[Rpm-ecosystem] Zchunk update

[Jonathan Dieter]

On Tue, 2018-04-17 at 09:08 +0200, Michal Novotny wrote:
> Hello Jonathan,
> 
> On Mon, Apr 16, 2018 at 2:47 PM, Jonathan Dieter <jdieter at gmail.com>
> wrote:
> > It's been a number of weeks since my last update, so I thought I'd
> > let
> > everyone know where things are at.
> > 
> > I've spent most of these last few weeks reworking zchunk's API to
> > make
> > it easier to use and more in line with what other compression tools
> > use, and I'm mostly happy with it now.  Writing a simple zchunk
> > file
> > can be done in a few lines of code, while reading one is also
> > simple.
> > I've also added zchunk support to createrepo_c (see 
> > https://github.com/jdieter/createrepo_c), but I haven't yet created
> > a
> > pull request because I'm not sure if my current implementation is
> > the
> > best method.  My current effort only zchunks primary.xml,
> > filelists.xml
> > and other.xml and doesn't change the sort order. 
> 
> Once it is in createrepo_c, we could try employing it in Fedora COPR.

Ok, done.  This copr currently has zchunk and createrepo_c in it.  I
did have to disable the python tests for createrepo_c which means I
probably wouldn't use the python bindings with this release.

https://copr.fedorainfracloud.org/coprs/jdieter/zchunk/

To enable zchunk creation, run createrepo_c --zck.  I've created
dictionaries that are appropriate for Fedora's metadata at
https://www.jdieter.net/downloads/zchunk-dicts, and they can be used
with --zck-primary-dict, --zck-filelists-dict and --zck-other-dict.

To make zchunk downloads efficient, the same dictionary must be used
each time metadata is generated.  Dictionaries aren't mandatory, but
they greatly reduce the size of the compressed metadata.

Jonathan