Re: cvs revision number -> git commit name?

[Johan Herland <johan@herland.net>]

On Tuesday 26 January 2010, Aaron Crane wrote:
> Hallvard B Furuseth <h.b.furuseth@usit.uio.no> wrote:
> > When moving from CVS to Git, what's a good way to help Git users
> > find an old commit given the original CVS revision number?  Are
> > there tools available to help?
> >
> > One could commit a table with a (file,revision)->commit mapping,
> > I suppose something can generate it when importing from cvs?
> 
> That's what we decided to do on a recent CVS-to-Git conversion, though
> like you, we also considered munging the log messages instead.  Our
> jury's still out on whether it was the right decision; we haven't had
> much cause to use the result yet.
> 
> One thing to be aware of (beyond the need to run grep to convert old
> CVS revision numbers to Git commit IDs) is that there's a good chance
> the mapping file will pollute the results of `git grep` for some
> tasks.  (We've put the mapping file into our repo, where it's easy to
> find.)  I'm considering gzipping the mapping file as a workaround;
> that would mean our users will need to use zgrep (or equivalent) to
> look up CVS revision numbers, which may or may not be a problem in
> your situation.
> 
> I have an initial patch to git-cvsimport that adds a switch to
> generate the mapping as it goes.  I'm currently trying to find time to
> clean it up and submit it.

You could consider adding the CVS revision numbers as notes (see "git help 
notes" in >= v1.6.6) to the corresponding commits. Then they don't pollute 
the commit messages, but instead live in a separate, but parallel hierarchy 
that can be easily pulled in when you need to reference them (e.g. 
GIT_NOTES_REF="refs/" git log).

The notes feature is still very new, and there are still outstanding patches 
to be merged, but the basics are there in v1.6.6.

FWIW, I was also working on a CVS-to-Git importer (based on what has later 
become the transport-helper infrastructure), that used notes to store 
exactly the metadata you mention above. However, I haven't worked on it for 
a while, and I probably won't have time to pick it up in the immediate 
future.


...Johan

-- 
Johan Herland, <johan@herland.net>
www.herland.net