On Mon, Dec 9, 2024 at 12:11 PM Karthik Nayak <karthik.188@xxxxxxxxx> wrote:
>
> 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. But, we can theoretically have multiple reflog
> updates in a given transaction.
Nit: Giving an example might help understand where multiple reflog
updates can happen in a given transaction. Alternatively pointing to
an existing doc that contains such an example or explanations might
help too.
> @@ -2572,18 +2588,25 @@ static int lock_ref_for_update(struct files_ref_store *refs,
> goto out;
> }
>
> - ret = lock_raw_ref(refs, update->refname, mustexist,
> - affected_refnames,
> - &lock, &referent,
> - &update->type, err);
> - if (ret) {
> - char *reason;
> + lock = strmap_get(&backend_data->ref_locks, update->refname);
> + if (lock) {
> + lock->count = lock->count + 1;
Nit:
lock->count++;
> + } else {
> + ret = lock_raw_ref(refs, update->refname, mustexist,
> + affected_refnames,
> + &lock, &referent,
> + &update->type, err);
> + if (ret) {
> + char *reason;
> +
> + reason = strbuf_detach(err, NULL);
> + strbuf_addf(err, "cannot lock ref '%s': %s",
> + ref_update_original_update_refname(update), reason);
> + free(reason);
> + goto out;
> + }
>
> - reason = strbuf_detach(err, NULL);
> - strbuf_addf(err, "cannot lock ref '%s': %s",
> - ref_update_original_update_refname(update), reason);
> - free(reason);
> - goto out;
> + strmap_put(&backend_data->ref_locks, update->refname, lock);
> }
>
> update->backend_data = lock;
