Files
sdk/tests/lib_2/async
Lasse R.H. Nielsen a15025fc85 Harden StreamIterator against out-of-order events.
Users have seen event being sent *during* the `listen` call
to the underlying stream. This caught the `StreamIterator`
in an unanticipated state (subscription wasn't available yet).

Sending events during a `listen` call can currently happen
using a synchronous broadcast stream controller adding
events in the `onListen` callback.
That should be fixed so that broadcast stream subscriptions
are treated as paused during the `onListen` call like
single-subscription streams already are.

This change hardens the class against that particular malpratice,
but it's still possible to get into inconsistent states if the
`listen` call somehow manages to call back into the same
stream-iterator again. So, don't do that.

(The class also assumes that no stream will send events/call callbacks
* while paused.
* after cancelling
* after a done event
* while delivering another event.

If a stream does so, things will still crash.
It is believed that no platform stream will do any of these.)

Fixes #43779.
BUG= http://dartbug.com/43779

Change-Id: If47065cfa9a1115425fdf51b147f2ed7154fef99
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/167800
Reviewed-by: Nate Bosch <nbosch@google.com>
Reviewed-by: Lasse R.H. Nielsen <lrn@google.com>
Commit-Queue: Lasse R.H. Nielsen <lrn@google.com>
2020-10-16 20:20:02 +00:00
..
2020-02-15 02:40:00 +00:00