Re: git clone --depth and git describe

[Duy Nguyen <pclouds@gmail.com>]

On Fri, May 10, 2013 at 3:42 PM, Ruediger Meier <sweet_f_a@gmx.de> wrote:
> On Friday 10 May 2013, Duy Nguyen wrote:
>> On Fri, May 10, 2013 at 6:07 AM, Ruediger Meier <sweet_f_a@gmx.de>
> wrote:
>> > Hi,
>> >
>> > I have a use case where I'd like to improve performance using "git
>> > clone --depth". But I also need "git describe" working on that
>> > clone.
>> >
>> > So something like
>> >  git clone --depth=describable
>> > would be nice to have.
>>
>> What does --depth=describable do?
>
> I mean automatically getting the minimum depth which gives us the
> history back to the last (annotated) tag. So that "git describe" and
> possibly other project specific administrative scripts (like
> git-version-gen or gitlog-to-changelog) would work safely on that
> shallow clone.

That should be possible to do. But you need to define it more clearly
if you start working on it. If you set --depth=v1.7.0, but another
branch in the source repo does not cross v1.7.0, what should we get?
Full history of that branch?

Just thinking out loud. We could make git-describe work with fixed
depth (e.g. --depth=12). The server could be made to send the client
some extended sha-1 syntax to get to related tags from the cut points,
e.g. v1.7.0 = <cut point>~12^2~14^1~20. And git-describe could be
modified to make use of that information when it traverses down to the
cut point. But I'm not sure if it's worth doing.

> Or maybe --depth could just generally accept a revspec as argument
> instead of number only. This would be more useful anyway IMO. Then
> perhaps something like "last_tag" could be a general magic revspec,
> probably useful for many other git commands too.

revspec is probably overkill. Take a look at
shallow.c:get_shallow_commits(). "cut at the first found tag" should
be easy to do, I think.
--
Duy