Support globals in frog isolates.

frog/lib/isolate.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.
 
 /**
  * A native object that is shared across isolates. This object is visible to all
  * isolates running on the same worker (either UI or background web worker).
  *
  * This is code that is intended to 'escape' the isolate boundaries in order to
  * implement the semantics of friendly isolates in JavaScript. Without this we
  * would have been forced to implement more code (including the top-level event
  * loop) in JavaScript itself.
  */
 GlobalState get _globalState() native "return \$globalState;";
 set _globalState(GlobalState val) native "\$globalState = val;";
 
 /**
  * Wrapper that takes the dart entry point and runs it within an isolate. The
- * frog compiler will inject a call of the form [: startAsIsolate(main); :] when
- * it determines that this wrapping is needed. For single-isolate applications
- * (e.g. hello world), this call is not emited.
+ * frog compiler will inject a call of the form [: startRootIsolate(main); :]
+ * when it determines that this wrapping is needed. For single-isolate
+ * applications (e.g. hello world), this call is not emitted.
  */
-void startAsIsolate(entry) {
+void startRootIsolate(entry) {
   _globalState = new GlobalState();
 
   // Don't start the main loop again, if we are in a worker.
-  if (_globalState.inWorker) return;
-  final entryIsolate = new IsolateContext();
-  _globalState.rootIsolate = entryIsolate;
+  if (_globalState.isWorker) return;
+  final rootContext = new IsolateContext();
+  _globalState.rootContext = rootContext;
+  _fillStatics(rootContext);
 
-  // BUG(5151491): Setting _thisISolate should not be necessary, but because
-  // closures passed to the DOM as event handlers do not bind their isolate
-  // automatically we try to give them a reasonable context to live in by having
-  // a "default" isolate (the first one created).
-  _globalState.currentIsolate = entryIsolate;
+  // BUG(5151491): Setting currentContext should not be necessary, but
+  // because closures passed to the DOM as event handlers do not bind their
+  // isolate automatically we try to give them a reasonable context to live in
+  // by having a "default" isolate (the first one created).
+  _globalState.currentContext = rootContext;
 
-  entryIsolate.eval(entry);
+  rootContext.eval(entry);
   _globalState.topEventLoop.run();
 }
 
+void _fillStatics(context) native @"""
+  $globals = context.isolateStatics;
+  $static_init();
+""";
+
 /** Global state associated with the current worker. See [_globalState]. */
+// TODO(sigmund): split in multiple classes: global, thread, main-worker states?
 class GlobalState {
 
   /** Next available isolate id. */
   int nextIsolateId = 0;
 
   /** Worker id associated with this worker. */
   int currentWorkerId = 0;
 
   /**
    * Next available worker id. Only used by the main worker to assign a unique
    * id to each worker created by it.
    */
   int nextWorkerId = 1;
 
   /** Context for the currently running [Isolate]. */
-  IsolateContext currentIsolate = null;
+  IsolateContext currentContext = null;
 
   /** Context for the root [Isolate] that first run in this worker. */
-  IsolateContext rootIsolate = null;
+  IsolateContext rootContext = null;
 
   /** The top-level event loop. */
   EventLoop topEventLoop;
 
   /** Whether this program is running in a background worker. */
-  bool inWorker;
+  bool isWorker;
 
   /** Whether this program is running in a UI worker. */
   bool inWindow;
 
   /** Whether we support spawning 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,
-   * even if not using web workers. Set to true to always use the web-worker
-   * JSON-based message serialization protocol, e.g. for testing purposes.
+   * 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 useWorkerSerializationProtocol() => useWorkers;
+  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 worker. */
   MainWorker mainWorker;
 
   /** Registry of active workers. Only used in the main worker. */
   Map<int, var> workers;
 
   GlobalState() {
     topEventLoop = new EventLoop();
     isolates = {};
     workers = {};
     mainWorker = new MainWorker();
     _nativeInit();
   }
 
   void _nativeInit() native @"""
-    this.inWorker = typeof ($globalThis['importScripts']) != 'undefined';
+    this.isWorker = typeof ($globalThis['importScripts']) != 'undefined';
     this.inWindow = typeof(window) !== 'undefined';
-    this.supportsWorkers = this.inWorker ||
+    this.supportsWorkers = this.isWorker ||
         ((typeof $globalThis['Worker']) != 'undefined');
 
     // if workers are supported, treat this as a main worker:
     if (this.supportsWorkers) {
       $globalThis.onmessage = function(e) {
         IsolateNatives._processWorkerMessage(this.mainWorker, e);
       };
     }
   """;
 
   /**
    * Close the worker running this code, called when there is nothing else to
    * run.
    */
   void closeWorker() {
-    if (inWorker) {
+    if (isWorker) {
       if (!isolates.isEmpty()) return;
       mainWorker.postMessage(
           _serializeMessage({'command': 'close'}));
-    } else if (isolates.containsKey(rootIsolate.id) && workers.isEmpty() &&
+    } else if (isolates.containsKey(rootContext.id) && workers.isEmpty() &&
                !supportsWorkers && !inWindow) {
       // This should only trigger when running on the command-line.
       // We don't want this check to execute in the browser where the isolate
       // might still be alive due to DOM callbacks.
       throw new Exception("Program exited with open ReceivePorts.");
     }
   }
 }
 
 _serializeMessage(message) {
-  if (_globalState.useWorkerSerializationProtocol) {
+  if (_globalState.needSerialization) {
     return new Serializer().traverse(message);
   } else {
     return new Copier().traverse(message);
   }
 }
 
 _deserializeMessage(message) {
-  if (_globalState.useWorkerSerializationProtocol) {
+  if (_globalState.needSerialization) {
     return new Deserializer().deserialize(message);
   } else {
     // Nothing more to do.
     return message;
   }
 }
 
 /** Default worker. */
 class MainWorker {
   int id = 0;
@@ skipping 10 matching lines @@
 
   /** Holds isolate globals (statics and top-level properties). */
   var isolateStatics; // native object containing all globals of an isolate.
 
   IsolateContext() {
     id = _globalState.nextIsolateId++;
     ports = {};
     initGlobals();
   }
 
-  // TODO(sigmund): actually do the initialization too.
-  void initGlobals() native "this.isolateStatics = {};";
+  // these are filled lazily the first time the isolate starts running.
+  void initGlobals() native 'this.isolateStatics = {};';
 
   /**
    * Run [code] in the context of the isolate represented by [this]. Note this
    * is marked as native because it is called from JavaScript (see $wrap_call in
    * corejs.dart).
    */
   void eval(Function code) native {
-    var old = _globalState.currentIsolate;
-    _globalState.currentIsolate = this;
+    var old = _globalState.currentContext;
+    _globalState.currentContext = this;
+    this._setGlobals();
     var result = null;
     try {
       result = code();
     } finally {
-      _globalState.currentIsolate = old;
+      _globalState.currentContext = old;
+      old._setGlobals();
     }
     return result;
   }
 
+  void _setGlobals() native @'$globals = this.isolateStatics;';
+
   /** Lookup a port registered for this isolate. */
   ReceivePort lookup(int id) => ports[id];
 
   /** 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
@@ skipping 28 matching lines @@
     final event = dequeue();
     if (event == null) {
       _globalState.closeWorker();
       return false;
     }
     event.process();
     return true;
   }
 
   /** Function equivalent to [:window.setTimeout:] when available, or null. */
-  static Function _platformDefer() native """
+  static Function _wrapSetTimeout() native """
       return typeof window != 'undefined' ?
           function(a, b) { window.setTimeout(a, b); } : undefined;
   """;
 
   /** 
    * Runs multiple iterations of the run-loop. If possible, each iteration is
    * run asynchronously.
    */
   void _runHelper() {
-    final setTimeout = _platformDefer();
+    final setTimeout = _wrapSetTimeout();
     if (setTimeout != null) {
       // Run each iteration from the browser's top event loop.
       void next() {
         if (!runIteration()) return;
         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 marked as native because it is called from JavaScript (see
    * $wrap_call in corejs.dart).
    */
   void run() native {
-    if (!_globalState.inWorker) {
+    if (!_globalState.isWorker) {
       _runHelper();
     } else {
       try {
         _runHelper();
       } catch(e) {
         // TODO(floitsch): try to send stack-trace to the other side.
         _globalState.mainWorker.postMessage(_serializeMessage(
             {'command': 'error', 'msg': "" + e }));
       }
     }
@@ skipping 66 matching lines @@
 
   factory ReceivePort.singleShot() {
     return new ReceivePortSingleShotImpl();
   }
 }
 
 /** Implementation of a multi-use [ReceivePort] on top of JavaScript. */
 class ReceivePortImpl implements ReceivePort {
   ReceivePortImpl()
       : _id = _nextFreeId++ {
-    _globalState.currentIsolate.register(_id, this);
+    _globalState.currentContext.register(_id, this);
   }
 
   void receive(void onMessage(var message, SendPort replyTo)) {
     _callback = onMessage;
   }
 
   void close() {
     _callback = null;
-    _globalState.currentIsolate.unregister(_id);
+    _globalState.currentContext.unregister(_id);
   }
 
   /**
    * Returns a fresh [SendPort]. The implementation is not allowed to cache
    * existing ports.
    */
   SendPort toSendPort() {
     return new SendPortImpl(
-        _globalState.currentWorkerId, _globalState.currentIsolate.id, _id);
+        _globalState.currentWorkerId, _globalState.currentContext.id, _id);
   }
 
   int _id;
   Function _callback;
 
   static int _nextFreeId = 1;
 }
 
 /** Implementation of a single-shot [ReceivePort]. */
 class ReceivePortSingleShotImpl implements ReceivePort {
@@ skipping 35 matching lines @@
       _startWorker(isolate, port.toSendPort());
     } else {
       _startNonWorker(isolate, port.toSendPort());
     }
 
     return completer.future;
   }
 
   static SendPort _startWorker(Isolate runnable, SendPort replyPort) {
     var factoryName = _getJSConstructorName(runnable);
-    if (_globalState.inWorker) {
+    if (_globalState.isWorker) {
       _globalState.mainWorker.postMessage(_serializeMessage({
           'command': 'spawn-worker',
           'factoryName': factoryName,
           'replyPort': replyPort}));
     } else {
       _spawnWorker(factoryName, _serializeMessage(replyPort));
     }
   }
 
 
   /**
    * The src url for the script tag that loaded this code. Used to create
    * JavaScript workers.
    */
   static String get _thisScript() =>
       _thisScriptCache != null ? _thisScriptCache : _computeThisScript();
 
   static String _thisScriptCache;
 
   // TODO(sigmund): fix - this code should be run synchronously when loading the
   // script. Running lazily on DOMContentLoaded will yield incorrect results.
   static String _computeThisScript() native @"""
-    if (!$globalState.supportsWorkers || $globalState.inWorker) return null;
+    if (!$globalState.supportsWorkers || $globalState.isWorker) return null;
 
     // TODO(5334778): Find a cross-platform non-brittle way of getting the
     // currently running script.
     var scripts = document.getElementsByTagName('script');
     // The scripts variable only contains the scripts that have already been
     // executed. The last one is the currently running script.
     var script = scripts[scripts.length - 1];
-    var src = script.src;
+    var src = script && script.src;

[Siggi Cherem (dart-lang), 2011/11/18 01:28:10]

this was unrelated to this CL, but something that will unblock a user.

     if (!src) {
       // TODO()
       src = "FIXME:5407062" + "_" + Math.random().toString();
-      script.src = src;
+      if (script) script.src = src;
     }
     IsolateNatives._thisScriptCache = src;
     return src;
   """;
 
   /** Starts a new worker with the given URL. */
   static void _newWorker(url) native "return new Worker(url)";
 
   /** 
    * Spawns an isolate in a worker. [factoryName] is the Javascript constructor
@@ skipping 46 matching lines @@
       case 'close':
         _log("Closing Worker");
         _globalState.workers.remove(sender.id);
         sender.terminate();
         _globalState.topEventLoop.run();
         break;
       case 'log':
         _log(msg['msg']);
         break;
       case 'print':
-        if (_globalState.inWorker) {
+        if (_globalState.isWorker) {
           _globalState.mainWorker.postMessage(
               _serializeMessage({'command': 'print', 'msg': msg}));
         } else {
           print(msg['msg']);
         }
         break;
       case 'error':
         throw msg['msg'];
         break;
     }
   }
 
   /** Log a message, forwarding to the main worker if appropriate. */
   static _log(msg) {
-    if (_globalState.inWorker) {
+    if (_globalState.isWorker) {
       _globalState.mainWorker.postMessage(
           _serializeMessage({'command': 'log', 'msg': msg }));
     } else {
       try {
         _consoleLog(msg);
       } catch(e, trace) {
         throw new Exception(trace);
       }
     }
   }
@@ skipping 33 matching lines @@
     // isolate. This way, we do not get cross-isolate references
     // through the runnable.
     final ctor = _getJSConstructor(runnable);
     _globalState.topEventLoop.enqueue(spawned, function() {
       _startIsolate(_allocate(ctor), replyTo);
     }, 'nonworker start');
   }
 
   /** Given a ready-to-start runnable, start running it. */
   static void _startIsolate(Isolate isolate, SendPort replyTo) {
+    _fillStatics(_globalState.currentContext);
     ReceivePort port = new ReceivePort();
     replyTo.send(_SPAWNED_SIGNAL, port.toSendPort());
     isolate._run(port);
   }
 
   static void _sendMessage(int workerId, int isolateId, int receivePortId,
       message, replyTo) {
     // Both the message and the replyTo are already serialized.
     if (workerId == _globalState.currentWorkerId) {
       var isolate = _globalState.isolates[isolateId];
       if (isolate == null) return;  // Isolate has been closed.
       var receivePort = isolate.lookup(receivePortId);
       if (receivePort == null) return;  // ReceivePort has been closed.
       _globalState.topEventLoop.enqueue(isolate, () {
         if (receivePort._callback != null) {
           receivePort._callback(
             _deserializeMessage(message), _deserializeMessage(replyTo));
         }
       }, 'receive ' + message);
     } else {
       var worker;
       // communication between workers go through the main worker
-      if (_globalState.inWorker) {
+      if (_globalState.isWorker) {
         worker = _globalState.mainWorker;
       } else {
         // TODO(sigmund): make sure this works
         worker = _globalState.workers[workerId];
       }
       worker.postMessage(_serializeMessage({
           'command': 'message',
           'workerId': workerId,
           'isolateId': isolateId,
           'portId': receivePortId,
           'msg': message,
           'replyTo': replyTo }));
     }
   }
 }