Revert "Unify dart:isolate."

lib/isolate/dart2js/isolateimpl.dart

+// 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.
+
+/**
+ * Concepts used here:
+ *
+ * "manager" - A manager contains one or more isolates, schedules their
+ * execution, and performs other plumbing on their behalf.  The isolate
+ * present at the creation of the manager is designated as its "root isolate".
+ * A manager may, for example, be implemented on a web Worker.
+ *
+ * [_Manager] - State present within a manager (exactly once, as a global).
+ *
+ * [_ManagerStub] - A handle held within one manager that allows interaction
+ * with another manager.  A target manager may be addressed by zero or more
+ * [_ManagerStub]s.
+ *
+ */
+
+/**
+ * A native object that is shared across isolates. This object is visible to all
+ * isolates running under the same manager (either UI or background web worker).
+ *
+ * This is code that is intended to 'escape' the isolate boundaries in order to
+ * implement the semantics of isolates in JavaScript. Without this we would have
+ * been forced to implement more code (including the top-level event loop) in
+ * JavaScript itself.
+ */
+// TODO(eub, sigmund): move the "manager" to be entirely in JS.
+// Running any Dart code outside the context of an isolate gives it
+// the change to break the isolate abstraction.
+_Manager get _globalState() native "return \$globalState;";
+set _globalState(_Manager val) native "\$globalState = val;";
+
+void _fillStatics(context) native @"""
+  $globals = context.isolateStatics;
+  $static_init();
+""";
+
+ReceivePort _lazyPort;
+ReceivePort get _port() {
+  if (_lazyPort === null) {
+    _lazyPort = new ReceivePort();
+  }
+  return _lazyPort;
+}
+
+SendPort _spawnFunction(void topLevelFunction()) {
+  final name = _IsolateNatives._getJSFunctionName(topLevelFunction);
+  if (name == null) {
+    throw new UnsupportedOperationException(
+        "only top-level functions can be spawned.");
+  }
+  return _IsolateNatives._spawn(name, null, false);
+}
+
+SendPort _spawnUri(String uri) {
+  return _IsolateNatives._spawn(null, uri, false);
+}
+
+/** State associated with the current manager. See [globalState]. */
+// TODO(sigmund): split in multiple classes: global, thread, main-worker states?
+class _Manager {
+
+  /** Next available isolate id within this [_Manager]. */
+  int nextIsolateId = 0;
+
+  /** id assigned to this [_Manager]. */
+  int currentManagerId = 0;
+
+  /**
+   * Next available manager id. Only used by the main manager to assign a unique
+   * id to each manager created by it.
+   */
+  int nextManagerId = 1;
+
+  /** Context for the currently running [Isolate]. */
+  _IsolateContext currentContext = null;
+
+  /** Context for the root [Isolate] that first run in this [_Manager]. */
+  _IsolateContext rootContext = null;
+
+  /** The top-level event loop. */
+  _EventLoop topEventLoop;
+
+  /** Whether this program is running from the command line. */
+  bool fromCommandLine;
+
+  /** Whether this [_Manager] is running as a web worker. */
+  bool isWorker;
+
+  /** Whether we support spawning web workers. */
+  bool supportsWorkers;
+
+  /**
+   * Whether to use web workers when implementing isolates. Set to false for
+   * debugging/testing.
+   */
+  bool get useWorkers() => supportsWorkers;
+
+  /**
+   * Whether to use the web-worker JSON-based message serialization protocol. By
+   * default this is only used with web workers. For debugging, you can force
+   * using this protocol by changing this field value to [true].
+   */
+  bool get needSerialization() => useWorkers;
+
+  /**
+   * Registry of isolates. Isolates must be registered if, and only if, receive
+   * ports are alive.  Normally no open receive-ports means that the isolate is
+   * dead, but DOM callbacks could resurrect it.
+   */
+  Map<int, _IsolateContext> isolates;
+
+  /** Reference to the main [_Manager].  Null in the main [_Manager] itself. */
+  _ManagerStub mainManager;
+
+  /** Registry of active [_ManagerStub]s.  Only used in the main [_Manager]. */
+  Map<int, _ManagerStub> managers;
+
+  _Manager() {
+    _nativeDetectEnvironment();
+    topEventLoop = new _EventLoop();
+    isolates = new Map<int, _IsolateContext>();
+    managers = new Map<int, _ManagerStub>();
+    if (isWorker) {  // "if we are not the main manager ourself" is the intent.
+      mainManager = new _MainManagerStub();
+      _nativeInitWorkerMessageHandler();
+    }
+  }
+
+  void _nativeDetectEnvironment() native @"""
+    this.isWorker = $isWorker;
+    this.supportsWorkers = $supportsWorkers;
+    this.fromCommandLine = typeof(window) == 'undefined';
+  """;
+
+  void _nativeInitWorkerMessageHandler() native @"""
+    $globalThis.onmessage = function (e) {
+      _IsolateNatives._processWorkerMessage(this.mainManager, e);
+    }
+  """;
+  /*: TODO: check that _processWorkerMessage is not discarded while treeshaking.
+  """ {
+    _IsolateNatives._processWorkerMessage(null, null);
+  }
+  */
+
+
+  /** Close the worker running this code if all isolates are done. */
+  void maybeCloseWorker() {
+    if (isolates.isEmpty()) {
+      mainManager.postMessage(_serializeMessage({'command': 'close'}));
+    }
+  }
+}
+
+/** Context information tracked for each isolate. */
+class _IsolateContext {
+  /** Current isolate id. */
+  int id;
+
+  /** Registry of receive ports currently active on this isolate. */
+  Map<int, ReceivePort> ports;
+
+  /** Holds isolate globals (statics and top-level properties). */
+  var isolateStatics; // native object containing all globals of an isolate.
+
+  _IsolateContext() {
+    id = _globalState.nextIsolateId++;
+    ports = new Map<int, ReceivePort>();
+    initGlobals();
+  }
+
+  // these are filled lazily the first time the isolate starts running.
+  void initGlobals() native @'$initGlobals(this);';
+
+  /**
+   * Run [code] in the context of the isolate represented by [this]. Note this
+   * is called from JavaScript (see $wrap_call in corejs.dart).
+   */
+  Dynamic eval(Function code) {
+    var old = _globalState.currentContext;
+    _globalState.currentContext = this;
+    this._setGlobals();
+    var result = null;
+    try {
+      result = code();
+    } finally {
+      _globalState.currentContext = old;
+      if (old != null) old._setGlobals();
+    }
+    return result;
+  }
+
+  void _setGlobals() native @'$setGlobals(this);';
+
+  /** Lookup a port registered for this isolate. */
+  ReceivePort lookup(int portId) => ports[portId];
+
+  /** Register a port on this isolate. */
+  void register(int portId, ReceivePort port)  {
+    if (ports.containsKey(portId)) {
+      throw new Exception("Registry: ports must be registered only once.");
+    }
+    ports[portId] = port;
+    _globalState.isolates[id] = this; // indicate this isolate is active
+  }
+
+  /** Unregister a port on this isolate. */
+  void unregister(int portId) {
+    ports.remove(portId);
+    if (ports.isEmpty()) {
+      _globalState.isolates.remove(id); // indicate this isolate is not active
+    }
+  }
+}
+
+/** Represent the event loop on a javascript thread (DOM or worker). */
+class _EventLoop {
+  Queue<_IsolateEvent> events;
+
+  _EventLoop() : events = new Queue<_IsolateEvent>();
+
+  void enqueue(isolate, fn, msg) {
+    events.addLast(new _IsolateEvent(isolate, fn, msg));
+  }
+
+  _IsolateEvent dequeue() {
+    if (events.isEmpty()) return null;
+    return events.removeFirst();
+  }
+
+  /** Process a single event, if any. */
+  bool runIteration() {
+    final event = dequeue();
+    if (event == null) {
+      if (_globalState.isWorker) {
+        _globalState.maybeCloseWorker();
+      } else if (_globalState.rootContext != null &&
+                 _globalState.isolates.containsKey(
+                     _globalState.rootContext.id) &&
+                 _globalState.fromCommandLine &&
+                 _globalState.rootContext.ports.isEmpty()) {
+        // We want to reach here only on the main [_Manager] and only
+        // on the command-line.  In the browser the isolate might
+        // still be alive due to DOM callbacks, but the presumption is
+        // that on the command-line, no future events can be injected
+        // into the event queue once it's empty.  Node has setTimeout
+        // so this presumption is incorrect there.  We think(?) that
+        // in d8 this assumption is valid.
+        throw new Exception("Program exited with open ReceivePorts.");
+      }
+      return false;
+    }
+    event.process();
+    return true;
+  }
+
+  /**
+   * Runs multiple iterations of the run-loop. If possible, each iteration is
+   * run asynchronously.
+   */
+  void _runHelper() {
+    // [_window] is defined in timer_provider.dart.
+    if (_window != null) {
+      // Run each iteration from the browser's top event loop.
+      void next() {
+        if (!runIteration()) return;
+        _window.setTimeout(next, 0);
+      }
+      next();
+    } else {
+      // Run synchronously until no more iterations are available.
+      while (runIteration()) {}
+    }
+  }
+
+  /**
+   * Call [_runHelper] but ensure that worker exceptions are propragated. Note
+   * this is called from JavaScript (see $wrap_call in corejs.dart).
+   */
+  void run() {
+    if (!_globalState.isWorker) {
+      _runHelper();
+    } else {
+      try {
+        _runHelper();
+      } catch(var e, var trace) {
+        _globalState.mainManager.postMessage(_serializeMessage(
+            {'command': 'error', 'msg': '$e\n$trace' }));
+      }
+    }
+  }
+}
+
+/** An event in the top-level event queue. */
+class _IsolateEvent {
+  _IsolateContext isolate;
+  Function fn;
+  String message;
+
+  _IsolateEvent(this.isolate, this.fn, this.message);
+
+  void process() {
+    isolate.eval(fn);
+  }
+}
+
+/** An interface for a stub used to interact with a manager. */
+interface _ManagerStub {
+  get id();
+  void set id(int i);
+  void set onmessage(Function f);
+  void postMessage(msg);
+  void terminate();
+}
+
+/** A stub for interacting with the main manager. */
+class _MainManagerStub implements _ManagerStub {
+  get id() => 0;
+  void set id(int i) { throw new NotImplementedException(); }
+  void set onmessage(f) {
+    throw new Exception("onmessage should not be set on MainManagerStub");
+  }
+  void postMessage(msg) native @"$globalThis.postMessage(msg);";
+  void terminate() {}  // Nothing useful to do here.
+}
+
+/**
+ * A stub for interacting with a manager built on a web worker. The
+ * type Worker is also defined in 'dart:dom_deprecated', but we define
+ * it here to avoid introducing a dependency from corelib to dom. This
+ * definition uses a 'hidden' type (* prefix on the native name) to
+ * enforce that the type is defined dynamically only when web workers
+ * are actually available.
+ */
+class _WorkerStub implements _ManagerStub native "*Worker" {
+  get id() native "return this.id;";
+  void set id(i) native "this.id = i;";
+  void set onmessage(f) native "this.onmessage = f;";
+  void postMessage(msg) native "return this.postMessage(msg);";
+  // terminate() is implemented by Worker.
+  abstract void terminate();
+}
+
+final String _SPAWNED_SIGNAL = "spawned";
+
+class _IsolateNatives {
+
+  /**
+   * The src url for the script tag that loaded this code. Used to create
+   * JavaScript workers.
+   */
+  static String get _thisScript() native @"return $thisScriptUrl";
+
+  /** Starts a new worker with the given URL. */
+  static _WorkerStub _newWorker(url) native "return new Worker(url);";
+
+  /**
+   * Assume that [e] is a browser message event and extract its message data.
+   * We don't import the dom explicitly so, when workers are disabled, this
+   * library can also run on top of nodejs.
+   */
+  static _getEventData(e) native "return e.data";
+
+  /**
+   * Process messages on a worker, either to control the worker instance or to
+   * pass messages along to the isolate running in the worker.
+   */
+  static void _processWorkerMessage(sender, e) {
+    var msg = _deserializeMessage(_getEventData(e));
+    switch (msg['command']) {
+      case 'start':
+        _globalState.currentManagerId = msg['id'];
+        Function entryPoint = _getJSFunctionFromName(msg['functionName']);
+        var replyTo = _deserializeMessage(msg['replyTo']);
+        _globalState.topEventLoop.enqueue(new _IsolateContext(), function() {
+          _startIsolate(entryPoint, replyTo);
+        }, 'worker-start');
+        _globalState.topEventLoop.run();
+        break;
+      case 'spawn-worker':
+        _spawnWorker(msg['functionName'], msg['uri'], msg['replyPort']);
+        break;
+      case 'message':
+        msg['port'].send(msg['msg'], msg['replyTo']);
+        _globalState.topEventLoop.run();
+        break;
+      case 'close':
+        _log("Closing Worker");
+        _globalState.managers.remove(sender.id);
+        sender.terminate();
+        _globalState.topEventLoop.run();
+        break;
+      case 'log':
+        _log(msg['msg']);
+        break;
+      case 'print':
+        if (_globalState.isWorker) {
+          _globalState.mainManager.postMessage(
+              _serializeMessage({'command': 'print', 'msg': msg}));
+        } else {
+          print(msg['msg']);
+        }
+        break;
+      case 'error':
+        throw msg['msg'];
+    }
+  }
+
+  /** Log a message, forwarding to the main [_Manager] if appropriate. */
+  static _log(msg) {
+    if (_globalState.isWorker) {
+      _globalState.mainManager.postMessage(
+          _serializeMessage({'command': 'log', 'msg': msg }));
+    } else {
+      try {
+        _consoleLog(msg);
+      } catch(var e, var trace) {
+        throw new Exception(trace);
+      }
+    }
+  }
+
+  static void _consoleLog(msg) native "\$globalThis.console.log(msg);";
+
+  /**
+   * Extract the constructor of runnable, so it can be allocated in another
+   * isolate.
+   */
+  static Dynamic _getJSConstructor(Isolate runnable) native """
+    return runnable.constructor;
+  """;
+
+  /** Extract the constructor name of a runnable */
+  // TODO(sigmund): find a browser-generic way to support this.
+  static Dynamic _getJSConstructorName(Isolate runnable) native """
+    return runnable.constructor.name;
+  """;
+
+  /** Find a constructor given its name. */
+  static Dynamic _getJSConstructorFromName(String factoryName) native """
+    return \$globalThis[factoryName];
+  """;
+
+  static Dynamic _getJSFunctionFromName(String functionName) native """
+    return \$globalThis[functionName];
+  """;
+
+  /**
+   * Get a string name for the function, if possible.  The result for
+   * anonymous functions is browser-dependent -- it may be "" or "anonymous"
+   * but you should probably not count on this.
+   */
+  static String _getJSFunctionName(Function f)
+    native @"return f.$name || (void 0);";
+
+  /** Create a new JavaScript object instance given its constructor. */
+  static Dynamic _allocate(var ctor) native "return new ctor();";
+
+  // TODO(sigmund): clean up above, after we make the new API the default:
+
+  static _spawn(String functionName, String uri, bool isLight) {
+    Completer<SendPort> completer = new Completer<SendPort>();
+    ReceivePort port = new ReceivePort();
+    port.receive((msg, SendPort replyPort) {
+      port.close();
+      assert(msg == _SPAWNED_SIGNAL);
+      completer.complete(replyPort);
+    });
+
+    SendPort signalReply = port.toSendPort();
+
+    if (_globalState.useWorkers && !isLight) {
+      _startWorker(functionName, uri, signalReply);
+    } else {
+      _startNonWorker(functionName, uri, signalReply);
+    }
+    return new _BufferingSendPort(
+        _globalState.currentContext.id, completer.future);
+  }
+
+  static SendPort _startWorker(
+      String functionName, String uri, SendPort replyPort) {
+    if (_globalState.isWorker) {
+      _globalState.mainManager.postMessage(_serializeMessage({
+          'command': 'spawn-worker',
+          'functionName': functionName,
+          'uri': uri,
+          'replyPort': replyPort}));
+    } else {
+      _spawnWorker(functionName, uri, replyPort);
+    }
+  }
+
+  static SendPort _startNonWorker(
+      String functionName, String uri, SendPort replyPort) {
+    // TODO(eub): support IE9 using an iframe -- Dart issue 1702.
+    if (uri != null) throw new UnsupportedOperationException(
+            "Currently spawnUri is not supported without web workers.");
+    _globalState.topEventLoop.enqueue(new _IsolateContext(), function() {
+      final func = _getJSFunctionFromName(functionName);
+      _startIsolate(func, replyPort);
+    }, 'nonworker start');
+  }
+
+  static void _startIsolate(Function topLevel, SendPort replyTo) {
+    _fillStatics(_globalState.currentContext);
+    _lazyPort = new ReceivePort();
+    replyTo.send(_SPAWNED_SIGNAL, port.toSendPort());
+    topLevel();
+  }
+
+  /**
+   * Spawns an isolate in a worker. [factoryName] is the Javascript constructor
+   * name for the isolate entry point class.
+   */
+  static void _spawnWorker(functionName, uri, replyPort) {
+    if (functionName == null) functionName = 'main';
+    if (uri == null) uri = _thisScript;
+    if (!(new Uri.fromString(uri).isAbsolute())) {
+      // The constructor of dom workers requires an absolute URL. If we use a
+      // relative path we will get a DOM exception.
+      String prefix = _thisScript.substring(0, _thisScript.lastIndexOf('/'));
+      uri = "$prefix/$uri";
+    }
+    final worker = _newWorker(uri);
+    worker.onmessage = (e) { _processWorkerMessage(worker, e); };
+    var workerId = _globalState.nextManagerId++;
+    // We also store the id on the worker itself so that we can unregister it.
+    worker.id = workerId;
+    _globalState.managers[workerId] = worker;
+    worker.postMessage(_serializeMessage({
+      'command': 'start',
+      'id': workerId,
+      // Note: we serialize replyPort twice because the child worker needs to
+      // first deserialize the worker id, before it can correctly deserialize
+      // the port (port deserialization is sensitive to what is the current
+      // workerId).
+      'replyTo': _serializeMessage(replyPort),
+      'functionName': functionName }));
+  }
+}