1096487 - make ipdl message creation marginally more efficient

Status: RESOLVED FIXED

(Core :: IPC, defect)

Description

[Nathan Froyd [:froydnj]]

We do double work during ipdl message creation:

- We initialize fields with the constructor;
- We re-initialize some fields with Message::set_* calls after that.

We should just let the constructor do as much of the work as it can.  We could
make the flag setting of set_{sync,interrupt,reply} more efficient, but that
would require poking through some abstraction boundaries.

Comment 1

[Nathan Froyd [:froydnj]]

Attachment: part 1 - make ipdl message constructors set their priority directly

The default constructor for ipdl-generated messages looks like:

    MOZ_IMPLICIT Msg_AsyncMessage() :
        IPC::Message(MSG_ROUTING_NONE, ID, IPC::Message::PRIORITY_NORMAL, COMPRESSION_NONE, "PContent::Msg_AsyncMessage")
    {
    }

IPC::Message::PRIORITY_NORMAL is 1, so any set_priority(1) calls are
just redudant.

Additionally, the priorities for messages are known at code generation
time, so we are always able to provide the right constants to the
message constructor, rather than using set_priority calls later.

Comment 2

[Nathan Froyd [:froydnj]]

Attachment: part 2 - make ipdl message constructors take their routing id

Similarly to part, there's no need to say we don't know the routing id
when constructing a message, and then turn around and set the routing id
immediately afterwards.  Just let the constructor do its work.

Comment 3

[Nathan Froyd [:froydnj]]

Attachment: diff showing codegen differences after patches

This isn't really a patch, just a diff showing what happens to codegen once you apply the patches.

Comment 4

[Ben Turner (not reading bugmail, use the needinfo flag!)]

Comment on attachment 8520072 [details] [diff] [review]
part 2 - make ipdl message constructors take their routing id

Review of attachment 8520072 [details] [diff] [review]:
-----------------------------------------------------------------

Thanks!

Comment 5

[Nathan Froyd [:froydnj]]

https://hg.mozilla.org/integration/mozilla-inbound/rev/9574d0021ac7
https://hg.mozilla.org/integration/mozilla-inbound/rev/811dd70771d5

Comment 6

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

https://hg.mozilla.org/mozilla-central/rev/9574d0021ac7
https://hg.mozilla.org/mozilla-central/rev/811dd70771d5