Reapply "Active stream subscriptions".

runtime/bin/socket_patch.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.
 
 patch class RawServerSocket  {
   /* patch */ static Future<RawServerSocket> bind(address,
                                                   int port,
                                                   {int backlog: 0,
                                                    bool v6Only: false}) {
     return _RawServerSocket.bind(address, port, backlog, v6Only);
@@ skipping 682 matching lines @@
   int get remotePort => _socket.remotePort;
 
   InternetAddress get address => _socket.address;
 
   String get remoteHost => _socket.remoteHost;
 
   bool get readEventsEnabled => _readEventsEnabled;
   void set readEventsEnabled(bool value) {
     if (value != _readEventsEnabled) {
       _readEventsEnabled = value;
-      if (!_controller.isPaused) _resume();
+      if (_controller.hasListener && !_controller.isPaused) _resume();
     }
   }
 
   bool get writeEventsEnabled => _writeEventsEnabled;
   void set writeEventsEnabled(bool value) {
     if (value != _writeEventsEnabled) {
       _writeEventsEnabled = value;
-      if (!_controller.isPaused) _resume();
+      if (_controller.hasListener && !_controller.isPaused) _resume();
     }
   }
 
   bool setOption(SocketOption option, bool enabled) =>
       _socket.setOption(option, enabled);
 
   _pause() {
     _socket.setListening(read: false, write: false);
   }
 
@@ skipping 108 matching lines @@
 
   void write() {
     try {
       if (subscription == null) return;
       assert(buffer != null);
       // Write as much as possible.
       offset += socket._write(buffer, offset, buffer.length - offset);
       if (offset < buffer.length) {
         if (!paused) {
           paused = true;
-          // TODO(ajohnsen): It would be nice to avoid this check.
-          // Some info: socket._write can emit an event, if it fails to write.
-          // If the user closes the socket in that event, stop() will be called
-          // before we get a change to pause.
-          if (subscription == null) return;
           subscription.pause();
         }
         socket._enableWriteEvent();
       } else {
         buffer = null;
         if (paused) {
           paused = false;
           subscription.resume();
         }
       }
@@ skipping 12 matching lines @@
         streamCompleter.complete(socket);
       }
       streamCompleter = null;
     }
   }
 
   void stop() {
     if (subscription == null) return;
     subscription.cancel();
     subscription = null;
+    paused = false;
     socket._disableWriteEvent();
   }
 }
 
 
 class _Socket extends Stream<List<int>> implements Socket {
   RawSocket _raw;  // Set to null when the raw socket is closed.
   bool _closed = false;  // Set to true when the raw socket is closed.
   StreamController _controller;
   bool _controllerClosed = false;
@@ skipping 182 matching lines @@
     if (_detachReady != null) {
       _detachReady.complete(null);
     } else {
       if (_raw != null) {
         _raw.shutdown(SocketDirection.SEND);
         _disableWriteEvent();
       }
     }
   }
 }