optimize:chan bool to chan struct{} (#1648)

contrib/config/nacos/config_test.go

@@ -88,10 +88,10 @@ logger:
 	}
 	fmt.Println("get value", name)
 
-	done := make(chan bool)
+	done := make(chan struct{})
 	err = c.Watch("logger.level", func(key string, value kconfig.Value) {
 		fmt.Println(key, " value change", value)
-		done <- true
+		done <- struct{}{}
 	})
 	if err != nil {
 		t.Fatal(err)

contrib/registry/nacos/watcher.go

@@ -18,7 +18,7 @@ type watcher struct {
 	groupName   string
 	ctx         context.Context
 	cancel      context.CancelFunc
-	watchChan   chan bool
+	watchChan   chan struct{}
 	cli         naming_client.INamingClient
 }
 
@@ -28,7 +28,7 @@ func newWatcher(ctx context.Context, cli naming_client.INamingClient, serviceNam
 		clusters:    clusters,
 		groupName:   groupName,
 		cli:         cli,
-		watchChan:   make(chan bool, 1),
+		watchChan:   make(chan struct{}, 1),
 	}
 	w.ctx, w.cancel = context.WithCancel(ctx)
 
@@ -37,7 +37,7 @@ func newWatcher(ctx context.Context, cli naming_client.INamingClient, serviceNam
 		Clusters:    clusters,
 		GroupName:   groupName,
 		SubscribeCallback: func(services []model.SubscribeService, err error) {
-			w.watchChan <- true
+			w.watchChan <- struct{}{}
 		},
 	})
 	return w, e

transport/grpc/resolver/discovery/builder.go

@@ -63,7 +63,7 @@ func (b *builder) Build(target resolver.Target, cc resolver.ClientConn, opts res
 		err error
 		w   registry.Watcher
 	)
-	done := make(chan bool, 1)
+	done := make(chan struct{}, 1)
 	ctx, cancel := context.WithCancel(context.Background())
 	go func() {
 		w, err = b.discoverer.Watch(ctx, strings.TrimPrefix(target.URL.Path, "/"))