Re: [PATCH 8/8] reflog_expire(): lock symbolic refs themselves, not their referent

From: Stefan Beller <sbeller@google.com>
Date: Feb 11, 2015, 00:49 UTC
Message-ID: <CAGZ79kaBGAOt-R1=mSG5H-5p=2UWjZEesktVwQcDAWFC-OW2Eg@mail.gmail.com>
In-Reply-To: <1423473164-6011-9-git-send-email-mhagger@alum.mit.edu>

On Mon, Feb 9, 2015 at 1:12 AM, Michael Haggerty <mhagger@alum.mit.edu> wrote:

> When processing the reflog of a symbolic ref, hold the lock on the
> symbolic reference itself, not on the reference that it points to.

I am not sure if that makes sense. So when expiring HEAD, you want to have a .git/HEAD.lock file instead of a .git/refs/heads/master.lock file?

What would happen if there is a concurrent modification to the master branch?

Show 22 quoted lines

>
> Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
> ---
>  refs.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/refs.c b/refs.c
> index 1b2a497..3fcf342 100644
> --- a/refs.c
> +++ b/refs.c
> @@ -4037,7 +4037,7 @@ int reflog_expire(const char *refname, const unsigned char *sha1,
>          * reference itself, plus we might need to update the
>          * reference if --updateref was specified:
>          */
> -       lock = lock_ref_sha1_basic(refname, sha1, NULL, 0, &type);
> +       lock = lock_ref_sha1_basic(refname, sha1, NULL, REF_NODEREF, &type);
>         if (!lock)
>                 return error("cannot lock ref '%s'", refname);
>         if (!reflog_exists(refname)) {
> --
> 2.1.4
>