embedded the mutex into the games global (one fewer global)

game.go

@@ -47,9 +47,9 @@ func (g *game) run() {
 		select {
 		case <-g.kill:
 			log.Printf("game %s: received kill signal, dying gracefully", g.id)
-			gameLock.Lock()
+			games.Lock()
-			delete(games, g.id)
+			delete(games.m, g.id)
-			gameLock.Unlock()
+			games.Unlock()
 			return
 		case p := <-g.register:
 			g.players[p] = true

http.go

@@ -22,19 +22,19 @@ func startGame(w http.ResponseWriter, req *http.Request) {
 	_g := NewGame(new_game_name, *width, *height)
 	go _g.run()
 
-	gameLock.Lock()
+	games.Lock()
-	games[new_game_name] = _g
+	games.m[new_game_name] = _g
 	log.Printf("%+v", games)
-	gameLock.Unlock()
+	games.Unlock()
 
 	w.Write([]byte(fmt.Sprintf(`{"id": "%s"}`, new_game_name)))
 }
 
 func listGames(w http.ResponseWriter, req *http.Request) {
-	gameLock.RLock()
+	games.RLock()
-	defer gameLock.RUnlock()
+	defer games.RUnlock()
 	ids := make([]string, 0)
-	for id, _ := range games {
+	for id, _ := range games.m {
 		ids = append(ids, id)
 	}
 	if err := json.NewEncoder(w).Encode(ids); err != nil {
@@ -51,9 +51,9 @@ func addPlayer(ws *websocket.Conn) {
 		return
 	}
 
-	gameLock.Lock()
+	games.Lock()
-	game, ok := games[gid.Id]
+	game, ok := games.m[gid.Id]
-	gameLock.Unlock()
+	games.Unlock()
 
 	if !ok {
 		log.Println("ERROR: game not found")

main.go

@@ -18,15 +18,20 @@ var height = flag.Float64("height", 550, "height of field")
 
 var delta float64
 
-var games map[string]*game
 var idg *IdGenerator
-var gameLock sync.RWMutex
+
+type MapLock struct {
+	m map[string]*game
+	sync.RWMutex
+}
+
+var games MapLock
 
 func main() {
 	rand.Seed(time.Now().UnixNano())
 	flag.Parse()
 
-	games = make(map[string]*game)
+	games = MapLock{m: make(map[string]*game)}
 	idg = NewIdGenerator()
 
 	delta = float64(*tick) / 1000