Subject: Re: [PATCH] refs.c: get_ref_cache: use a bucket hash

From: Jeff King <[email-masked]>
Date: Tue, 17 Mar 2015 01:48:00 -0400

On Mon, Mar 16, 2015 at 10:35:18PM -0700, Junio C Hamano wrote:

> > It looks like we don't even really care about the value of HEAD. We just
> > want to know "is it a git directory?". I think in other places (like
> > "git add"), we just do an existence check for "$dir/.git". That would
> > not catch a bare repository, but I do not think the current check does
> > either (it is looking for submodules, which always have a .git).
> 
> If we wanted to be consistent, perhaps we should be reusing the "is
> this a git repository?" check used by the auto-discovery codepath
> (setup.c:is_git_directory(), perhaps?), but the idea looks simple
> enough and sounds sensible.

Yeah, I almost suggested that, but I'm concerned that would make us
inconsistent with how we report untracked files. I thought that dir.c
used ".git" as a magic token there.

But it seems I'm wrong. We do ignore ".git" directly in treat_path(),
but treat_directory actually checks resolve_gitlink_ref. I think this
will suffer the same problem as Andreas's original issue (e.g., if you
run "git ls-files -o").

Likewise, I think dir.c:remove_dir_recurse is in a similar boat.
Grepping for resolve_gitlink_ref, it looks like there may be others,
too.

All of these should be using the same test, I think. Doing that with
is_git_directory() is probably OK. It is a little more expensive than we
might want for mass-use (it actually opens and parses the HEAD file in
each directory), but it quits early when we _don't_ see a git directory,
which would be the common case here.

-Peff