From: Jakub Narebski <jnareb@gmail.com>
To: Shawn Pearce <spearce@spearce.org>
Cc: Johannes Sixt <j.sixt@viscovery.net>,
Clemens Buchacher <drizzd@aon.at>, Jeff King <peff@peff.net>,
Junio C Hamano <gitster@pobox.com>,
Jonathan Nieder <jrnieder@gmail.com>,
netroby <hufeng1987@gmail.com>,
Git Mail List <git@vger.kernel.org>,
Tomas Carnecky <tom@dbservice.com>
Subject: Re: New Feature wanted: Is it possible to let git clone continue last break point?
Date: Fri, 04 Nov 2011 08:55:32 -0700 (PDT) [thread overview]
Message-ID: <m3k47f51f0.fsf@localhost.localdomain> (raw)
In-Reply-To: <CAJo=hJtsiEEHA33CQn1MCvb7vFv7uEF+U292YgBa7EWv7P8Jng@mail.gmail.com>
Shawn Pearce <spearce@spearce.org> writes:
> On Fri, Nov 4, 2011 at 02:35, Johannes Sixt <j.sixt@viscovery.net> wrote:
> > Am 11/4/2011 9:56, schrieb Clemens Buchacher:
> > > Cache ... not the pack but the information
> > > to re-create it...
> >
> > It has been discussed. It doesn't work. Because with threaded pack
> > generation, the resulting pack is not deterministic.
>
> The information to create a pack for a repository with 2M objects
> (e.g. Linux kernel tree) is *at least* 152M of data. This is just a
> first order approximation of what it takes to write out the 2M SHA-1s,
> along with say a 4 byte length so you can find given an offset
> provided by the client roughly where to resumse in the object stream.
> This is like 25% of the pack size itself. Ouch.
Well, perhaps caching a few most popular packs in some kind of cache
(packfile is saved to disk as it is streamed if we detect that it will
be large), indexing by WANT / HAVE?
> This data is still insufficient to resume from. A correct solution
> would allow you to resume in the middle of an object, which means we
> also need to store some sort of indicator of which representation was
> chosen from an existing pack file for object reuse. Which adds more
> data to the stream. And then there is the not so simple problem of how
> to resume in the middle of an object that was being recompressed on
> the fly, such as a large loose object.
Well, so you wouldn't be able to just concatenate packs^W received
data. Still it should be possible to "repair" halfway downloaded
partial pack...
Just my 2 eurocents^W groszy.
--
Jakub Narębski
next prev parent reply other threads:[~2011-11-04 15:55 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CAEZo+gfKVY-YgMjd=bEYzRV4-460kqDik-yVcQ9Xs=DoCZOMDg@mail.gmail.com>
2011-10-31 2:28 ` New Feature wanted: Is it possible to let git clone continue last break point? netroby
2011-10-31 4:00 ` Tay Ray Chuan
2011-10-31 9:07 ` Jonathan Nieder
2011-10-31 9:16 ` netroby
2011-11-02 22:06 ` Jeff King
2011-11-02 22:41 ` Junio C Hamano
2011-11-02 23:27 ` Jeff King
2011-11-03 0:06 ` Shawn Pearce
2011-11-03 2:42 ` Jeff King
2011-11-03 4:19 ` Shawn Pearce
2011-11-04 8:56 ` Clemens Buchacher
2011-11-04 9:35 ` Johannes Sixt
2011-11-04 14:22 ` Shawn Pearce
2011-11-04 15:55 ` Jakub Narebski [this message]
2011-11-04 16:05 ` Nguyen Thai Ngoc Duy
2011-11-05 10:00 ` Clemens Buchacher
2011-10-31 9:14 ` Jakub Narebski
2011-10-31 12:49 ` Michael Schubert
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