Re: Performance

[Alexander Larsson <alexl redhat com>]

On Mon, 2003-11-10 at 12:32, Michael Meeks wrote:
> Hi Alex,
> 
> On Mon, 2003-11-10 at 09:38, Alexander Larsson wrote:
> > My guess is that konqueror is faster in this example because it matches
> > mime types for mp3 by extension, instead of sniffing. I prefer getting
> > correct results over speed though.
> 
> 	Hmm - but surely our architecture is in fact rather good for the
> "Instant Guesstimate" -> "refined perfection" type thing with the
> add/changed type API ?
> 
> 	Would it not be possible to instantly guesstimate the MIME type so the
> icon view can render something quickly thats ~ 95% accurate, and then
> step-wise refine the incorrect guesses later ?
> 
> 	Then again I havn't dug there in many moons,

Basically for the same reason we recently disabled incremental loading.
You would get something displayed in the view pretty quickly, but you
can't really use it, because:
a) nautilus is still working hard reading the real data, so its not
totally responsive
b) when we get further data, chances are that sizes change, so we would
have to re-layout causing icons to change and whatnot, so clicking on
icons before the directory is stable can be dangerous. The icon you
wanted to click on might move before you click.
c) Incremental loading means the total time is longer than just reading
it once, because changing things after you've already done them once
costs more than doing it right initially.

However, for the specific case of mimetypes this might not be as bad as
the general case. The fast approximation (extension) is right in most
cases, so we would have to do very few fixups, if we make sure that
updates to the same mimetype cause no work. And even if we do need
fixups, this typically only affects the icon, which means the layout
will be the same, so we don't get any jumping icons. There are cases
where the layout could change, if for instance the icons were different
sizes, or the user was showing the mime type in the icon caption,
however, these wouldn't be common. We might need some work in the icon
view to make sure we don't do to much layout if only the icon changes.

=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
 Alexander Larsson                                            Red Hat, Inc 
                   alexl redhat com    alla lysator liu se 
He's a shy amnesiac boxer with nothing left to lose. She's a scantily clad 
insomniac opera singer with the power to see death. They fight crime!