Add first version of runAsync.

sdk/lib/async/event_loop.dart

Index: sdk/lib/async/event_loop.dart
diff --git a/sdk/lib/async/event_loop.dart b/sdk/lib/async/event_loop.dart
new file mode 100644
index 0000000000000000000000000000000000000000..9bd552631c7bbfe62458ab188cd06b1468cc47eb
--- /dev/null
+++ b/sdk/lib/async/event_loop.dart
@@ -0,0 +1,54 @@
+// Copyright (c) 2013, 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 dart.async;
+
+typedef void _AsyncCallback();
+
+bool _callbacksAreEnqueued = false;
+List<_AsyncCallback> _asyncCallbacks = <_AsyncCallback>[];
+
+void _asyncRunCallback() {
+  // As long as we are iterating over the registered callbacks we don't
+  // unset the [_callbacksAreEnqueued] boolean.
+  while (!_asyncCallbacks.isEmpty) {
+    List callbacks = _asyncCallbacks;
+    // Create a new list, to avoid that the we grow too much if the callbacks
+    // add new callbacks themselves.
+    _asyncCallbacks = <_AsyncCallback>[];
+    for (int i = 0; i < callbacks.length; i++) {
+      Function callback = callbacks[i];
+      callbacks[i] = null;
+      try {
+        callback();
+      } catch (e) {
+        List remainingCallbacks =
+            _asyncCallbacks.getRange(i + 1, _asyncCallbacks.length - i + 1);
+        List newCallbacks = _asyncCallbacks;
+        _asyncCallbacks = [];
+        _asyncCallbacks.addAll(remainingCallbacks);
+        _asyncCallbacks.addAll(newCallbacks);
+        _AsyncRun._enqueueImmediate(_asyncRunCallback);
+        throw;
+      }
+    }
+  }
+  // Any new callback must register a callback function now.
+  _callbacksAreEnqueued = false;
+}
+
+void runAsync(void callback()) {
+  // Optimizing a group of Timer.run callbacks to be executed in the
+  // same Timer callback.
+  _asyncCallbacks.add(callback);
+  if (!_callbacksAreEnqueued) {
+    _AsyncRun._enqueueImmediate(_asyncRunCallback);
+    _callbacksAreEnqueued = true;
+  }
+}
+
+class _AsyncRun {

[floitsch, 2013/03/01 14:08:21]

Without the class the VM won't find the external function.

[floitsch, 2013/03/08 20:04:40]

Debugged with Ivan. For now the class is necessary.

+  /** Enqueues the given callback before any other event in the event-loop. */
+  external static void _enqueueImmediate(void callback());
+}