Re: add 'ls-remote' option to limit output records

From: Jeff King <peff@peff.net>
Date: May 1, 2019, 18:23 UTC
Message-ID: <20190501182323.GD4109@sigill.intra.peff.net>
In-Reply-To: <CAGyf7-G+FEDVe=WiVVNJr1ALn-ryA4862qbjdDCNXM+LhpjORQ@mail.gmail.com>

On Fri, Apr 26, 2019 at 12:32:51PM -0700, Bryan Turner wrote:

Show 11 quoted lines

> >         $ git ls-remote -n1 --tags --sort=v:refname origin "v*"
> [...]
> With the v2 wire protocol, the client could provide a prefix (like
> `refs/tags/`, or potentially `refs/tags/v`) to reduce what the server
> included in the ref advertisement, but even the v2 protocol doesn't
> have anything for telling the server "Version parse these names and
> then return the first N". That means the parsing, sorting and trimming
> for the advertised tags would still all have to happen locally. (I'm
> sure someone can correct me if I've misstated what protocol v2 can do
> for filtering, but I don't see any "ls-refs" options that look like
> they enable anything other than prefix matching.)

No, that sounds right. The "--tags" in the original command should cause v2 to ask only for refs/tags/. But because of the way ls-remote matching works, "v*" is not a pure prefix match, and would find "refs/tags/foo/v1.2.3". So we can't use protocol-level matching to ask for "refs/tags/v*".

There are no provisions in the protocol for sorting, nor for limiting the output.

I didn't check, but I suspect some hosting-platform APIs might be able to answer this with a single query.

-Peff