[PATCH]: KIconLoader::loadIcon() speed ups

[Aaron J. Seigo]

On Monday 05 November 2007, Philippe Fremy wrote:
> Dan Meltzer wrote:
> > On 11/5/07, Aaron J. Seigo <aseigo at kde.org> wrote:
> >> hi all..
> >>
> >> attached is a patch that rather dramatically improves the speed of
> >> KIconLoader::loadIcon().
> >>
> >> i felt like playing with code tonight, but on something other than
> >> plasma (in an attempt to stave off getting burnt out dealing with QGV
> >> madnesses[1]) ... so when i saw a bug report from Hamish on KIconLoader
> >> performance[2] i fired up my text editor and got kcachegrind ready.
> >>
> >> the main culprits were KIconLoaderPrivate::removeIconExtension which was
> >> doing this a little suboptimally but more importantly had a debug
> >> statement that's probably superfluous at this stage in devel. off it
> >> went, and that revealed the next horror shows.
> >>
> >> it was using QDir::isRelativePath exactly once and that was now
> >> accounting for fully 33.46% of execution time. that's because it creaes
> >> a QFileInfo which init's a file engine ...... yeah. way too much for a
> >> hot path like loadIcon. i figure we don't -really- care if it's an
> >> absolute or relative path and we can fudge it by asking if the first
> >> character is '/'.
> >>
> >> i'm going to out on a limb and guess that this breaks on windows. if so,
> >> i can wrap it in an ifdef because the win is just way too big to ignore.
> >
> > how about something like this to make them win folks happy?
> > ..Completely untested of course, and I don't know what the exact
> > specifications on win drive names are.. but I think they are char + :
> > + \ ? is / possible for the third character? if not the check can be
> > simplified more.
>
> Looking at the Qt code, a windows filename can be considered absolute if
> it looks like:
> - letter + ':' + '/' + path
> - '//' + path
>
> That's assuming of course that '\' have been converted to '/' already.

i took the safe route: i cc'd the kde windows mailing list with an explanation 
so that someone who knows and can test can fix this if they choose to.

-- 
Aaron J. Seigo
humru othro a kohnu se
GPG Fingerprint: 8B8B 2209 0C6F 7C47 B1EA  EE75 D6B7 2EB1 A7F1 DB43

KDE core developer sponsored by Trolltech
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