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refs/files: support symbolic and root refs in initial transaction

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The "files" backend has implemented special logic when committing
the first transactions in an otherwise empty ref store: instead of
writing all refs as separate loose files, it instead knows to write them
all into a "packed-refs" file directly. This is significantly more
efficient than having to write each of the refs as separate "loose" ref.

The only user of this optimization is git-clone(1), which only uses this
mechanism to write regular refs. Consequently, the implementation does
not know how to handle both symbolic and root refs. While fine in the
context of git-clone(1), this keeps us from using the mechanism in more
cases.

Adapt the logic to also support symbolic and root refs by using a second
transaction that we use for all of the refs that need to be written as
loose refs.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Patrick Steinhardt
2024-11-20 08:51:33 +01:00
committed by Junio C Hamano
parent 1c299d03e5
commit c0b9cf3b55
1 changed files with 34 additions and 10 deletions
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44
refs/files-backend.c
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@ -2995,6 +2995,7 @@ static int files_transaction_finish_initial(struct files_ref_store *refs,
int ret = 0;
struct string_list affected_refnames = STRING_LIST_INIT_NODUP;
struct ref_transaction *packed_transaction = NULL;
struct ref_transaction *loose_transaction = NULL;
assert(err);
@ -3040,6 +3041,7 @@ static int files_transaction_finish_initial(struct files_ref_store *refs,
if ((update->flags & REF_HAVE_OLD) &&
!is_null_oid(&update->old_oid))
BUG("initial ref transaction with old_sha1 set");
if (refs_verify_refname_available(&refs->base, update->refname,
&affected_refnames, NULL,
err)) {
@ -3048,26 +3050,48 @@ static int files_transaction_finish_initial(struct files_ref_store *refs,
}
/*
* Add a reference creation for this reference to the
* packed-refs transaction:
* packed-refs don't support symbolic refs and root refs, so we
* have to queue these references via the loose transaction.
*/
ref_transaction_add_update(packed_transaction, update->refname,
update->flags & ~REF_HAVE_OLD,
&update->new_oid, &update->old_oid,
NULL, NULL, NULL);
if (update->new_target || is_root_ref(update->refname)) {
if (!loose_transaction) {
loose_transaction = ref_store_transaction_begin(&refs->base, 0, err);
if (!loose_transaction) {
ret = TRANSACTION_GENERIC_ERROR;
goto cleanup;
}
}
ref_transaction_add_update(loose_transaction, update->refname,
update->flags & ~REF_HAVE_OLD,
update->new_target ? NULL : &update->new_oid, NULL,
update->new_target, NULL, NULL);
} else {
ref_transaction_add_update(packed_transaction, update->refname,
update->flags & ~REF_HAVE_OLD,
&update->new_oid, &update->old_oid,
NULL, NULL, NULL);
}
}
if (packed_refs_lock(refs->packed_ref_store, 0, err)) {
if (packed_refs_lock(refs->packed_ref_store, 0, err) ||
ref_transaction_commit(packed_transaction, err)) {
ret = TRANSACTION_GENERIC_ERROR;
goto cleanup;
}
packed_refs_unlock(refs->packed_ref_store);
if (ref_transaction_commit(packed_transaction, err)) {
ret = TRANSACTION_GENERIC_ERROR;
if (loose_transaction) {
if (ref_transaction_prepare(loose_transaction, err) ||
ref_transaction_commit(loose_transaction, err)) {
ret = TRANSACTION_GENERIC_ERROR;
goto cleanup;
}
}
packed_refs_unlock(refs->packed_ref_store);
cleanup:
if (loose_transaction)
ref_transaction_free(loose_transaction);
if (packed_transaction)
ref_transaction_free(packed_transaction);
transaction->state = REF_TRANSACTION_CLOSED;