Re: Moving NetBSD from CVS to svn|git|hg|fossil

[David Holland <dholland-tech%netbsd.org@localhost>]

On Sun, Apr 24, 2016 at 12:41:19AM +0200, Kamil Rytarowski wrote:
 > >> Going out of cvs to svn/git will alienate significant part of
 > >> Tier 1 port machines and most of the Tier 2 ones.
 > >> 
 > >> Could you please list your wish list of features to add/improve
 > >> in cvs(1 )?
 > > 
 > > see e.g.
 > > http://mail-index.netbsd.org/tech-repository/2008/07/29/msg000036.html
 > >
 > >  Improving CVS is not feasible.
 > 
 > I wrote privately librcs to parse the RCS format with flex + byacc...
 > with plans to add libcvs, however the performance of processing all ,v
 > files in src xsrc isn't acceptable. I will try to rewrite it in pure C.

that's... not entirely surprising :(

 > All the pointed features could be added including renames with RCS -
 > just store common commit id for delete and create. The bottleneck is
 > with the format, it's not trivial to process it quickly, unless we are
 > close to HEAD.

You'd at least need additional on-disk data structures for the
non-local information. And, handling renames so they work right (that
is, history lookups cross renames transparently or near-transparently)
would require a lot of work all over the CVS code. And the resulting
performance would likely be terrible.

Also I'm not convinced that it's possible to rectify the gaps in CVS's
branch semantics this way.

 > I'm not sure that it's worth to invent new format.. and break
 > compatibility with the world.

I dunno. ISTM that if one is going to put this much effort in,
implementing bikeshed is a better plan -- probably less work total and
you get something better out -- but it's a core principle in NetBSD
that you don't tell other people what they ought to be working on.

-- 
David A. Holland
dholland%netbsd.org@localhost