store: convert Watch to interface

etcdserver/etcdhttp/http.go

@@ -288,7 +288,7 @@ func encodeResponse(ctx context.Context, w http.ResponseWriter, resp etcdserver.
 	return nil
 }
 
-func waitForEvent(ctx context.Context, w http.ResponseWriter, wa *store.Watcher) (*store.Event, error) {
+func waitForEvent(ctx context.Context, w http.ResponseWriter, wa store.Watcher) (*store.Event, error) {
 	// TODO(bmizerany): support streaming?
 	defer wa.Remove()
 	var nch <-chan bool
@@ -297,7 +297,7 @@ func waitForEvent(ctx context.Context, w http.ResponseWriter, wa *store.Watcher)
 	}
 
 	select {
-	case ev := <-wa.EventChan:
+	case ev := <-wa.EventChan():
 		return ev, nil
 	case <-nch:
 		elog.TODO()

etcdserver/server.go

@@ -21,7 +21,7 @@ type SendFunc func(m []raftpb.Message)
 
 type Response struct {
 	Event   *store.Event
-	Watcher *store.Watcher
+	Watcher store.Watcher
 	err     error
 }
 

store/store.go

@@ -51,7 +51,7 @@ type Store interface {
 	Delete(nodePath string, recursive, dir bool) (*Event, error)
 	CompareAndDelete(nodePath string, prevValue string, prevIndex uint64) (*Event, error)
 
-	Watch(prefix string, recursive, stream bool, sinceIndex uint64) (*Watcher, error)
+	Watch(prefix string, recursive, stream bool, sinceIndex uint64) (Watcher, error)
 
 	Save() ([]byte, error)
 	Recovery(state []byte) error
@@ -344,14 +344,14 @@ func (s *store) CompareAndDelete(nodePath string, prevValue string, prevIndex ui
 	return e, nil
 }
 
-func (s *store) Watch(key string, recursive, stream bool, sinceIndex uint64) (*Watcher, error) {
+func (s *store) Watch(key string, recursive, stream bool, sinceIndex uint64) (Watcher, error) {
 	s.worldLock.RLock()
 	defer s.worldLock.RUnlock()
 
 	key = path.Clean(path.Join("/", key))
 	nextIndex := s.CurrentIndex + 1
 
-	var w *Watcher
+	var w Watcher
 	var err *etcdErr.Error
 
 	if sinceIndex == 0 {

store/store_bench_test.go

@@ -113,7 +113,7 @@ func BenchmarkWatch(b *testing.B) {
 
 		e := newEvent("set", kvs[i][0], uint64(i+1), uint64(i+1))
 		s.WatcherHub.notify(e)
-		<-w.EventChan
+		<-w.EventChan()
 		s.CurrentIndex++
 	}
 
@@ -135,7 +135,7 @@ func BenchmarkWatchWithSet(b *testing.B) {
 		w, _ := s.Watch(kvs[i][0], false, false, 0)
 
 		s.Set(kvs[i][0], false, "test", Permanent)
-		<-w.EventChan
+		<-w.EventChan()
 	}
 }
 
@@ -145,7 +145,7 @@ func BenchmarkWatchWithSetBatch(b *testing.B) {
 	kvs, _ := generateNRandomKV(b.N, 128)
 	b.StartTimer()
 
-	watchers := make([]*Watcher, b.N)
+	watchers := make([]Watcher, b.N)
 
 	for i := 0; i < b.N; i++ {
 		watchers[i], _ = s.Watch(kvs[i][0], false, false, 0)
@@ -156,14 +156,14 @@ func BenchmarkWatchWithSetBatch(b *testing.B) {
 	}
 
 	for i := 0; i < b.N; i++ {
-		<-watchers[i].EventChan
+		<-watchers[i].EventChan()
 	}
 
 }
 
 func BenchmarkWatchOneKey(b *testing.B) {
 	s := newStore()
-	watchers := make([]*Watcher, b.N)
+	watchers := make([]Watcher, b.N)
 
 	for i := 0; i < b.N; i++ {
 		watchers[i], _ = s.Watch("/foo", false, false, 0)
@@ -172,7 +172,7 @@ func BenchmarkWatchOneKey(b *testing.B) {
 	s.Set("/foo", false, "", Permanent)
 
 	for i := 0; i < b.N; i++ {
-		<-watchers[i].EventChan
+		<-watchers[i].EventChan()
 	}
 }
 

store/store_test.go

@@ -535,7 +535,7 @@ func TestStoreCompareAndSwapPrevIndexFailsIfNotMatch(t *testing.T) {
 func TestStoreWatchCreate(t *testing.T) {
 	s := newStore()
 	w, _ := s.Watch("/foo", false, false, 0)
-	c := w.EventChan
+	c := w.EventChan()
 	s.Create("/foo", false, "bar", false, Permanent)
 	e := nbselect(c)
 	assert.Equal(t, e.Action, "create", "")
@@ -549,7 +549,7 @@ func TestStoreWatchRecursiveCreate(t *testing.T) {
 	s := newStore()
 	w, _ := s.Watch("/foo", true, false, 0)
 	s.Create("/foo/bar", false, "baz", false, Permanent)
-	e := nbselect(w.EventChan)
+	e := nbselect(w.EventChan())
 	assert.Equal(t, e.Action, "create", "")
 	assert.Equal(t, e.Node.Key, "/foo/bar", "")
 }
@@ -560,7 +560,7 @@ func TestStoreWatchUpdate(t *testing.T) {
 	s.Create("/foo", false, "bar", false, Permanent)
 	w, _ := s.Watch("/foo", false, false, 0)
 	s.Update("/foo", "baz", Permanent)
-	e := nbselect(w.EventChan)
+	e := nbselect(w.EventChan())
 	assert.Equal(t, e.Action, "update", "")
 	assert.Equal(t, e.Node.Key, "/foo", "")
 }
@@ -571,7 +571,7 @@ func TestStoreWatchRecursiveUpdate(t *testing.T) {
 	s.Create("/foo/bar", false, "baz", false, Permanent)
 	w, _ := s.Watch("/foo", true, false, 0)
 	s.Update("/foo/bar", "baz", Permanent)
-	e := nbselect(w.EventChan)
+	e := nbselect(w.EventChan())
 	assert.Equal(t, e.Action, "update", "")
 	assert.Equal(t, e.Node.Key, "/foo/bar", "")
 }
@@ -582,7 +582,7 @@ func TestStoreWatchDelete(t *testing.T) {
 	s.Create("/foo", false, "bar", false, Permanent)
 	w, _ := s.Watch("/foo", false, false, 0)
 	s.Delete("/foo", false, false)
-	e := nbselect(w.EventChan)
+	e := nbselect(w.EventChan())
 	assert.Equal(t, e.Action, "delete", "")
 	assert.Equal(t, e.Node.Key, "/foo", "")
 }
@@ -593,7 +593,7 @@ func TestStoreWatchRecursiveDelete(t *testing.T) {
 	s.Create("/foo/bar", false, "baz", false, Permanent)
 	w, _ := s.Watch("/foo", true, false, 0)
 	s.Delete("/foo/bar", false, false)
-	e := nbselect(w.EventChan)
+	e := nbselect(w.EventChan())
 	assert.Equal(t, e.Action, "delete", "")
 	assert.Equal(t, e.Node.Key, "/foo/bar", "")
 }
@@ -604,7 +604,7 @@ func TestStoreWatchCompareAndSwap(t *testing.T) {
 	s.Create("/foo", false, "bar", false, Permanent)
 	w, _ := s.Watch("/foo", false, false, 0)
 	s.CompareAndSwap("/foo", "bar", 0, "baz", Permanent)
-	e := nbselect(w.EventChan)
+	e := nbselect(w.EventChan())
 	assert.Equal(t, e.Action, "compareAndSwap", "")
 	assert.Equal(t, e.Node.Key, "/foo", "")
 }
@@ -615,7 +615,7 @@ func TestStoreWatchRecursiveCompareAndSwap(t *testing.T) {
 	s.Create("/foo/bar", false, "baz", false, Permanent)
 	w, _ := s.Watch("/foo", true, false, 0)
 	s.CompareAndSwap("/foo/bar", "baz", 0, "bat", Permanent)
-	e := nbselect(w.EventChan)
+	e := nbselect(w.EventChan())
 	assert.Equal(t, e.Action, "compareAndSwap", "")
 	assert.Equal(t, e.Node.Key, "/foo/bar", "")
 }
@@ -634,7 +634,7 @@ func TestStoreWatchExpire(t *testing.T) {
 	s.Create("/foofoo", false, "barbarbar", false, time.Now().Add(500*time.Millisecond))
 
 	w, _ := s.Watch("/", true, false, 0)
-	c := w.EventChan
+	c := w.EventChan()
 	e := nbselect(c)
 	assert.Nil(t, e, "")
 	time.Sleep(600 * time.Millisecond)
@@ -642,7 +642,7 @@ func TestStoreWatchExpire(t *testing.T) {
 	assert.Equal(t, e.Action, "expire", "")
 	assert.Equal(t, e.Node.Key, "/foo", "")
 	w, _ = s.Watch("/", true, false, 4)
-	e = nbselect(w.EventChan)
+	e = nbselect(w.EventChan())
 	assert.Equal(t, e.Action, "expire", "")
 	assert.Equal(t, e.Node.Key, "/foofoo", "")
 }
@@ -653,19 +653,19 @@ func TestStoreWatchStream(t *testing.T) {
 	w, _ := s.Watch("/foo", false, true, 0)
 	// first modification
 	s.Create("/foo", false, "bar", false, Permanent)
-	e := nbselect(w.EventChan)
+	e := nbselect(w.EventChan())
 	assert.Equal(t, e.Action, "create", "")
 	assert.Equal(t, e.Node.Key, "/foo", "")
 	assert.Equal(t, *e.Node.Value, "bar", "")
-	e = nbselect(w.EventChan)
+	e = nbselect(w.EventChan())
 	assert.Nil(t, e, "")
 	// second modification
 	s.Update("/foo", "baz", Permanent)
-	e = nbselect(w.EventChan)
+	e = nbselect(w.EventChan())
 	assert.Equal(t, e.Action, "update", "")
 	assert.Equal(t, e.Node.Key, "/foo", "")
 	assert.Equal(t, *e.Node.Value, "baz", "")
-	e = nbselect(w.EventChan)
+	e = nbselect(w.EventChan())
 	assert.Nil(t, e, "")
 }
 
@@ -732,10 +732,10 @@ func TestStoreWatchCreateWithHiddenKey(t *testing.T) {
 	s := newStore()
 	w, _ := s.Watch("/_foo", false, false, 0)
 	s.Create("/_foo", false, "bar", false, Permanent)
-	e := nbselect(w.EventChan)
+	e := nbselect(w.EventChan())
 	assert.Equal(t, e.Action, "create", "")
 	assert.Equal(t, e.Node.Key, "/_foo", "")
-	e = nbselect(w.EventChan)
+	e = nbselect(w.EventChan())
 	assert.Nil(t, e, "")
 }
 
@@ -744,14 +744,14 @@ func TestStoreWatchRecursiveCreateWithHiddenKey(t *testing.T) {
 	s := newStore()
 	w, _ := s.Watch("/foo", true, false, 0)
 	s.Create("/foo/_bar", false, "baz", false, Permanent)
-	e := nbselect(w.EventChan)
+	e := nbselect(w.EventChan())
 	assert.Nil(t, e, "")
 	w, _ = s.Watch("/foo", true, false, 0)
 	s.Create("/foo/_baz", true, "", false, Permanent)
-	e = nbselect(w.EventChan)
+	e = nbselect(w.EventChan())
 	assert.Nil(t, e, "")
 	s.Create("/foo/_baz/quux", false, "quux", false, Permanent)
-	e = nbselect(w.EventChan)
+	e = nbselect(w.EventChan())
 	assert.Nil(t, e, "")
 }
 
@@ -761,10 +761,10 @@ func TestStoreWatchUpdateWithHiddenKey(t *testing.T) {
 	s.Create("/_foo", false, "bar", false, Permanent)
 	w, _ := s.Watch("/_foo", false, false, 0)
 	s.Update("/_foo", "baz", Permanent)
-	e := nbselect(w.EventChan)
+	e := nbselect(w.EventChan())
 	assert.Equal(t, e.Action, "update", "")
 	assert.Equal(t, e.Node.Key, "/_foo", "")
-	e = nbselect(w.EventChan)
+	e = nbselect(w.EventChan())
 	assert.Nil(t, e, "")
 }
 
@@ -774,7 +774,7 @@ func TestStoreWatchRecursiveUpdateWithHiddenKey(t *testing.T) {
 	s.Create("/foo/_bar", false, "baz", false, Permanent)
 	w, _ := s.Watch("/foo", true, false, 0)
 	s.Update("/foo/_bar", "baz", Permanent)
-	e := nbselect(w.EventChan)
+	e := nbselect(w.EventChan())
 	assert.Nil(t, e, "")
 }
 
@@ -784,10 +784,10 @@ func TestStoreWatchDeleteWithHiddenKey(t *testing.T) {
 	s.Create("/_foo", false, "bar", false, Permanent)
 	w, _ := s.Watch("/_foo", false, false, 0)
 	s.Delete("/_foo", false, false)
-	e := nbselect(w.EventChan)
+	e := nbselect(w.EventChan())
 	assert.Equal(t, e.Action, "delete", "")
 	assert.Equal(t, e.Node.Key, "/_foo", "")
-	e = nbselect(w.EventChan)
+	e = nbselect(w.EventChan())
 	assert.Nil(t, e, "")
 }
 
@@ -797,7 +797,7 @@ func TestStoreWatchRecursiveDeleteWithHiddenKey(t *testing.T) {
 	s.Create("/foo/_bar", false, "baz", false, Permanent)
 	w, _ := s.Watch("/foo", true, false, 0)
 	s.Delete("/foo/_bar", false, false)
-	e := nbselect(w.EventChan)
+	e := nbselect(w.EventChan())
 	assert.Nil(t, e, "")
 }
 
@@ -815,7 +815,7 @@ func TestStoreWatchExpireWithHiddenKey(t *testing.T) {
 	s.Create("/foofoo", false, "barbarbar", false, time.Now().Add(1000*time.Millisecond))
 
 	w, _ := s.Watch("/", true, false, 0)
-	c := w.EventChan
+	c := w.EventChan()
 	e := nbselect(c)
 	assert.Nil(t, e, "")
 	time.Sleep(600 * time.Millisecond)
@@ -833,7 +833,7 @@ func TestStoreWatchRecursiveCreateDeeperThanHiddenKey(t *testing.T) {
 	w, _ := s.Watch("/_foo/bar", true, false, 0)
 	s.Create("/_foo/bar/baz", false, "baz", false, Permanent)
 
-	e := nbselect(w.EventChan)
+	e := nbselect(w.EventChan())
 	assert.NotNil(t, e, "")
 	assert.Equal(t, e.Action, "create", "")
 	assert.Equal(t, e.Node.Key, "/_foo/bar/baz", "")
@@ -841,7 +841,7 @@ func TestStoreWatchRecursiveCreateDeeperThanHiddenKey(t *testing.T) {
 
 // Ensure that slow consumers are handled properly.
 //
-// Since Watcher.EventChan has a buffer of size 1 we can only queue 1
+// Since Watcher.EventChan() has a buffer of size 1 we can only queue 1
 // event per watcher. If the consumer cannot consume the event on time and
 // another event arrives, the channel is closed and event is discarded.
 // This test ensures that after closing the channel, the store can continue

store/watcher.go

@@ -16,8 +16,13 @@ limitations under the License.
 
 package store
 
-type Watcher struct {
-	EventChan  chan *Event
+type Watcher interface {
+	EventChan() chan *Event
+	Remove()
+}
+
+type watcher struct {
+	eventChan  chan *Event
 	stream     bool
 	recursive  bool
 	sinceIndex uint64
@@ -26,9 +31,13 @@ type Watcher struct {
 	remove     func()
 }
 
+func (w *watcher) EventChan() chan *Event {
+	return w.eventChan
+}
+
 // notify function notifies the watcher. If the watcher interests in the given path,
 // the function will return true.
-func (w *Watcher) notify(e *Event, originalPath bool, deleted bool) bool {
+func (w *watcher) notify(e *Event, originalPath bool, deleted bool) bool {
 	// watcher is interested the path in three cases and under one condition
 	// the condition is that the event happens after the watcher's sinceIndex
 
@@ -45,15 +54,15 @@ func (w *Watcher) notify(e *Event, originalPath bool, deleted bool) bool {
 	// For example a watcher is watching at "/foo/bar". And we deletes "/foo". The watcher
 	// should get notified even if "/foo" is not the path it is watching.
 	if (w.recursive || originalPath || deleted) && e.Index() >= w.sinceIndex {
-		// We cannot block here if the EventChan capacity is full, otherwise
-		// etcd will hang. EventChan capacity is full when the rate of
+		// We cannot block here if the eventChan capacity is full, otherwise
+		// etcd will hang. eventChan capacity is full when the rate of
 		// notifications are higher than our send rate.
 		// If this happens, we close the channel.
 		select {
-		case w.EventChan <- e:
+		case w.eventChan <- e:
 		default:
 			// We have missed a notification. Remove the watcher.
-			// Removing the watcher also closes the EventChan.
+			// Removing the watcher also closes the eventChan.
 			w.remove()
 		}
 		return true
@@ -63,11 +72,11 @@ func (w *Watcher) notify(e *Event, originalPath bool, deleted bool) bool {
 
 // Remove removes the watcher from watcherHub
 // The actual remove function is guaranteed to only be executed once
-func (w *Watcher) Remove() {
+func (w *watcher) Remove() {
 	w.hub.mutex.Lock()
 	defer w.hub.mutex.Unlock()
 
-	close(w.EventChan)
+	close(w.eventChan)
 	if w.remove != nil {
 		w.remove()
 	}

store/watcher_hub.go

@@ -34,19 +34,19 @@ func newWatchHub(capacity int) *watcherHub {
 	}
 }
 
-// Watch function returns a watcher.
+// Watch function returns a Watcher.
 // If recursive is true, the first change after index under key will be sent to the event channel of the watcher.
 // If recursive is false, the first change after index at key will be sent to the event channel of the watcher.
 // If index is zero, watch will start from the current index + 1.
-func (wh *watcherHub) watch(key string, recursive, stream bool, index uint64) (*Watcher, *etcdErr.Error) {
+func (wh *watcherHub) watch(key string, recursive, stream bool, index uint64) (Watcher, *etcdErr.Error) {
 	event, err := wh.EventHistory.scan(key, recursive, index)
 
 	if err != nil {
 		return nil, err
 	}
 
-	w := &Watcher{
-		EventChan:  make(chan *Event, 1), // use a buffered channel
+	w := &watcher{
+		eventChan:  make(chan *Event, 1), // use a buffered channel
 		recursive:  recursive,
 		stream:     stream,
 		sinceIndex: index,
@@ -54,7 +54,7 @@ func (wh *watcherHub) watch(key string, recursive, stream bool, index uint64) (*
 	}
 
 	if event != nil {
-		w.EventChan <- event
+		w.eventChan <- event
 		return w, nil
 	}
 
@@ -75,7 +75,7 @@ func (wh *watcherHub) watch(key string, recursive, stream bool, index uint64) (*
 	}
 
 	w.remove = func() {
-		if w.removed { // avoid remove it twice
+		if w.removed { // avoid removing it twice
 			return
 		}
 		w.removed = true
@@ -121,7 +121,7 @@ func (wh *watcherHub) notifyWatchers(e *Event, nodePath string, deleted bool) {
 		for curr != nil {
 			next := curr.Next() // save reference to the next one in the list
 
-			w, _ := curr.Value.(*Watcher)
+			w, _ := curr.Value.(*watcher)
 
 			originalPath := (e.Node.Key == nodePath)
 			if (originalPath || !isHidden(nodePath, e.Node.Key)) && w.notify(e, originalPath, deleted) {

store/watcher_test.go

@@ -27,7 +27,7 @@ func TestWatcher(t *testing.T) {
 	if err != nil {
 		t.Fatalf("%v", err)
 	}
-	c := w.EventChan
+	c := w.EventChan()
 
 	select {
 	case <-c:
@@ -47,7 +47,7 @@ func TestWatcher(t *testing.T) {
 	}
 
 	w, _ = wh.watch("/foo", false, false, 2)
-	c = w.EventChan
+	c = w.EventChan()
 
 	e = newEvent(Create, "/foo/bar", 2, 2)
 
@@ -72,7 +72,7 @@ func TestWatcher(t *testing.T) {
 
 	// ensure we are doing exact matching rather than prefix matching
 	w, _ = wh.watch("/fo", true, false, 1)
-	c = w.EventChan
+	c = w.EventChan()
 
 	select {
 	case re = <-c: