Remove race condition between read go-routine and stop

client/ws_client.go

@@ -86,7 +86,6 @@ func (wsc *WSClient) dial() error {
 func (wsc *WSClient) OnStop() {
 	wsc.BaseService.OnStop()
 	wsc.Conn.Close()
-	wsc.Conn = nil
 	// ResultsCh/ErrorsCh is closed in receiveEventsRoutine.
 }
 
@@ -112,6 +111,9 @@ func (wsc *WSClient) receiveEventsRoutine() {
 			wsc.ResultsCh <- *response.Result
 		}
 	}
+	// this must be modified in the same go-routine that reads from the
+	// connection to avoid race conditions
+	wsc.Conn = nil
 
 	// Cleanup
 	close(wsc.ResultsCh)

server/handlers.go

@@ -347,12 +347,15 @@ func NewWSConnection(baseConn *websocket.Conn, funcMap map[string]*RPCFunc, evsw
 func (wsc *wsConnection) OnStart() error {
 	wsc.BaseService.OnStart()
 
+	// these must be set before the readRoutine is created, as it may
+	// call wsc.Stop(), which accesses these timers
+	wsc.readTimeout = time.NewTimer(time.Second * wsReadTimeoutSeconds)
+	wsc.pingTicker = time.NewTicker(time.Second * wsPingTickerSeconds)
+
 	// Read subscriptions/unsubscriptions to events
 	go wsc.readRoutine()
 
 	// Custom Ping handler to touch readTimeout
-	wsc.readTimeout = time.NewTimer(time.Second * wsReadTimeoutSeconds)
-	wsc.pingTicker = time.NewTicker(time.Second * wsPingTickerSeconds)
 	wsc.baseConn.SetPingHandler(func(m string) error {
 		// NOTE: https://github.com/gorilla/websocket/issues/97
 		go wsc.baseConn.WriteControl(websocket.PongMessage, []byte(m), time.Now().Add(time.Second*wsWriteTimeoutSeconds))