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From: Stefan Beller <sbeller@google.com>
To: Jeff King <peff@peff.net>
Cc: Josh Triplett <josh@joshtriplett.org>,
	"git@vger.kernel.org" <git@vger.kernel.org>
Subject: Re: upload-pack/ls-remote: showing non-HEAD symbolic refs?
Date: Tue, 16 Aug 2016 11:50:11 -0700
Message-ID: <CAGZ79kZ7dzh6AhQRQZsEFdWB4MQxW431yfDuEXao=k_meNE8Nw@mail.gmail.com> (raw)
In-Reply-To: <20160816182852.inyqzplee5m3wzt6@sigill.intra.peff.net>

On Tue, Aug 16, 2016 at 11:28 AM, Jeff King <peff@peff.net> wrote:
> On Tue, Aug 16, 2016 at 10:34:44AM -0700, Josh Triplett wrote:
>
>> > Sadly you cannot use a capability to fix that, because all of this
>> > happens before the client agrees to any capabilities (you can find
>> > discussion of a "v2" protocol on the list which solves this, but it's
>> > sort of languishing in the design phase).
>>
>> As a potential 1.1 version, which could work in a backward-compatible
>> way with existing servers and no additional round-trip: what if, in the
>> smart HTTP protocol, the client advertised client capabilities with an
>> additional HTTP header (e.g.  "Git-Client-Caps: symrefs othershiny
>> featurenames"?  git-http-backend could then pass those capabilities to
>> git-upload-pack (--client-caps='...'), which could take them into
>> account in the initial response?
>>
>> That wouldn't work as a single-pass approach for SSH, since the client
>> can't know if the server's upload-pack supports --client-caps, but it
>> would work for the smart HTTP protocol.
>
> You can dig up the discussion on the list under the name "protocol v2",
> but basically yes, that approach has been considered. It's a little
> gross just because it leaves other protocols behind http (and it is not
> necessarily a good idea to push people into http, because it has some
> fundamental drawbacks over the other protocols because of its
> half-duplex nature).

Some more thoughts on protocol v2 (the good parts to be attributed to
jrnieder@gmail.com):

* In case of http we can use the http header and know information
  about the client, i.e. if it may support the following ideas:

* Instead of introducing a new protocol we introduce a capability\
  "resend-ref-advertisement" and only advertise very few refs (e.g.
  only the branches, not the pending changes in case of Gerrit)

* The client can then ignore the refs advertisement and ask for a resend
  of the refs with more specification,
  e.g. "want refs/heads/*", so allowing more than just sha1s in the
  want line but complex things like branch patterns.

>
>> > That should Just Work over the existing http protocol without requiring
>> > an extra request.
>>
>> It'd require one extra request for git ls-remote, which normally doesn't
>> need the second round-trip, but that still seems reasonable.
>
> Good point. I don't think there's an easy way around that short of v2 or
> v1.1 that you mention above. I agree it's probably reasonable, though.
>
> -Peff
> --
> To unsubscribe from this list: send the line "unsubscribe git" in
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> More majordomo info at  http://vger.kernel.org/majordomo-info.html

  reply	other threads:[~2016-08-16 18:50 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-08-16 16:18 Josh Triplett
2016-08-16 16:31 ` Jeff King
2016-08-16 17:34   ` Josh Triplett
2016-08-16 18:28     ` Jeff King
2016-08-16 18:50       ` Stefan Beller [this message]
2016-08-16 20:34         ` Josh Triplett
2016-08-16 20:31       ` Josh Triplett
2016-08-16 20:54         ` Jeff King
2016-08-16 21:11           ` Josh Triplett
2016-08-16 21:15             ` Jeff King
2016-08-16 22:24               ` Josh Triplett
2016-08-19 13:47                 ` Jeff King

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