[pacman-dev] Add delta creation to repo-add.

[Xavier]

On Fri, Feb 15, 2008 at 08:34:52PM -0500, Nathan Jones wrote:
> For the first patch, I added the -n flag to gzip in order to prevent the
> md5sum problem. The apply-delta script is not as efficient as it could
> be. There is an extra gunzip+gzip step that could be avoided if we
> create a delta on the .tar rather than the .tar.gz. Doing so would
> complicate makepkg a bit, so I stuck with the extra step.
> 

Hm well, I have a stupid question : why is this better than the previous way
of recreating the package?
Before your patch, we only had overhead once at package / delta creation
time, while after, we have it every time the delta is applied, right?

> For the second patch, I created a second function, create_xdelta_latest,
> which creates a delta for the latest package with a given package name.
> I did this because otherwise a delta would be created for every package
> given on the command line which is annoying for me because I use
> *.pkg.tar.gz.
> 

My comment here is rather on the previous code that you refactored than your
patch itself. I really wish things could be much simpler here, it's all
pretty complicated.
What about dropping all this filenames parsing / version comparisons stuff,
and try to reimplement this in a much more basic way in repo-add?
Since repo-add removes an entry and add a new one in the database, we should
be able to easily fetch the informations from these entries, and generate a
delta between both. What do you think?

I think this should work perfectly when using core / extra / community repos.
Using testing repo complicates everything though, because packages are
moved between repos. But is it really a big problem if the tools don't handle
this situation automatically?
Maybe we could allow a way to let the packager specify from which packages deltas
should be created.