Improve websocket write handling (#45)

Increase the buffer size of the write channel to 1024. This way adding
messages will never block if e.g. at the same time the connection is
closed. If the buffer is full, return an error, as sending isn’t
possible.

This fixes #42

ws/websocket.go

@@ -80,8 +80,8 @@ func (w *WebsocketConnection) isConnClosed() bool {
 }
 
 func (w *WebsocketConnection) run() {
-	w.shipWriteChannel = make(chan []byte, 1) // Send outgoing ship messages
-	w.closeChannel = make(chan struct{}, 1)   // Listen to close events
+	w.shipWriteChannel = make(chan []byte, 1024) // Send outgoing ship messages
+	w.closeChannel = make(chan struct{}, 1)      // Listen to close events
 
 	go w.readShipPump()
 	go w.writeShipPump()
@@ -258,7 +258,13 @@ func (w *WebsocketConnection) WriteMessageToWebsocketConnection(message []byte)
 		return errors.New(connIsClosedError)
 	}
 
-	w.shipWriteChannel <- message
+	select {
+	case w.shipWriteChannel <- message:
+	default:
+		// too many messages are pending, this doesn't look good
+		return errors.New("could not send message, buffer is full")
+	}
+
 	return nil
 }
 

ws/websocket_test.go

@@ -128,6 +128,23 @@ func (s *WebsocketSuite) TestConnectionClose() {
 	assert.NotNil(s.T(), err)
 }
 
+func (s *WebsocketSuite) TestWriteBufferFull() {
+	amountNil := 0
+	amountNotNil := 0
+	for i := 0; i < 10000; i++ {
+		msg := []byte{1}
+		msg = append(msg, []byte("message")...)
+		err := s.sut.WriteMessageToWebsocketConnection(msg)
+		if err == nil {
+			amountNil++
+		} else {
+			amountNotNil++
+		}
+	}
+	assert.Greater(s.T(), amountNotNil, 0)
+	assert.Greater(s.T(), amountNil, 0)
+}
+
 func (s *WebsocketSuite) TestPingPeriod() {
 	isClosed, err := s.sut.IsDataConnectionClosed()
 	assert.Equal(s.T(), false, isClosed)