1385533 - Consider reserving space for one pointer in mMutationObservers

Status: RESOLVED FIXED

(Core :: DOM: Core & HTML, enhancement)

Description

[(no longer active)]

This way setting an input value for example won't incur an allocation here when a range gets created for the selection, and we won't be growing the slot by too much.

We still have the static asserts in FragmentOrElement.cpp imposing a maximum size on our slots.

Comment 1

[(no longer active)]

Attachment: Reserve space for one pointer in the mMutationObservers array on node slots

This helps avoid allocations for the first mutation observer (for example, Range)
created by a caller.

Comment 2

[(no longer active)]

(The macros in nsTObserverArray.h are copied from similar macros adjacent to them, just changing the array type used in them.)

Comment 3

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/mozilla-inbound/rev/559f7f92c891
Reserve space for one pointer in the mMutationObservers array on node slots; r=smaug

Comment 4

[Sebastian Hengst [:aryx] (needinfo me if it's about an intermittent or backout)]

https://hg.mozilla.org/mozilla-central/rev/559f7f92c891