On Thu, Mar 20, 2025 at 12:44:02PM +0100, Karthik Nayak wrote:
> diff --git a/refs.c b/refs.c
> index b34ec198f5..f719046f47 100644
> --- a/refs.c
> +++ b/refs.c
> @@ -2540,6 +2540,7 @@ enum ref_transaction_error refs_verify_refnames_available(struct ref_store *refs
> const struct string_list *refnames,
> const struct string_list *extras,
> const struct string_list *skip,
> + struct ref_transaction *transaction,
> unsigned int initial_transaction,
> struct strbuf *err)
> {
> @@ -2599,12 +2601,26 @@ enum ref_transaction_error refs_verify_refnames_available(struct ref_store *refs
> if (!initial_transaction &&
> !refs_read_raw_ref(refs, dirname.buf, &oid, &referent,
> &type, &ignore_errno)) {
> + if (transaction && ref_transaction_maybe_set_rejected(
> + transaction, *update_idx,
> + REF_TRANSACTION_ERROR_NAME_CONFLICT)) {
> + strset_remove(&dirnames, dirname.buf);
> + continue;
> + }
> +
Okay. We have to remove the dirname from `dirnames` again so that the
next reference that creates a reference in the same directory would also
be marked as conflicting. It does have the consequence that we now have
to read the dirname N times again, where N is the number of refs that
are created below that directory.
We could probably improve this by using another map that contains the
conflicting names, right?
> diff --git a/refs/files-backend.c b/refs/files-backend.c
> index be758ffff5..1d50d4013c 100644
> --- a/refs/files-backend.c
> +++ b/refs/files-backend.c
> @@ -864,7 +868,9 @@ static enum ref_transaction_error lock_raw_ref(struct files_ref_store *refs,
> * make sure there is no existing packed ref that conflicts
> * with refname. This check is deferred so that we can batch it.
> */
> - string_list_append(refnames_to_check, refname);
> + item = string_list_append(refnames_to_check, refname);
> + item->util = xmalloc(sizeof(update_idx));
> + memcpy(item->util, &update_idx, sizeof(update_idx));
> }
>
> ret = 0;
Hm, so we have to allocate the `util` field now to store the update
index, which is a bit unfortunate because all of this is part of the hot
loop. We cannot store a direct pointer though because the array of
updates may be reallocated, which would invalidate any pointers pointing
into the array.
I was wondering whether we could abuse an `uintptr_t` and use it to
store the update index as a pointer. It does feel somewhat dirty though.
Patrick
