From: Jeff King <peff@peff.net>
Date: Thu, 30 Aug 2012 03:55:52 GMT
Subject: Re: [PATCH 3/3] name-rev: --weight option (WIP)
Message-ID: <20120830035552.GC32268@sigill.intra.peff.net>
In-Reply-To: <7vharlujaq.fsf@alter.siamese.dyndns.org>

On Wed, Aug 29, 2012 at 08:53:49PM -0700, Junio C Hamano wrote:

> Jeff King <peff@peff.net> writes:
> 
> > I wonder if you can
> > define the weight as a recursive function of the parents.
> 
> I do not think we can.  A merge Z between X (that has N commits
> behind it) and Y (that has M commits behind it) has at most N+M+1
> commits behind it (counting itself), but we cannot tell how many
> among these N and M are shared.
> 
> > That would double-count "A" and "B" in this example. But maybe there is
> > a clever way to define it that avoids that.
> 
> We've dealt with this issue long time ago when we optimized the
> bisection count, which involves exactly the same issue.

OK. I didn't think too hard about it, so I'll trust you that it is not
easy. I wonder if using the generation number would be another way of
defining "oldest" that would be easier to calculate.

-Peff