func (self *Pump) runMsger(msgerName string, resp http.ResponseWriter, allowCrossDomain bool) {
var msger *messenger.Messenger
if self.msgers[msgerName] == nil {
msger = messenger.New(msgerName)
self.RegisterMessenger(msgerName, msger)
// TODO: fix display format to subscribe/events/id
log.Println("SSE endpoint: listening /subscribe/" + msger.Name())
} else {
msger = self.msgers[msgerName]
}
go self.subscribeRedis(msgerName, msger)
// Make sure that the writer supports flushing.
//
f, ok := resp.(http.Flusher)
if !ok {
http.Error(resp, "Streaming unsupported", http.StatusInternalServerError)
return
}
c, ok := resp.(http.CloseNotifier)
if !ok {
http.Error(resp, "Close notification unsupported", http.StatusInternalServerError)
return
}
closer := c.CloseNotify()
// Create a new channel, over which the broker can
// send self client messages.
messageChan := make(chan string)
// Add self client to the map of those that should
// receive updates
msger.AddClient(messageChan)
// Remove self client from the map of attached clients
// when `EventHandler` exits.
defer func() {
msger.RemoveClient(messageChan)
}()
// Set the headers related to event streaming.
resp.Header().Set("Content-Type", "text/event-stream")
resp.Header().Set("Cache-Control", "no-cache")
resp.Header().Set("Connection", "keep-alive")
if allowCrossDomain {
resp.Header().Set("Access-Control-Allow-Origin", "*")
}
// Use the CloseNotifier interface
// https://code.google.com/p/go/source/detail?name=3292433291b2
//
// NOTE: we could loop endlessly; however, then you
// could not easily detect clients that dettach and the
// server would continue to send them messages long after
// they're gone due to the "keep-alive" header. One of
// the nifty aspects of SSE is that clients automatically
// reconnect when they lose their connection.
//
for {
select {
case msg := <-messageChan:
fmt.Fprintf(resp, "data: %s\n\n", msg)
f.Flush()
case <-closer:
log.Println("Closing connection")
return
}
}
}
