[GitHub] [dubbo-go] flycash commented on a change in pull request #1368: Refactor to remove event dispatcher completely

[GitBox <gi...@apache.org>]

flycash commented on a change in pull request #1368:
URL: https://github.com/apache/dubbo-go/pull/1368#discussion_r704234145



##########
File path: registry/etcdv3/service_discovery.go
##########
@@ -215,31 +216,19 @@ func (e *etcdV3ServiceDiscovery) GetRequestInstances(serviceNames []string, offs
 // see addServiceInstancesChangedListener in Java
 func (e *etcdV3ServiceDiscovery) AddListener(listener registry.ServiceInstancesChangedListener) error {
 	for _, t := range listener.GetServiceNames().Values() {
-		serviceName := t.(string)
-		err := e.registerSreviceWatcher(serviceName)
+		err2 := e.registerServiceInstanceListener(t.(string), listener)
+		if err2 != nil {
+			return err2
+		}
+
+		err := e.registerServiceWatcher(t.(string))

Review comment:
       ```go
   err := e.registerServiceInstanceListener(t.(string), listener)
   // ....
   err = e.registerServiceWatcher(t.(string))
   ```
   looks better?

##########
File path: registry/etcdv3/service_discovery.go
##########
@@ -282,7 +287,15 @@ func (e *etcdV3ServiceDiscovery) DataChange(eventType remoting.Event) bool {
 			instance.ServiceName = ""
 		}
 
-		if err := e.DispatchEventByServiceName(instance.ServiceName); err != nil {
+		// notify instance listener instance change
+		name := instance.ServiceName
+		instances := e.GetInstances(name)
+		for _, lis := range e.instanceListenerMap[instance.ServiceName].Values() {

Review comment:
       I am not sure if we should iterate all listeners even some of them return error.

##########
File path: registry/nacos/service_discovery.go
##########
@@ -210,8 +211,27 @@ func (n *nacosServiceDiscovery) GetRequestInstances(serviceNames []string, offse
 	return res
 }
 
+func (n *nacosServiceDiscovery) registerInstanceListener(listener registry.ServiceInstancesChangedListener) {
+	for _, t := range listener.GetServiceNames().Values() {

Review comment:
       it's not thread safe here. Should we think about `race condition`?




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