54715 - replace indicies with string iterators in nsXULTemplateBuilder::ParseAttribute()

Status: RESOLVED FIXED

(Core :: XUL, defect, P3)

Description

[Chris Waterson]

Currently, we use integer indicies to maintain our position in
nsXULTemplateBuilder::ParseAttribute (because currenty, we can only create a
Substring() using indicies). This requires us to make a ton of calls to
CharAt(), and accounts for 26% of the time spent in ParseAttribute(). (That
translates to about 2.5% of the overall time spent scrolling a mail threadpane,
for example.)

Replacing the index-based implementation with iterators will significantly
reduce this cost.

Comment 1

[Chris Waterson]

Depends on iterator-based API for Substring()

Comment 2

[Chris Waterson]

Attachment: use scc's new iterators instead of indices

Comment 3

[Chris Waterson]

Well, this wasn't the 2.5% speedup I was hoping for. In reality, we've just
inlined a bunch of the work, so Quantify shows the time-in-function increases a
bit, even though there is no time spent in CharAt() anymore. It's a small net
win: about 1%. (Last cookie...fatness...)

Comment 4

[Scott Collins]

r=scc :-)

Comment 5

[David Hyatt]

a=hyatt

Comment 6

[Chris Waterson]

fix checked in.