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From: Junio C Hamano <gitster@pobox•com>
To: Marc Branchaud <marcnarc@xiplink•com>
Cc: git@vger•kernel.org
Subject: Re: [PATCH] clone: --dissociate option to mark that reference is only temporary
Date: Wed, 15 Oct 2014 10:29:24 -0700	[thread overview]
Message-ID: <xmqqwq81w8az.fsf@gitster.dls.corp.google.com> (raw)
In-Reply-To: <543E85FA.6050404@xiplink.com> (Marc Branchaud's message of "Wed, 15 Oct 2014 10:34:34 -0400")

Marc Branchaud <marcnarc@xiplink•com> writes:

> I think things would be more understandable if the option was "--dissociate
> <repository>" and was an explicit alternative to --reference:
> 	[[--reference | --dissociate] <repository>]
>
> I'm still not liking the name "--dissociate" though.  The original suggestion
> of "--borrow" is better.  Perhaps "--library" or "--local-cache"?  I dunno...

I was not thinking when I originally started the topic with
"--borrow", until I realized that it would not make much sense,
primarily because we allow multiple references.

What should this command line do, and how would you implement such a
behaviour?

    $ git clone \
        --reference=/local/pool/linux.git \
        --borrow=../my/neighbour/linux-hack.git \
        git://git.kernel.org/...../linux.git

With "do the usual --reference thing, but then dissociate the result
from referents" option, there is no ambiguity and that is why I did
not go with the "--borrow" option suggested in the original thread.

> So now I'm wondering if the implementation would be more efficient as an
> extension of the --local operation.  That is, instead of a post-clone repack,
> do a --local clone first followed by a simple "git fetch" from the source repo.

The network overhead may be comparable to the "--reference"
optimization, but if your "clone --local" ends up copying (instead
of hard-linking), the initial cost to copy locally would be a pure
extra price over "clone --reference and then --dissociate".  If the
local clone uses hard-linking, it would be cheaper, but it still
costs more than dropping an entry into .git/objects/info/alternates,
I would imagine.  You will pay with your scheme the same cost to run
"repack -a -d", which is paid by "--dissociate" at the end of clone,
eventually at the first "gc", so there is no efficiency advantage,
either.

The above is my knee-jerk assessment without any measuring, though.

  reply	other threads:[~2014-10-15 17:29 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-10-14 19:57 [PATCH] clone: --dissociate option to mark that reference is only temporary Junio C Hamano
2014-10-15 14:34 ` Marc Branchaud
2014-10-15 17:29   ` Junio C Hamano [this message]
2014-10-15 20:51     ` Marc Branchaud
2014-10-15 21:33       ` Junio C Hamano
2014-10-15 21:44         ` Marc Branchaud
2014-10-15 21:50           ` Junio C Hamano
2014-10-16 15:26             ` Marc Branchaud
2014-10-17 12:47               ` Jakub Narębski
2014-10-16 19:27     ` Junio C Hamano
2014-10-15 19:44 ` Johannes Sixt
2014-10-15 21:33   ` Junio C Hamano

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