Re: [QUESTION] about .git/info/grafts file

From: Junio C Hamano <junkio@cox.net>
Date: Jan 20, 2006, 17:59 UTC
Message-ID: <7v4q3ybx0m.fsf@assigned-by-dhcp.cox.net>
In-Reply-To: <cda58cb80601200207g7c3495ddx@mail.gmail.com>

Franck <vagabon.xyz@gmail.com> writes:

Show 5 quoted lines

> 2006/1/20, Junio C Hamano <junkio@cox.net>:
>
>>         $ git clone git.git junk
>>         $ cd junk ;# I am not brave enough to risk the real thing ;-)
>>         $ git rev-parse master~4 >.git/refs/info/grafts

Typo: 	's|.git/refs/info/grafts|.git/info/grafts|'

BTW the above exact sequence will not work with my "master" today, since I merged up bunch of things last night. You have to cauterize all the paths that lead to earlier history. For example, if I have this:

   ---o---o---x---o---o---o---o (master)
       \         /
        o---o---o

cauterizing at master~4 ('x') will still leak history via the side branch, if you follow the history from the tip and go backwards. I have to also cauterize the merge commit after that to remove the side branch, or cauterize the leftmost branch point and live with a bit deeper history. The choice depends on how much real history I want to keep in the pruned history.

For example, to pretend the history was like this:

   ---o---o   x---o---o---o---o (master)
       \         
        o---o---o

	$ git rev-parse master~4 >.git/info/grafts ;# 'x'
        $ git rev-parse master~3 master~4 >.git/info/grafts

The second line says master~3 (the one that comes after 'x') has only a single parent, which is master~4, in order to throw the side branch away [*1*].

Back to the original example...

Show 6 quoted lines

>>         $ cd ..
>>         $ mkdir cloned
>>         $ cd cloned
>>         $ git init-db
>>         $ cp ../junk/.git/info/grafts .git/info/
>>         $ git clone-pack ../baz

There are a couple of typos here and that was the reason your experiment did not work. Sorry. The "clone-pack" should have been like this:

        $ git clone-pack ../junk master
        Packing 471 objects
        e7555785f4edcf4988c53305349e3f525216e2cb refs/heads/master
	$ git-rev-parse e7555785f >.git/refs/heads/master

This 'cloned' is the lightweight one.

> does the git protocol is really needed in your example ? or can rsync
> work fine too since "franck.git" repo is cautorized so every objects
> of this repo shouldn't be part of old history, so they should be
> usefull, no ?

rsync may for the initial clone but its use afterwards is frowned upon for other reasons these days.

[Footnote]

*1* There still is an anomaly if you look at "git log" after pruning side branch this way; master~3 commit is still shown as "merge". I think you could call it a bug, but I am not sure it is worth fixing.