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Re: incremental conversion from other SCM to svn by vcp

From: Chia-liang Kao <clkao_at_clkao.org>
Date: 2003-06-13 19:40:29 CEST

On Fri, Jun 13, 2003 at 11:21:35AM -0500, kfogel@collab.net wrote:
> - The subversion dest driver for VCP handles branches pretty well,
> because VCP itself already does the branch-point finding. So
> branches are created as copies, with the appropriate files added
> or removed when necessary. The revision history of your sample
> repository at http://svn.openfoundry.org/svn/sympa/ shows this.

actually the vcp core does only per-file branch point deduction. but
the revision in svn semantic (svn cp trunk -r <which>) for branching
is decided by the create_branch function in VCP::Dest::svn i wrote.

> - But it doesn't handle tags, because VCP doesn't deduce the tag
> points in the same way. Instead, it just marks the tags per file
> revision... which doesn't help us much in Subversion.

it shouldn't be hard to implement that. since the deduction is pretty much
like I did in branching point: decide the `global point' from from points of
every files.

> - The conversion time seems a bit slow to me (7 hours for 2000 svn
> revs with four branches). Extrapolating from cvs2svn.py's
> performance right now, I think it would do that in 10 minutes at
> the most. But perhaps there are optimizations you are planning?

as i saw in the profiling from vcp log, svn commit takes some time, the
longest is 20 sec or so for one large commit. but the bottle neck right
now is how it extracts every revision from cvs: doing cvs checkout -r
<revision> <onefile> for every file. i'll be implementing fast retrieval
of cvs by setting date tag and verifying the resulting revision, hopefully
this would boost conversion time. but more importantly is that the conversion
is incremental, so even if the very first conversion of a large repository is
slow, subsequent conversion of newly committed files won't take long.

> Because of the tag problem, and the timings, I'm continuing with
> cvs2svn.py (which I judge to be "near" completion, famous last words).
> But I hope you're planning to continue with the VCP work -- it's an
> important gateway to other SCM systems. And if it eventually makes
> cvs2svn obsolete, no one will be happier than me! :-)

yes I do. basically it's motivated by scratch-ones-own-itches as I mentioned
on irc. :) another advantage of vcp is that there source driver for other
scm, specifically p4, which the perl folks are currently using, and it's
said to be a consensus to switch to svn.


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Received on Fri Jun 13 19:41:08 2003

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