Fix race conditions when creating watches (knative#1113)

* Fix a race condition between creating a watch and initiating the action that emits the event it is watching for

* update changelog

* add PR ID to changelog entry

* Fix merge in Changelog

* Fix table format in Changelog

CHANGELOG.adoc

@@ -17,6 +17,10 @@
 |===
 | | Description | PR
 
+| 🐛
+| Fix a race condition when using Kubernetes watches
+| https://github.com/knative/client/pull/1113[#1113]
+
 | 🐛
 | Embed the namespace in request body while creating channels
 | https://github.com/knative/client/pull/1117[#1117]

pkg/eventing/v1beta1/client.go

@@ -245,12 +245,17 @@ func (c *knEventingClient) DeleteBroker(name string, timeout time.Duration) erro
 		return c.deleteBroker(name, apis_v1.DeletePropagationBackground)
 	}
 	waitC := make(chan error)
+	watcher, err := c.WatchBroker(name, timeout)
+	if err != nil {
+		return nil
+	}
+	defer watcher.Stop()
 	go func() {
-		waitForEvent := wait.NewWaitForEvent("broker", c.WatchBroker, func(evt *watch.Event) bool { return evt.Type == watch.Deleted })
-		err, _ := waitForEvent.Wait(name, wait.Options{Timeout: &timeout}, wait.NoopMessageCallback())
+		waitForEvent := wait.NewWaitForEvent("broker", func(evt *watch.Event) bool { return evt.Type == watch.Deleted })
+		err, _ := waitForEvent.Wait(watcher, name, wait.Options{Timeout: &timeout}, wait.NoopMessageCallback())
 		waitC <- err
 	}()
-	err := c.deleteBroker(name, apis_v1.DeletePropagationForeground)
+	err = c.deleteBroker(name, apis_v1.DeletePropagationForeground)
 	if err != nil {
 		return err
 	}

pkg/serving/v1/client.go

@@ -319,12 +319,17 @@ func (cl *knServingClient) DeleteService(serviceName string, timeout time.Durati
 		return cl.deleteService(serviceName, v1.DeletePropagationBackground)
 	}
 	waitC := make(chan error)
+	watcher, err := cl.WatchService(serviceName, timeout)
+	if err != nil {
+		return nil
+	}
+	defer watcher.Stop()
 	go func() {
-		waitForEvent := wait.NewWaitForEvent("service", cl.WatchService, func(evt *watch.Event) bool { return evt.Type == watch.Deleted })
-		err, _ := waitForEvent.Wait(serviceName, wait.Options{Timeout: &timeout}, wait.NoopMessageCallback())
+		waitForEvent := wait.NewWaitForEvent("service", func(evt *watch.Event) bool { return evt.Type == watch.Deleted })
+		err, _ := waitForEvent.Wait(watcher, serviceName, wait.Options{Timeout: &timeout}, wait.NoopMessageCallback())
 		waitC <- err
 	}()
-	err := cl.deleteService(serviceName, v1.DeletePropagationForeground)
+	err = cl.deleteService(serviceName, v1.DeletePropagationForeground)
 	if err != nil {
 		return err
 	}
@@ -346,8 +351,13 @@ func (cl *knServingClient) deleteService(serviceName string, propagationPolicy v
 
 // Wait for a service to become ready, but not longer than provided timeout
 func (cl *knServingClient) WaitForService(name string, timeout time.Duration, msgCallback wait.MessageCallback) (error, time.Duration) {
-	waitForReady := wait.NewWaitForReady("service", cl.WatchService, serviceConditionExtractor)
-	return waitForReady.Wait(name, wait.Options{Timeout: &timeout}, msgCallback)
+	watcher, err := cl.WatchService(name, timeout)
+	if err != nil {
+		return err, timeout
+	}
+	defer watcher.Stop()
+	waitForReady := wait.NewWaitForReady("service", serviceConditionExtractor)
+	return waitForReady.Wait(watcher, name, wait.Options{Timeout: &timeout}, msgCallback)
 }
 
 // Get the configuration for a service
@@ -460,9 +470,14 @@ func (cl *knServingClient) DeleteRevision(name string, timeout time.Duration) er
 		return cl.deleteRevision(name)
 	}
 	waitC := make(chan error)
+	watcher, err := cl.WatchRevision(name, timeout)
+	if err != nil {
+		return err
+	}
+	defer watcher.Stop()
 	go func() {
-		waitForEvent := wait.NewWaitForEvent("revision", cl.WatchRevision, func(evt *watch.Event) bool { return evt.Type == watch.Deleted })
-		err, _ := waitForEvent.Wait(name, wait.Options{Timeout: &timeout}, wait.NoopMessageCallback())
+		waitForEvent := wait.NewWaitForEvent("revision", func(evt *watch.Event) bool { return evt.Type == watch.Deleted })
+		err, _ := waitForEvent.Wait(watcher, name, wait.Options{Timeout: &timeout}, wait.NoopMessageCallback())
 		waitC <- err
 	}()
 	err = cl.deleteRevision(name)

pkg/wait/wait_for_ready.go

@@ -27,16 +27,14 @@ import (
 
 // Callbacks and configuration used while waiting
 type waitForReadyConfig struct {
-	watchMaker          WatchMaker
 	conditionsExtractor ConditionsExtractor
 	kind                string
 }
 
 // Callbacks and configuration used while waiting for event
 type waitForEvent struct {
-	watchMaker WatchMaker
-	eventDone  EventDone
-	kind       string
+	eventDone EventDone
+	kind      string
 }
 
 // EventDone is a marker to stop actual waiting on given event state
@@ -49,7 +47,7 @@ type Wait interface {
 	// Wait on resource the resource with this name
 	// and write event messages for unknown event to the status writer.
 	// Returns an error (if any) and the overall time it took to wait
-	Wait(name string, options Options, msgCallback MessageCallback) (error, time.Duration)
+	Wait(watcher watch.Interface, name string, options Options, msgCallback MessageCallback) (error, time.Duration)
 }
 
 type Options struct {
@@ -71,21 +69,19 @@ type ConditionsExtractor func(obj runtime.Object) (apis.Conditions, error)
 type MessageCallback func(durationSinceState time.Duration, message string)
 
 // NewWaitForReady waits until the condition is set to Ready == True
-func NewWaitForReady(kind string, watchMaker WatchMaker, extractor ConditionsExtractor) Wait {
+func NewWaitForReady(kind string, extractor ConditionsExtractor) Wait {
 	return &waitForReadyConfig{
 		kind:                kind,
-		watchMaker:          watchMaker,
 		conditionsExtractor: extractor,
 	}
 }
 
 // NewWaitForEvent creates a Wait object which waits until a specific event (i.e. when
 // the EventDone function returns true)
-func NewWaitForEvent(kind string, watchMaker WatchMaker, eventDone EventDone) Wait {
+func NewWaitForEvent(kind string, eventDone EventDone) Wait {
 	return &waitForEvent{
-		kind:       kind,
-		watchMaker: watchMaker,
-		eventDone:  eventDone,
+		kind:      kind,
+		eventDone: eventDone,
 	}
 }
 
@@ -112,13 +108,13 @@ func NoopMessageCallback() MessageCallback {
 // (e.g. "service"), `timeout` is a timeout after which the watch should be cancelled if no
 // target state has been entered yet and `out` is used for printing out status messages
 // msgCallback gets called for every event with an 'Ready' condition == UNKNOWN with the event's message.
-func (w *waitForReadyConfig) Wait(name string, options Options, msgCallback MessageCallback) (error, time.Duration) {
+func (w *waitForReadyConfig) Wait(watcher watch.Interface, name string, options Options, msgCallback MessageCallback) (error, time.Duration) {
 
 	timeout := options.timeoutWithDefault()
 	floatingTimeout := timeout
 	for {
 		start := time.Now()
-		retry, timeoutReached, err := w.waitForReadyCondition(start, name, floatingTimeout, options.errorWindowWithDefault(), msgCallback)
+		retry, timeoutReached, err := w.waitForReadyCondition(watcher, start, name, floatingTimeout, options.errorWindowWithDefault(), msgCallback)
 		if err != nil {
 			return err, time.Since(start)
 		}
@@ -141,13 +137,7 @@ func (w *waitForReadyConfig) Wait(name string, options Options, msgCallback Mess
 // An errorWindow can be specified which takes into account of intermediate "false" ready conditions. So before returning
 // an error, this methods waits for the errorWindow duration and if an "True" or "Unknown" event arrives in the meantime
 // for the "Ready" condition, then the method continues to wait.
-func (w *waitForReadyConfig) waitForReadyCondition(start time.Time, name string, timeout time.Duration, errorWindow time.Duration, msgCallback MessageCallback) (retry bool, timeoutReached bool, err error) {
-
-	watcher, err := w.watchMaker(name, timeout)
-	if err != nil {
-		return false, false, err
-	}
-	defer watcher.Stop()
+func (w *waitForReadyConfig) waitForReadyCondition(watcher watch.Interface, start time.Time, name string, timeout time.Duration, errorWindow time.Duration, msgCallback MessageCallback) (retry bool, timeoutReached bool, err error) {
 
 	// channel used to transport the error that has been received
 	errChan := make(chan error)
@@ -239,13 +229,8 @@ func (w *waitForReadyConfig) waitForReadyCondition(start time.Time, name string,
 }
 
 // Wait until the expected EventDone is satisfied
-func (w *waitForEvent) Wait(name string, options Options, msgCallback MessageCallback) (error, time.Duration) {
+func (w *waitForEvent) Wait(watcher watch.Interface, name string, options Options, msgCallback MessageCallback) (error, time.Duration) {
 	timeout := options.timeoutWithDefault()
-	watcher, err := w.watchMaker(name, timeout)
-	if err != nil {
-		return err, 0
-	}
-	defer watcher.Stop()
 	start := time.Now()
 	// channel used to transport the error
 	errChan := make(chan error)
@@ -255,7 +240,7 @@ func (w *waitForEvent) Wait(name string, options Options, msgCallback MessageCal
 		select {
 		case <-timer.C:
 			return fmt.Errorf("timeout: %s '%s' not ready after %d seconds", w.kind, name, int(timeout/time.Second)), time.Since(start)
-		case err = <-errChan:
+		case err := <-errChan:
 			return err, time.Since(start)
 		case event := <-watcher.ResultChan():
 			if w.eventDone(&event) {

pkg/wait/wait_for_ready_test.go

@@ -41,15 +41,12 @@ func TestAddWaitForReady(t *testing.T) {
 
 		waitForReady := NewWaitForReady(
 			"blub",
-			func(name string, timeout time.Duration) (watch.Interface, error) {
-				return fakeWatchApi, nil
-			},
 			func(obj runtime.Object) (apis.Conditions, error) {
 				return apis.Conditions(obj.(*servingv1.Service).Status.Conditions), nil
 			})
 		fakeWatchApi.Start()
 		var msgs []string
-		err, _ := waitForReady.Wait("foobar", Options{Timeout: &tc.timeout}, func(_ time.Duration, msg string) {
+		err, _ := waitForReady.Wait(fakeWatchApi, "foobar", Options{Timeout: &tc.timeout}, func(_ time.Duration, msg string) {
 			msgs = append(msgs, msg)
 		})
 		close(fakeWatchApi.eventChan)
@@ -69,8 +66,8 @@ func TestAddWaitForReady(t *testing.T) {
 		// check messages
 		assert.Assert(t, cmp.DeepEqual(tc.messagesExpected, msgs), "%d: Messages expected to be equal", i)
 
-		if fakeWatchApi.StopCalled != 1 {
-			t.Errorf("%d: Exactly one 'stop' should be called, but got %d", i, fakeWatchApi.StopCalled)
+		if fakeWatchApi.StopCalled != 0 {
+			t.Errorf("%d: Exactly zero 'stop' should be called, but got %d", i, fakeWatchApi.StopCalled)
 		}
 
 	}
@@ -82,13 +79,10 @@ func TestAddWaitForDelete(t *testing.T) {
 
 		waitForEvent := NewWaitForEvent(
 			"blub",
-			func(name string, timeout time.Duration) (watch.Interface, error) {
-				return fakeWatchAPI, nil
-			},
 			func(evt *watch.Event) bool { return evt.Type == watch.Deleted })
 		fakeWatchAPI.Start()
 
-		err, _ := waitForEvent.Wait("foobar", Options{Timeout: &tc.timeout}, NoopMessageCallback())
+		err, _ := waitForEvent.Wait(fakeWatchAPI, "foobar", Options{Timeout: &tc.timeout}, NoopMessageCallback())
 		close(fakeWatchAPI.eventChan)
 
 		if tc.errorText == "" && err != nil {
@@ -103,8 +97,8 @@ func TestAddWaitForDelete(t *testing.T) {
 			}
 		}
 
-		if fakeWatchAPI.StopCalled != 1 {
-			t.Errorf("%d: Exactly one 'stop' should be called, but got %d", i, fakeWatchAPI.StopCalled)
+		if fakeWatchAPI.StopCalled != 0 {
+			t.Errorf("%d: Exactly zero 'stop' should be called, but got %d", i, fakeWatchAPI.StopCalled)
 		}
 	}
 }