Very simple version of Isolates.

tests/standalone/io/socket_close_test.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.
 //
 // VMOptions=
 // VMOptions=--short_socket_read
 // VMOptions=--short_socket_write
 // VMOptions=--short_socket_read --short_socket_write
 //
 // Test socket close events.
 
 import 'dart:async';
 import 'dart:io';
 import 'dart:isolate';
 
 import "package:async_helper/async_helper.dart";
 import "package:expect/expect.dart";
 
 const SERVERSHUTDOWN = -1;
 const ITERATIONS = 10;
 
 
+Future sendReceive(SendPort port, message) {
+  ReceivePort receivePort = new ReceivePort();
+  port.send([message, receivePort.sendPort]);
+  return receivePort.first;
+}
+
 class SocketClose {
 
   SocketClose.start(this._mode, this._done)
-      : _receivePort = new ReceivePort(),
-        _sendPort = null,
+      : _sendPort = null,
         _readBytes = 0,
         _dataEvents = 0,
         _closeEvents = 0,
         _errorEvents = 0,
         _iterations = 0 {
-    _sendPort = spawnFunction(startSocketCloseServer);
     initialize();
   }
 
   void proceed() {
     if (_iterations < ITERATIONS) {
       Timer.run(sendData);
     } else {
       shutdown();
     }
   }
@@ skipping 91 matching lines @@
           break;
         default:
           Expect.fail("Unknown test mode");
       }
     }
 
     Socket.connect(SocketCloseServer.HOST, _port).then(connectHandler);
   }
 
   void initialize() {
-    _receivePort.receive((var message, SendPort replyTo) {
-      _port = message;
-      proceed();
+    ReceivePort receivePort = new ReceivePort();
+    var remote = Isolate.spawn(startSocketCloseServer, receivePort.sendPort);
+
+    receivePort.first.then((message) {
+      this._sendPort = message;
+      sendReceive(_sendPort, _mode).then((int port) {
+        this._port = port;
+        proceed();
+      });
     });
-    _sendPort.send(_mode, _receivePort.toSendPort());
   }
 
   void shutdown() {
-    _sendPort.send(SERVERSHUTDOWN, _receivePort.toSendPort());
-    _receivePort.receive((message, ignore) {
-      _done();
-      _receivePort.close();
-    });
+    sendReceive(_sendPort, SERVERSHUTDOWN).then((_) { _done(); });
 
     switch (_mode) {
       case 0:
       case 1:
         Expect.equals(0, _dataEvents);
         Expect.equals(ITERATIONS, _closeEvents);
         break;
       case 2:
         Expect.equals(0, _dataEvents);
         Expect.equals(ITERATIONS, _closeEvents);
         break;
       case 3:
       case 4:
         Expect.isTrue(_dataEvents <= ITERATIONS);
         Expect.isTrue(_dataEvents >= 0);
         Expect.equals(ITERATIONS, _closeEvents);
         break;
       case 5:
       case 6:
         Expect.equals(ITERATIONS, _dataEvents);
         Expect.equals(ITERATIONS, _closeEvents);
         break;
       default:
         Expect.fail("Unknown test mode");
     }
     Expect.equals(0, _errorEvents);
   }
 
   int _port;
-  ReceivePort _receivePort;
   SendPort _sendPort;
   List<int> _buffer;
   int _readBytes;
   int _dataEvents;
   int _closeEvents;
   int _errorEvents;
   int _iterations;
   int _mode;
   Function _done;
 }
 
 
 class ConnectionData {
   ConnectionData(Socket this.connection) : readBytes = 0;
   Socket connection;
   int readBytes;
 }
 
 
-void startSocketCloseServer() {
+void startSocketCloseServer(SendPort replyTo) {
   var server = new SocketCloseServer();
-  port.receive(server.dispatch);
+  replyTo.send(server.dispatchSendPort);
 }
 
 class SocketCloseServer {
 
   static const HOST = "127.0.0.1";
 
-  SocketCloseServer() : super() {}
+  SocketCloseServer() : _dispatchPort = new ReceivePort() {
+    _dispatchPort.listen(dispatch);
+  }
 
   void connectionHandler(ConnectionData data) {
     var connection = data.connection;
 
     void readBytes(bytes, whenFiveBytes) {
       data.readBytes += bytes.length;
       Expect.isTrue(data.readBytes <= 5);
       if (data.readBytes == 5) {
         whenFiveBytes();
       }
@@ skipping 91 matching lines @@
         case 5:
         case 6:
           Expect.equals(ITERATIONS, _dataEvents);
           Expect.equals(ITERATIONS, _closeEvents);
           break;
         default:
           Expect.fail("Unknown test mode");
       }
       Expect.equals(0, _errorEvents);
       _server.close();
-      port.close();
+      _dispatchPort.close();
       _donePort.send(null);
     } else {
       new Timer(new Duration(milliseconds: 100), waitForResult);
     }
   }
 
-  void dispatch(message, SendPort replyTo) {
+  SendPort get dispatchSendPort => _dispatchPort.sendPort;
+
+  void dispatch(message) {
+    var command = message[0];
+    SendPort replyTo = message[1];
     _donePort = replyTo;
-    if (message != SERVERSHUTDOWN) {
+    if (command != SERVERSHUTDOWN) {
       _readBytes = 0;
       _errorEvents = 0;
       _dataEvents = 0;
       _closeEvents = 0;
       _iterations = 0;
-      _mode = message;
+      _mode = command;
       ServerSocket.bind("127.0.0.1", 0).then((server) {
         _server = server;
         _server.listen(
           (socket) {
             var data = new ConnectionData(socket);
             connectionHandler(data);
           },
           onError: errorHandlerServer
         );
         replyTo.send(_server.port, null);
       });
     } else {
       Timer.run(waitForResult);
     }
   }
 
   ServerSocket _server;
+  final ReceivePort _dispatchPort;
   SendPort _donePort;
   int _readBytes;
   int _errorEvents;
   int _dataEvents;
   int _closeEvents;
   int _iterations;
   int _mode;
 }
 
 
 main() {
   // Run the close test in these different "modes".
   // 0: Client closes without sending at all.
   // 1: Client sends and destroys.
   // 2: Client sends. Server destroys.
   // 3: Client sends. Server responds and destroys.
   // 4: Client sends and half-closes. Server responds and destroys.
   // 5: Client sends. Server responds and half closes.
   // 6: Client sends and half-closes. Server responds and half closes.
   var tests = 7;
   for (var i = 0; i < tests; i++) {
     asyncStart();
     new SocketClose.start(i, asyncEnd);
   }
 }