Implement asBroadcast using a _MultiplexStreamController.

Implement asBroadcast using a _MultiplexStreamController.

R=floitsch@google.com

Committed: https://code.google.com/p/dart/source/detail?r=23342

[floitsch, 2013-05-29 09:39:58]

LGTM.

https://codereview.chromium.org/15673006/diff/1/sdk/lib/async/stream_controll...
File sdk/lib/async/stream_controller.dart (right):

https://codereview.chromium.org/15673006/diff/1/sdk/lib/async/stream_controll...
sdk/lib/async/stream_controller.dart:511: // TODO(lrn): Handle stacktrace.
That should be less than 5 lines of code.

https://codereview.chromium.org/15673006/diff/1/sdk/lib/async/stream_controll...
sdk/lib/async/stream_controller.dart:605: if (_isFiring || _hasPending) {
add comment when _hasPending but not _isFiring.

https://codereview.chromium.org/15673006/diff/1/sdk/lib/async/stream_impl.dart
File sdk/lib/async/stream_impl.dart (right):

https://codereview.chromium.org/15673006/diff/1/sdk/lib/async/stream_impl.dar...
sdk/lib/async/stream_impl.dart:743: void _close() {
call it _onCancel.

[Lasse Reichstein Nielsen, 2013-05-29 10:39:12]

https://codereview.chromium.org/15673006/diff/1/sdk/lib/async/stream_controll...
File sdk/lib/async/stream_controller.dart (right):

https://codereview.chromium.org/15673006/diff/1/sdk/lib/async/stream_controll...
sdk/lib/async/stream_controller.dart:511: // TODO(lrn): Handle stacktrace.
On 2013/05/29 09:39:58, floitsch wrote:
> That should be less than 5 lines of code.

Done.

https://codereview.chromium.org/15673006/diff/1/sdk/lib/async/stream_controll...
sdk/lib/async/stream_controller.dart:605: if (_isFiring || _hasPending) {
It's only during the onCancel callback after removing the last listener while
firing.
I'll just make it clear all events in that case, which is consistent with not
having any listeners. That means that during onCancel, there are never pending
events.

https://codereview.chromium.org/15673006/diff/1/sdk/lib/async/stream_impl.dart
File sdk/lib/async/stream_impl.dart (right):

https://codereview.chromium.org/15673006/diff/1/sdk/lib/async/stream_impl.dar...
sdk/lib/async/stream_impl.dart:743: void _close() {
On 2013/05/29 09:39:58, floitsch wrote:
> call it _onCancel.

Done.

[Lasse Reichstein Nielsen, 2013-05-29 10:39:45]

Committed patchset #2 manually as r23342 (presubmit successful).