Make changing a record's type an atomic operation.

Make changing a record's type an atomic operation.

Accessing the type_id is generally thread-safe within the PMA
code because it is only accessed once the memory is owned to
the exclusion of any other allocator. The same can't be said,
however, once access to it is given to a caller and so
protection needs to be added so that callers can't introduce
race conditions due to their inter-process thread-unsafety.

BUG=546019
Committed: https://crrev.com/84a8e0963774266d197d9bf90c952d983ab74869
Cr-Commit-Position: refs/heads/master@{#397711}

[bcwhite, 2016-06-03 14:58:48]

bcwhite@chromium.org changed reviewers:
+ asvitkine@chromium.org

[Alexei Svitkine (slow), 2016-06-03 15:07:33]

lgtm

[bcwhite, 2016-06-03 15:15:13]

The CQ bit was checked by bcwhite@chromium.org

[commit-bot: I haz the power, 2016-06-03 15:15:30]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/2034813003/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/2034813003/1

[commit-bot: I haz the power, 2016-06-03 15:19:47]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-06-03 15:21:46]

Description was changed from

==========
Make changing a record's type an atomic operation.

Accessing the type_id is generally thread-safe within the PMA
code because it is only accessed once the memory is owned to
the exclusion of any other allocator. The same can't be said,
however, once access to it is given to a caller and so
protection needs to be added so that callers can't introduce
race conditions due to their inter-process thread-unsafety.

BUG=546019
==========

to

==========
Make changing a record's type an atomic operation.

Accessing the type_id is generally thread-safe within the PMA
code because it is only accessed once the memory is owned to
the exclusion of any other allocator. The same can't be said,
however, once access to it is given to a caller and so
protection needs to be added so that callers can't introduce
race conditions due to their inter-process thread-unsafety.

BUG=546019

Committed: https://crrev.com/84a8e0963774266d197d9bf90c952d983ab74869
Cr-Commit-Position: refs/heads/master@{#397711}
==========

[commit-bot: I haz the power, 2016-06-03 15:21:48]

Patchset 1 (id:??) landed as
https://crrev.com/84a8e0963774266d197d9bf90c952d983ab74869
Cr-Commit-Position: refs/heads/master@{#397711}