[Fontconfig] Re: Structure of cache files

[Matthias Clasen]

On Mon, 2005-10-03 at 16:17 -0400, Matthias Clasen wrote:
> On Mon, 2005-10-03 at 15:51 -0400, Patrick Lam wrote:
> > Matthias Clasen wrote:
> > > Just trying this again, it worked when copying an x86_64 cache to a i386
> > > machine.  Let me try the other way around again. I notice though, that
> > > FcDirCacheValid() needs to become a bit smarter. It should not consider
> > > a cache valid if it doesn't contain a section for the current platform.
> > > Otherwise, fc-cache may fail to add a section for the current plaform,
> > > since the cache file appears uptodate, timestamp-wise.
> > 
> > Great.  It ought to work the other way, if it works one way.  But let me
> > know what you find out.
> > 
> > Good catch on FcDirCacheValid.  I've just committed a fix for that which
> > will be in 2.3.92.  (Your mail arrived just a minute after I posted
> > 2.3.91.  Oh well.)  Could you test that out too?
> > 

Actually, thinking about FcDirCacheValid some more, I don't see how the
single per-file timestamp can work at all with multi-platform cache
files. Imagine that a new font gets installed in a directory with a
multi-platform cache. If you then run fc-cache on i386, it'll update
only the i386 section of the cache, but update the timestamp, marking
the whole cache file as uptodate, so a later run on x86_64 will not
update the x86_64 segment. I think the only solution to this is to put 
per-segment timestamps into the file, and use them to determine
cache-outdatedness on a per-platform basis. Or simply use one cache file
per platform...

Matthias