},

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

@@ -641,6 +641,12 @@ func (w *watchCache) Resync() error {
 	return nil
 }
 
+func (w *watchCache) getResourceVersion() uint64 {
+	w.RLock()
+	defer w.RUnlock()
+	return w.resourceVersion
+}
+
 func (w *watchCache) currentCapacity() int {
 	w.RLock()
 	defer w.RUnlock()