Gorilla Web Sockets Example

gorilla-ws.go

var (
	SyncOutput              = make(chan string)
	SyncClients             = make(map[*websocket.Conn]bool)
	SyncClientsLock         = sync.RWMutex{}
	FileSyncing             = false
	FileSyncLock            = sync.RWMutex{}
)

var upgrader = websocket.Upgrader{
	ReadBufferSize:  1024,
	WriteBufferSize: 1024,
}

go WatchOutPutChannel()


func runSync() {
	cmd := exec.Command("python", "-u", config.SyncFilesScript)
	stdout, err := cmd.StdoutPipe()
	if err != nil {
		fmt.Println(fmt.Sprintf("Error: %s", err))
	}
	FileSyncLock.Lock()
	FileSyncing = true
	FileSyncLock.Unlock()
	err = cmd.Start()
	go WatchOutPut(stdout)
}

func WatchOutPut(out io.Reader) {
	scanner := bufio.NewScanner(out)
	for scanner.Scan() {
		SyncOutput <- scanner.Text()
	}
	FileSyncLock.Lock()
	FileSyncing = false
	FileSyncLock.Unlock()
	SyncOutput <- "Sync Finished"
}

func WatchOutPutChannel() {
	for {
		output := <-SyncOutput
		SyncClientsLock.RLock()
		for client := range SyncClients {
			client.WriteMessage(1, []byte(output))
		}
		SyncClientsLock.RUnlock()
	}
}

func wsHandlerSync(w http.ResponseWriter, r *http.Request) {
	conn, err := upgrader.Upgrade(w, r, nil)
	if err != nil {
		fmt.Println("Failed to set websocket upgrade: %+v", err)
		return
	}
	SyncClientsLock.Lock()
	SyncClients[conn] = true
	SyncClientsLock.Unlock()
	for {
		_, _, err := conn.ReadMessage()
		if err != nil {
			break
		}
	}
	SyncClientsLock.Lock()
	delete(SyncClients, conn)
	SyncClientsLock.Unlock()
	conn.Close()
}