1391865 - Use same PBackgroundChild for all cooperative threads

Status: RESOLVED FIXED

(Core :: IPC, enhancement)

Description

[Bill McCloskey [inactive unless it's an emergency] (:billm)]

Attachment: patch

Originally we talked about using one PBackgroundChild actor for each cooperative thread. However, this won't work. All the cooperative threads share a single event queue. Suppose that one PBackgroundChild sent a message to the background thread. It might be received on a different cooperative thread, which would have a different PBackgroundChild stored in its TLS. Even if we made it work, it would be very confusing.

This patch makes us use a single PBackgroundChild actor for all the main threads. It does so by storing the PBackgroundChild actor for the main thread in a global variable instead of in TLS.

Comment 1

[Bevis Tseng[:bevis][:btseng](Exited)]

Comment on attachment 8899030 [details] [diff] [review]
patch

Review of attachment 8899030 [details] [diff] [review]:
-----------------------------------------------------------------

::: ipc/glue/BackgroundImpl.cpp
@@ +1603,5 @@
>  // static
>  void
>  ChildImpl::CloseForCurrentThread()
>  {
> +  MOZ_ASSERT(!NS_IsMainThread());

nit:
MOZ_ASSERT(!NS_IsMainThread(), "The TLS on the main thread shall always be closed from ChildImpl::Shutdown().");

Comment 2

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/mozilla-inbound/rev/f7ed5293a8cd
Use same PBackground for all cooperative threads (r=bevis)

Comment 3

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

https://hg.mozilla.org/mozilla-central/rev/f7ed5293a8cd