Re: Quick update on git-dpm migration script
On 10/06/2014 03:24 PM, Stefano Rivera wrote:
> Further updates:
>
> I used my sprint time at PyCon.ZA to poke at the migration.
> I was lucky enough to have Gary van der Merwe, with deep VCS experience,
> get involved, and we made some significant progress.
>
> http://anonscm.debian.org/cgit/users/stefanor/dpmt-migration.git/
>
> svn2git.py Takes the SVN repository, and spits out a billion git ones.
>
> If you want to run it, you can find dumps of the svn repo in my home dir
> on alioth. I recommend loading the dump in /dev/shm (and putting the git
> repos there, too).
>
> Gary figured out how to de-octopus all the svn-buildpackage tags, to
> create a linearish history.
>
> (svn-buildpackage tags by copying your working directory to the remote,
> meaning different directories can be at different revisions, and the tag
> has multiple ancestors)
>
> We determined that my unhappyness with git-dpm history (the debian
> directory appearing from scratch on after every upstream merge, rather
> than having a useful history) is the result of a bug in git-dpm's import
> code, it's missing a parent link between these commits. But we didn't
> find where the bug is (or write a detailed bug report).
>
> Right now, we're not trying to convert to dpm, but just to
> svn-buildpackage style (which is simpler).
>
> https://bugs.debian.org/720448 means that history isn't round-trippable
> through dpm, without adding noise. This probably wouldn't go down well
> with the release team when preparing stable package updates for before
> the migration.
>
> The next step (which Gary is working on) is to start combining the
> imported-from-svn tree with an imported-from-dscs tree, so that we have
> full source packages, with all the svn history.
>
> I'm busy paying down all the technical debt we took on in the svn2git
> rules, to get the conversion running in a hurry. We need to capture all
> the branches, to have less disconnected tags in the repos.
>
>> I took a look at Stefano's dpmt-migration branch. His code is working at a
>> different level than mine; whereas I am working on single package imports,
>> he's looking at doing the full migration of all DPMT and PAPT packages. We'll
>> need that whenever we flip the switch.
>
> This might have been a bad approach (on my side). To perfectly migrate
> all repos, we may have to do multiple runs (with individual rules files)
> rather than one all-in-one migration. The reason for that is that
> svn2git only writes each svn change to 1 git-repo. It can't understand
> that repos will fork from each other later, and changes must be written
> to both, until then. (e.g. beautifulsoup gets copied to beautifulsoup4,
> but both are still in the archive)
>
> We could also deal with that situation by running svn2git for n
> revisions, copying git repos, then running another m revisions, etc.
>
> SR
Thanks a lot to all of you for working on this.
Thomas
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