Xavier wrote:
There has never been any real official interests for delta. This seems
to make a requirement the ability to make a separate delta server.
This seems to require a separate delta database. This implies a new
level of complexity and code bloat in pacman. Now maybe it is worth
it, I don't know, it still makes me wondering why we put all this
delta stuff in pacman to begin with. What was the problem with
XferCommand, it seemed like it was a great idea. Now that
wget-xdelta.sh script is just a toy, but a much more powerful python
script could be written that has basically the same logic as pacman
currently has + the ability to fetch and parse a separate delta
database.
Unless the server is out of disk space, I'm not too sure exactly why
there's a requirement for a separate server. If pacman is distributed
with the delta option turned on by default, the server doing the actual
"serving" of the updates is probably going to have 60 to 85% less work
to do.
I will grant that there would be a new level of complexity involved, for
example, if I've missed 4 updates, we'd have to "chain link" the tar.gz
in my cache via 4 delta patches to get the current tar.gz.
I believe that the following would be the simplest implementation both
in terms of how much implementation work is needed and the probable
effectiveness:
Put delta files into a separate folder (thus also avoiding a snapshot
from containing the deltas):
http://archlinux.mirror.ac.za/delta/core/os/x86_64/kernel26-2.6.28.4-1-x86_64.kernel26-2.6.28.5-1.pkg.xd3.tar.gz
Thus, I could do the following (bash pseudocode)
curl http://archlinux.mirror.ac.za/delta/core/os/x86_64/ > tmpfile
grep $pkgname < tmpfile > listing
failed=false
cat listing | while read delta
do
[ $pkgname-$currentpkgversion-$pkgarch.xd3.tar.gz *within* $delta ] &&
start=true
if [ start=true ]
then while read delta
do
wget http://archlinux.mirror.ac.za/delta/core/os/x86_64/$delta &&
applydelta $delta $curfile
[ $output=$pkgname-$newpkgversion-$pkgarch.tar.gz ] && break
curfile=`ls -rt | tail -n 1`
done
fi
[ $output=$pkgname-$newpkgversion-$pkgarch.tar.gz ] && break
done
The above requires no db implementation at all and can work well even
using the above very simple logic.
And yes, by my own standards, the above is very bad bash pseudo-code. :P
Of the above, what is already implemented in pacman?
__________
Brendan Hide
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