fenics team mailing list archive

[Anders Logg <logg@xxxxxxxxx>]

Thanks to Florian for the great assistance.

The files needed to convert a branch which has a FEniCS component
trunk branch as an ancestor can be found here, together with the
script used to do the conversion:

http://fenicsproject.org/pub/software/git/bzr-to-git-conversion-2013-03-19/

  We will store this data on the server for an eternity.

If you don't know what that means or don't care, you can ignore
this message.

New Git branches of FEniCS components have been created here:

https://bitbucket.org/fenics-project

These should now be used as the main development branches, but please
hang on for a day or as we work out some more details.

--
Anders


On Tue, Mar 19, 2013 at 11:43:04PM +0000, Florian Rathgeber wrote:
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>>
>> Correction from Florian. Let's do this:
>>
>> bzr fast-export --export-marks=marks.bzr `pwd` | git fast-import
>> --export-marks=marks.git
>>
>> The marks files can be used by anyone who wants to convert their
>> existing feature branches and then merge them on the git side. They
>> will be put on the web page for download. More info here:
>>
>> http://dgleich.wordpress.com/2011/01/22/convert-bazaar-to-git/
>>
>> Garth and I are currently converting the repositories for DOLFIN,
>> UFC, UFL, FFC, Instant and FIAT so please don't touch the
>> Launchpad repos now.
> Anders, Garth and I sat down this evening to work out a migration
> strategy and I think we've arrived at something workable.
> Just a few words of explanation about the pitfalls: Converting the
> trunk is relatively straightforward (and the conversion scripts should
> have finished by now), but we need to be very careful when migrating
> feature branches s.t. they keep the correct ancestry relationship.
> Consider the following situation of a feature branch branching of
> trunk after revision 1803:
> o trunk (r 1806) --> d9e67c2
> |
> o  + feature-branch (r 1805) --> 16c0470
> |  |
> o  +
> | /
> |/
> o base (r 1803) --> dafb344
> |
> After converting trunk to Git, bzr revision 1806 becomes git revision
> d9e67c2 and 1803 becomes dafb344. When migrating feature-branch, it is
> *critical* that revision 16c0470 is a descendant of dafb344.
> For this to work, bzr fast-export needs to know which revisions it has
> already exported and git fast-import needs to know which revisions it
> has already seen (and both need to agree on that!). Therefore you need
> to have access to the *same* marks file that was used when converting
> trunk.
> If it doesn't have access to this information when importing
> feature-branch, fast-{im,ex}port will go ahead and do all the
> conversion for revision 1803 and its ancestors *again* and you will
> end up with *the entire history replicated* but *different* git
> revision ids s.t. git has no way of knowing that feature-branch should
> be a descendant of dafb344.
> Anders will make all the marks files used for the conversions of the
> FEniCS projects available and we'll send detailed migration
> instructions for feature branches once all the infrastructure is in
> place. I've already sketched out how that is going to work:
> https://gist.github.com/kynan/41b7e7f405ce38fa250a
> Florian



>> -- Anders
>>
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