Doing it any other way is totally insane. Once bug 1136873 lands I think we can fix things up so that this invariant holds.

We assert in CheckInDecodeComplete as well for good measure, since that's the last caller of SetState that doesn't already assert it.

Comment on attachment 8582861 [details] [diff] [review] Part 2 - Make MDSM::StartBuffering happen on the state machine thread. v1 Review of attachment 8582861 [details] [diff] [review]: ----------------------------------------------------------------- ::: dom/media/MediaDecoder.cpp @@ +1498,5 @@ > if (mResource) { > mResource->Resume(); > } > if (aForceBuffering) { > ReentrantMonitorAutoEnter mon(GetReentrantMonitor()); Do we still need this monitor? We should be able to read/write |mDecoderStateMachine| on the main thread without the monitor. @@ +1502,5 @@ > ReentrantMonitorAutoEnter mon(GetReentrantMonitor()); > if (mDecoderStateMachine) { > + RefPtr<nsRunnable> r = > + NS_NewRunnableMethod(mDecoderStateMachine, &MediaDecoderStateMachine::StartBuffering); > + mDecoderStateMachine->TaskQueue()->Dispatch(r.forget()); I would prefer to do the dispatch inside StartBuffering() to hide the details about threading model employed by MDSM. As far as MediaDecoder can see, MediaDecoderStateMachine::StartBuffering() should be a thread-safe function.

Comment on attachment 8582862 [details] [diff] [review] Part 3 - Assert state machine thread for SetState. v1 In general, feel free to do a drive-by r+ on state machine patches. :-)

Per jww's suggestion.

Comment on attachment 8582898 [details] [diff] [review] Part 4 - Dispatch all audiosink notifications asynchronously. v1 Review of attachment 8582898 [details] [diff] [review]: ----------------------------------------------------------------- LGTM. Btw, MediaDecoder::UpdatePlaybackOffset() can now assert instead of acquiring the monitor. Stricter check makes it less likely to go unexpected.

So I did a try push of all of these patches: https://treeherder.mozilla.org/#/jobs?repo=try&revision=d40c2e06cd66 There was one failure in test_loop.html, which I confirmed to be caused by the topmost patch: https://treeherder.mozilla.org/#/jobs?repo=try&revision=5b1b04b6ad68 https://treeherder.mozilla.org/#/jobs?repo=try&revision=855887ee7041 I split the topmost patch out into bug 1148571, and am going to push the rest of the patches here.

(the topmost patch was an extra "nice to have" suggestion by jww, and not really intrinsic to this bug to begin with)

remote: https://hg.mozilla.org/integration/mozilla-inbound/rev/18af605c42d2 remote: https://hg.mozilla.org/integration/mozilla-inbound/rev/954ec67d86f4 remote: https://hg.mozilla.org/integration/mozilla-inbound/rev/e5c5a0f31dbe

https://hg.mozilla.org/mozilla-central/rev/18af605c42d2 https://hg.mozilla.org/mozilla-central/rev/954ec67d86f4 https://hg.mozilla.org/mozilla-central/rev/e5c5a0f31dbe