Remove StreamController.broadcast.

Remove StreamController.broadcast.

Committed: https://code.google.com/p/dart/source/detail?r=21499

[floitsch, 2013-04-13 01:08:08]

Attempt to remove Stream.broadcast.
It breaks the broadcast state-tests. If necessary I can try to look into fixing
them later.

The plan is that asBroadcast has the following semantics:
first subscriber to a broadcast stream initiates the listening to the original
stream.
last subscriber cancels the subscription to the original stream.

This has one big drawback. The following wouldn't work:
stream = someOtherStream.asBroadcastStream();
stream.first.then(stream.listen(...)).
Since the first would cancel before the listen in the 'then'  starts, it would
be too late.

The current plan is to do the following:
stream = new DispatcherStream(someOtherStream);
stream.first.then(stream.listen(...));

a dispatcher stream would pause whenever it receives a cancel. It has the
potential for memory leaks if the user doesn't cancel the original stream when
errors occurred.

An alternative would be to wait with cancelling until the next asynchronous
cycle. This would give users the time to register a new event-handler. However
it would mean that some streams would continue feeding data (like a socket) even
though, they already know that they can't use it (for instance, because writing
to a file already filed).

Remember: for a stream there is no difference between cancelling due to an
error, or cancelling because of a "first" future. (or any other reason).

[Anders Johnsen, 2013-04-15 10:22:34]

LGTM

https://chromiumcodereview.appspot.com/14136004/diff/1/tools/dom/templates/ht...
File tools/dom/templates/html/impl/impl_Node.darttemplate (right):

https://chromiumcodereview.appspot.com/14136004/diff/1/tools/dom/templates/ht...
tools/dom/templates/html/impl/impl_Node.darttemplate:344: return
_modelChangedStream.stream;
.asBroadcastStream?

https://chromiumcodereview.appspot.com/14136004/diff/1/tools/dom/templates/ht...
File tools/dom/templates/html/impl/impl_Window.darttemplate (right):

https://chromiumcodereview.appspot.com/14136004/diff/1/tools/dom/templates/ht...
tools/dom/templates/html/impl/impl_Window.darttemplate:326: return
controller.stream;
.asBroadcastStream?

[floitsch, 2013-04-15 19:08:41]

Committed patchset #1 manually as r21499 (presubmit successful).

[floitsch, 2013-04-15 22:58:11]

https://chromiumcodereview.appspot.com/14136004/diff/1/tools/dom/templates/ht...
File tools/dom/templates/html/impl/impl_Node.darttemplate (right):

https://chromiumcodereview.appspot.com/14136004/diff/1/tools/dom/templates/ht...
tools/dom/templates/html/impl/impl_Node.darttemplate:344: return
_modelChangedStream.stream;
On 2013/04/15 10:22:34, Anders Johnsen wrote:
> .asBroadcastStream?

No. But this is not the correct fix...

https://chromiumcodereview.appspot.com/14136004/diff/1/tools/dom/templates/ht...
File tools/dom/templates/html/impl/impl_Window.darttemplate (right):

https://chromiumcodereview.appspot.com/14136004/diff/1/tools/dom/templates/ht...
tools/dom/templates/html/impl/impl_Window.darttemplate:326: return
controller.stream;
On 2013/04/15 10:22:34, Anders Johnsen wrote:
> .asBroadcastStream?

No. I prefer if HTML controllers are single subscription.