Eventsource golang : how to detect client disconnection?

huangapple
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英文:

Eventsource golang : how to detect client disconnection?

问题

我正在使用https://github.com/antage/eventsource包基于Twitter标签开发聊天室，并使用服务器发送事件。我遇到了一个关于客户端断开连接的问题。我在一个goroutine中向客户端发送消息，但是当客户端断开连接时，goroutine仍然在运行。

我不知道如何在服务器端检测到客户端已断开连接。

以下是代码示例：

  1. func (sh StreamHandler) ServeHTTP(resp http.ResponseWriter, req *http.Request) {
  3. 	es := eventsource.New(
  4. 		&eventsource.Settings{
  5. 			Timeout:        2 * time.Second,
  6. 			CloseOnTimeout: true,
  7. 			IdleTimeout:    2 * time.Second,
  8. 			Gzip:           true,
  9. 		},
  10. 		func(req *http.Request) [][]byte {
  11. 			return [][]byte{
  12. 				[]byte("X-Accel-Buffering: no"),
  13. 				[]byte("Access-Control-Allow-Origin: *"),
  14. 			}
  15. 		},
  16. 	)
  18. 	es.ServeHTTP(resp, req)
  20. 	go func() {
  21. 		var id int
  22. 		for {
  23. 			id++
  24. 			time.Sleep(1 * time.Second)
  25. 			es.SendEventMessage("blabla", "message", strconv.Itoa(id))
  26. 		}
  27. 	}()
  29. }

请问有什么我可以帮助你的吗？

英文:

I'm developing chat rooms based on Twitter hashtag with Server sent events, with the package https://github.com/antage/eventsource

I have a problem concerning the disconnection of the client. I run a goroutine to send messages to the client, but when the client disconnects, the goroutine still runs.

I don't know how to detect on the server side that the client is disconnected.

  1. func (sh StreamHandler) ServeHTTP(resp http.ResponseWriter, req *http.Request) {
  3. 	es := eventsource.New(
  4. 		&eventsource.Settings{
  5. 			Timeout:        2 * time.Second,
  6. 			CloseOnTimeout: true,
  7. 			IdleTimeout:    2 * time.Second,
  8. 			Gzip:           true,
  9. 		},
  10. 		func(req *http.Request) [][]byte {
  11. 			return [][]byte{
  12. 				[]byte("X-Accel-Buffering: no"),
  13. 				[]byte("Access-Control-Allow-Origin: *"),
  14. 			}
  15. 		},
  16. 	)
  18. 	es.ServeHTTP(resp, req)
  20. 	go func() {
  21. 		var id int
  22. 		for {
  23. 			id++
  24. 			time.Sleep(1 * time.Second)
  25. 			es.SendEventMessage("blabla", "message", strconv.Itoa(id))
  26. 		}
  27. 	}()
  29. }

答案1

得分: 11

截至2018年12月，显然CloseNotifier已被弃用。推荐的解决方案是使用Request上下文。以下代码对我有效：

  1. done := make(chan bool)
  2. go func() {
  3.     <-req.Context().Done()
  4.     done <- true
  5. }()
  6. <-done
英文:

As of December 2018, apparently CloseNotifier is deprecated. The recommended solution is to use the Request Context. The following worked for me:

  1. done := make(chan bool)
  2. go func() {
  3.         &lt;-req.Context().Done()
  4.         done &lt;- true
  5. }()
  6. &lt;-done

答案2

得分: 6

你可以使用CloseNotifier来判断底层的HTTP连接是否关闭。例如：

  1. notify := w.(http.CloseNotifier).CloseNotify()
  2. go func() {
  3. 	<-notify
  4. 	// 连接关闭，进行清理等操作
  5. }()

希望对你有帮助。

英文:

You can use CloseNotifier which lets you know if the underlying http connection has closed. Like:

  1. notify := w.(http.CloseNotifier).CloseNotify()
  2. go func() {
  3. 	&lt;-notify
  4. 	// connection close, do cleanup, etc.
  5. }()

HTH

答案3

得分: 3

你可以检查ConsumersCount()函数：

  1. go func() {
  2.     var id int
  3.     for es.ConsumersCount() > 0 {
  4.         id++
  5.         es.SendEventMessage("blabla", "message", strconv.Itoa(id))
  6.         time.Sleep(1 * time.Second)
  7.     }
  8.     fmt.Println("closed")
  9. }()

这种方法可能有点巧妙，但似乎可以工作。

你可能最好使用其他包或自己编写代码，这样你可以更好地控制goroutine的生命周期。你可以在.Write方法中检测到连接关闭（该包没有公开该方法）。

如果你想要的话，这里有一个使用TCP的聊天服务器示例：chat-server。
还有一个配套的视频教程：tutorial。

对于SSE，相同的基本模式应该适用。

英文:

You could check ConsumersCount():

  1. 	go func() {
  2. 		var id int
  3. 		for es.ConsumersCount() &gt; 0 {
  4. 			id++
  5. 			es.SendEventMessage(&quot;blabla&quot;, &quot;message&quot;, strconv.Itoa(id))
  6. 			time.Sleep(1 * time.Second)
  7. 		}
  8. 		fmt.Println(&quot;closed&quot;)
  9. 	}()

Kinda hacky, but it seems to work.

You may be better off using a different package or rolling your own so you could have better control over the lifetime of your goroutines. You can detect a closed connection on .Write (which this package isn't exposing).

If you want here's an example chat server in TCP: chat-server.
And a video tutorial to go with it: tutorial.

The same basic pattern should work for SSE.

huangapple
  • 本文由 发表于 2015年8月21日 00:27:30
  • 转载请务必保留本文链接：https://go.coder-hub.com/32123546.html
  • go
  • server-sent-events
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