[Fontconfig] Re: Fontconfig performance question.

Keith Packard fontconfig@fontconfig.org
Tue, 13 May 2003 10:47:20 -0700

Around 13 o'clock on May 13, Krzysztof Dabrowski wrote:

> You haven't commented on my binary cache idea (email from Friday 10:04).
> Was it that stupid? :)

I thought I'd answered it indirectly.  Using a binary format file is mostly 
interesting because we could use mmap and share the data among all 
processes, so the format would need to be interpretable without adjusting 
the data.

Secondly, the cache files are per-directory for several reasons, so we 
can't really save the whole data structure to a single file.

> And about versioning: such things like this cache can be in my opinion
> realy library-version dependant, if the cache is from older version,
> re-creating it takes just a second or two..

I'd prefer to avoid versioning the cache files that frequently; it makes 
distributed environments that share fonts over a network file system more 
difficult to manage, and it clutters the file system with stale cache 
files which may still be needed by some statically linked application.

In my environment, it takes 90 seconds to regenerate the font cache files, 
making it pretty essential that the font installation mechanism be able to 
compute the bulk of the cache contents so that the user isn't surprised by 
a delay of this length on login or other application startup.