Building Real-Time Chat with Go & WebSockets

1type Hub struct {
2	clients    map[*Client]bool
3	broadcast  chan []byte
4	register   chan *Client
5	unregister chan *Client
6	mu         sync.RWMutex
7}
8
9func NewHub() *Hub {
10	return &Hub{
11		clients:    make(map[*Client]bool),
12		broadcast:  make(chan []byte, 256),
13		register:   make(chan *Client),
14		unregister: make(chan *Client),
15	}
16}
17
18func (h *Hub) Run() {
19	for {
20		select {
21		case client := <-h.register:
22			h.mu.Lock()
23			h.clients[client] = true
24			h.mu.Unlock()
25		case client := <-h.unregister:
26			h.mu.Lock()
27			if _, ok := h.clients[client]; ok {
28				delete(h.clients, client)
29				close(client.send)
30			}
31			h.mu.Unlock()
32		case message := <-h.broadcast:
33			h.mu.RLock()
34			for client := range h.clients {
35				select {
36				case client.send <- message:
37				default:
38					close(client.send)
39					delete(h.clients, client)
40				}
41			}
42			h.mu.RUnlock()
43		}
44	}
45}

1var upgrader = websocket.Upgrader{
2	ReadBufferSize:  1024,
3	WriteBufferSize: 1024,
4	CheckOrigin: func(r *http.Request) bool {
5		return r.Header.Get("Origin") == "https://gochat.manishh.in"
6	},
7}
8
9func ServeWs(hub *Hub, w http.ResponseWriter, r *http.Request) {
10	conn, err := upgrader.Upgrade(w, r, nil)
11	if err != nil {
12		log.Printf("upgrade error: %v", err)
13		return
14	}
15	client := &Client{
16		hub:  hub,
17		conn: conn,
18		send: make(chan []byte, 256),
19	}
20	hub.register <- client
21	go client.writePump()
22	go client.readPump()
23}

# Clone and run
git clone https://github.com/lordofthemind/gochat
cd gochat
docker compose up -d redis
go run ./cmd/server/main.go

# Server starts at http://localhost:8080
# WebSocket endpoint: ws://localhost:8080/ws