Merge pull request #21 from grid-x/fix/fix_close_nil_channel_panic_on_stop

Improve Handling of stopped channel stopping the Server

Author: Marco Trettner

ocppj/central_system_test.go

@@ -54,6 +54,20 @@ func (suite *OcppJTestSuite) TestServerStoppedError() {
 	assert.Error(t, err, "ocppj server is not started, couldn't send request")
 }
 
+func (suite *OcppJTestSuite) TestServerStopBeforeStart() {
+	t := suite.T()
+
+	// Stop server
+	suite.mockServer.On("Stop").Return(nil)
+	suite.centralSystem.Stop()
+
+	// Start server (should return)
+	suite.mockServer.On("Start", mock.AnythingOfType("int"), mock.AnythingOfType("string")).Return(nil)
+	suite.centralSystem.Start(8887, "/{ws}")
+
+	assert.True(t, suite.serverDispatcher.IsRunning())
+}
+
 // ----------------- SendRequest tests -----------------
 
 func (suite *OcppJTestSuite) TestCentralSystemSendRequest() {

ocppj/dispatcher.go

@@ -381,6 +381,7 @@ func NewDefaultServerDispatcher(queueMap ServerQueueMap) *DefaultServerDispatche
 		requestChannel:   nil,
 		readyForDispatch: make(chan string, 1),
 		timeout:          defaultMessageTimeout,
+		stoppedC:         make(chan struct{}, 1),
 	}
 	d.pendingRequestState = NewServerState(&d.mutex)
 	return d
@@ -389,7 +390,6 @@ func NewDefaultServerDispatcher(queueMap ServerQueueMap) *DefaultServerDispatche
 func (d *DefaultServerDispatcher) Start() {
 	d.requestChannel = make(chan string, 20)
 	d.timerC = make(chan string, 10)
-	d.stoppedC = make(chan struct{}, 1)
 	d.running = true
 	go d.messagePump()
 }
@@ -404,7 +404,12 @@ func (d *DefaultServerDispatcher) Stop() {
 	d.mutex.Lock()
 	defer d.mutex.Unlock()
 	d.running = false
-	close(d.stoppedC)
+
+	select {
+	case <-d.stoppedC:
+	default:
+		close(d.stoppedC)
+	}
 }
 
 func (d *DefaultServerDispatcher) SetTimeout(timeout time.Duration) {

ocppj/server.go

@@ -67,7 +67,8 @@ func NewServer(wsServer ws.WsServer, dispatcher ServerDispatcher, stateHandler S
 		server:       wsServer,
 		RequestState: stateHandler,
 		dispatcher:   dispatcher,
-		stopped:      make(chan struct{})}
+		stopped:      make(chan struct{}),
+	}
 	for _, profile := range profiles {
 		s.AddProfile(profile)
 	}
@@ -148,7 +149,11 @@ func (s *Server) Start(listenPort int, listenPath string) {
 // Stops the server.
 // This clears all pending requests and causes the Start function to return.
 func (s *Server) Stop() {
-	close(s.stopped)
+	select {
+	case <-s.stopped:
+	default:
+		close(s.stopped)
+	}
 	s.waitGroup.Wait()
 	s.server.Stop()
 	s.dispatcher.Stop()