1081766 - clean up MediaSourceReader/TrackBuffer shutdown a bit

Status: RESOLVED FIXED

(Core :: Audio/Video, defect)

Description

[Karl Tomlinson (:karlt)]

TrackBuffer::Shutdown() is run from MediaSourceReader::Shutdown(), while the
MDStateMachine shuts down its mDecodeTaskQueue.

MediaSourceReader::BreakCycles() later runs on the main thread from
MDStateMachine's nsDecoderDisposeEvent.
It tries to call BreakCycles on each TrackBuffer, but mTrackBuffers is already
empty from Shutdown.

TrackBuffer::BreakCycles() would try to call BreakCycles on
mDecoders[i]->GetReader(), but mDecoders is already empty from Shutdown().

Comment 1

[Karl Tomlinson (:karlt)]

Attachment: clear audio/video track/reader only once

Clearing tracks after Shutdown of TrackBuffers means they are cleared
after any more can be added.

Comment 2

[Karl Tomlinson (:karlt)]

Attachment: don't clear mTrackBuffers in Shutdown so that BreakCycles can recurse

Comment 3

[Karl Tomlinson (:karlt)]

Attachment: clear mInitializedDecoders and mParentDecoder only once

Comment 4

[Karl Tomlinson (:karlt)]

Attachment: don't clear mDecoders in TrackBuffer::Shutdown so that BreakCycles can recurse

Comment 5

[Karl Tomlinson (:karlt)]

Attachment: clear mDecoders in BreakCycles to save dispatching another task

Comment 6

[Karl Tomlinson (:karlt)]

I don't know of real problems fixed in these patches.  They provide that BreakCycles will run on the readers, make it clearer what happens when, and simplify the code a little.

Comment 7

[Karl Tomlinson (:karlt)]

https://hg.mozilla.org/integration/mozilla-inbound/rev/a5eca3f1dee8
https://hg.mozilla.org/integration/mozilla-inbound/rev/3a3d2d09ccca
https://hg.mozilla.org/integration/mozilla-inbound/rev/bfd5484930fd
https://hg.mozilla.org/integration/mozilla-inbound/rev/e4e161c1604f
https://hg.mozilla.org/integration/mozilla-inbound/rev/100285c306d0

Comment 8

[Carsten Book [:Tomcat]]

https://hg.mozilla.org/mozilla-central/rev/a5eca3f1dee8
https://hg.mozilla.org/mozilla-central/rev/3a3d2d09ccca
https://hg.mozilla.org/mozilla-central/rev/bfd5484930fd
https://hg.mozilla.org/mozilla-central/rev/e4e161c1604f
https://hg.mozilla.org/mozilla-central/rev/100285c306d0