Use more modern function channel approach in websocket forwarder.

cmd/mtwebmapper/forwardupdates.go

@@ -15,10 +15,8 @@ import (
 
 type websocketForwarder struct {
 	upgrader    *websocket.Upgrader
-	register    chan *connection
-	unregister  chan *connection
-	broadcast   chan msg
-	connections map[*connection]bool
+	connections map[*connection]struct{}
+	funcs       chan func(*websocketForwarder)
 }
 
 type connection struct {
@@ -32,49 +30,74 @@ type msg struct {
 }
 
 func newWebsocketForwarder() *websocketForwarder {
-	upgrader := &websocket.Upgrader{ReadBufferSize: 512, WriteBufferSize: 2048}
+	upgrader := &websocket.Upgrader{
+		ReadBufferSize:  512,
+		WriteBufferSize: 2048,
+		//CheckOrigin:     func(*http.Request) bool { return true },
+	}
 	return &websocketForwarder{
 		upgrader:    upgrader,
-		register:    make(chan *connection),
-		unregister:  make(chan *connection),
-		broadcast:   make(chan msg),
-		connections: make(map[*connection]bool)}
+		connections: make(map[*connection]struct{}),
+		funcs:       make(chan func(*websocketForwarder)),
+	}
 }
 
 func (wsf *websocketForwarder) run() {
-	for {
-		select {
-		case c := <-wsf.register:
-			wsf.connections[c] = true
-		case c := <-wsf.unregister:
-			if _, ok := wsf.connections[c]; ok {
+	for fn := range wsf.funcs {
+		fn(wsf)
+	}
+}
+
+func (wsf *websocketForwarder) register(c *connection) {
+	wsf.funcs <- func(wsf *websocketForwarder) {
+		wsf.connections[c] = struct{}{}
+	}
+}
+
+func (wsf *websocketForwarder) unregister(c *connection) {
+	wsf.funcs <- func(wsf *websocketForwarder) {
+		if _, ok := wsf.connections[c]; ok {
+			delete(wsf.connections, c)
+			close(c.send)
+		}
+	}
+}
+
+func (wsf *websocketForwarder) send(m *msg) {
+	wsf.funcs <- func(wsf *websocketForwarder) {
+		if len(wsf.connections) == 0 {
+			return
+		}
+
+		var buf bytes.Buffer
+
+		encoder := json.NewEncoder(&buf)
+		if err := encoder.Encode(m); err != nil {
+			log.Printf("encoding changes failed: %s\n", err)
+			return
+		}
+
+		data := buf.Bytes()
+
+		for c := range wsf.connections {
+			select {
+			case c.send <- data:
+			default:
 				delete(wsf.connections, c)
 				close(c.send)
 			}
-		case message := <-wsf.broadcast:
-			if len(wsf.connections) == 0 {
-				continue
-			}
-
-			var buf bytes.Buffer
-			encoder := json.NewEncoder(&buf)
-			if err := encoder.Encode(message); err != nil {
-				log.Printf("encoding changes failed: %s\n", err)
-				continue
-			}
-			m := buf.Bytes()
-			for c := range wsf.connections {
-				select {
-				case c.send <- m:
-				default:
-					delete(wsf.connections, c)
-					close(c.send)
-				}
-			}
 		}
 	}
 }
 
+func (wsf *websocketForwarder) BaseTilesUpdated(changes []xz) {
+	wsf.send(&msg{Tiles: changes})
+}
+
+func (wsf *websocketForwarder) BroadcastPlayers(pls []*player) {
+	wsf.send(&msg{Pls: pls})
+}
+
 func (wsf *websocketForwarder) ServeHTTP(rw http.ResponseWriter, r *http.Request) {
 	ws, err := wsf.upgrader.Upgrade(rw, r, nil)
 	if err != nil {
@@ -82,20 +105,12 @@ func (wsf *websocketForwarder) ServeHTTP(rw http.ResponseWriter, r *http.Request
 		return
 	}
 	c := &connection{ws: ws, send: make(chan []byte, 8)}
-	wsf.register <- c
-	defer func() { wsf.unregister <- c }()
+	wsf.register(c)
+	defer wsf.unregister(c)
 	go c.writer()
 	c.reader()
 }
 
-func (wsf *websocketForwarder) BaseTilesUpdated(changes []xz) {
-	wsf.broadcast <- msg{Tiles: changes}
-}
-
-func (wsf *websocketForwarder) BroadcastPlayers(pls []*player) {
-	wsf.broadcast <- msg{Pls: pls}
-}
-
 func (c *connection) writer() {
 	defer c.ws.Close()
 	for msg := range c.send {