[Fontconfig] Fontconfig performance question.

[Keith Packard]

Around 17 o'clock on May 8, Krzysztof Dabrowski wrote:

> After such mapping you would have to "parse" it somehow anyway otherwise you 
> will have realy slow access to the whole thing in the memory.

A carefully designed format should be interpretable by the library with 
minimal parsing -- reformatting the data would increase memory usage which 
obviates a lot of the utility of a mapped file.

> But such serialisation would be realy dependant on the structure format - any 
> change in the structure would require a new serialiser.

That's a significant issue.  We have versioned cache file names, but it 
would be best if the format could remain compatible across several 
versions of the library.

> I'm realy not against the daemon thing. It could be realy transparent - if
> you have it up and running - fontconfig could obtain it's data from it. If
> it's not up and running it can fall back to the old behaviour. 30% of app's
> startup time is worth it in my opinion.

A solution which doesn't depend on shared memory among processes will 
reduce security and stability issues.  Let's see how far we can get 
without that.

-keith