Merge branch 'ps/refname-avail-check-optim'

The code paths to check whether a refname X is available (by seeing if another ref X/Y exists, etc.) have been optimized. * ps/refname-avail-check-optim: refs: reuse iterators when determining refname availability refs/iterator: implement seeking for files iterators refs/iterator: implement seeking for packed-ref iterators refs/iterator: implement seeking for ref-cache iterators refs/iterator: implement seeking for reftable iterators refs/iterator: implement seeking for merged iterators refs/iterator: provide infrastructure to re-seek iterators refs/iterator: separate lifecycle from iteration refs: stop re-verifying common prefixes for availability refs/files: batch refname availability checks for initial transactions refs/files: batch refname availability checks for normal transactions refs/reftable: batch refname availability checks refs: introduce function to batch refname availability checks builtin/update-ref: skip ambiguity checks when parsing object IDs object-name: allow skipping ambiguity checks in `get_oid()` family object-name: introduce `repo_get_oid_with_flags()`
author: Junio C Hamano <gitster@pobox.com> 2025-03-29 16:39:07 +0900
committer: Junio C Hamano <gitster@pobox.com> 2025-03-29 16:39:07 +0900
commit: 8d6413a1bef7876b9c17a79358bd70b764ffacba (patch)
tree: ae6597f607ea6f315a9356180d96281bd14cf9e5 /refs
parent: 01d17c05305edefbbe62926f5a5425207324a87f (diff)
parent: 87d297f48367737444810f8c3e76ef88cb6aa4e3 (diff)
download: git-8d6413a1bef7876b9c17a79358bd70b764ffacba.tar.gz
7 files changed, 359 insertions, 245 deletions
diff --git a/refs/debug.c b/refs/debug.c
index fbc4df08b4..5390fa9c18 100644
--- a/refs/debug.c
+++ b/refs/debug.c
@@ -169,6 +169,16 @@ static int debug_ref_iterator_advance(struct ref_iterator *ref_iterator)
 	return res;
 }
 
+static int debug_ref_iterator_seek(struct ref_iterator *ref_iterator,
+				   const char *prefix)
+{
+	struct debug_ref_iterator *diter =
+		(struct debug_ref_iterator *)ref_iterator;
+	int res = diter->iter->vtable->seek(diter->iter, prefix);
+	trace_printf_key(&trace_refs, "iterator_seek: %s: %d\n", prefix ? prefix : "", res);
+	return res;
+}
+
 static int debug_ref_iterator_peel(struct ref_iterator *ref_iterator,
 				   struct object_id *peeled)
 {
@@ -179,19 +189,19 @@ static int debug_ref_iterator_peel(struct ref_iterator *ref_iterator,
 	return res;
 }
 
-static int debug_ref_iterator_abort(struct ref_iterator *ref_iterator)
+static void debug_ref_iterator_release(struct ref_iterator *ref_iterator)
 {
 	struct debug_ref_iterator *diter =
 		(struct debug_ref_iterator *)ref_iterator;
-	int res = diter->iter->vtable->abort(diter->iter);
-	trace_printf_key(&trace_refs, "iterator_abort: %d\n", res);
-	return res;
+	diter->iter->vtable->release(diter->iter);
+	trace_printf_key(&trace_refs, "iterator_abort\n");
 }
 
 static struct ref_iterator_vtable debug_ref_iterator_vtable = {
 	.advance = debug_ref_iterator_advance,
+	.seek = debug_ref_iterator_seek,
 	.peel = debug_ref_iterator_peel,
-	.abort = debug_ref_iterator_abort,
+	.release = debug_ref_iterator_release,
 };
 
 static struct ref_iterator *
diff --git a/refs/files-backend.c b/refs/files-backend.c
index 6c6e67dc1c..ff54a4bb7e 100644
--- a/refs/files-backend.c
+++ b/refs/files-backend.c
@@ -678,6 +678,7 @@ static void unlock_ref(struct ref_lock *lock)
  */
 static int lock_raw_ref(struct files_ref_store *refs,
 			const char *refname, int mustexist,
+			struct string_list *refnames_to_check,
 			const struct string_list *extras,
 			struct ref_lock **lock_p,
 			struct strbuf *referent,
@@ -855,16 +856,11 @@ retry:
 		}
 
 		/*
-		 * If the ref did not exist and we are creating it,
-		 * make sure there is no existing packed ref that
-		 * conflicts with refname:
+		 * If the ref did not exist and we are creating it, we have to
+		 * make sure there is no existing packed ref that conflicts
+		 * with refname. This check is deferred so that we can batch it.
 		 */
-		if (refs_verify_refname_available(
-				    refs->packed_ref_store, refname,
-				    extras, NULL, 0, err)) {
-			ret = TRANSACTION_NAME_CONFLICT;
-			goto error_return;
-		}
+		string_list_append(refnames_to_check, refname);
 	}
 
 	ret = 0;
@@ -919,13 +915,17 @@ static int files_ref_iterator_advance(struct ref_iterator *ref_iterator)
 		return ITER_OK;
 	}
 
-	iter->iter0 = NULL;
-	if (ref_iterator_abort(ref_iterator) != ITER_DONE)
-		ok = ITER_ERROR;
-
 	return ok;
 }
 
+static int files_ref_iterator_seek(struct ref_iterator *ref_iterator,
+				   const char *prefix)
+{
+	struct files_ref_iterator *iter =
+		(struct files_ref_iterator *)ref_iterator;
+	return ref_iterator_seek(iter->iter0, prefix);
+}
+
 static int files_ref_iterator_peel(struct ref_iterator *ref_iterator,
 				   struct object_id *peeled)
 {
@@ -935,23 +935,18 @@ static int files_ref_iterator_peel(struct ref_iterator *ref_iterator,
 	return ref_iterator_peel(iter->iter0, peeled);
 }
 
-static int files_ref_iterator_abort(struct ref_iterator *ref_iterator)
+static void files_ref_iterator_release(struct ref_iterator *ref_iterator)
 {
 	struct files_ref_iterator *iter =
 		(struct files_ref_iterator *)ref_iterator;
-	int ok = ITER_DONE;
-
-	if (iter->iter0)
-		ok = ref_iterator_abort(iter->iter0);
-
-	base_ref_iterator_free(ref_iterator);
-	return ok;
+	ref_iterator_free(iter->iter0);
 }
 
 static struct ref_iterator_vtable files_ref_iterator_vtable = {
 	.advance = files_ref_iterator_advance,
+	.seek = files_ref_iterator_seek,
 	.peel = files_ref_iterator_peel,
-	.abort = files_ref_iterator_abort,
+	.release = files_ref_iterator_release,
 };
 
 static struct ref_iterator *files_ref_iterator_begin(
@@ -1382,7 +1377,7 @@ static int should_pack_refs(struct files_ref_store *refs,
 				    iter->flags, opts))
 			refcount++;
 		if (refcount >= limit) {
-			ref_iterator_abort(iter);
+			ref_iterator_free(iter);
 			return 1;
 		}
 	}
@@ -1390,6 +1385,7 @@ static int should_pack_refs(struct files_ref_store *refs,
 	if (ret != ITER_DONE)
 		die("error while iterating over references");
 
+	ref_iterator_free(iter);
 	return 0;
 }
 
@@ -1456,6 +1452,7 @@ static int files_pack_refs(struct ref_store *ref_store,
 	packed_refs_unlock(refs->packed_ref_store);
 
 	prune_refs(refs, &refs_to_prune);
+	ref_iterator_free(iter);
 	strbuf_release(&err);
 	return 0;
 }
@@ -2303,35 +2300,33 @@ static int files_reflog_iterator_advance(struct ref_iterator *ref_iterator)
 		return ITER_OK;
 	}
 
-	iter->dir_iterator = NULL;
-	if (ref_iterator_abort(ref_iterator) == ITER_ERROR)
-		ok = ITER_ERROR;
 	return ok;
 }
 
+static int files_reflog_iterator_seek(struct ref_iterator *ref_iterator UNUSED,
+				      const char *prefix UNUSED)
+{
+	BUG("ref_iterator_seek() called for reflog_iterator");
+}
+
 static int files_reflog_iterator_peel(struct ref_iterator *ref_iterator UNUSED,
 				      struct object_id *peeled UNUSED)
 {
 	BUG("ref_iterator_peel() called for reflog_iterator");
 }
 
-static int files_reflog_iterator_abort(struct ref_iterator *ref_iterator)
+static void files_reflog_iterator_release(struct ref_iterator *ref_iterator)
 {
 	struct files_reflog_iterator *iter =
 		(struct files_reflog_iterator *)ref_iterator;
-	int ok = ITER_DONE;
-
-	if (iter->dir_iterator)
-		ok = dir_iterator_abort(iter->dir_iterator);
-
-	base_ref_iterator_free(ref_iterator);
-	return ok;
+	dir_iterator_free(iter->dir_iterator);
 }
 
 static struct ref_iterator_vtable files_reflog_iterator_vtable = {
 	.advance = files_reflog_iterator_advance,
+	.seek = files_reflog_iterator_seek,
 	.peel = files_reflog_iterator_peel,
-	.abort = files_reflog_iterator_abort,
+	.release = files_reflog_iterator_release,
 };
 
 static struct ref_iterator *reflog_iterator_begin(struct ref_store *ref_store,
@@ -2569,6 +2564,7 @@ static int lock_ref_for_update(struct files_ref_store *refs,
 			       struct ref_update *update,
 			       struct ref_transaction *transaction,
 			       const char *head_ref,
+			       struct string_list *refnames_to_check,
 			       struct string_list *affected_refnames,
 			       struct strbuf *err)
 {
@@ -2597,7 +2593,7 @@ static int lock_ref_for_update(struct files_ref_store *refs,
 		lock->count++;
 	} else {
 		ret = lock_raw_ref(refs, update->refname, mustexist,
-				   affected_refnames,
+				   refnames_to_check, affected_refnames,
 				   &lock, &referent,
 				   &update->type, err);
 		if (ret) {
@@ -2811,6 +2807,7 @@ static int files_transaction_prepare(struct ref_store *ref_store,
 	size_t i;
 	int ret = 0;
 	struct string_list affected_refnames = STRING_LIST_INIT_NODUP;
+	struct string_list refnames_to_check = STRING_LIST_INIT_NODUP;
 	char *head_ref = NULL;
 	int head_type;
 	struct files_transaction_backend_data *backend_data;
@@ -2898,7 +2895,8 @@ static int files_transaction_prepare(struct ref_store *ref_store,
 		struct ref_update *update = transaction->updates[i];
 
 		ret = lock_ref_for_update(refs, update, transaction,
-					  head_ref, &affected_refnames, err);
+					  head_ref, &refnames_to_check,
+					  &affected_refnames, err);
 		if (ret)
 			goto cleanup;
 
@@ -2930,6 +2928,26 @@ static int files_transaction_prepare(struct ref_store *ref_store,
 		}
 	}
 
+	/*
+	 * Verify that none of the loose reference that we're about to write
+	 * conflict with any existing packed references. Ideally, we'd do this
+	 * check after the packed-refs are locked so that the file cannot
+	 * change underneath our feet. But introducing such a lock now would
+	 * probably do more harm than good as users rely on there not being a
+	 * global lock with the "files" backend.
+	 *
+	 * Another alternative would be to do the check after the (optional)
+	 * lock, but that would extend the time we spend in the globally-locked
+	 * state.
+	 *
+	 * So instead, we accept the race for now.
+	 */
+	if (refs_verify_refnames_available(refs->packed_ref_store, &refnames_to_check,
+					   &affected_refnames, NULL, 0, err)) {
+		ret = TRANSACTION_NAME_CONFLICT;
+		goto cleanup;
+	}
+
 	if (packed_transaction) {
 		if (packed_refs_lock(refs->packed_ref_store, 0, err)) {
 			ret = TRANSACTION_GENERIC_ERROR;
@@ -2972,6 +2990,7 @@ static int files_transaction_prepare(struct ref_store *ref_store,
 cleanup:
 	free(head_ref);
 	string_list_clear(&affected_refnames, 0);
+	string_list_clear(&refnames_to_check, 0);
 
 	if (ret)
 		files_transaction_cleanup(refs, transaction);
@@ -3036,6 +3055,7 @@ static int files_transaction_finish_initial(struct files_ref_store *refs,
 	size_t i;
 	int ret = 0;
 	struct string_list affected_refnames = STRING_LIST_INIT_NODUP;
+	struct string_list refnames_to_check = STRING_LIST_INIT_NODUP;
 	struct ref_transaction *packed_transaction = NULL;
 	struct ref_transaction *loose_transaction = NULL;
 
@@ -3085,11 +3105,7 @@ static int files_transaction_finish_initial(struct files_ref_store *refs,
 		    !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, 1, err)) {
-			ret = TRANSACTION_NAME_CONFLICT;
-			goto cleanup;
-		}
+		string_list_append(&refnames_to_check, update->refname);
 
 		/*
 		 * packed-refs don't support symbolic refs, root refs and reflogs,
@@ -3125,8 +3141,19 @@ static int files_transaction_finish_initial(struct files_ref_store *refs,
 		}
 	}
 
-	if (packed_refs_lock(refs->packed_ref_store, 0, err) ||
-	    ref_transaction_commit(packed_transaction, err)) {
+	if (packed_refs_lock(refs->packed_ref_store, 0, err)) {
+		ret = TRANSACTION_GENERIC_ERROR;
+		goto cleanup;
+	}
+
+	if (refs_verify_refnames_available(&refs->base, &refnames_to_check,
+					   &affected_refnames, NULL, 1, err)) {
+		packed_refs_unlock(refs->packed_ref_store);
+		ret = TRANSACTION_NAME_CONFLICT;
+		goto cleanup;
+	}
+
+	if (ref_transaction_commit(packed_transaction, err)) {
 		ret = TRANSACTION_GENERIC_ERROR;
 		goto cleanup;
 	}
@@ -3147,6 +3174,7 @@ cleanup:
 		ref_transaction_free(packed_transaction);
 	transaction->state = REF_TRANSACTION_CLOSED;
 	string_list_clear(&affected_refnames, 0);
+	string_list_clear(&refnames_to_check, 0);
 	return ret;
 }
 
@@ -3808,6 +3836,7 @@ static int files_fsck_refs_dir(struct ref_store *ref_store,
 		ret = error(_("failed to iterate over '%s'"), sb.buf);
 
 out:
+	dir_iterator_free(iter);
 	strbuf_release(&sb);
 	strbuf_release(&refname);
 	return ret;
diff --git a/refs/iterator.c b/refs/iterator.c
index d25e568bf0..766d96e795 100644
--- a/refs/iterator.c
+++ b/refs/iterator.c
@@ -15,15 +15,26 @@ int ref_iterator_advance(struct ref_iterator *ref_iterator)
 	return ref_iterator->vtable->advance(ref_iterator);
 }
 
+int ref_iterator_seek(struct ref_iterator *ref_iterator,
+		      const char *prefix)
+{
+	return ref_iterator->vtable->seek(ref_iterator, prefix);
+}
+
 int ref_iterator_peel(struct ref_iterator *ref_iterator,
 		      struct object_id *peeled)
 {
 	return ref_iterator->vtable->peel(ref_iterator, peeled);
 }
 
-int ref_iterator_abort(struct ref_iterator *ref_iterator)
+void ref_iterator_free(struct ref_iterator *ref_iterator)
 {
-	return ref_iterator->vtable->abort(ref_iterator);
+	if (ref_iterator) {
+		ref_iterator->vtable->release(ref_iterator);
+		/* Help make use-after-free bugs fail quickly: */
+		ref_iterator->vtable = NULL;
+		free(ref_iterator);
+	}
 }
 
 void base_ref_iterator_init(struct ref_iterator *iter,
@@ -36,20 +47,19 @@ void base_ref_iterator_init(struct ref_iterator *iter,
 	iter->flags = 0;
 }
 
-void base_ref_iterator_free(struct ref_iterator *iter)
-{
-	/* Help make use-after-free bugs fail quickly: */
-	iter->vtable = NULL;
-	free(iter);
-}
-
 struct empty_ref_iterator {
 	struct ref_iterator base;
 };
 
-static int empty_ref_iterator_advance(struct ref_iterator *ref_iterator)
+static int empty_ref_iterator_advance(struct ref_iterator *ref_iterator UNUSED)
+{
+	return ITER_DONE;
+}
+
+static int empty_ref_iterator_seek(struct ref_iterator *ref_iterator UNUSED,
+				   const char *prefix UNUSED)
 {
-	return ref_iterator_abort(ref_iterator);
+	return 0;
 }
 
 static int empty_ref_iterator_peel(struct ref_iterator *ref_iterator UNUSED,
@@ -58,16 +68,15 @@ static int empty_ref_iterator_peel(struct ref_iterator *ref_iterator UNUSED,
 	BUG("peel called for empty iterator");
 }
 
-static int empty_ref_iterator_abort(struct ref_iterator *ref_iterator)
+static void empty_ref_iterator_release(struct ref_iterator *ref_iterator UNUSED)
 {
-	base_ref_iterator_free(ref_iterator);
-	return ITER_DONE;
 }
 
 static struct ref_iterator_vtable empty_ref_iterator_vtable = {
 	.advance = empty_ref_iterator_advance,
+	.seek = empty_ref_iterator_seek,
 	.peel = empty_ref_iterator_peel,
-	.abort = empty_ref_iterator_abort,
+	.release = empty_ref_iterator_release,
 };
 
 struct ref_iterator *empty_ref_iterator_begin(void)
@@ -87,7 +96,8 @@ int is_empty_ref_iterator(struct ref_iterator *ref_iterator)
 struct merge_ref_iterator {
 	struct ref_iterator base;
 
-	struct ref_iterator *iter0, *iter1;
+	struct ref_iterator *iter0, *iter0_owned;
+	struct ref_iterator *iter1, *iter1_owned;
 
 	ref_iterator_select_fn *select;
 	void *cb_data;
@@ -179,9 +189,8 @@ static int merge_ref_iterator_advance(struct ref_iterator *ref_iterator)
 			iter->select(iter->iter0, iter->iter1, iter->cb_data);
 
 		if (selection == ITER_SELECT_DONE) {
-			return ref_iterator_abort(ref_iterator);
+			return ITER_DONE;
 		} else if (selection == ITER_SELECT_ERROR) {
-			ref_iterator_abort(ref_iterator);
 			return ITER_ERROR;
 		}
 
@@ -211,10 +220,31 @@ static int merge_ref_iterator_advance(struct ref_iterator *ref_iterator)
 	}
 
 error:
-	ref_iterator_abort(ref_iterator);
 	return ITER_ERROR;
 }
 
+static int merge_ref_iterator_seek(struct ref_iterator *ref_iterator,
+				   const char *prefix)
+{
+	struct merge_ref_iterator *iter =
+		(struct merge_ref_iterator *)ref_iterator;
+	int ret;
+
+	iter->current = NULL;
+	iter->iter0 = iter->iter0_owned;
+	iter->iter1 = iter->iter1_owned;
+
+	ret = ref_iterator_seek(iter->iter0, prefix);
+	if (ret < 0)
+		return ret;
+
+	ret = ref_iterator_seek(iter->iter1, prefix);
+	if (ret < 0)
+		return ret;
+
+	return 0;
+}
+
 static int merge_ref_iterator_peel(struct ref_iterator *ref_iterator,
 				   struct object_id *peeled)
 {
@@ -227,28 +257,19 @@ static int merge_ref_iterator_peel(struct ref_iterator *ref_iterator,
 	return ref_iterator_peel(*iter->current, peeled);
 }
 
-static int merge_ref_iterator_abort(struct ref_iterator *ref_iterator)
+static void merge_ref_iterator_release(struct ref_iterator *ref_iterator)
 {
 	struct merge_ref_iterator *iter =
 		(struct merge_ref_iterator *)ref_iterator;
-	int ok = ITER_DONE;
-
-	if (iter->iter0) {
-		if (ref_iterator_abort(iter->iter0) != ITER_DONE)
-			ok = ITER_ERROR;
-	}
-	if (iter->iter1) {
-		if (ref_iterator_abort(iter->iter1) != ITER_DONE)
-			ok = ITER_ERROR;
-	}
-	base_ref_iterator_free(ref_iterator);
-	return ok;
+	ref_iterator_free(iter->iter0_owned);
+	ref_iterator_free(iter->iter1_owned);
 }
 
 static struct ref_iterator_vtable merge_ref_iterator_vtable = {
 	.advance = merge_ref_iterator_advance,
+	.seek = merge_ref_iterator_seek,
 	.peel = merge_ref_iterator_peel,
-	.abort = merge_ref_iterator_abort,
+	.release = merge_ref_iterator_release,
 };
 
 struct ref_iterator *merge_ref_iterator_begin(
@@ -267,8 +288,8 @@ struct ref_iterator *merge_ref_iterator_begin(
 	 */
 
 	base_ref_iterator_init(ref_iterator, &merge_ref_iterator_vtable);
-	iter->iter0 = iter0;
-	iter->iter1 = iter1;
+	iter->iter0 = iter->iter0_owned = iter0;
+	iter->iter1 = iter->iter1_owned = iter1;
 	iter->select = select;
 	iter->cb_data = cb_data;
 	iter->current = NULL;
@@ -310,10 +331,10 @@ struct ref_iterator *overlay_ref_iterator_begin(
 	 * them.
 	 */
 	if (is_empty_ref_iterator(front)) {
-		ref_iterator_abort(front);
+		ref_iterator_free(front);
 		return back;
 	} else if (is_empty_ref_iterator(back)) {
-		ref_iterator_abort(back);
+		ref_iterator_free(back);
 		return front;
 	}
 
@@ -350,19 +371,15 @@ static int prefix_ref_iterator_advance(struct ref_iterator *ref_iterator)
 
 	while ((ok = ref_iterator_advance(iter->iter0)) == ITER_OK) {
 		int cmp = compare_prefix(iter->iter0->refname, iter->prefix);
-
 		if (cmp < 0)
 			continue;
-
-		if (cmp > 0) {
-			/*
-			 * As the source iterator is ordered, we
-			 * can stop the iteration as soon as we see a
-			 * refname that comes after the prefix:
-			 */
-			ok = ref_iterator_abort(iter->iter0);
-			break;
-		}
+		/*
+		 * As the source iterator is ordered, we
+		 * can stop the iteration as soon as we see a
+		 * refname that comes after the prefix:
+		 */
+		if (cmp > 0)
+			return ITER_DONE;
 
 		if (iter->trim) {
 			/*
@@ -386,12 +403,19 @@ static int prefix_ref_iterator_advance(struct ref_iterator *ref_iterator)
 		return ITER_OK;
 	}
 
-	iter->iter0 = NULL;
-	if (ref_iterator_abort(ref_iterator) != ITER_DONE)
-		return ITER_ERROR;
 	return ok;
 }
 
+static int prefix_ref_iterator_seek(struct ref_iterator *ref_iterator,
+				    const char *prefix)
+{
+	struct prefix_ref_iterator *iter =
+		(struct prefix_ref_iterator *)ref_iterator;
+	free(iter->prefix);
+	iter->prefix = xstrdup_or_null(prefix);
+	return ref_iterator_seek(iter->iter0, prefix);
+}
+
 static int prefix_ref_iterator_peel(struct ref_iterator *ref_iterator,
 				    struct object_id *peeled)
 {
@@ -401,23 +425,19 @@ static int prefix_ref_iterator_peel(struct ref_iterator *ref_iterator,
 	return ref_iterator_peel(iter->iter0, peeled);
 }
 
-static int prefix_ref_iterator_abort(struct ref_iterator *ref_iterator)
+static void prefix_ref_iterator_release(struct ref_iterator *ref_iterator)
 {
 	struct prefix_ref_iterator *iter =
 		(struct prefix_ref_iterator *)ref_iterator;
-	int ok = ITER_DONE;
-
-	if (iter->iter0)
-		ok = ref_iterator_abort(iter->iter0);
+	ref_iterator_free(iter->iter0);
 	free(iter->prefix);
-	base_ref_iterator_free(ref_iterator);
-	return ok;
 }
 
 static struct ref_iterator_vtable prefix_ref_iterator_vtable = {
 	.advance = prefix_ref_iterator_advance,
+	.seek = prefix_ref_iterator_seek,
 	.peel = prefix_ref_iterator_peel,
-	.abort = prefix_ref_iterator_abort,
+	.release = prefix_ref_iterator_release,
 };
 
 struct ref_iterator *prefix_ref_iterator_begin(struct ref_iterator *iter0,
@@ -453,20 +473,14 @@ int do_for_each_ref_iterator(struct ref_iterator *iter,
 	current_ref_iter = iter;
 	while ((ok = ref_iterator_advance(iter)) == ITER_OK) {
 		retval = fn(iter->refname, iter->referent, iter->oid, iter->flags, cb_data);
-		if (retval) {
-			/*
-			 * If ref_iterator_abort() returns ITER_ERROR,
-			 * we ignore that error in deference to the
-			 * callback function's return value.
-			 */
-			ref_iterator_abort(iter);
+		if (retval)
 			goto out;
-		}
 	}
 
 out:
 	current_ref_iter = old_ref_iter;
 	if (ok == ITER_ERROR)
-		return -1;
+		retval = -1;
+	ref_iterator_free(iter);
 	return retval;
 }
diff --git a/refs/packed-backend.c b/refs/packed-backend.c
index 813e5020e4..b4289a7d9c 100644
--- a/refs/packed-backend.c
+++ b/refs/packed-backend.c
@@ -841,6 +841,8 @@ struct packed_ref_iterator {
 
 	struct snapshot *snapshot;
 
+	char *prefix;
+
 	/* The current position in the snapshot's buffer: */
 	const char *pos;
 
@@ -863,11 +865,9 @@ struct packed_ref_iterator {
 };
 
 /*
- * Move the iterator to the next record in the snapshot, without
- * respect for whether the record is actually required by the current
- * iteration. Adjust the fields in `iter` and return `ITER_OK` or
- * `ITER_DONE`. This function does not free the iterator in the case
- * of `ITER_DONE`.
+ * Move the iterator to the next record in the snapshot. Adjust the fields in
+ * `iter` and return `ITER_OK` or `ITER_DONE`. This function does not free the
+ * iterator in the case of `ITER_DONE`.
  */
 static int next_record(struct packed_ref_iterator *iter)
 {
@@ -967,6 +967,9 @@ static int packed_ref_iterator_advance(struct ref_iterator *ref_iterator)
 	int ok;
 
 	while ((ok = next_record(iter)) == ITER_OK) {
+		const char *refname = iter->base.refname;
+		const char *prefix = iter->prefix;
+
 		if (iter->flags & DO_FOR_EACH_PER_WORKTREE_ONLY &&
 		    !is_per_worktree_ref(iter->base.refname))
 			continue;
@@ -976,15 +979,41 @@ static int packed_ref_iterator_advance(struct ref_iterator *ref_iterator)
 					    &iter->oid, iter->flags))
 			continue;
 
+		while (prefix && *prefix) {
+			if (*refname < *prefix)
+				BUG("packed-refs backend yielded reference preceding its prefix");
+			else if (*refname > *prefix)
+				return ITER_DONE;
+			prefix++;
+			refname++;
+		}
+
 		return ITER_OK;
 	}
 
-	if (ref_iterator_abort(ref_iterator) != ITER_DONE)
-		ok = ITER_ERROR;
-
 	return ok;
 }
 
+static int packed_ref_iterator_seek(struct ref_iterator *ref_iterator,
+				    const char *prefix)
+{
+	struct packed_ref_iterator *iter =
+		(struct packed_ref_iterator *)ref_iterator;
+	const char *start;
+
+	if (prefix && *prefix)
+		start = find_reference_location(iter->snapshot, prefix, 0);
+	else
+		start = iter->snapshot->start;
+
+	free(iter->prefix);
+	iter->prefix = xstrdup_or_null(prefix);
+	iter->pos = start;
+	iter->eof = iter->snapshot->eof;
+
+	return 0;
+}
+
 static int packed_ref_iterator_peel(struct ref_iterator *ref_iterator,
 				   struct object_id *peeled)
 {
@@ -1001,23 +1030,21 @@ static int packed_ref_iterator_peel(struct ref_iterator *ref_iterator,
 	}
 }
 
-static int packed_ref_iterator_abort(struct ref_iterator *ref_iterator)
+static void packed_ref_iterator_release(struct ref_iterator *ref_iterator)
 {
 	struct packed_ref_iterator *iter =
 		(struct packed_ref_iterator *)ref_iterator;
-	int ok = ITER_DONE;
-
 	strbuf_release(&iter->refname_buf);
 	free(iter->jump);
+	free(iter->prefix);
 	release_snapshot(iter->snapshot);
-	base_ref_iterator_free(ref_iterator);
-	return ok;
 }
 
 static struct ref_iterator_vtable packed_ref_iterator_vtable = {
 	.advance = packed_ref_iterator_advance,
+	.seek = packed_ref_iterator_seek,
 	.peel = packed_ref_iterator_peel,
-	.abort = packed_ref_iterator_abort
+	.release = packed_ref_iterator_release,
 };
 
 static int jump_list_entry_cmp(const void *va, const void *vb)
@@ -1129,7 +1156,6 @@ static struct ref_iterator *packed_ref_iterator_begin(
 {
 	struct packed_ref_store *refs;
 	struct snapshot *snapshot;
-	const char *start;
 	struct packed_ref_iterator *iter;
 	struct ref_iterator *ref_iterator;
 	unsigned int required_flags = REF_STORE_READ;
@@ -1145,14 +1171,6 @@ static struct ref_iterator *packed_ref_iterator_begin(
 	 */
 	snapshot = get_snapshot(refs);
 
-	if (prefix && *prefix)
-		start = find_reference_location(snapshot, prefix, 0);
-	else
-		start = snapshot->start;
-
-	if (start == snapshot->eof)
-		return empty_ref_iterator_begin();
-
 	CALLOC_ARRAY(iter, 1);
 	ref_iterator = &iter->base;
 	base_ref_iterator_init(ref_iterator, &packed_ref_iterator_vtable);
@@ -1162,19 +1180,15 @@ static struct ref_iterator *packed_ref_iterator_begin(
 
 	iter->snapshot = snapshot;
 	acquire_snapshot(snapshot);
-
-	iter->pos = start;
-	iter->eof = snapshot->eof;
 	strbuf_init(&iter->refname_buf, 0);
-
 	iter->base.oid = &iter->oid;
-
 	iter->repo = ref_store->repo;
 	iter->flags = flags;
 
-	if (prefix && *prefix)
-		/* Stop iteration after we've gone *past* prefix: */
-		ref_iterator = prefix_ref_iterator_begin(ref_iterator, prefix, 0);
+	if (packed_ref_iterator_seek(&iter->base, prefix) < 0) {
+		ref_iterator_free(&iter->base);
+		return NULL;
+	}
 
 	return ref_iterator;
 }
@@ -1387,8 +1401,10 @@ static int write_with_updates(struct packed_ref_store *refs,
 	 */
 	iter = packed_ref_iterator_begin(&refs->base, "", NULL,
 					 DO_FOR_EACH_INCLUDE_BROKEN);
-	if ((ok = ref_iterator_advance(iter)) != ITER_OK)
+	if ((ok = ref_iterator_advance(iter)) != ITER_OK) {
+		ref_iterator_free(iter);
 		iter = NULL;
+	}
 
 	i = 0;
 
@@ -1436,8 +1452,10 @@ static int write_with_updates(struct packed_ref_store *refs,
 				 * the iterator over the unneeded
 				 * value.
 				 */
-				if ((ok = ref_iterator_advance(iter)) != ITER_OK)
+				if ((ok = ref_iterator_advance(iter)) != ITER_OK) {
+					ref_iterator_free(iter);
 					iter = NULL;
+				}
 				cmp = +1;
 			} else {
 				/*
@@ -1474,8 +1492,10 @@ static int write_with_updates(struct packed_ref_store *refs,
 					       peel_error ? NULL : &peeled))
 				goto write_error;
 
-			if ((ok = ref_iterator_advance(iter)) != ITER_OK)
+			if ((ok = ref_iterator_advance(iter)) != ITER_OK) {
+				ref_iterator_free(iter);
 				iter = NULL;
+			}
 		} else if (is_null_oid(&update->new_oid)) {
 			/*
 			 * The update wants to delete the reference,
@@ -1524,9 +1544,7 @@ write_error:
 		    get_tempfile_path(refs->tempfile), strerror(errno));
 
 error:
-	if (iter)
-		ref_iterator_abort(iter);
-
+	ref_iterator_free(iter);
 	delete_tempfile(&refs->tempfile);
 	return -1;
 }
diff --git a/refs/ref-cache.c b/refs/ref-cache.c
index 02f09e4df8..c1f1bab1d5 100644
--- a/refs/ref-cache.c
+++ b/refs/ref-cache.c
@@ -362,9 +362,7 @@ struct cache_ref_iterator {
 	struct ref_iterator base;
 
 	/*
-	 * The number of levels currently on the stack. This is always
-	 * at least 1, because when it becomes zero the iteration is
-	 * ended and this struct is freed.
+	 * The number of levels currently on the stack.
 	 */
 	size_t levels_nr;
 
@@ -376,7 +374,7 @@ struct cache_ref_iterator {
 	 * The prefix is matched textually, without regard for path
 	 * component boundaries.
 	 */
-	const char *prefix;
+	char *prefix;
 
 	/*
 	 * A stack of levels. levels[0] is the uppermost level that is
@@ -389,6 +387,9 @@ struct cache_ref_iterator {
 	struct cache_ref_iterator_level *levels;
 
 	struct repository *repo;
+	struct ref_cache *cache;
+
+	int prime_dir;
 };
 
 static int cache_ref_iterator_advance(struct ref_iterator *ref_iterator)
@@ -396,6 +397,9 @@ static int cache_ref_iterator_advance(struct ref_iterator *ref_iterator)
 	struct cache_ref_iterator *iter =
 		(struct cache_ref_iterator *)ref_iterator;
 
+	if (!iter->levels_nr)
+		return ITER_DONE;
+
 	while (1) {
 		struct cache_ref_iterator_level *level =
 			&iter->levels[iter->levels_nr - 1];
@@ -409,7 +413,7 @@ static int cache_ref_iterator_advance(struct ref_iterator *ref_iterator)
 		if (++level->index == level->dir->nr) {
 			/* This level is exhausted; pop up a level */
 			if (--iter->levels_nr == 0)
-				return ref_iterator_abort(ref_iterator);
+				return ITER_DONE;
 
 			continue;
 		}
@@ -444,6 +448,41 @@ static int cache_ref_iterator_advance(struct ref_iterator *ref_iterator)
 	}
 }
 
+static int cache_ref_iterator_seek(struct ref_iterator *ref_iterator,
+				   const char *prefix)
+{
+	struct cache_ref_iterator *iter =
+		(struct cache_ref_iterator *)ref_iterator;
+	struct cache_ref_iterator_level *level;
+	struct ref_dir *dir;
+
+	dir = get_ref_dir(iter->cache->root);
+	if (prefix && *prefix)
+		dir = find_containing_dir(dir, prefix);
+	if (!dir) {
+		iter->levels_nr = 0;
+		return 0;
+	}
+
+	if (iter->prime_dir)
+		prime_ref_dir(dir, prefix);
+	iter->levels_nr = 1;
+	level = &iter->levels[0];
+	level->index = -1;
+	level->dir = dir;
+
+	if (prefix && *prefix) {
+		free(iter->prefix);
+		iter->prefix = xstrdup(prefix);
+		level->prefix_state = PREFIX_WITHIN_DIR;
+	} else {
+		FREE_AND_NULL(iter->prefix);
+		level->prefix_state = PREFIX_CONTAINS_DIR;
+	}
+
+	return 0;
+}
+
 static int cache_ref_iterator_peel(struct ref_iterator *ref_iterator,
 				   struct object_id *peeled)
 {
@@ -452,21 +491,19 @@ static int cache_ref_iterator_peel(struct ref_iterator *ref_iterator,
 	return peel_object(iter->repo, ref_iterator->oid, peeled) ? -1 : 0;
 }
 
-static int cache_ref_iterator_abort(struct ref_iterator *ref_iterator)
+static void cache_ref_iterator_release(struct ref_iterator *ref_iterator)
 {
 	struct cache_ref_iterator *iter =
 		(struct cache_ref_iterator *)ref_iterator;
-
-	free((char *)iter->prefix);
+	free(iter->prefix);
 	free(iter->levels);
-	base_ref_iterator_free(ref_iterator);
-	return ITER_DONE;
 }
 
 static struct ref_iterator_vtable cache_ref_iterator_vtable = {
 	.advance = cache_ref_iterator_advance,
+	.seek = cache_ref_iterator_seek,
 	.peel = cache_ref_iterator_peel,
-	.abort = cache_ref_iterator_abort
+	.release = cache_ref_iterator_release,
 };
 
 struct ref_iterator *cache_ref_iterator_begin(struct ref_cache *cache,
@@ -474,39 +511,22 @@ struct ref_iterator *cache_ref_iterator_begin(struct ref_cache *cache,
 					      struct repository *repo,
 					      int prime_dir)
 {
-	struct ref_dir *dir;
 	struct cache_ref_iterator *iter;
 	struct ref_iterator *ref_iterator;
-	struct cache_ref_iterator_level *level;
-
-	dir = get_ref_dir(cache->root);
-	if (prefix && *prefix)
-		dir = find_containing_dir(dir, prefix);
-	if (!dir)
-		/* There's nothing to iterate over. */
-		return empty_ref_iterator_begin();
-
-	if (prime_dir)
-		prime_ref_dir(dir, prefix);
 
 	CALLOC_ARRAY(iter, 1);
 	ref_iterator = &iter->base;
 	base_ref_iterator_init(ref_iterator, &cache_ref_iterator_vtable);
 	ALLOC_GROW(iter->levels, 10, iter->levels_alloc);
 
-	iter->levels_nr = 1;
-	level = &iter->levels[0];
-	level->index = -1;
-	level->dir = dir;
+	iter->repo = repo;
+	iter->cache = cache;
+	iter->prime_dir = prime_dir;
 
-	if (prefix && *prefix) {
-		iter->prefix = xstrdup(prefix);
-		level->prefix_state = PREFIX_WITHIN_DIR;
-	} else {
-		level->prefix_state = PREFIX_CONTAINS_DIR;
+	if (cache_ref_iterator_seek(&iter->base, prefix) < 0) {
+		ref_iterator_free(&iter->base);
+		return NULL;
 	}
 
-	iter->repo = repo;
-
 	return ref_iterator;
 }
diff --git a/refs/refs-internal.h b/refs/refs-internal.h
index 8894b43d1d..e5862757a7 100644
--- a/refs/refs-internal.h
+++ b/refs/refs-internal.h
@@ -273,11 +273,11 @@ enum do_for_each_ref_flags {
  * the next reference and returns ITER_OK. The data pointed at by
  * refname and oid belong to the iterator; if you want to retain them
  * after calling ref_iterator_advance() again or calling
- * ref_iterator_abort(), you must make a copy. When the iteration has
+ * ref_iterator_free(), you must make a copy. When the iteration has
  * been exhausted, ref_iterator_advance() releases any resources
  * associated with the iteration, frees the ref_iterator object, and
  * returns ITER_DONE. If you want to abort the iteration early, call
- * ref_iterator_abort(), which also frees the ref_iterator object and
+ * ref_iterator_free(), which also frees the ref_iterator object and
  * any associated resources. If there was an internal error advancing
  * to the next entry, ref_iterator_advance() aborts the iteration,
  * frees the ref_iterator, and returns ITER_ERROR.
@@ -293,7 +293,7 @@ enum do_for_each_ref_flags {
  *
  *     while ((ok = ref_iterator_advance(iter)) == ITER_OK) {
  *             if (want_to_stop_iteration()) {
- *                     ok = ref_iterator_abort(iter);
+ *                     ok = ITER_DONE;
  *                     break;
  *             }
  *
@@ -307,6 +307,7 @@ enum do_for_each_ref_flags {
  *
  *     if (ok != ITER_DONE)
  *             handle_error();
+ *     ref_iterator_free(iter);
  */
 struct ref_iterator {
 	struct ref_iterator_vtable *vtable;
@@ -327,18 +328,30 @@ struct ref_iterator {
 int ref_iterator_advance(struct ref_iterator *ref_iterator);
 
 /*
+ * Seek the iterator to the first reference with the given prefix.
+ * The prefix is matched as a literal string, without regard for path
+ * separators. If prefix is NULL or the empty string, seek the iterator to the
+ * first reference again.
+ *
+ * This function is expected to behave as if a new ref iterator with the same
+ * prefix had been created, but allows reuse of iterators and thus may allow
+ * the backend to optimize. Parameters other than the prefix that have been
+ * passed when creating the iterator will remain unchanged.
+ *
+ * Returns 0 on success, a negative error code otherwise.
+ */
+int ref_iterator_seek(struct ref_iterator *ref_iterator,
+		      const char *prefix);
+
+/*
  * If possible, peel the reference currently being viewed by the
  * iterator. Return 0 on success.
  */
 int ref_iterator_peel(struct ref_iterator *ref_iterator,
 		      struct object_id *peeled);
 
-/*
- * End the iteration before it has been exhausted, freeing the
- * reference iterator and any associated resources and returning
- * ITER_DONE. If the abort itself failed, return ITER_ERROR.
- */
-int ref_iterator_abort(struct ref_iterator *ref_iterator);
+/* Free the reference iterator and any associated resources. */
+void ref_iterator_free(struct ref_iterator *ref_iterator);
 
 /*
  * An iterator over nothing (its first ref_iterator_advance() call
@@ -438,13 +451,6 @@ struct ref_iterator *prefix_ref_iterator_begin(struct ref_iterator *iter0,
 void base_ref_iterator_init(struct ref_iterator *iter,
 			    struct ref_iterator_vtable *vtable);
 
-/*
- * Base class destructor for ref_iterators. Destroy the ref_iterator
- * part of iter and shallow-free the object. This is meant to be
- * called only by the destructors of derived classes.
- */
-void base_ref_iterator_free(struct ref_iterator *iter);
-
 /* Virtual function declarations for ref_iterators: */
 
 /*
@@ -456,6 +462,13 @@ void base_ref_iterator_free(struct ref_iterator *iter);
 typedef int ref_iterator_advance_fn(struct ref_iterator *ref_iterator);
 
 /*
+ * Seek the iterator to the first reference matching the given prefix. Should
+ * behave the same as if a new iterator was created with the same prefix.
+ */
+typedef int ref_iterator_seek_fn(struct ref_iterator *ref_iterator,
+				 const char *prefix);
+
+/*
  * Peels the current ref, returning 0 for success or -1 for failure.
  */
 typedef int ref_iterator_peel_fn(struct ref_iterator *ref_iterator,
@@ -463,15 +476,15 @@ typedef int ref_iterator_peel_fn(struct ref_iterator *ref_iterator,
 
 /*
  * Implementations of this function should free any resources specific
- * to the derived class, then call base_ref_iterator_free() to clean
- * up and free the ref_iterator object.
+ * to the derived class.
  */
-typedef int ref_iterator_abort_fn(struct ref_iterator *ref_iterator);
+typedef void ref_iterator_release_fn(struct ref_iterator *ref_iterator);
 
 struct ref_iterator_vtable {
 	ref_iterator_advance_fn *advance;
+	ref_iterator_seek_fn *seek;
 	ref_iterator_peel_fn *peel;
-	ref_iterator_abort_fn *abort;
+	ref_iterator_release_fn *release;
 };
 
 /*
diff --git a/refs/reftable-backend.c b/refs/reftable-backend.c
index 771f50df38..ae434cd248 100644
--- a/refs/reftable-backend.c
+++ b/refs/reftable-backend.c
@@ -547,7 +547,7 @@ struct reftable_ref_iterator {
 	struct reftable_ref_record ref;
 	struct object_id oid;
 
-	const char *prefix;
+	char *prefix;
 	size_t prefix_len;
 	char **exclude_patterns;
 	size_t exclude_patterns_index;
@@ -711,20 +711,27 @@ static int reftable_ref_iterator_advance(struct ref_iterator *ref_iterator)
 		break;
 	}
 
-	if (iter->err > 0) {
-		if (ref_iterator_abort(ref_iterator) != ITER_DONE)
-			return ITER_ERROR;
+	if (iter->err > 0)
 		return ITER_DONE;
-	}
-
-	if (iter->err < 0) {
-		ref_iterator_abort(ref_iterator);
+	if (iter->err < 0)
 		return ITER_ERROR;
-	}
-
 	return ITER_OK;
 }
 
+static int reftable_ref_iterator_seek(struct ref_iterator *ref_iterator,
+				      const char *prefix)
+{
+	struct reftable_ref_iterator *iter =
+		(struct reftable_ref_iterator *)ref_iterator;
+
+	free(iter->prefix);
+	iter->prefix = xstrdup_or_null(prefix);
+	iter->prefix_len = prefix ? strlen(prefix) : 0;
+	iter->err = reftable_iterator_seek_ref(&iter->iter, prefix);
+
+	return iter->err;
+}
+
 static int reftable_ref_iterator_peel(struct ref_iterator *ref_iterator,
 				      struct object_id *peeled)
 {
@@ -740,7 +747,7 @@ static int reftable_ref_iterator_peel(struct ref_iterator *ref_iterator,
 	return -1;
 }
 
-static int reftable_ref_iterator_abort(struct ref_iterator *ref_iterator)
+static void reftable_ref_iterator_release(struct ref_iterator *ref_iterator)
 {
 	struct reftable_ref_iterator *iter =
 		(struct reftable_ref_iterator *)ref_iterator;
@@ -751,14 +758,14 @@ static int reftable_ref_iterator_abort(struct ref_iterator *ref_iterator)
 			free(iter->exclude_patterns[i]);
 		free(iter->exclude_patterns);
 	}
-	free(iter);
-	return ITER_DONE;
+	free(iter->prefix);
 }
 
 static struct ref_iterator_vtable reftable_ref_iterator_vtable = {
 	.advance = reftable_ref_iterator_advance,
+	.seek = reftable_ref_iterator_seek,
 	.peel = reftable_ref_iterator_peel,
-	.abort = reftable_ref_iterator_abort
+	.release = reftable_ref_iterator_release,
 };
 
 static int qsort_strcmp(const void *va, const void *vb)
@@ -815,8 +822,6 @@ static struct reftable_ref_iterator *ref_iterator_for_stack(struct reftable_ref_
 
 	iter = xcalloc(1, sizeof(*iter));
 	base_ref_iterator_init(&iter->base, &reftable_ref_iterator_vtable);
-	iter->prefix = prefix;
-	iter->prefix_len = prefix ? strlen(prefix) : 0;
 	iter->base.oid = &iter->oid;
 	iter->flags = flags;
 	iter->refs = refs;
@@ -830,8 +835,11 @@ static struct reftable_ref_iterator *ref_iterator_for_stack(struct reftable_ref_
 	if (ret)
 		goto done;
 
-	reftable_stack_init_ref_iterator(stack, &iter->iter);
-	ret = reftable_iterator_seek_ref(&iter->iter, prefix);
+	ret = reftable_stack_init_ref_iterator(stack, &iter->iter);
+	if (ret)
+		goto done;
+
+	ret = reftable_ref_iterator_seek(&iter->base, prefix);
 	if (ret)
 		goto done;
 
@@ -1069,6 +1077,7 @@ static int reftable_be_transaction_prepare(struct ref_store *ref_store,
 		reftable_be_downcast(ref_store, REF_STORE_WRITE|REF_STORE_MAIN, "ref_transaction_prepare");
 	struct strbuf referent = STRBUF_INIT, head_referent = STRBUF_INIT;
 	struct string_list affected_refnames = STRING_LIST_INIT_NODUP;
+	struct string_list refnames_to_check = STRING_LIST_INIT_NODUP;
 	struct reftable_transaction_data *tx_data = NULL;
 	struct reftable_backend *be;
 	struct object_id head_oid;
@@ -1224,12 +1233,7 @@ static int reftable_be_transaction_prepare(struct ref_store *ref_store,
 			 * can output a proper error message instead of failing
 			 * at a later point.
 			 */
-			ret = refs_verify_refname_available(ref_store, u->refname,
-							    &affected_refnames, NULL,
-							    transaction->flags & REF_TRANSACTION_FLAG_INITIAL,
-							    err);
-			if (ret < 0)
-				goto done;
+			string_list_append(&refnames_to_check, u->refname);
 
 			/*
 			 * There is no need to write the reference deletion
@@ -1379,6 +1383,12 @@ static int reftable_be_transaction_prepare(struct ref_store *ref_store,
 		}
 	}
 
+	ret = refs_verify_refnames_available(ref_store, &refnames_to_check, &affected_refnames, NULL,
+					     transaction->flags & REF_TRANSACTION_FLAG_INITIAL,
+					     err);
+	if (ret < 0)
+		goto done;
+
 	transaction->backend_data = tx_data;
 	transaction->state = REF_TRANSACTION_PREPARED;
 
@@ -1394,6 +1404,7 @@ done:
 	string_list_clear(&affected_refnames, 0);
 	strbuf_release(&referent);
 	strbuf_release(&head_referent);
+	string_list_clear(&refnames_to_check, 0);
 
 	return ret;
 }
@@ -2017,20 +2028,20 @@ static int reftable_reflog_iterator_advance(struct ref_iterator *ref_iterator)
 		break;
 	}
 
-	if (iter->err > 0) {
-		if (ref_iterator_abort(ref_iterator) != ITER_DONE)
-			return ITER_ERROR;
+	if (iter->err > 0)
 		return ITER_DONE;
-	}
-
-	if (iter->err < 0) {
-		ref_iterator_abort(ref_iterator);
+	if (iter->err < 0)
 		return ITER_ERROR;
-	}
-
 	return ITER_OK;
 }
 
+static int reftable_reflog_iterator_seek(struct ref_iterator *ref_iterator UNUSED,
+					 const char *prefix UNUSED)
+{
+	BUG("reftable reflog iterator cannot be seeked");
+	return -1;
+}
+
 static int reftable_reflog_iterator_peel(struct ref_iterator *ref_iterator UNUSED,
 					 struct object_id *peeled UNUSED)
 {
@@ -2038,21 +2049,20 @@ static int reftable_reflog_iterator_peel(struct ref_iterator *ref_iterator UNUSE
 	return -1;
 }
 
-static int reftable_reflog_iterator_abort(struct ref_iterator *ref_iterator)
+static void reftable_reflog_iterator_release(struct ref_iterator *ref_iterator)
 {
 	struct reftable_reflog_iterator *iter =
 		(struct reftable_reflog_iterator *)ref_iterator;
 	reftable_log_record_release(&iter->log);
 	reftable_iterator_destroy(&iter->iter);
 	strbuf_release(&iter->last_name);
-	free(iter);
-	return ITER_DONE;
 }
 
 static struct ref_iterator_vtable reftable_reflog_iterator_vtable = {
 	.advance = reftable_reflog_iterator_advance,
+	.seek = reftable_reflog_iterator_seek,
 	.peel = reftable_reflog_iterator_peel,
-	.abort = reftable_reflog_iterator_abort
+	.release = reftable_reflog_iterator_release,
 };
 
 static struct reftable_reflog_iterator *reflog_iterator_for_stack(struct reftable_ref_store *refs,
author	Junio C Hamano <gitster@pobox.com>	2025-03-29 16:39:07 +0900
committer	Junio C Hamano <gitster@pobox.com>	2025-03-29 16:39:07 +0900
commit	8d6413a1bef7876b9c17a79358bd70b764ffacba (patch)
tree	ae6597f607ea6f315a9356180d96281bd14cf9e5 /refs
parent	01d17c05305edefbbe62926f5a5425207324a87f (diff)
parent	87d297f48367737444810f8c3e76ef88cb6aa4e3 (diff)
download	git-8d6413a1bef7876b9c17a79358bd70b764ffacba.tar.gz