ufl team mailing list archive

[Anders Logg <logg@xxxxxxxxx>]

On Tue, May 10, 2011 at 10:57:07PM +0200, Martin Sandve Alnæs wrote:
> On 10 May 2011 17:52, Anders Logg <logg@xxxxxxxxx> wrote:
> > On Tue, May 10, 2011 at 03:49:18PM +0200, Martin Sandve Alnæs wrote:
> >> On 3 May 2011 18:25, Johannes Ring <johannr@xxxxxxxxx> wrote:
> >> > On Tue, May 3, 2011 at 3:52 PM, Anders Logg <logg@xxxxxxxxx> wrote:
> >> >> It happens to me a lot. Johannes has tried to explain to me why it
> >> >> happens a number of times but I still don't understand why.
> >> >>
> >> >> Maybe he can try to explain it again to you and then I might also
> >> >> understand. :-)
> >> >
> >> > I think I just bring up the following instructions (which I think looks good):
> >> >
> >> >  http://wiki.squid-cache.org/BzrInstructions
> >>
> >> Thanks Johannes.
> >>
> >> Basically the problem is that bazaar numbers commits with contiguous
> >> integers, and when Bob and Alice works locally they will get the same
> >> commit ids for different commits. When you stand in branch Alice and
> >> merge from branch Bob, the commit numbers of branch Alice are
> >> conserved and a single new merge commit is recorded on top there. The
> >> commit numbers from branch Bob are lost in the merge. Therefore, to
> >> conserve the commit ids in the central branch, you have to merge from
> >> your own branch into the server branch, not the other way around.
> >> Otherwise we can never safely use the commit revisions from the
> >> central branch, since they may change every time somebody merges the
> >> 'wrong way'.
> >>
> >> This problem does not occur with hg or git, because they use a hash
> >> value to identify a each commit.
> >
> > So if I'm Bob and Alice has pushed some changes to the main branch
> > before me, which exact commands should I write?
>
> Depends on how you set up your repositories, where your branches are
> located, etc...
>
> You really have to read up on it and try it out a bit to understand
> it, and I doubt I can write it better than what Johannes linked to +
> the bazaar docs.
>
> I plan to keep a local repository with multiple branches like this:
>   ~/dev/fenics/ufl/ - local ufl repository

Is this a repository? Or is it just a directory named ufl inside which
you keep a number of different repositories?

>   ~/dev/fenics/ufl/trunk/ - local checkout of central ufl branch lp:ufl
>   ~/dev/fenics/ufl/work/ - local branch where I usually do my work
> (  ~/dev/fenics/ufl/somefeature/ - local branch with some half
> finished feature if needed)
>
> One branch locally for normal work, one checkout locally mirroring the
> central trunk, and any number of branches locally and on launchpad for
> alternative half-finished work.
>
> Then I do:
>
> cd .../ufl/work/
> <work work work>
> bzr push lp:ufl # fails because Bob has pushed stuff
>
> cd ../trunk # should have no local changes now
> bzr update # gets the latest version of lp:ufl
> bzr merge ../work # merge my work into trunk
> bzr commit -m'Merge my work on <superfeature>.' # Commit merge into trunk
>
> If trunk is a _checkout_ and not just a _branch_, the last commit here
> will actually both commit and push the merge to lp:ufl directly.

So the trunk should always be a checkout?

--
Anders


> To use bazaar correctly, everybody really needs to read up on it and
> understand the differences beteween e.g. a checkout and branch.
> Otherwise nobody can ever trust FEniCS revision numbers to mean
> anything... I'm a bit surprised on this bazaar 'feature'.
>
> Martin