Implement correct back-throttleing for web-sockets.

sdk/lib/io/websocket_impl.dart

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 part of dart.io;
 
 const String _webSocketGUID = "258EAFA5-E914-47DA-95CA-C5AB0DC85B11";
 
 class _WebSocketMessageType {
   static const int NONE = 0;
@@ skipping 554 matching lines @@
   }
 }
 
 
 class _WebSocketConsumer implements StreamConsumer {
   final _WebSocketImpl webSocket;
   final Socket socket;
   StreamController _controller;
   StreamSubscription _subscription;
   bool _issuedPause = false;
+  bool _reportError = false;
   Completer _closeCompleter = new Completer();
   Completer _completer;
 
   _WebSocketConsumer(_WebSocketImpl this.webSocket, Socket this.socket);
 
   void _onListen() {
     if (_subscription != null) {
       _subscription.cancel();
     }
   }
@@ skipping 21 matching lines @@
                                        onResume: _onResume,
                                        onCancel: _onListen);
     var stream = _controller.stream.transform(
         new _WebSocketOutgoingTransformer(webSocket));
     socket.addStream(stream)
         .then((_) {
                 _done();
                 _closeCompleter.complete(webSocket);
               },
               onError: (error) {
-                if (!_done(error)) {
-                  _closeCompleter.completeError(error);
+                if (_reportError) {
+                  if (!_done(error)) {
+                    _closeCompleter.completeError(error);
+                  }
+                } else {
+                  _done();
+                  _closeCompleter.complete(webSocket);
                 }
               });
   }
 
   bool _done([error]) {
     if (_completer == null) return false;
     if (error != null) {
       _completer.completeError(error);
     } else {
       _completer.complete(webSocket);
     }
     _completer = null;
     return true;
   }
 
   Future addStream(var stream) {
     _ensureController();
     _completer = new Completer();
     _subscription = stream.listen(
         (data) {
+          _reportError = true;
           _controller.add(data);
         },
         onDone: () {
           _done();
         },
         onError: (error) {
           _done(error);
         },
         cancelOnError: true);
     if (_issuedPause) {
       _subscription.pause();
       _issuedPause = false;
     }
     return _completer.future;
   }
 
   Future close() {
     _ensureController();
     Future closeSocket() {
       return socket.close().then((_) => webSocket);
     }
     _controller.close();
     return _closeCompleter.future.then((_) => closeSocket());
   }
 
   void add(data) {
     _ensureController();
+    _reportError = false;
     _controller.add(data);
   }
 }
 
 
 class _WebSocketImpl extends Stream implements WebSocket {
-  final StreamController _controller = new StreamController(sync: true);
+  StreamController _controller;
   StreamSink _sink;
 
   final Socket _socket;
   final bool _serverSide;
   int _readyState = WebSocket.CONNECTING;
   bool _writeClosed = false;
   int _closeCode;
   String _closeReason;
   Duration _pingInterval;
   Timer _pingTimer;
   _WebSocketConsumer _consumer;
+  var _subscription;
 
   int _outCloseCode;
   String _outCloseReason;
 
   static final HttpClient _httpClient = new HttpClient();
 
   static Future<WebSocket> connect(String url, [protocols]) {
     Uri uri = Uri.parse(url);
     if (uri.scheme != "ws" && uri.scheme != "wss") {
       throw new WebSocketException("Unsupported URL scheme '${uri.scheme}'");
@@ skipping 63 matching lines @@
       });
   }
 
   _WebSocketImpl._fromSocket(Socket this._socket,
                              [bool this._serverSide = false]) {
     _consumer = new _WebSocketConsumer(this, _socket);
     _sink = new _StreamSinkImpl(_consumer);
     _readyState = WebSocket.OPEN;
 
     var transformer = new _WebSocketProtocolTransformer(_serverSide);
-    _socket.transform(transformer).listen(
+    _subscription = _socket.transform(transformer).listen(
         (data) {
+          // Simply set pingInterval, as it'll cancel any timers.
+          pingInterval = _pingInterval;
           if (data is _WebSocketPing) {
             if (!_writeClosed) _consumer.add(new _WebSocketPong(data.payload));
           } else if (data is _WebSocketPong) {
-            // Simply set pingInterval, as it'll cancel any timers.
-            pingInterval = _pingInterval;
+            // Already handled.
           } else {
             _controller.add(data);
           }
         },
         onError: (error) {
           if (error is ArgumentError) {
             close(WebSocketStatus.INVALID_FRAME_PAYLOAD_DATA);
           } else {
             close(WebSocketStatus.PROTOCOL_ERROR);
           }
           _controller.addError(error);
           _controller.close();
         },
         onDone: () {
           if (_readyState == WebSocket.OPEN) {
             _readyState = WebSocket.CLOSING;
             if (!_isReservedStatusCode(transformer.closeCode)) {
               close(transformer.closeCode);
             } else {
               close();
             }
             _readyState = WebSocket.CLOSED;
           }
           _closeCode = transformer.closeCode;
           _closeReason = transformer.closeReason;
           _controller.close();
         },
         cancelOnError: true);
+    _subscription.pause();
+    _controller = new StreamController(sync: true,
+                                       onListen: _subscription.resume,
+                                       onPause: _subscription.pause,
+                                       onResume: _subscription.resume);
   }
 
   StreamSubscription listen(void onData(message),
                             {void onError(error),
                              void onDone(),
                              bool cancelOnError}) {
     return _controller.stream.listen(onData,
                                      onError: onError,
                                      onDone: onDone,
                                      cancelOnError: cancelOnError);
   }
 
   Duration get pingnterval => _pingInterval;
 
   void set pingInterval(Duration interval) {
     if (_writeClosed) return;
     if (_pingTimer != null) _pingTimer.cancel();
     _pingInterval = interval;
 
     if (_pingInterval == null) return;
 
     _pingTimer = new Timer(_pingInterval, () {
       if (_writeClosed) return;
       _consumer.add(new _WebSocketPing());
       _pingTimer = new Timer(_pingInterval, () {
         // No pong received.
+        _closeCode = WebSocketStatus.GOING_AWAY;
+        _subscription.cancel();
         close(WebSocketStatus.GOING_AWAY);
       });
     });
   }
 
   int get readyState => _readyState;
 
   String get extensions => null;
   String get protocol => null;
   int get closeCode => _closeCode;
@@ skipping 21 matching lines @@
            (code < WebSocketStatus.NORMAL_CLOSURE ||
             code == WebSocketStatus.RESERVED_1004 ||
             code == WebSocketStatus.NO_STATUS_RECEIVED ||
             code == WebSocketStatus.ABNORMAL_CLOSURE ||
             (code > WebSocketStatus.INTERNAL_SERVER_ERROR &&
              code < WebSocketStatus.RESERVED_1015) ||
             (code >= WebSocketStatus.RESERVED_1015 &&
              code < 3000));
   }
 }