send empty players array if no player is online any more.

cmd/mtwebmapper/forwardupdates.go

@@ -24,10 +24,14 @@ type connection struct {
 	send chan []byte
 }
 
-type msg struct {
-	Tiles []xz      `json:"tiles,omitempty"`
-	Pls   []*player `json:"players,omitempty"`
-}
+type (
+	tilesMsg struct {
+		Tiles []xz `json:"tiles,omitempty"`
+	}
+	plsMsg struct {
+		Pls []*player `json:"players,omitempty"`
+	}
+)
 
 func newWebsocketForwarder() *websocketForwarder {
 	upgrader := &websocket.Upgrader{
@@ -63,7 +67,7 @@ func (wsf *websocketForwarder) unregister(c *connection) {
 	}
 }
 
-func (wsf *websocketForwarder) send(m *msg) {
+func (wsf *websocketForwarder) send(m interface{}) {
 	wsf.funcs <- func(wsf *websocketForwarder) {
 		if len(wsf.connections) == 0 {
 			return
@@ -79,6 +83,8 @@ func (wsf *websocketForwarder) send(m *msg) {
 
 		data := buf.Bytes()
 
+		log.Printf("sending: %s\n", string(data))
+
 		for c := range wsf.connections {
 			select {
 			case c.send <- data:
@@ -91,11 +97,11 @@ func (wsf *websocketForwarder) send(m *msg) {
 }
 
 func (wsf *websocketForwarder) BaseTilesUpdated(changes []xz) {
-	wsf.send(&msg{Tiles: changes})
+	wsf.send(&tilesMsg{Tiles: changes})
 }
 
 func (wsf *websocketForwarder) BroadcastPlayers(pls []*player) {
-	wsf.send(&msg{Pls: pls})
+	wsf.send(&plsMsg{Pls: pls})
 }
 
 func (wsf *websocketForwarder) ServeHTTP(rw http.ResponseWriter, r *http.Request) {

cmd/mtwebmapper/players.go

@@ -160,6 +160,9 @@ func (ps *players) run() {
 		}
 		ps.mu.Unlock()
 		if change && ps.wsf != nil {
+			if pls == nil {
+				pls = []*player{}
+			}
 			// TODO: Throttle this!
 			ps.wsf.BroadcastPlayers(pls)
 		}