From mboxrd@z Thu Jan  1 00:00:00 1970
From: Paul Mackerras <paulus@samba.org>
Subject: Re: [RFC] gitweb wishlist and TODO list
Date: Sat, 1 Jul 2006 20:35:52 +1000
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Cc: "Jakub Narebski" <jnareb@gmail.com>, git@vger.kernel.org
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To: "Martin Langhoff" <martin.langhoff@gmail.com>
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Martin Langhoff writes:

> > If I remember correctly, it was done in the background, and it was done
> > at least partially _in_ gitk (Tcl/Tk).
> 
> I suspect it is doing a whole lot of git-merge-base invocations, which
> are rather costly. I don't know of any cheaper way to ask that
> question.

There's no git-merge-base involved.  Gitk does a

git-rev-list --all --topo-order --parents

and reads the output of that, and then traverses the entire graph
forwards and backwards (in Tcl).  (This is after gitk has read the
output of git ls-remote $GIT_DIR, so it knows which commits have
tags.)

Paul.