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From: Shawn Pearce <spearce@spearce.org>
To: Jeff King <peff@peff.net>
Cc: git <git@vger.kernel.org>
Subject: Re: RFC: Resumable clone based on hybrid "smart" and "dumb" HTTP
Date: Sat, 13 Feb 2016 18:14:31 -0800	[thread overview]
Message-ID: <CAJo=hJv-GWZOsv31iekW+AdNazLGQ=XYD=UXMO+RuB15baTsow@mail.gmail.com> (raw)
In-Reply-To: <20160210214945.GA5853@sigill.intra.peff.net>

On Wed, Feb 10, 2016 at 1:49 PM, Jeff King <peff@peff.net> wrote:
> On Wed, Feb 10, 2016 at 12:11:46PM -0800, Shawn Pearce wrote:
>
>> On Wed, Feb 10, 2016 at 10:59 AM, Shawn Pearce <spearce@spearce.org> wrote:
>> >
>> > ... Thoughts?
>>
>> Several of us at $DAY_JOB talked about this more today and thought a
>> variation makes more sense:
>>
>> 1. Clients attempting clone ask for /info/refs?service=git-upload-pack
>> like they do today.
>>
>> 2. Servers that support resumable clone include a "resumable"
>> capability in the advertisement.
>
> Because the magic happens in the git protocol, that would mean this does
> not have to be limited to git-over-http. It could be "resumable=<url>"
> to point the client anywhere (the same server over a different protocol,
> another server, etc).
>
>> 3. Updated clients on clone request GET /info/refs?service=git-resumable-clone.
>>
>> 4. The server may return a 302 Redirect to its current "mostly whole"
>> pack file. This can be more flexible than "refs/heads/*", it just
>> needs to be a mostly complete pack file that contains a complete graph
>> from any arbitrary roots.
>
> And with "resumable=<url>", the client does not have to hit the server
> to do a redirect; it can go straight to the final URL, saving a
> round-trip.

It occurred to me today that to make the above ("resumable=<url>") as
efficient as possible, we should allow HTTP clients to include
&resumable=1 in the GET /info/refs URL as a hint to the server that if
it serves a resumable=<url> it can shrink the ref advertisement to 1
line containing the capabilities.

Clients are going to follow the returned <url> to get a bundle header,
which contains the references. And then incremental fetch from the
server after downloading the pack. So returning references with the
resumable URL during a clone is an unnecessary waste of bandwidth.

We could also consider allowing resumable=<url> to be relative to the
repository, so that on HTTP schemes a server could just reply
resumable=pack-HASH.info or something short and not worry about
overflowing the capabilities line.

  parent reply	other threads:[~2016-02-14  2:14 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-02-10 18:59 RFC: Resumable clone based on hybrid "smart" and "dumb" HTTP Shawn Pearce
2016-02-10 20:11 ` Shawn Pearce
2016-02-10 20:23   ` Stefan Beller
2016-02-10 20:57     ` Junio C Hamano
2016-02-10 21:22       ` Jonathan Nieder
2016-02-10 22:03         ` Jeff King
2016-02-10 21:01     ` Jonathan Nieder
2016-02-10 21:07       ` Junio C Hamano
2016-02-11  3:43       ` Junio C Hamano
2016-02-11 18:04         ` Shawn Pearce
2016-02-11 23:53       ` Duy Nguyen
2016-02-13  5:07         ` Junio C Hamano
2016-02-10 21:49   ` Jeff King
2016-02-10 22:17     ` Jonathan Nieder
2016-02-10 23:03       ` Jeff King
2016-02-10 22:40     ` Junio C Hamano
2016-02-11 21:32     ` Junio C Hamano
2016-02-11 21:46       ` Jeff King
2016-02-13  1:40     ` Blake Burkhart
2016-02-13 17:00       ` Jeff King
2016-02-14  2:14     ` Shawn Pearce [this message]
2016-02-14 17:05       ` Jeff King
2016-02-14 17:56         ` Shawn Pearce
2016-02-16 18:34         ` Stefan Beller

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