Elimiteted race condition in the AudioMixer.

Elimiteted race condition in the AudioMixer.

The mixer allocates an audio frame for each added data source. This
audio frame was deallocated when a source was removed from the
mixer. Source removal could happen during the mixing, and the existing
locking scheme (and the Clang thread checker) was not sufficient to
prevent a data race.

After this change, the mixer doesn't release its lock until it is
finished with the sources' Audio frames. Since multi-threaded access to
the mixer only happens when a source is added or removed, we believe
that this change wouldn't have any noticeable performance impact.

NOTRY=True

BUG=webrtc:6346
Committed: https://crrev.com/1655e45d85be0ecbf172115031bdbbc88a65c1b2
Cr-Commit-Position: refs/heads/master@{#14744}

[aleloi, 2016-10-24 09:40:53]

Patchset #1 (id:1) has been deleted

[aleloi, 2016-10-24 09:41:26]

aleloi@webrtc.org changed reviewers:
+ ivoc@webrtc.org

[aleloi, 2016-10-24 09:41:26]

Please take a look!

[aleloi, 2016-10-24 10:44:21]

Description was changed from

==========
Elimiteted race condition in the AudioMixer.

The mixer allocates an audio frame for each added data source. This
audio frame was deallocated when a source was removed from the
mixer. Source removal could happen during the mixing, and the existing
locking scheme (and the Clang thread checker) was not sufficient to
prevent a data race.

This change avoids holding more locks and instead delays frame
deallocation until the end of a mixing iteration, thus preventing access
of a deleted pointer.

BUG=webrtc:6346
==========

to

==========
Elimiteted race condition in the AudioMixer.

The mixer allocates an audio frame for each added data source. This
audio frame was deallocated when a source was removed from the
mixer. Source removal could happen during the mixing, and the existing
locking scheme (and the Clang thread checker) was not sufficient to
prevent a data race.

After this change, the mixer doesn't release its lock until it is
finished with the sources' Audio frames. Since multi-threaded access to
the mixer only happens when a source is added or removed, we believe 
that this change wouldn't have any noticeable performance impact.

BUG=webrtc:6346
==========

[ivoc, 2016-10-24 11:03:30]

Nice, lgtm!

[aleloi, 2016-10-24 11:18:01]

Description was changed from

==========
Elimiteted race condition in the AudioMixer.

The mixer allocates an audio frame for each added data source. This
audio frame was deallocated when a source was removed from the
mixer. Source removal could happen during the mixing, and the existing
locking scheme (and the Clang thread checker) was not sufficient to
prevent a data race.

After this change, the mixer doesn't release its lock until it is
finished with the sources' Audio frames. Since multi-threaded access to
the mixer only happens when a source is added or removed, we believe 
that this change wouldn't have any noticeable performance impact.

BUG=webrtc:6346
==========

to

==========
Elimiteted race condition in the AudioMixer.

The mixer allocates an audio frame for each added data source. This
audio frame was deallocated when a source was removed from the
mixer. Source removal could happen during the mixing, and the existing
locking scheme (and the Clang thread checker) was not sufficient to
prevent a data race.

After this change, the mixer doesn't release its lock until it is
finished with the sources' Audio frames. Since multi-threaded access to
the mixer only happens when a source is added or removed, we believe 
that this change wouldn't have any noticeable performance impact.

NOTRY=True

BUG=webrtc:6346
==========

[aleloi, 2016-10-24 13:54:57]

The CQ bit was checked by aleloi@webrtc.org

[commit-bot: I haz the power, 2016-10-24 13:55:05]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.webrtc.org/...

[commit-bot: I haz the power, 2016-10-24 13:56:59]

Description was changed from

==========
Elimiteted race condition in the AudioMixer.

The mixer allocates an audio frame for each added data source. This
audio frame was deallocated when a source was removed from the
mixer. Source removal could happen during the mixing, and the existing
locking scheme (and the Clang thread checker) was not sufficient to
prevent a data race.

After this change, the mixer doesn't release its lock until it is
finished with the sources' Audio frames. Since multi-threaded access to
the mixer only happens when a source is added or removed, we believe 
that this change wouldn't have any noticeable performance impact.

NOTRY=True

BUG=webrtc:6346
==========

to

==========
Elimiteted race condition in the AudioMixer.

The mixer allocates an audio frame for each added data source. This
audio frame was deallocated when a source was removed from the
mixer. Source removal could happen during the mixing, and the existing
locking scheme (and the Clang thread checker) was not sufficient to
prevent a data race.

After this change, the mixer doesn't release its lock until it is
finished with the sources' Audio frames. Since multi-threaded access to
the mixer only happens when a source is added or removed, we believe 
that this change wouldn't have any noticeable performance impact.

NOTRY=True

BUG=webrtc:6346
==========

[commit-bot: I haz the power, 2016-10-24 13:57:00]

Committed patchset #2 (id:40001)

[commit-bot: I haz the power, 2016-10-24 13:57:10]

Description was changed from

==========
Elimiteted race condition in the AudioMixer.

The mixer allocates an audio frame for each added data source. This
audio frame was deallocated when a source was removed from the
mixer. Source removal could happen during the mixing, and the existing
locking scheme (and the Clang thread checker) was not sufficient to
prevent a data race.

After this change, the mixer doesn't release its lock until it is
finished with the sources' Audio frames. Since multi-threaded access to
the mixer only happens when a source is added or removed, we believe 
that this change wouldn't have any noticeable performance impact.

NOTRY=True

BUG=webrtc:6346
==========

to

==========
Elimiteted race condition in the AudioMixer.

The mixer allocates an audio frame for each added data source. This
audio frame was deallocated when a source was removed from the
mixer. Source removal could happen during the mixing, and the existing
locking scheme (and the Clang thread checker) was not sufficient to
prevent a data race.

After this change, the mixer doesn't release its lock until it is
finished with the sources' Audio frames. Since multi-threaded access to
the mixer only happens when a source is added or removed, we believe
that this change wouldn't have any noticeable performance impact.

NOTRY=True

BUG=webrtc:6346

Committed: https://crrev.com/1655e45d85be0ecbf172115031bdbbc88a65c1b2
Cr-Commit-Position: refs/heads/master@{#14744}
==========

[commit-bot: I haz the power, 2016-10-24 13:57:11]

Patchset 2 (id:??) landed as
https://crrev.com/1655e45d85be0ecbf172115031bdbbc88a65c1b2
Cr-Commit-Position: refs/heads/master@{#14744}