1574172 - make telemetry bits around arrays relatively more efficient

Status: NEW

(Toolkit :: Telemetry, task, P3)

Description

[Nathan Froyd [:froydnj]]

I have a bunch of changes in toolkit/components/telemetry/ that use the newly-developed nsTArray::EmplaceBack (bug 1571759). A lot of these changes depend on explicitly declaring constructors for classes, so you can convert:

  array.AppendElement(Klass{...});

into:

  array.EmplaceBack(...);

as the former doesn't require an explicit constructor, but the latter does.

Is it preferable to roll all such changes into one big patch, or to have separate patches for each such structure changed and the corresponding AppendElement calls converted?

Comment 1

[Chris H-C :chutten]

A quick check suggests that there's only about four dozen AppendElement calls in telemetry, so I leave the choice up to whichever makes you most comfortable. I'm confident I can review either just as effectively.

Comment 2

[Chris H-C :chutten]

Dropping to P3 due to inactivity.

Comment 3

[Florian Quèze [:florian]]

(I'm triaging this as low priority for fxperf because there's no indication of how much of an impact fixing this bug would have)

Comment 4

[:Gijs (he/him)]

I'm just doing some triage bits for fxperf whiteboard tags but part of me wonders if this is effectively wontfix with the plan being to migrate to glean? OTOH if we think this code is likely to be with us for a few more years then that might change our thinking.