Only call the dataReceived callback for sockets if there is actually data available

runtime/bin/socket_impl.dart

 // Copyright (c) 2011, 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.
 
 /*
  * SocketNativeWrapper is defined in native and holds a field to store the
  * native socket object.
  */
 class _SocketBase {
 
@@ skipping 24 matching lines @@
   /*
    * Multiplexes socket events to the right socket handler.
    */
   void _multiplex(List<int> message) {
     assert(message.length == 1);
     _canActivateHandlers = false;
     int event_mask = message[0];
       for (int i = _FIRST_EVENT; i <= _LAST_EVENT; i++) {
         if (((event_mask & (1 << i)) != 0) && _handlerMap[i] !== null) {
           var handleEvent = _handlerMap[i];
-          /*
-           * Unregister the out handler before executing it.
-           */
-          if (i == _OUT_EVENT) {
-            _setHandler(i, null);
-          }
+
+          // Unregister the out handler before executing it.
+          if (i == _OUT_EVENT) _setHandler(i, null);
+
+          // Don't call the in handler if there is no data available
+          // after all.
+          if (i == _IN_EVENT && this is _Socket && available() == 0) continue;
+
           handleEvent();
         }
       }
     _canActivateHandlers = true;
     _doActivateHandlers();
   }
 
   void _setHandler(int event, void callback()) {
     if (callback === null) {
       _handlerMask &= ~(1 << event);
@@ skipping 226 matching lines @@
     if (_outputStream == null) {
       _outputStream = new SocketOutputStream(this);
     }
     return _outputStream;
   }
 
   SocketInputStream _inputStream;
   SocketOutputStream _outputStream;
 }