isolates refactor: this change introduces 'dart:isolate' as a library. This is a

lib/isolate/frog/ports.dart

Index: lib/isolate/frog/ports.dart
diff --git a/lib/isolate/frog/ports.dart b/lib/isolate/frog/ports.dart
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+++ b/lib/isolate/frog/ports.dart
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+// Copyright (c) 2012, 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.
+
+/** Common functionality to all send ports. */
+class _BaseSendPort implements SendPort {
+  /** Id for the destination isolate. */
+  final int _isolateId;
+
+  _BaseSendPort(this._isolateId);
+
+  _ReceivePortSingleShotImpl call(var message) {
+    final result = new _ReceivePortSingleShotImpl();
+    this.send(message, result.toSendPort());
+    return result;
+  }
+
+  static void checkReplyTo(SendPort replyTo) {
+    if (replyTo !== null
+        && replyTo is! _NativeJsSendPort
+        && replyTo is! _WorkerSendPort
+        && replyTo is! _BufferingSendPort) {
+      throw new Exception("SendPort.send: Illegal replyTo port type");
+    }
+  }
+
+  // TODO(sigmund): replace the current SendPort.call with the following:
+  //Future call(var message) {
+  //   final completer = new Completer();
+  //   final port = new _ReceivePort.singleShot();
+  //   send(message, port.toSendPort());
+  //   port.receive((value, ignoreReplyTo) {
+  //     if (value is Exception) {
+  //       completer.completeException(value);
+  //     } else {
+  //       completer.complete(value);
+  //     }
+  //   });
+  //   return completer.future;
+  //}
+
+  abstract void send(var message, [SendPort replyTo]);
+  abstract bool operator ==(var other);
+  abstract int hashCode();
+}
+
+/** A send port that delivers messages in-memory via native JavaScript calls. */
+class _NativeJsSendPort extends _BaseSendPort implements SendPort {
+  final _ReceivePortImpl _receivePort;
+
+  const _NativeJsSendPort(this._receivePort, int isolateId) : super(isolateId);
+
+  void send(var message, [SendPort replyTo = null]) {
+    _waitForPendingPorts([message, replyTo], () {
+      checkReplyTo(replyTo);
+      // Check that the isolate still runs and the port is still open
+      final isolate = globalState.isolates[_isolateId];
+      if (isolate == null) return;
+      if (_receivePort._callback == null) return;
+
+      // We force serialization/deserialization as a simple way to ensure
+      // isolate communication restrictions are respected between isolates that
+      // live in the same worker. [_NativeJsSendPort] delivers both messages
+      // from the same worker and messages from other workers. In particular,
+      // messages sent from a worker via a [_WorkerSendPort] are received at
+      // [_processWorkerMessage] and forwarded to a native port. In such cases,
+      // here we'll see [globalState.currentContext == null].
+      final shouldSerialize = globalState.currentContext != null
+          && globalState.currentContext.id != _isolateId;
+      var msg = message;
+      var reply = replyTo;
+      if (shouldSerialize) {
+        msg = _serializeMessage(msg);
+        reply = _serializeMessage(reply);
+      }
+      globalState.topEventLoop.enqueue(isolate, () {
+        if (_receivePort._callback != null) {
+          if (shouldSerialize) {
+            msg = _deserializeMessage(msg);
+            reply = _deserializeMessage(reply);
+          }
+          _receivePort._callback(msg, reply);
+        }
+      }, 'receive ' + message);
+    });
+  }
+
+  bool operator ==(var other) => (other is _NativeJsSendPort) &&
+      (_receivePort == other._receivePort);
+
+  int hashCode() => _receivePort._id;
+}
+
+/** A send port that delivers messages via worker.postMessage. */
+class _WorkerSendPort extends _BaseSendPort implements SendPort {
+  final int _workerId;
+  final int _receivePortId;
+
+  const _WorkerSendPort(this._workerId, int isolateId, this._receivePortId)
+      : super(isolateId);
+
+  void send(var message, [SendPort replyTo = null]) {
+    _waitForPendingPorts([message, replyTo], () {
+      checkReplyTo(replyTo);
+      final workerMessage = _serializeMessage({
+          'command': 'message',
+          'port': this,
+          'msg': message,
+          'replyTo': replyTo});
+
+      if (globalState.isWorker) {
+        // communication from one worker to another go through the main worker:
+        globalState.mainWorker.postMessage(workerMessage);
+      } else {
+        globalState.workers[_workerId].postMessage(workerMessage);
+      }
+    });
+  }
+
+  bool operator ==(var other) {
+    return (other is _WorkerSendPort) &&
+        (_workerId == other._workerId) &&
+        (_isolateId == other._isolateId) &&
+        (_receivePortId == other._receivePortId);
+  }
+
+  int hashCode() {
+    // TODO(sigmund): use a standard hash when we get one available in corelib.
+    return (_workerId << 16) ^ (_isolateId << 8) ^ _receivePortId;
+  }
+}
+
+/** A port that buffers messages until an underlying port gets resolved. */
+class _BufferingSendPort extends _BaseSendPort implements SendPort {
+  /** Internal counter to assign unique ids to each port. */
+  static int _idCount = 0;
+
+  /** For implementing equals and hashcode. */
+  final int _id;
+
+  /** Underlying port, when resolved. */
+  SendPort _port;
+
+  /**
+   * Future of the underlying port, so that we can detect when this port can be
+   * sent on messages.
+   */
+  Future<SendPort> _futurePort;
+
+  /** Pending messages (and reply ports). */
+  List pending;
+
+  _BufferingSendPort(isolateId, this._futurePort)
+      : super(isolateId), _id = _idCount, pending = [] {
+    _idCount++;
+    _futurePort.then((p) {
+      _port = p;
+      for (final item in pending) {
+        p.send(item['message'], item['replyTo']);
+      }
+      pending = null;
+    });
+  }
+
+  _BufferingSendPort.fromPort(isolateId, this._port)
+      : super(isolateId), _id = _idCount {
+    _idCount++;
+  }
+
+  void send(var message, [SendPort replyTo]) {
+    if (_port != null) {
+      _port.send(message, replyTo);
+    } else {
+      pending.add({'message': message, 'replyTo': replyTo});
+    }
+  }
+
+  bool operator ==(var other) =>
+      other is _BufferingSendPort && _id == other._id;
+  int hashCode() => _id;
+}
+
+/** Default factory for receive ports. */
+class _ReceivePortFactory {
+
+  factory ReceivePort() {
+    return new _ReceivePortImpl();
+  }
+
+  factory ReceivePort.singleShot() {
+    return new _ReceivePortSingleShotImpl();
+  }
+}
+
+/** Implementation of a multi-use [ReceivePort] on top of JavaScript. */
+class _ReceivePortImpl implements ReceivePort {
+  int _id;
+  Function _callback;
+  static int _nextFreeId = 1;
+
+  _ReceivePortImpl()
+      : _id = _nextFreeId++ {
+    globalState.currentContext.register(_id, this);
+  }
+
+  void receive(void onMessage(var message, SendPort replyTo)) {
+    _callback = onMessage;
+  }
+
+  void close() {
+    _callback = null;
+    globalState.currentContext.unregister(_id);
+  }
+
+  SendPort toSendPort() {
+    return new _NativeJsSendPort(this, globalState.currentContext.id);
+  }
+}
+
+/** Implementation of a single-shot [ReceivePort]. */
+class _ReceivePortSingleShotImpl implements ReceivePort {
+
+  _ReceivePortSingleShotImpl() : _port = new _ReceivePortImpl() { }
+
+  void receive(void callback(var message, SendPort replyTo)) {
+    _port.receive((var message, SendPort replyTo) {
+      _port.close();
+      callback(message, replyTo);
+    });
+  }
+
+  void close() {
+    _port.close();
+  }
+
+  SendPort toSendPort() => _port.toSendPort();
+
+  final _ReceivePortImpl _port;
+}
+
+/** Wait until all ports in a message are resolved. */
+_waitForPendingPorts(var message, void callback()) {
+  final finder = new _PendingSendPortFinder();
+  finder.traverse(message);
+  Futures.wait(finder.ports).then((_) => callback());
+}
+
+
+/** Visitor that finds all unresolved [SendPort]s in a message. */
+class _PendingSendPortFinder extends _MessageTraverser {
+  List<Future<SendPort>> ports;
+  _PendingSendPortFinder() : super(), ports = [];
+
+  visitPrimitive(x) {}
+  visitNativeJsSendPort(_NativeJsSendPort port) {}
+  visitWorkerSendPort(_WorkerSendPort port) {}
+  visitReceivePort(_ReceivePortImpl port) {}
+  visitReceivePortSingleShot(_ReceivePortSingleShotImpl port) {}
+
+  visitList(List list) {
+    final visited = _getInfo(list);
+    if (visited !== null) return;
+    _attachInfo(list, true);
+    // TODO(sigmund): replace with the following: (bug #1660)
+    // list.forEach(_dispatch);
+    list.forEach((e) => _dispatch(e));
+  }
+
+  visitMap(Map map) {
+    final visited = _getInfo(map);
+    if (visited !== null) return;
+
+    _attachInfo(map, true);
+    // TODO(sigmund): replace with the following: (bug #1660)
+    // map.getValues().forEach(_dispatch);
+    map.getValues().forEach((e) => _dispatch(e));
+  }
+
+  visitBufferingSendPort(_BufferingSendPort port) {
+    if (port._port == null) {
+      ports.add(port._futurePort);
+    }
+  }
+}