Re: git pack/unpack over bittorrent - works!

From: Luke Kenneth Casson Leighton <luke.leighton@gmail.com>
To: gitzilla@gmail.com
Cc: Nguyen Thai Ngoc Duy <pclouds@gmail.com>, git <git@vger.kernel.org>
Subject: Re: git pack/unpack over bittorrent - works!
Date: Thu, 2 Sep 2010 16:51:46 +0100	[thread overview]
Message-ID: <AANLkTi=W3QwWSrNTie-K4QDDrucSVGQa5e3Ldy7m7ihy@mail.gmail.com> (raw)
In-Reply-To: <AANLkTikBnKQJmgOms2wK1+6fCLtHWiWkhuCVMN7kKLXP@mail.gmail.com>

On Thu, Sep 2, 2010 at 4:42 PM, Luke Kenneth Casson Leighton
<luke.leighton@gmail.com> wrote:
> On Thu, Sep 2, 2010 at 4:33 PM, A Large Angry SCM <gitzilla@gmail.com> wrote:

> * is it possible to _make_ the repository guaranteed to produce
> identical pack objects?

 i.e. looking at these options, listed from
Documentation/technical/protocol.txt:

    00887217a7c7e582c46cec22a130adf4b9d7d950fba0 HEAD\0multi_ack
thin-pack side-band side-band-64k ofs-delta shallow no-progress
include-tag

 is it possible to use shallow, thin-pack, side-band or side-band-64k
to guarantee that the pack object will be identical?

 another important question:

* if after performing a "git unpack" of one pack-object, can it be
guaranteed that performing a "git pack-object" on the *exact* same ref
and the *exact* same object-ref, will produce the *exact* same
pack-object that was used by "git unpack", as long as the exact same
arguments are used?  if not, why not, and if not under _some_
circumstances, under what circumstances _can_ the exact same
pack-object be retrieved that was just used?

if there is absolutely absolutely no way to guarantee that the
pack-objects can be the same, under no circumstances or combinations
of arguments or by forcing only compatible versions to communicate
etc. etc., a rather awful work-around can be applied which is to share
and permanently cache every single pack-object, rather than use what's
gone into the repo.

l.