Re: Git commit generation numbers

On Fri, Jul 15, 2011 at 09:10, Linus Torvalds
[off-list ref] wrote:

Right now, we do *have* a "generation number". It's just that it's
very easy to corrupt even by mistake. It's called "committer date". We
could improve on it.

...

If I had realized how small the patch was to add generation counters,
and that it wouldn't have broken backwards compatibility (ie fsck
doesn't start complaining). I would have done it originally, instead
of all the crazy hacks we did for commit date verification.

What about going forward making the requirement that a new commit must
have a committer date whose date is >= the maximum date of its
parents?

We could also add a check during fast-forward merges to refuse to
perform the merge if the incoming commit has a committer date too far
forward in the future (e.g. more than 5 minutes). If you pull from a
moron whose system clock is set such that the committer date isn't a
proxy for generation number, Git would just refuse the merge, and you
could ask them to fix their objects.

-- 
Shawn.