[PATCH v3 1/2] object: apply skip_hash and discard_tree optimizations to unknown blobs too

From: Aaron Plattner <aplattner@nvidia.com>
Date: Dec 9, 2025, 01:48 UTC
Message-ID: <20251209014900.402637-2-aplattner@nvidia.com>
In-Reply-To: <20251209014900.402637-1-aplattner@nvidia.com>

parse_object_with_flags() has an optimization to skip parsing blobs if PARSE_OBJECT_SKIP_HASH_CHECK is set and the object hasn't been seen before or might be a blob but hasn't been parsed yet. The latter can happen, for example, if add_tree_entries() walks a path that references a blob object that hasn't been seen before: lookup_blob() marks the referenced oid as being a blob, but does not provide any additional information about it until it is parsed.

It's possible for an object to be created without even a type, such as when prepare_revision_walk() uses mark_uninteresting() to mark all promisor objects as uninteresting. These objects have obj->parsed == false and obj->type == OBJ_NONE.

The skip_hash optimization does not consider this kind of object, so parse_object_with_flags() proceeds to fully parse the object to determine its type.

Improve the optimization by applying it to OBJ_NONE objects as well as OBJ_BLOB ones. Apply a similar fix for trees.

Fixes: 8db2dad7a045 ("parse_object(): check on-disk type of suspected blob")
Signed-off-by: Aaron Plattner <aplattner@nvidia.com>
---
 object.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/object.c b/object.c
index b08fc7a163..4669b8d65e 100644
--- a/object.c
+++ b/object.c
@@ -328,7 +328,7 @@ struct object *parse_object_with_flags(struct repository *r,
 			return &commit->object;
 	}
 
-	if ((!obj || obj->type == OBJ_BLOB) &&
+	if ((!obj || obj->type == OBJ_NONE || obj->type == OBJ_BLOB) &&
 	    odb_read_object_info(r->objects, oid, NULL) == OBJ_BLOB) {
 		if (!skip_hash && stream_object_signature(r, repl) < 0) {
 			error(_("hash mismatch %s"), oid_to_hex(oid));
@@ -344,7 +344,7 @@ struct object *parse_object_with_flags(struct repository *r,
 	 * have the on-disk object with the correct type.
 	 */
 	if (skip_hash && discard_tree &&
-	    (!obj || obj->type == OBJ_TREE) &&
+	    (!obj || obj->type == OBJ_NONE || obj->type == OBJ_TREE) &&
 	    odb_read_object_info(r->objects, oid, NULL) == OBJ_TREE) {
 		return &lookup_tree(r, oid)->object;
 	}

-- 
2.52.0