[Fontconfig] Streamlining fontconfig scanning

[Behdad Esfahbod]

Ok, now that you made a release, I'll go ahead and merge this so we get
maximum testing.  I'm also making some more variable-fonts changes and I
prefer to merge this first and work on top.

I'll continue regarding the lock in a separate thread.

Thanks

On Wed, Aug 16, 2017 at 9:10 PM, Akira TAGOH <akira at tagoh.org> wrote:

> Speeding up the scanning is really nice but IMHO we can't remove the
> lock as long as fontconfig has a possibility to update caches from
> multiple processes at the same time. improving the speed of updating
> caches may reduces the chance to see the issue, but that's it. in
> other words, there are still an opportunity to see it if the condition
> is met. in fact, that issue was there since quite a long time ago. but
> it bagan to happen these days because of processing the updates of
> caches in parallel by the package manager etc. so I don't want to do
> that unless we have any idea to detect that breakage before writing or
> any way to do update cache safely. otherwise we'll see some wired
> issues in the future.
>
> On Tue, Aug 8, 2017 at 2:30 AM, Behdad Esfahbod <behdad at behdad.org> wrote:
> > Hi everyone,
> >
> > I have a proposed patchset speeding up fontconfig scanning by 10x,
> simply by
> > not loading glyphs at all, and trusting fonts having correct cmap:
> >
> >   https://bugs.freedesktop.org/show_bug.cgi?id=64766#c56
> >
> > If no one has comments, I like to merge this and get it out for testing
> in
> > the wild.
> >
> > After this, I think we should fix the relocatable feature to not touch
> > mmaped cache files.  Here's my proposed approach:
> >
> >   https://bugs.freedesktop.org/show_bug.cgi?id=101889#c17
> >
> > After that, we should clean up the cache race patches and remove the
> > locking.  We should accept that cache updates will always remain racy,
> > simply because we don't have or want to use the kinds of synchronization
> > primitives that guarantee no race.  With scanning 10x faster this
> shouldn't
> > be a problem in practice.  I like to get back to each process trying to
> > update the cache and possibly discarding its result if another process
> > already did...
> >
> > Cheers,
> >
> > --
> > behdad
> > http://behdad.org/
> >
> > _______________________________________________
> > Fontconfig mailing list
> > Fontconfig at lists.freedesktop.org
> > https://lists.freedesktop.org/mailman/listinfo/fontconfig
> >
>
>
>
> --
> Akira TAGOH
>



-- 
behdad
http://behdad.org/
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.freedesktop.org/archives/fontconfig/attachments/20170912/9a6d2b33/attachment.html>