From: Junio C Hamano <gitster@pobox.com>
Date: Thu, 22 Apr 2010 00:19:16 GMT
Subject: Re: 'git notes merge' implementation questions
Message-ID: <7vzl0w730b.fsf@alter.siamese.dyndns.org>
In-Reply-To: <201004220208.03706.johan@herland.net>

Johan Herland <johan@herland.net> writes:

> Next, we will need to be somewhat careful about using "ls-tree", to avoid 
> needlessly unpacking subtrees that are identical between <ours> and 
> <theirs>.

My mentioning of "ls-tree" is only about what needs to be done at the
conceptual level.  In practice, assuming that notes trees have mostly the
same fan-out structure, you would run "diff-tree -r" of (base,ours) and
(base,theirs) pair _without_ anything fancy like rename detection, and
pick out pieces (one tree may have ab/cdx{36} while the other tree may
have abcd/x{36} that are notes about the same object---you treat this as
if it is a partial ls-tree output that pertains only to the different
parts, and make canonical "list of annotated objects" by removing '/'.

All of this is very specific to merging "notes" and normal "merge" does
not even want to know about it; I don't think you can avoid doing this
yourself without touching "merge" if you want to merge "notes" correctly.