Re: Git commit generation numbers

From: Junio C Hamano <gitster@pobox.com>
Date: Jul 14, 2011, 20:26 UTC
Message-ID: <7vmxgg38xz.fsf@alter.siamese.dyndns.org>
In-Reply-To: <20110714183710.GA26820@sigill.intra.peff.net>

Jeff King <peff@peff.net> writes:

> There's also one other issue with generation numbers. How do you handle
> grafts and object-replacement refs?  If you graft history, your embedded
> generation numbers will all be junk, and you can't trust them.

By the way, I doubt your "invalidate and recompute generation cache when replacement changes" would really work when we consider object transfer (which is the whole point of deprecating graft with object replacement mechanism). For the purpose of connectivity check during object transfer, we deliberately _ignore_ the object replacements, so you would at least want to have an ability to show the generation number according to the "true" history recorded in commits (which can come from Linus's in-commit generation number once everybody migrates) and the generation number that takes grafts and replacements into account (for which we cannot depend on in-commit record).