gorilla/websocket的chat示例代码简单分析

 代码地址：https://github.com/gorilla/websocket/tree/main/examples/chat

文件包含：main.go、hub.go、client.go、home.html

main.go文件

func main() {
	flag.Parse()
	hub := newHub() // 实例化Hub
	go hub.run() // 使用chan处理 增删Hub的连接 和 广播消息

	http.HandleFunc("/", serveHome) // 访问home.html页面

    // 处理websocket
	http.HandleFunc("/ws", func(w http.ResponseWriter, r *http.Request) {
		serveWs(hub, w, r)
	})

	server := &http.Server{
		Addr:              *addr,
		ReadHeaderTimeout: 3 * time.Second,
	}
	err := server.ListenAndServe()
	if err != nil {
		log.Fatal("ListenAndServe: ", err)
	}
}

hub.go文件

// 相当于连接池
type Hub struct {
	// Registered clients.
	clients map[*Client]bool // 存放所有websocket连接

	// Inbound messages from the clients.
	broadcast chan []byte // 广播消息

	// Register requests from the clients.
	register chan *Client // 添加websocket连接

	// Unregister requests from clients.
	unregister chan *Client // 删除websocket连接
}

// 实例化Hub
func newHub() *Hub {
	return &Hub{
		broadcast:  make(chan []byte),
		register:   make(chan *Client),
		unregister: make(chan *Client),
		clients:    make(map[*Client]bool),
	}
}

// 使用chan处理 增删Hub的连接 和 广播消息
func (h *Hub) run() {
	for {
		select {
		case client := <-h.register:
			h.clients[client] = true // 添加连接
		case client := <-h.unregister:
			if _, ok := h.clients[client]; ok {
				delete(h.clients, client) // 删除连接
				close(client.send)
			}
		case message := <-h.broadcast:
			for client := range h.clients {
				select {
				case client.send <- message: // 广播消息
				default:
					close(client.send)
					delete(h.clients, client)
				}
			}
		}
	}
}

client.go文件

// 连接
type Client struct {
	hub *Hub // 引用Hub

	// The websocket connection.
	conn *websocket.Conn // websocket连接

	// Buffered channel of outbound messages.
	send chan []byte // 消息发送chan
}

// readPump pumps messages from the websocket connection to the hub.
//
// The application runs readPump in a per-connection goroutine. The application
// ensures that there is at most one reader on a connection by executing all
// reads from this goroutine.
func (c *Client) readPump() { // 读数据
	defer func() {
		c.hub.unregister <- c
		c.conn.Close()
	}()
	c.conn.SetReadLimit(maxMessageSize)
	c.conn.SetReadDeadline(time.Now().Add(pongWait))
	c.conn.SetPongHandler(func(string) error { c.conn.SetReadDeadline(time.Now().Add(pongWait)); return nil })
	for {
		_, message, err := c.conn.ReadMessage() // 接收消息
		if err != nil {
			if websocket.IsUnexpectedCloseError(err, websocket.CloseGoingAway, websocket.CloseAbnormalClosure) {
				log.Printf("error: %v", err)
			}
			break
		}
		message = bytes.TrimSpace(bytes.Replace(message, newline, space, -1))
		c.hub.broadcast <- message // 将消息发送到广播消息chan
	}
}

// writePump pumps messages from the hub to the websocket connection.
//
// A goroutine running writePump is started for each connection. The
// application ensures that there is at most one writer to a connection by
// executing all writes from this goroutine.
func (c *Client) writePump() { // 写数据
	ticker := time.NewTicker(pingPeriod)
	defer func() {
		ticker.Stop()
		c.conn.Close()
	}()
	for {
		select {
		case message, ok := <-c.send: // 从连接的chan接收消息
			c.conn.SetWriteDeadline(time.Now().Add(writeWait))
			if !ok {
				// The hub closed the channel.
				c.conn.WriteMessage(websocket.CloseMessage, []byte{})
				return
			}

			w, err := c.conn.NextWriter(websocket.TextMessage)
			if err != nil {
				return
			}
			w.Write(message) // 发送消息

			// Add queued chat messages to the current websocket message.
			n := len(c.send)
			for i := 0; i < n; i++ {
				w.Write(newline)
				w.Write(<-c.send)
			}

			if err := w.Close(); err != nil {
				return
			}
		case <-ticker.C:
			c.conn.SetWriteDeadline(time.Now().Add(writeWait))
			if err := c.conn.WriteMessage(websocket.PingMessage, nil); err != nil {
				return
			}
		}
	}
}

// serveWs handles websocket requests from the peer.
func serveWs(hub *Hub, w http.ResponseWriter, r *http.Request) {
	conn, err := upgrader.Upgrade(w, r, nil)
	if err != nil {
		log.Println(err)
		return
	}

    // 初始化Client
	client := &Client{hub: hub, conn: conn, send: make(chan []byte, 256)}
	client.hub.register <- client

	// Allow collection of memory referenced by the caller by doing all work in
	// new goroutines.
	go client.writePump() // 写数据
	go client.readPump() // 读数据
}

其他chat参考：

https://github.com/android-coco/chat 

https://github.com/GoLangFengShen/chat

https://www.golangblogs.com/read/im/date-2023.02.19.09.38.24