Implement scheduleImmediate for the VM.

runtime/lib/isolate_patch.dart

Index: runtime/lib/isolate_patch.dart
diff --git a/runtime/lib/isolate_patch.dart b/runtime/lib/isolate_patch.dart
index 46e4f4039fb0280e74acec775d4b2dd9a71c2e31..b8c01663d6b82f50363f871b673fc91bba43029b 100644
--- a/runtime/lib/isolate_patch.dart
+++ b/runtime/lib/isolate_patch.dart
@@ -57,6 +57,15 @@ class _ReceivePortImpl extends Stream implements ReceivePort {
   StreamController _controller;
 }
 
+var _pendingImmediateCallback;

[floitsch, 2013/11/20 19:37:13]

Not yet typed. Will do that.

[floitsch, 2013/11/21 17:39:47]

Done.

+void _isolateScheduleImmediate(void callback()) {
+  assert(_pendingImmediateCallback == null);
+  _pendingImmediateCallback = callback;
+}
+Function _getIsolateScheduleImmediateClosure() {

[floitsch, 2013/11/20 19:37:13]

ditto.

[floitsch, 2013/11/21 17:39:47]

In the end didn't type it. It's only used for the embedder and I didn't want to
add yet another typedef.

+  return _isolateScheduleImmediate;
+}
+
 class _RawReceivePortImpl implements RawReceivePort {
   factory _RawReceivePortImpl() native "RawReceivePortImpl_factory";
 
@@ -92,7 +101,15 @@ class _RawReceivePortImpl implements RawReceivePort {
   static void _handleMessage(
       _RawReceivePortImpl port, int replyId, var message) {
     assert(port != null);
+    // TODO(floitsch): this relies on the fact that any exception aborts the
+    // VM. Once we have non-fatal global exceptions we need to catch errors
+    // so that we can run the immediate callbacks.
     port._handler(message);
+    if (_pendingImmediateCallback != null) {
+      var callback = _pendingImmediateCallback;
+      _pendingImmediateCallback = null;
+      callback();
+    }
   }
 
   // Call into the VM to close the VM maintained mappings.