Re: [Monotone-devel] Re: Request for help adding monotone output to cvs2svn

[Markus Schiltknecht]

Hi,

Bruce Stephens wrote:
> OK, that's probably worth doing.  For repositories which include
> imports, I suspect many of the tags will require a branch.  I guess it
> would depend on how one uses CVS tags as to whether it's often the
> case that a branch is unnecessary.  (At work we quite often (more
> often than I'd like) move CVS tags: we tag the repository, but as
> release preparation progresses we move tags on selected files as bugs
> get fixed.  It's a part of the change control procedure.)

That's certainly a problem for monotone. Not only for CVS import, but 
also when importing subversion repositories. Those also don't really 
have tags (in the monotone sense, i.e. on exactly one revision, which 
cannot change underneath).

This is one of the things monotone is different. Back at the time when I 
had to decide to use cvs2svn or not, Michael et al proposed to use 
subversion's dump format as a general purpose base format. That's where 
I've just rolled my eyes and went away. Maybe I should have been more 
patient in explaining the differences.

> > (I don't know whether monotone makes the same distinction.)
>
> Monotone stores revisions in a DAG, and a revision is in a branch b if
> it has a branch cert for b attached to it.  A revision may be in any
> number of branches (including none).  Using the normal interface it's
> tricky to create a branchless revision; I'm not sure whether the
> automate feature makes it easier---probably.  Unlike git, it's normal
> for a single branch to fork.
>
> So I'd guess a natural way to do it in monotone is to have everything
> on branches, but for tags where you need to, just fork off the branch.
>
> Oh, darn, that doesn't work, because the tagged revision then becomes
> a head of the branch.  OK, it'll need to be a separate branch, I
> guess.

Right. For every tag and branchpoint which cannot be matched to exactly 
only one revision, you'll have to add an artificial revisions which you 
can tag. (AFAICT, git allows such an artificial revision to have 
multiple parents, monotone does only allow two parentsn. So for 
monotone, you'll have to add multiple artificial revisions).

For branchpoints, it's quite clear that such artificial revisions for 
those can go into the branch they initiate. But for tags, you'll 
probably have to create an 'artificial' branch, or not assign any branch 
cert to those revisions.

> (In git it's normal for a branch to contain divergence in its past,

Uh.. what do you mean by that?

Regards

Markus