fix: routinegroup & etcd watch goroutine leak (#4514)

Co-authored-by: Kevin Wan <wanjunfeng@gmail.com>

core/discov/internal/registry_test.go

@@ -160,8 +160,10 @@ func TestCluster_Watch(t *testing.T) {
 			var wg sync.WaitGroup
 			wg.Add(1)
 			c := &cluster{
-				listeners: make(map[string][]UpdateListener),
 				values:    make(map[string]map[string]string),
+				listeners: make(map[string][]UpdateListener),
+				watchCtx:  make(map[string]context.CancelFunc),
+				watchFlag: make(map[string]bool),
 			}
 			listener := NewMockUpdateListener(ctrl)
 			c.listeners["any"] = []UpdateListener{listener}
@@ -211,7 +213,7 @@ func TestClusterWatch_RespFailures(t *testing.T) {
 			ch := make(chan clientv3.WatchResponse)
 			cli.EXPECT().Watch(gomock.Any(), "any/", gomock.Any()).Return(ch).AnyTimes()
 			cli.EXPECT().Ctx().Return(context.Background()).AnyTimes()
-			c := new(cluster)
+			c := newCluster([]string{})
 			c.done = make(chan lang.PlaceholderType)
 			go func() {
 				ch <- resp
@@ -231,7 +233,7 @@ func TestClusterWatch_CloseChan(t *testing.T) {
 	ch := make(chan clientv3.WatchResponse)
 	cli.EXPECT().Watch(gomock.Any(), "any/", gomock.Any()).Return(ch).AnyTimes()
 	cli.EXPECT().Ctx().Return(context.Background()).AnyTimes()
-	c := new(cluster)
+	c := newCluster([]string{})
 	c.done = make(chan lang.PlaceholderType)
 	go func() {
 		close(ch)
@@ -240,6 +242,37 @@ func TestClusterWatch_CloseChan(t *testing.T) {
 	c.watch(cli, "any", 0)
 }
 
+func TestClusterWatch_CtxCancel(t *testing.T) {
+	ctrl := gomock.NewController(t)
+	defer ctrl.Finish()
+	cli := NewMockEtcdClient(ctrl)
+	restore := setMockClient(cli)
+	defer restore()
+	ch := make(chan clientv3.WatchResponse)
+	cli.EXPECT().Watch(gomock.Any(), "any/", gomock.Any()).Return(ch).AnyTimes()
+	ctx, cancelFunc := context.WithCancel(context.Background())
+	cli.EXPECT().Ctx().Return(ctx).AnyTimes()
+	c := newCluster([]string{})
+	c.done = make(chan lang.PlaceholderType)
+	go func() {
+		cancelFunc()
+		close(ch)
+	}()
+	c.watch(cli, "any", 0)
+}
+
+func TestCluster_ClearWatch(t *testing.T) {
+	ctx, cancel := context.WithCancel(context.Background())
+	c := &cluster{
+		watchCtx:  map[string]context.CancelFunc{"foo": cancel},
+		watchFlag: map[string]bool{"foo": true},
+	}
+	c.clearWatch()
+	assert.Equal(t, ctx.Err(), context.Canceled)
+	assert.Equal(t, 0, len(c.watchCtx))
+	assert.Equal(t, 0, len(c.watchFlag))
+}
+
 func TestValueOnlyContext(t *testing.T) {
 	ctx := contextx.ValueOnlyFrom(context.Background())
 	ctx.Done()
@@ -286,6 +319,8 @@ func TestRegistry_Monitor(t *testing.T) {
 					"bar": "baz",
 				},
 			},
+			watchCtx:  map[string]context.CancelFunc{},
+			watchFlag: map[string]bool{},
 		},
 	}
 	GetRegistry().lock.Unlock()
@@ -293,15 +328,11 @@ func TestRegistry_Monitor(t *testing.T) {
 }
 
 func TestRegistry_Unmonitor(t *testing.T) {
-	svr, err := mockserver.StartMockServers(1)
-	assert.NoError(t, err)
-	svr.StartAt(0)
-
-	endpoints := []string{svr.Servers[0].Address}
+	l := new(mockListener)
 	GetRegistry().lock.Lock()
 	GetRegistry().clusters = map[string]*cluster{
 		getClusterKey(endpoints): {
-			listeners: map[string][]UpdateListener{},
+			listeners: map[string][]UpdateListener{"foo": {l}},
 			values: map[string]map[string]string{
 				"foo": {
 					"bar": "baz",