Subject: Re: upload-pack is slow with lots of refs

From: Sascha Cunz <[email-masked]>
Date: Thu, 04 Oct 2012 23:52:13 +0200

Am Mittwoch, 3. Oktober 2012, 16:13:16 schrieb Jeff King:
> On Wed, Oct 03, 2012 at 12:41:38PM -0700, Shawn O. Pearce wrote:
> > > Out of curiosity, how are you thinking about triggering such a new
> > > behavior in a backwards-compatible way? Invoke git-upload-pack2, and
> > > fall back to reconnecting to start git-upload-pack if it fails?
> > 
> > Basically, yes. New clients connect for git-upload-pack2. Over git://
> > the remote peer will just close the TCP socket with no messages. The
> > client can fallback to git-upload-pack and try again. Over SSH a
> > similar thing will happen in the sense there is no data output from
> > the remote side, so the client can try again. This has the downside of
> > authentication twice over SSH, which may prompt for a password twice.
> > But the user can get out of this by setting remote.NAME.uploadpack =
> > git-upload-pack and thus force the Git client to use the current
> > protocol if they have a new client and must continue to work over SSH
> > with an old server, and don't use an ssh-agent.
> 
> It's a shame that we have to reestablish the TCP or ssh connection to do
> the retry. The password thing is annoying, but also it just wastes a
> round-trip. It means we'd probably want to default the v2 probe to off
> (and let the user turn it on for a specific remote) until v2 is much
> more common than v1. Otherwise everyone pays the price.

Would it be possible to use this workflow:

- Every client connects per default to v1

- If server is capable of v2, it sends a flag along with the usual response
  (A v1 server will obviously not send that flag)

- If client is also capable of v2 and gets the flag, it enables v2 for
  just that remote (probably unless the user said, "i never want to")

- Next time the client connects to that remote it will use v2.

I'm not sure, if this is possible, since I think to remember that I have read 
in the Documentation folder something along the line: Capabilities announced 
from the server mean "I want you to use exactly these flags".

Sascha