Re: [PATCH 4/5] upload-pack: implement protocol extension "symbolic-ref"

[Junio C Hamano <gitster@pobox.com>]

Jeff King <peff@peff.net> writes:

> On Sun, Nov 30, 2008 at 01:57:29AM -0800, Junio C Hamano wrote:
> ...
>> This is unfortunate because it forces an extra round trip (receiving end
>> sends a "please tell me symbolic-ref" packet, and then upload side sends
>> "here are the requested information" packet), but it has to be implemented
>> this way because (1) ls-remote may need to ask for this information, in
>> which case there is no "want" to be sent; and (2) the transport API
>> insists that transport_get_remote_refs() returns the final list, and does
>> not allow augmenting what was initially obtained from the call to it by
>> later calls to transport_fetch_refs() easily.
>
> Hrm. For (1), could we allow either interaction method? IOW, allow
> requesting a symref on the first want line, _or_ by separate "symbolic
> ref" packet? That would allow clients who are using "want" to
> piggy-back the symref request as an optimization, but not restrict those
> that just want to ask for it?

I think I found another hole in the protocol that we can use to carry the
"which branch does HEAD points at" information in a backward compatible
way, and it would be a much less intrusive although more sneaky way.  And
it would not have to suffer from the above issues at all.

A patchset follows shortly...