Move cl.WriteLoop() to attachClient() and call cl.Stop() in loadClients() to update client.State. (#344)

* Moving go cl.WriteLoop() out of NewClient() and placing it in server.attachClient().

* Call cl.Stop() to cancel the context, update cl.State with information such as disconnected time, and set the stopCause.

* update README-CN.md

---------

Co-authored-by: JB <28275108+mochi-co@users.noreply.github.com>

README-CN.md

@@ -200,7 +200,7 @@ server := mqtt.New(&mqtt.Options{
 | 数据持久性    | [mochi-mqtt/server/hooks/storage/redis](hooks/storage/redis/redis.go)    | 使用 [Redis](https://redis.io) 进行持久性存储。                         | 
 | 调试跟踪      | [mochi-mqtt/server/hooks/debug](hooks/debug/debug.go)                    | 调试输出以查看数据包在服务端的链路追踪。   |
 
-许多内部函数都已开放给开发者，你可以参考上述示例创建自己的Hook钩子。如果你有更好的关于Hook钩子方面的建议或者疑问，你可以[提交问题](https://github.com/mochi-mqtt/server/issues)给我们。                  | 
+许多内部函数都已开放给开发者，你可以参考上述示例创建自己的Hook钩子。如果你有更好的关于Hook钩子方面的建议或者疑问，你可以[提交问题](https://github.com/mochi-mqtt/server/issues)给我们。
 
 ### 访问控制(Access Control)
 

server.go

@@ -233,8 +233,6 @@ func (s *Server) NewClient(c net.Conn, listener string, id string, inline bool)
 		// By default, we don't want to restrict developer publishes,
 		// but if you do, reset this after creating inline client.
 		cl.State.Inflight.ResetReceiveQuota(math.MaxInt32)
-	} else {
-		go cl.WriteLoop() // can only write to real clients
 	}
 
 	return cl
@@ -332,6 +330,8 @@ func (s *Server) EstablishConnection(listener string, c net.Conn) error {
 func (s *Server) attachClient(cl *Client, listener string) error {
 	defer s.Listeners.ClientsWg.Done()
 	s.Listeners.ClientsWg.Add(1)
+	
+	go cl.WriteLoop()
 	defer cl.Stop(nil)
 
 	pk, err := s.readConnectionPacket(cl)
@@ -1554,6 +1554,9 @@ func (s *Server) loadClients(v []storage.Client) {
 		}
 		cl.Properties.Will = Will(c.Will)
 
+		// cancel the context, update cl.State such as disconnected time and stopCause.
+		cl.Stop(packets.ErrServerShuttingDown)
+		
 		expire := (cl.Properties.ProtocolVersion == 5 && cl.Properties.Props.SessionExpiryInterval == 0) || (cl.Properties.ProtocolVersion < 5 && cl.Properties.Clean)
 		s.hooks.OnDisconnect(cl, packets.ErrServerShuttingDown, expire)
 		if expire {