1295763 - Allow ThreadSafeAutoRefCnt with XPCOM_GLUE

Status: RESOLVED FIXED

(Core :: XPCOM, defect)

Description

[Gerald Squelart (he/him) (not at Mozilla since 2022-09-15)]

As I was trying to introduce some thread-safe ref-counted structures in xpcom/glue, I discovered that three years ago, bug 884061 made thread-safe ref-counting use mozilla::Atomics, which depends on <atomic>, which because of build dependencies then could not be #included from XPCOM_GLUE code; and therefore 'ThreadSafeAutoRefCnt' was forcefully #ifndef'd-out in XPCOM_GLUE code, making thread-safe ref-counting unusable in this case. (See bug 884061 comment 91)

Since it was a long time ago, and that bug didn't get its promised follow-up, and I think Atomics have had some work done, I just tried removing the crippling |#ifndef XPCOM_GLUE|'s and everything compiled just fine:
https://treeherder.mozilla.org/#/jobs?repo=try&revision=d7ffd66645540383e680795138a0d49dadb34055

It's not obvious there, but that try includes my proposed patch https://hg.mozilla.org/try/rev/1ad7e862655a

Also the 'timerutils WIP' patch shows the new code that would not compile otherwise. I'm not sure yet whether that code will be accepted & stay there, so it could all end up being a moot point. Anyway I think we should just get rid of these old limitations if possible, as it has hurt people from the start (bug 884061 comment 90).

Comment 1

[Gerald Squelart (he/him) (not at Mozilla since 2022-09-15)]

Attachment: Bug 1295763 - Allow ThreadSafeAutoRefCnt with XPCOM_GLUE -

Removed '#ifndef XPCOM_GLUE' that blocked usage of thread-safe ref-counting
from XPCOM_GLUE code.

Review commit: https://reviewboard.mozilla.org/r/72084/diff/#index_header
See other reviews: https://reviewboard.mozilla.org/r/72084/

Comment 2

[Nathan Froyd [:froydnj]]

Comment on attachment 8781737 [details]
Bug 1295763 - Allow ThreadSafeAutoRefCnt with XPCOM_GLUE -

https://reviewboard.mozilla.org/r/72084/#review72000

Comment 3

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/b004e438bdc9
Allow ThreadSafeAutoRefCnt with XPCOM_GLUE - r=froydnj

Comment 4

[Wes Kocher (:KWierso) (Not reading bugmail; email directly if needed)]

https://hg.mozilla.org/mozilla-central/rev/b004e438bdc9