From: David Turner <dturner@twopensource.com>
To: Jeff King <peff@peff.net>
Cc: Shawn Pearce <spearce@spearce.org>,
Junio C Hamano <gitster@pobox.com>,
git@vger.kernel.org
Subject: Re: [PATCH/RFC 4/6] transport: add refspec list parameters to functions
Date: Mon, 25 Apr 2016 12:44:07 -0400 [thread overview]
Message-ID: <1461602647.25914.2.camel@twopensource.com> (raw)
In-Reply-To: <20160420205726.GA17876@sigill.intra.peff.net>
On Wed, 2016-04-20 at 16:57 -0400, Jeff King wrote:
> On Wed, Apr 20, 2016 at 04:46:55PM -0400, David Turner wrote:
>
> > As you note, it appears that git-daemon does sort-of have support
> > for
> > extra args -- see parse_host_arg. So it wouldn't be hard to add
> > something here. Unfortunately, current versions of git die on
> > unknown
> > args. So this change would not be backwards-compatible. We could
> > put
> > a decider on it so that clients would only try it when explicitly
> > enabled. Or we could have clients try it with, and in the event of
> > an
> > error, retry without. Neither is ideal, but both are possible.
>
> Right. This ends up being the same difficulty that the v2 protocol
> encountered; how do you figure out what you can speak without
> resorting
> to expensive fallbacks, when do you flip the switch, do you remember
> the
> protocol you used last time with this server, etc.
Right.
[moved]
> > If I read this code correctly, git-over-ssh will pass through
> > arbitrary
> > arguments. So this should be trivial.
>
> It does if you are ssh-ing to a real shell-level account on the
> server,
> but if you are using git-shell or some other wrapper to restrict
> clients
> from running arbitrary commands, it will likely reject it.
Oh, I see how I was mis-reading shell.c. Oops.
[/moved]
> Which isn't to say it's necessarily a bad thing. Maybe the path
> forward
> instead of v2 is to shoe-horn this data into the pre-protocol
> conversation, and go from there. The protocol accepts that "somehow"
> it
> got some extra data from the transport layer, and acts on its
> uniformly.
OK, so it seems like only HTTP (and non-git-shell-git://) allow backwar
ds-compatible optional pre-protocol messages. So we don't have good
options; we only have bad ones. We have to decide which particular
kind of badness we're willing to accept, and to what degree we care
about extensibility. As I see it, the badness options are (in no
particular order):
1. Nothing changes.
2. HTTP grows more extensions; other protocols stagnate.
3. HTTP grows extensions; other protocols get extensions but:
a. only use them on explicit client configuration or
b. try/fail/remember per-remote
4. A backwards-incompatible protocol v2 is introduced, which
hits alternate endpoints (with the same a/b as above). This is
different from 3. in that protocol v2 is explicitly designed around
a capabilities negotiation phase rather than unilateral client-side
decisions.
5. Think of another way to make fetch performant with many refs, and
defer the extension decision.
next prev parent reply other threads:[~2016-04-25 16:44 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-04-15 19:19 [PATCH/RFC 0/6] fetch with refspec David Turner
2016-04-15 19:19 ` [PATCH/RFC 1/6] http-backend: use argv_array functions David Turner
2016-04-18 18:34 ` Junio C Hamano
2016-04-19 19:11 ` David Turner
2016-04-15 19:19 ` [PATCH/RFC 2/6] remote-curl.c: fix variable shadowing David Turner
2016-04-18 18:35 ` Junio C Hamano
2016-04-19 19:14 ` David Turner
2016-04-15 19:19 ` [PATCH/RFC 3/6] http-backend: handle refspec argument David Turner
2016-04-17 1:51 ` Eric Sunshine
2016-04-19 18:57 ` David Turner
2016-04-15 19:19 ` [PATCH/RFC 4/6] transport: add refspec list parameters to functions David Turner
2016-04-18 18:45 ` Junio C Hamano
2016-04-19 7:14 ` Jeff King
2016-04-19 18:04 ` Stefan Beller
2016-04-19 20:55 ` Junio C Hamano
2016-04-19 21:40 ` David Turner
2016-04-19 23:22 ` Jeff King
2016-04-19 23:43 ` David Turner
2016-04-20 1:17 ` Jeff King
2016-04-20 20:46 ` David Turner
2016-04-20 20:57 ` Jeff King
2016-04-25 16:44 ` David Turner [this message]
2016-04-25 22:10 ` Stefan Beller
2016-04-27 3:59 ` Stefan Beller
2016-04-27 4:11 ` Jeff King
2016-04-27 15:07 ` Junio C Hamano
2016-04-29 23:05 ` David Turner
2016-04-29 23:12 ` Stefan Beller
2016-04-19 19:31 ` David Turner
2016-04-15 19:19 ` [PATCH/RFC 5/6] fetch: pass refspec to http server David Turner
2016-04-17 2:33 ` Eric Sunshine
2016-04-19 21:25 ` David Turner
2016-04-15 19:19 ` [PATCH/RFC 6/6] clone: send refspec for single-branch clones David Turner
2016-04-17 2:36 ` Eric Sunshine
2016-04-19 21:24 ` David Turner
2016-04-15 19:30 ` [PATCH/RFC 0/6] fetch with refspec Stefan Beller
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
List information: http://vger.kernel.org/majordomo-info.html
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=1461602647.25914.2.camel@twopensource.com \
--to=dturner@twopensource.com \
--cc=git@vger.kernel.org \
--cc=gitster@pobox.com \
--cc=peff@peff.net \
--cc=spearce@spearce.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
Code repositories for project(s) associated with this public inbox
https://80x24.org/mirrors/git.git
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).