Merge pull request #77434 from mikedanese/watching

staging/src/k8s.io/client-go/tools/watch/informerwatcher.go

@@ -18,42 +18,86 @@ package watch
 
 import (
 	"sync"
-	"sync/atomic"
 
 	"k8s.io/apimachinery/pkg/runtime"
 	"k8s.io/apimachinery/pkg/watch"
 	"k8s.io/client-go/tools/cache"
 )
 
-func newTicketer() *ticketer {
-	return &ticketer{
+func newEventProcessor(out chan<- watch.Event) *eventProcessor {
+	return &eventProcessor{
+		out:  out,
 		cond: sync.NewCond(&sync.Mutex{}),
+		done: make(chan struct{}),
 	}
 }
 
-type ticketer struct {
-	counter uint64
+// eventProcessor buffers events and writes them to an out chan when a reader
+// is waiting. Because of the requirement to buffer events, it synchronizes
+// input with a condition, and synchronizes output with a channels. It needs to
+// be able to yield while both waiting on an input condition and while blocked
+// on writing to the output channel.
+type eventProcessor struct {
+	out chan<- watch.Event
 
-	cond    *sync.Cond
-	current uint64
+	cond *sync.Cond
+	buff []watch.Event
+
+	done chan struct{}
 }
 
-func (t *ticketer) GetTicket() uint64 {
-	// -1 to start from 0
-	return atomic.AddUint64(&t.counter, 1) - 1
+func (e *eventProcessor) run() {
+	for {
+		batch := e.takeBatch()
+		e.writeBatch(batch)
+		if e.stopped() {
+			return
+		}
+	}
 }
 
-func (t *ticketer) WaitForTicket(ticket uint64, f func()) {
-	t.cond.L.Lock()
-	defer t.cond.L.Unlock()
-	for ticket != t.current {
-		t.cond.Wait()
+func (e *eventProcessor) takeBatch() []watch.Event {
+	e.cond.L.Lock()
+	defer e.cond.L.Unlock()
+
+	for len(e.buff) == 0 && !e.stopped() {
+		e.cond.Wait()
 	}
 
-	f()
+	batch := e.buff
+	e.buff = nil
+	return batch
+}
+
+func (e *eventProcessor) writeBatch(events []watch.Event) {
+	for _, event := range events {
+		select {
+		case e.out <- event:
+		case <-e.done:
+			return
+		}
+	}
+}
 
-	t.current++
-	t.cond.Broadcast()
+func (e *eventProcessor) push(event watch.Event) {
+	e.cond.L.Lock()
+	defer e.cond.L.Unlock()
+	defer e.cond.Signal()
+	e.buff = append(e.buff, event)
+}
+
+func (e *eventProcessor) stopped() bool {
+	select {
+	case <-e.done:
+		return true
+	default:
+		return false
+	}
+}
+
+func (e *eventProcessor) stop() {
+	close(e.done)
+	e.cond.Signal()
 }
 
 // NewIndexerInformerWatcher will create an IndexerInformer and wrap it into watch.Interface
@@ -61,55 +105,44 @@ func (t *ticketer) WaitForTicket(ticket uint64, f func()) {
 // it also returns a channel you can use to wait for the informers to fully shutdown.
 func NewIndexerInformerWatcher(lw cache.ListerWatcher, objType runtime.Object) (cache.Indexer, cache.Controller, watch.Interface, <-chan struct{}) {
 	ch := make(chan watch.Event)
-	doneCh := make(chan struct{})
 	w := watch.NewProxyWatcher(ch)
-	t := newTicketer()
+	e := newEventProcessor(ch)
 
 	indexer, informer := cache.NewIndexerInformer(lw, objType, 0, cache.ResourceEventHandlerFuncs{
 		AddFunc: func(obj interface{}) {
-			go t.WaitForTicket(t.GetTicket(), func() {
-				select {
-				case ch <- watch.Event{
-					Type:   watch.Added,
-					Object: obj.(runtime.Object),
-				}:
-				case <-w.StopChan():
-				}
+			e.push(watch.Event{
+				Type:   watch.Added,
+				Object: obj.(runtime.Object),
 			})
 		},
 		UpdateFunc: func(old, new interface{}) {
-			go t.WaitForTicket(t.GetTicket(), func() {
-				select {
-				case ch <- watch.Event{
-					Type:   watch.Modified,
-					Object: new.(runtime.Object),
-				}:
-				case <-w.StopChan():
-				}
+			e.push(watch.Event{
+				Type:   watch.Modified,
+				Object: new.(runtime.Object),
 			})
 		},
 		DeleteFunc: func(obj interface{}) {
-			go t.WaitForTicket(t.GetTicket(), func() {
-				staleObj, stale := obj.(cache.DeletedFinalStateUnknown)
-				if stale {
-					// We have no means of passing the additional information down using watch API based on watch.Event
-					// but the caller can filter such objects by checking if metadata.deletionTimestamp is set
-					obj = staleObj
-				}
-
-				select {
-				case ch <- watch.Event{
-					Type:   watch.Deleted,
-					Object: obj.(runtime.Object),
-				}:
-				case <-w.StopChan():
-				}
+			staleObj, stale := obj.(cache.DeletedFinalStateUnknown)
+			if stale {
+				// We have no means of passing the additional information down using
+				// watch API based on watch.Event but the caller can filter such
+				// objects by checking if metadata.deletionTimestamp is set
+				obj = staleObj
+			}
+
+			e.push(watch.Event{
+				Type:   watch.Deleted,
+				Object: obj.(runtime.Object),
 			})
 		},
 	}, cache.Indexers{})
 
+	go e.run()
+
+	doneCh := make(chan struct{})
 	go func() {
 		defer close(doneCh)
+		defer e.stop()
 		informer.Run(w.StopChan())
 	}()
 

staging/src/k8s.io/client-go/tools/watch/informerwatcher_test.go

@@ -17,8 +17,9 @@ limitations under the License.
 package watch
 
 import (
-	"math/rand"
+	"context"
 	"reflect"
+	goruntime "runtime"
 	"sort"
 	"testing"
 	"time"
@@ -28,6 +29,7 @@ import (
 	corev1 "k8s.io/api/core/v1"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/runtime"
+	"k8s.io/apimachinery/pkg/runtime/schema"
 	"k8s.io/apimachinery/pkg/util/diff"
 	"k8s.io/apimachinery/pkg/watch"
 	fakeclientset "k8s.io/client-go/kubernetes/fake"
@@ -35,58 +37,100 @@ import (
 	"k8s.io/client-go/tools/cache"
 )
 
-type byEventTypeAndName []watch.Event
+// TestEventProcessorExit is expected to timeout if the event processor fails
+// to exit when stopped.
+func TestEventProcessorExit(t *testing.T) {
+	event := watch.Event{}
 
-func (a byEventTypeAndName) Len() int      { return len(a) }
-func (a byEventTypeAndName) Swap(i, j int) { a[i], a[j] = a[j], a[i] }
-func (a byEventTypeAndName) Less(i, j int) bool {
-	if a[i].Type < a[j].Type {
-		return true
+	tests := []struct {
+		name  string
+		write func(e *eventProcessor)
+	}{
+		{
+			name: "exit on blocked read",
+			write: func(e *eventProcessor) {
+				e.push(event)
+			},
+		},
+		{
+			name: "exit on blocked write",
+			write: func(e *eventProcessor) {
+				e.push(event)
+				e.push(event)
+			},
+		},
 	}
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			out := make(chan watch.Event)
+			e := newEventProcessor(out)
 
-	if a[i].Type > a[j].Type {
-		return false
-	}
+			test.write(e)
 
-	return a[i].Object.(*corev1.Secret).Name < a[j].Object.(*corev1.Secret).Name
+			exited := make(chan struct{})
+			go func() {
+				e.run()
+				close(exited)
+			}()
+
+			<-out
+			e.stop()
+			goruntime.Gosched()
+			<-exited
+		})
+	}
 }
 
-func TestTicketer(t *testing.T) {
-	tg := newTicketer()
+type apiInt int
 
-	const numTickets = 100 // current golang limit for race detector is 8192 simultaneously alive goroutines
-	var tickets []uint64
-	for i := 0; i < numTickets; i++ {
-		ticket := tg.GetTicket()
-		tickets = append(tickets, ticket)
+func (apiInt) GetObjectKind() schema.ObjectKind { return nil }
+func (apiInt) DeepCopyObject() runtime.Object   { return nil }
 
-		exp, got := uint64(i), ticket
-		if got != exp {
-			t.Fatalf("expected ticket %d, got %d", exp, got)
+func TestEventProcessorOrdersEvents(t *testing.T) {
+	out := make(chan watch.Event)
+	e := newEventProcessor(out)
+	go e.run()
+
+	numProcessed := 0
+	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
+	go func() {
+		for i := 0; i < 1000; i++ {
+			e := <-out
+			if got, want := int(e.Object.(apiInt)), i; got != want {
+				t.Errorf("unexpected event: got=%d, want=%d", got, want)
+			}
+			numProcessed++
 		}
+		cancel()
+	}()
+
+	for i := 0; i < 1000; i++ {
+		e.push(watch.Event{Object: apiInt(i)})
 	}
 
-	// shuffle tickets
-	rand.Shuffle(len(tickets), func(i, j int) {
-		tickets[i], tickets[j] = tickets[j], tickets[i]
-	})
-
-	res := make(chan uint64, len(tickets))
-	for _, ticket := range tickets {
-		go func(ticket uint64) {
-			time.Sleep(time.Duration(rand.Intn(50)) * time.Millisecond)
-			tg.WaitForTicket(ticket, func() {
-				res <- ticket
-			})
-		}(ticket)
+	<-ctx.Done()
+	e.stop()
+
+	if numProcessed != 1000 {
+		t.Errorf("unexpected number of events processed: %d", numProcessed)
 	}
 
-	for i := 0; i < numTickets; i++ {
-		exp, got := uint64(i), <-res
-		if got != exp {
-			t.Fatalf("expected ticket %d, got %d", exp, got)
-		}
+}
+
+type byEventTypeAndName []watch.Event
+
+func (a byEventTypeAndName) Len() int      { return len(a) }
+func (a byEventTypeAndName) Swap(i, j int) { a[i], a[j] = a[j], a[i] }
+func (a byEventTypeAndName) Less(i, j int) bool {
+	if a[i].Type < a[j].Type {
+		return true
+	}
+
+	if a[i].Type > a[j].Type {
+		return false
 	}
+
+	return a[i].Object.(*corev1.Secret).Name < a[j].Object.(*corev1.Secret).Name
 }
 
 func TestNewInformerWatcher(t *testing.T) {