[Fontconfig] Application startup performance

[u-pnrz at aetey.se]

On Wed, Jan 13, 2016 at 08:11:36PM +0000, Nick Alcock wrote:
> On 12 Jan 2016, Keith Packard said:
> 
> > u-pnrz at aetey.se writes:
> >
> >> I would rather postulate fc-cache to be run and risk ignoring some fonts
> >> until this is done. Is the risk really significant? Distros run fc-cache,
> >> users who add fonts on their own would know they have to run fc-cache.
> >
> > Yes, it's pretty clear we've gotten distros to understand that running
> > fc-cache is required after installing fonts.
> 
> However, users who add fonts on their own would definitely *not* know,

Why? If this is documented for a year or two they really should know
or should blame themselves.

> and programs that do it are not currently explicitly running fc-cache,
> so there'd be a big installed base problem to deal with.

That's why I said (I think I did?) this needs time.

> I think automated out-of-date cache detection and cache updating must
> stay for $HOME. It's only system fonts that are problematic for me

Relying on $HOME is a heuristics and is unreliable, there are users who
can not (or do not wish!) do any automatic updates there.

Leaving the heuristics aside, in the short run the behavior
should not be changed of course, but in the long run making fc-cache
mandatory is fully possible. The only requirement is documentation
of the change well in advance.

Regards,
Rune