Re: [PATCH 3/7] refs/files: add count field to ref_lock

From: Christian Couder <christian.couder@gmail.com>
Date: Dec 11, 2024, 09:05 UTC
Message-ID: <CAP8UFD3StHePPGe+44c83qBYoZLZme+Gw-cP7Weg-neyJg8DOw@mail.gmail.com>
In-Reply-To: <20241209-320-git-refs-migrate-reflogs-v1-3-d4bc37ee860f@gmail.com>

On Mon, Dec 9, 2024 at 12:11 PM Karthik Nayak <karthik.188@gmail.com> wrote:

Show 10 quoted lines

>
> When refs are updated in the files-backend, a lock is obtained for the
> corresponding file path. This is the case even for reflogs, i.e. a lock
> is obtained on the reference path instead of the reflog path. This
> works, since generally, reflogs are updated alongside the ref.
>
> The upcoming patches will add support for reflog updates in ref
> transaction. This means, in a particular transaction we want to have ref
> updates and reflog updates. For refs, in a given transaction there can
> only be one update.

Maybe something like: "For a given ref in a given transaction there can be at most one update."

> But, we can theoretically have multiple reflog
> updates in a given transaction.

And: "But we can theoretically have multiple reflog updates for a
given ref in a given transaction."

Show 10 quoted lines

> diff --git a/refs/files-backend.c b/refs/files-backend.c
> index 13f8539e6caa923cd4834775fcb0cd7f90d82014..9c929c1ac33bc62a75620e684a809d46b574f1c6 100644
> --- a/refs/files-backend.c
> +++ b/refs/files-backend.c
> @@ -71,6 +71,8 @@ struct ref_lock {
>         char *ref_name;
>         struct lock_file lk;
>         struct object_id old_oid;
> +       /* count keeps track of users of the lock */
> +       unsigned int count;

Nit: maybe the following is a bit better:

      unsigned int count; /* track users of the lock (ref update +
reflog updates) */

>  };