KDirModelV2, KDirListerV2 and UDSEntryV2 suggestions

[Mark]

On Tue, Feb 5, 2013 at 8:03 AM, Frank Reininghaus
<frank78ac at googlemail.com> wrote:
> Hi Mark,
>
> 2013/2/4 Mark:
>> I really really really dislike KDirModel and friends (KDirLister,
>> KFileItem).
>
> before you get even more emotional in your next reply to this thread,
> please consider reading
>
> http://www.kde.org/code-of-conduct/
>
> I sort of got used to reading disrespectful messages with little
> useful content from a small minority of our user base, but I feel at
> least mildly offended when I read such statements on a developer-only
> mailing list. Not only because the classes you mention have been
> serving us well for quite some time and David does an awesome job
> maintaining them (he fixes a bug in no time at all as soon as I throw
> a half-ready unit test at him), but also because they contain some
> contributions from myself. Yes, it's mostly unit tests and one-line
> patches, but in some cases, I needed a few hours of backtrace and code
> reading before I could figure out what's going wrong [1].
>
> Thanks for your understanding and best regards,
> Frank
>
> [1] https://bugs.kde.org/show_bug.cgi?id=196695

Hi Frank,

the "really really really dislike" part was meant to be taken
seriously. Specially not after adding a screenshot with it's memory
usage. I like diving into those classes and try to figure out more
optimal ways of doing things, i certainly don't hate them nor
disrespect the authors of them.

The thing i'm puzzling most with right now is how i can optimize
UDSEntry. Internally it's a hash and that very visible in profiling.
Also in KFileItem one part that i find a little strange is this line:
http://quickgit.kde.org/?p=kdelibs.git&a=blob&h=6667a90ee9e1d57488bb7e085167658f2fb9f172&hb=533b48c610319f3ad67e6f5f0cbb65028b009b8f&f=kio%2Fkio%2Fkfileitem.cpp
(line 290). That line is causing a chain of performance penalties.
Which is very odd because i'm testing this benchmark with 500.000
files, not directories. It should not even end up in that if.

Or am i reading massif wrong..? Massif shows me that line for KUrl
data consumption.. One of the highest memory consumptions.