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Re: jigdo


Jigdo is lovely - thanks! I'm hoping to try and make it run faster
when generating templates, as at the moment that's the bottleneck I'm
hitting in trying to generate woody r2 images.

I've been poring over the jigdo source code, and I'm looking at the
main loop in MkTemplate::scanImage(), especially the code where it
compares the current hash against the hashes cached for known files. I
don't know if you've thought of this (you may even have tried it, and
it runs even slower), but when we first start looking for matches (a
new file), could we not possibly short cut some of the work here by
using the directory information that we have from the CD image itself?

We know what the current offset in the image file is, and the
directory information from the image can tell us the name of the file
that starts at that offset (sector number). I appreciate that this
would be horribly ISO9660-specific (for now), but do you think it
might gain us anything to try this? Of course, changing the code here
may not help, if I'm trying to optimise performance in an area that's
not critical.


Steve McIntyre, Cambridge, UK.                                steve@einval.com
Support the Campaign for Audiovisual Free Expression: http://www.eff.org/cafe/

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