一个频道只能收到一条消息

Question

我创建了一个全局通道，并且每当 ExampleNewWatcher 内部发生新事件时都会向它发送消息。第一次发生事件时，消息会在通道的接收端收到。但是，第二次发生事件时，我在通道的接收端没有收到消息。

var messages = make(chan string)

func ExampleNewWatcher(){

  watcher, err := fsnotify.NewWatcher()

  if err != nil{

    log.Fatal(err)

  }

  defer watcher.Close(0

  done := make(chan bool)

  go func(){

     for {

        select{

           case event := <- watcher.Events:

              if event.Op&fsnotify.Write == fsnotify.Write{

                 log.Println("this logs twice if I create two write events")

                 messages <- "this message only gets sent once even if I create two events"

              }

           case err := <- watcher.Errors:

               log.Println("error", err)

        }

     }

  }()

  err = watcher.Add("/tmp/watchedfile")

  <-done

}

func Websock(ws *websocket.Conn){

   msg := <-messages

   log.Println("only one message arrives, even if I create for two events", msg)

   err := websocket.Message.Send(ws, msg)

}

func main(){

 go ExampleNewWatcher() //for some reason, the server doesn't run unless I prefix a go routine to this watcher function, but that's another issue ...

  http.Handle("/websock", websocket.Handler(Websock))

 log.Fatal(http.ListenAndServe(":8000", nil))

}

Answer 1

您的 WebSock 函数需要包含一个接收循环来接收多个消息。否则，您的函数将终止并且 websocket 连接将被关闭。

Answer 2

将您的Websock功能修改为：func Websock(ws *websocket.Conn) {&nbsp; &nbsp; for {&nbsp; &nbsp; &nbsp; &nbsp; msg := <-messages&nbsp; &nbsp; &nbsp; &nbsp; log.Println("only one message arrives, even if I create for two events", msg)&nbsp; &nbsp; &nbsp; &nbsp; if err := websocket.Message.Send(ws, msg); err != nil {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; log.Fatal(err)&nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; }}