Zsync for Packages files

[Paul Sladen]

On Tue, 21 Jul 2009, Lars Wirzenius wrote:
> ma, 2009-07-20 kello 22:46 +0200, Tollef Fog Heen kirjoitti:
> > You'll need to get quite a lot of small files,
> Surely apt uses a single TCP connection to fetch all the pdiff files?

The current implemenation is fairly dumb, the loop being roughly:

  while hash(Packages) != latest_hash:
      fetch_and_apply_new_pdiff(hash)

A major optimisation would be to have apt pre-calculate the entire path
through the available pdiffs.  Calculating a path beforehand would allow
deciding if a fresh download would be smaller/faster, or if a shorter path
(via a per-day, or per-week combined patch) would work out better.

However, the concept of contextual diffs for updates is not-great as they
duplicate not only the data to be applied, but also the data to be removed.

It is however, simple.

	-Paul
-- 
Why do one side of a triangle when you can do all three.  Somewhere, GB.