1642738 - Make the MessageChannel Send and Call methods take a UniquePtr argument

Status: RESOLVED FIXED

(Core :: IPC, task, P3)

Description

[Andrew McCreight [:mccr8]]

There are a few messages on MessageChannel that could take UniquePtr<Message> arguments.

Note that the ones with replies still take a Message* argument for that, because they work by getting a stack-allocated Message passed in, which is move-assigned into. Honestly it feels like passing in a UniquePtr& would be better, because we're heap allocating the reply message anyways, but changing that would require work at the code gen layer, and I expect the move constructor for Message isn't very expensive.

Comment 1

[Andrew McCreight [:mccr8]]

I have patches for this. I'm just waiting for a try run to make sure it builds on Windows and in Fuzzing, though I think it shouldn't be an issue.

Comment 2

[Andrew McCreight [:mccr8]]

Attachment: Bug 1642738, part 1 - Make the non-reply MessageChannel Send messages take a UniquePtr.

This fixes the leak of a ShmemCreated in the case where ShareHandle fails.

Comment 3

[Andrew McCreight [:mccr8]]

Attachment: Bug 1642738, part 2 - Make the message arg to two more MessageChannel send methods into a UniquePtr.

The reply argument that gets passed in is a stack reference which is move
assigned into, so it doesn't make sense as a unique pointer, although the
code could be restructured to return a freshly allocated object instead.

This mostly just eliminates a spurious round trip from UniquePtr to *
and back. The bulk of the patch is renaming uses of |msg| to |aMsg|.

Comment 4

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/d9e450307863
part 1 - Make the non-reply MessageChannel Send messages take a UniquePtr. r=froydnj
https://hg.mozilla.org/integration/autoland/rev/6b7a59f43f9b
part 2 - Make the message arg to two more MessageChannel send methods into a UniquePtr. r=froydnj

Comment 5

[Dorel Luca [:dluca]]

https://hg.mozilla.org/mozilla-central/rev/d9e450307863
https://hg.mozilla.org/mozilla-central/rev/6b7a59f43f9b