77586 - nsTextFragment::SetTo() optimizations

Status: RESOLVED DUPLICATE of bug 566942

(Core :: DOM: Core & HTML, defect, P3)

Description

[Chris Waterson]

nsTextFramgment::SetTo() may benefit from the following optimizations. (Sorry, 
haven't measured how much time is spent here; cf. bug 77540.)

- we scan the entire string once to determine if we need to use a
  double-byte buffer. (Which sorta means that we're going to end up
  in a worst-case situation, since most web pages are probably 7-bit
  ASCII.)

  - Since we've probably scanned the string two or three times
    by this point, the caller could probably pass this information
    in.

  - Or, if we can't do that, then maybe we could optimisitcally
    allocate a single-byte buffer and start copying, and then
    fault and restart if it ends up being double-byte.

  - Or, pessimistically allocate a double-byte buffer and realloc()
    it to a smaller size if we get lucky and end up with a single-byte
    string?

- Why do we need our own implementation of memcpy() in SetTo()? Why
  not use the one provided with the standard library, as it's likely to
  be hand-optimized.

Comment 1

[Tomi Leppikangas]

I think time spend in SetTo is minor, like 0.05sec out ot 120sec for long pages.
Measured with sun's gprof

Comment 2

[Asa Dotzler [:asa]]

Bugs targeted at mozilla1.0 without the mozilla1.0 keyword moved to mozilla1.0.1 
(you can query for this string to delete spam or retrieve the list of bugs I've 
moved)

Comment 3

[Johnny Stenback (:jst)]

Mass-reassigning bugs to [e-mail]