feat(server): UDP listener, hub WebSocket, Gauges Prometheus

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

server/websocket/handler.go

@@ -0,0 +1,34 @@
+package websocket
+
+import (
+	"log"
+	"net/http"
+
+	"github.com/gorilla/websocket"
+)
+
+var upgrader = websocket.Upgrader{
+	ReadBufferSize:  1024,
+	WriteBufferSize: 4096,
+	CheckOrigin:    func(r *http.Request) bool { return true },
+}
+
+func Handler(hub *Hub) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		conn, err := upgrader.Upgrade(w, r, nil)
+		if err != nil {
+			log.Printf("[ws] upgrade: %v", err)
+			return
+		}
+		hub.Register(conn)
+		defer func() {
+			hub.Unregister(conn)
+			conn.Close()
+		}()
+		for {
+			if _, _, err := conn.ReadMessage(); err != nil {
+				break
+			}
+		}
+	}
+}

server/websocket/hub.go

@@ -0,0 +1,51 @@
+package websocket
+
+import (
+	"encoding/json"
+	"log"
+	"sync"
+
+	"github.com/gorilla/websocket"
+)
+
+type Hub struct {
+	mu      sync.RWMutex
+	clients map[*websocket.Conn]struct{}
+}
+
+func NewHub() *Hub {
+	return &Hub{clients: make(map[*websocket.Conn]struct{})}
+}
+
+func (h *Hub) Register(conn *websocket.Conn) {
+	h.mu.Lock()
+	h.clients[conn] = struct{}{}
+	h.mu.Unlock()
+}
+
+func (h *Hub) Unregister(conn *websocket.Conn) {
+	h.mu.Lock()
+	delete(h.clients, conn)
+	h.mu.Unlock()
+}
+
+func (h *Hub) Broadcast(msg interface{}) {
+	data, err := json.Marshal(msg)
+	if err != nil {
+		log.Printf("[ws] marshal: %v", err)
+		return
+	}
+	h.mu.RLock()
+	defer h.mu.RUnlock()
+	for conn := range h.clients {
+		if err := conn.WriteMessage(websocket.TextMessage, data); err != nil {
+			log.Printf("[ws] write: %v", err)
+		}
+	}
+}
+
+func (h *Hub) Count() int {
+	h.mu.RLock()
+	defer h.mu.RUnlock()
+	return len(h.clients)
+}

server/websocket/hub_test.go

@@ -0,0 +1,40 @@
+package websocket_test
+
+import (
+	"encoding/json"
+	"net/http/httptest"
+	"strings"
+	"testing"
+	"time"
+
+	wslib "github.com/gorilla/websocket"
+	"github.com/user/nanometrics/server/websocket"
+)
+
+func TestHubBroadcast(t *testing.T) {
+	hub := websocket.NewHub()
+	srv := httptest.NewServer(websocket.Handler(hub))
+	defer srv.Close()
+
+	url := "ws" + strings.TrimPrefix(srv.URL, "http") + "/ws"
+	conn, _, err := wslib.DefaultDialer.Dial(url, nil)
+	if err != nil {
+		t.Fatalf("dial: %v", err)
+	}
+	defer conn.Close()
+
+	time.Sleep(50 * time.Millisecond)
+
+	hub.Broadcast(map[string]string{"type": "test", "msg": "hello"})
+
+	conn.SetReadDeadline(time.Now().Add(time.Second))
+	_, data, err := conn.ReadMessage()
+	if err != nil {
+		t.Fatalf("read: %v", err)
+	}
+	var got map[string]string
+	json.Unmarshal(data, &got)
+	if got["msg"] != "hello" {
+		t.Errorf("attendu hello, eu %s", got["msg"])
+	}
+}