Re: [Boost-users] What's happened to Ryppl?

Subject: Re: [Boost-users] What's happened to Ryppl?
From: Dave Abrahams (dave_at_[hidden])
Date: 2011-01-25 11:58:13

At Mon, 24 Jan 2011 22:36:02 -0500,
John Wiegley wrote:
> 
> Dave Abrahams <dave_at_[hidden]> writes:
> 
> >> Exactly.  I'm 98% of the way toward a branchified sequence today.
> >
> > Awesome!
> 
> OK, branchification is working!  All that's left is submodulization as part of
> the same run.

What do you mean by "submodulization?"  I don't think we'll end up
using Git submodules much in the end, but I can imagine why you'd want
to do that now.

> This will actually not be very difficult, just time consuming to run.  I'll
> use Eric's manifest.txt file, plus 'git log --follow -C --find-copies-harder'
> on each element of each submodule, run against the flat history.  The man page
> says this is an O(N^2) operation -- where N is very large in Boost's case --
> so I may end up having to do some pruning to keep it from getting out of hand.
> 
> Actually, the speed of this script is already too slow, so I'm rewriting it in
> C++ today both for the native speed increase (10x so far, for dump-file
> parsing), and because it lets me use libgit2 (https://github.com/libgit2) to
> create Git objects directly, rather than shelling out to git-hash-object and
> git-mktree over a million times.  That alone takes over 15 hours to do on my
> Mac Pro.  Don't even ask how long the git gc takes to run!  (It's longer).
> 
> If anyone wonders whether my process -- which works for any Subversion repo,
> btw, not just Boost -- preserves more information than plain git-svn: consider
> that my branchified Git has just over one million Git objects in it, while the
> boost-svn repository on ryppl has only 593026 right now.  That means over 40%
> of the repository's objects got dropped on the cutting floor by git-svn's
> hueristics.

Yay, John! :-)

-- 
Dave Abrahams
BoostPro Computing
http://www.boostpro.com