fix data race in case of unregister services

Author: smallnest

server/server.go

@@ -126,7 +126,8 @@ type Server struct {
 	ServerErrorFunc func(res *protocol.Message, err error) string
 
 	// The server is started.
-	Started chan struct{}
+	Started           chan struct{}
+	unregisterAllOnce sync.Once
 }
 
 // NewServer returns a server.
@@ -955,11 +956,8 @@ func (s *Server) Shutdown(ctx context.Context) error {
 		s.mu.Lock()
 
 		// 主动注销注册的服务
-		if s.Plugins != nil {
-			for name := range s.serviceMap {
-				s.Plugins.DoUnregister(name)
-			}
-		}
+		s.UnregisterAll()
+
 		if s.ln != nil {
 			s.ln.Close()
 		}

server/service.go

@@ -325,7 +325,12 @@ func suitableMethods(typ reflect.Type, reportErr bool) map[string]*methodType {
 // UnregisterAll unregisters all services.
 // You can call this method when you want to shutdown/upgrade this node.
 func (s *Server) UnregisterAll() error {
-	return s.unregisterAll()
+	var err error
+	s.unregisterAllOnce.Do(func() {
+		err = s.unregisterAll()
+	})
+
+	return err
 }
 
 func (s *Server) unregisterAll() error {