[webkit-reviews] review granted: [Bug 230623] MediaStream canvas.captureStream() playback to LocalSampleBufferDisplayLayer is flaky : [Attachment 449663] Patch

[bugzilla-daemon at webkit.org]

Kimmo Kinnunen <kkinnunen at apple.com> has granted  review:
Bug 230623: MediaStream canvas.captureStream() playback to
LocalSampleBufferDisplayLayer is flaky
https://bugs.webkit.org/show_bug.cgi?id=230623

Attachment 449663: Patch

https://bugs.webkit.org/attachment.cgi?id=449663&action=review




--- Comment #8 from Kimmo Kinnunen <kkinnunen at apple.com> ---
Comment on attachment 449663
  --> https://bugs.webkit.org/attachment.cgi?id=449663
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=449663&action=review

It is a step forward for the users, which is good.
The reenqueue logic is broken in many ways and not very good pattern for
correct software and the class has numerous race conditions. We should spend
some more time writing tests and fixing those for this class, at some point.

>
Source/WebCore/platform/graphics/avfoundation/objc/MediaPlayerPrivateMediaStrea
mAVFObjC.mm:284
> +    Locker locker { AdoptLock, m_currentVideoSampleLock };

This is like saying  "Try to send the sample. if it's a bit inconvenient, maybe
you can just skip sending it."
Either the sample is needed for correct operation and send it or it's not
needed and it should not be sent.
This  especially  does not make sense in this "reenqueue" phase. 
So you can consider using unconditional locking.