Redirect pure isolate print to helper isolate.

tools/dom/src/native_DOMImplementation.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.
 
 part of html;
 
 class _Utils {
   static double dateTimeToDouble(DateTime dateTime) =>
       dateTime.millisecondsSinceEpoch.toDouble();
   static DateTime doubleToDateTime(double dateTime) {
@@ skipping 40 matching lines @@
 
   static bool isMap(obj) => obj is Map;
 
   static Map createMap() => {};
 
   static makeUnimplementedError(String fileName, int lineNo) {
     return new UnsupportedError('[info: $fileName:$lineNo]');
   }
 
   static window() native "Utils_window";
-  static print(String message) native "Utils_print";
   static forwardingPrint(String message) native "Utils_forwardingPrint";
   static void spawnDomFunction(Function topLevelFunction, int replyTo) native "Utils_spawnDomFunction";
   static int _getNewIsolateId() native "Utils_getNewIsolateId";
   static bool shadowRootSupported(Document document) native "Utils_shadowRootSupported";
 }
 
 class _NPObject extends NativeFieldWrapperClass1 {
   _NPObject.internal();
   static _NPObject retrieve(String key) native "NPObject_retrieve";
   property(String propertyName) native "NPObject_property";
@@ skipping 53 matching lines @@
   String putIfAbsent(String key, String ifAbsent()) => Maps.putIfAbsent(this, key, ifAbsent);
   String remove(String key) native "DOMStringMap_remove_Callback";
   void clear() => Maps.clear(this);
   void forEach(void f(String key, String value)) => Maps.forEach(this, f);
   Collection<String> get keys native "DOMStringMap_getKeys_Callback";
   Collection<String> get values => Maps.getValues(this);
   int get length => Maps.length(this);
   bool get isEmpty => Maps.isEmpty(this);
 }
 
-get _printClosure => (s) {
-  try {
-    window.console.log(s);
-  } catch (_) {
-    _Utils.print(s);
-  }
+final Future<SendPort> _HELPER_ISOLATE_PORT =
+    spawnDomFunction(_helperIsolateMain);
+
+final _TIMER_REGISTRY = new Map<SendPort, Timer>();
+
+const _NEW_TIMER = 'NEW_TIMER';
+const _CANCEL_TIMER = 'CANCEL_TIMER';
+const _TIMER_PING = 'TIMER_PING';
+const _PRINT = 'PRINT';
+
+_helperIsolateMain() {
+  port.receive((msg, replyTo) {
+    final cmd = msg[0];
+    if (cmd == _NEW_TIMER) {
+      final duration = new Duration(milliseconds: msg[1]);
+      bool periodic = msg[2];
+      final callback = () { replyTo.send(_TIMER_PING); };
+      _TIMER_REGISTRY[replyTo] = periodic ?
+          new Timer.periodic(duration, callback) :
+          new Timer(duration, callback);
+    } else if (cmd == _CANCEL_TIMER) {
+      _TIMER_REGISTRY.remove(replyTo).cancel();
+    } else if (cmd == _PRINT) {
+      final message = msg[1];
+      // TODO(antonm): we need somehow identify those isolates.
+      print('[From isolate] $message');

[vsm, 2013/03/29 14:14:54]

We have the id we're using for interop (_Utils._getNewIsolateId) ... if that
works on background isolates.

Do you know if workers print any ID?  That is what dart2js isolates should be
mapping to. 

[Anton Muhin, 2013/03/29 16:14:33]

Sorry, no, I do not immediately now.  Ideally we should probably print something
like root library url and some unique id.

On 2013/03/29 14:14:54, vsm wrote:

+    }
+  });
+}
+
+final _printClosure = window.console.log;

[vsm, 2013/03/29 14:14:54]

Is there a way at the Dart-level to programmatically tell whether I'm on a DOM
isolate (without a try-catch)?  Could use a pattern like:

final _printClosure = _hasDomAccess ? window.console.log :
_pureIsolatePrintClosure;

instead of wiring up in c++.

[Anton Muhin, 2013/03/29 16:14:33]

Not right now.  We can expose it via Utils, but I am not sure if it's worth it
or not.

On 2013/03/29 14:14:54, vsm wrote:

+final _pureIsolatePrintClosure = (s) {
+  _HELPER_ISOLATE_PORT.then((sendPort) {
+    sendPort.send([_PRINT, s]);
+  });
 };
 
 final _forwardingPrintClosure = _Utils.forwardingPrint;