lookup_commit_reference_gently unconditionally parses the object given
to it. This slows down git-describe a lot if you have a repository
with large tagged blobs in it: parse_object() will read the entire
blob and verify that its sha1 matches, only to then throw it away.
Speed it up by checking the type with sha1_object_info() prior to
unpacking.
The reason that deref_tag() does not need the same fix is a bit
subtle: parse_tag_buffer() does not fill the 'tagged' member of the
tag struct if the tagged object is a blob.
Reported-by: Alex Bennée <kernel-hacker@xxxxxxxxxx>
Signed-off-by: Thomas Rast <trast@xxxxxxxxxxx>
---
commit.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/commit.c b/commit.c
index 888e02a..00e8d4a 100644
--- a/commit.c
+++ b/commit.c
@@ -31,8 +31,12 @@ static struct commit *check_commit(struct object *obj,
struct commit *lookup_commit_reference_gently(const unsigned char *sha1,
int quiet)
{
- struct object *obj = deref_tag(parse_object(sha1), NULL, 0);
-
+ struct object *obj;
+ int type = sha1_object_info(sha1, NULL);
+ /* If it's neither tag nor commit, parsing the object is wasted effort */
+ if (type != OBJ_TAG && type != OBJ_COMMIT)
+ return NULL;
+ obj = deref_tag(parse_object(sha1), NULL, 0);
if (!obj)
return NULL;
return check_commit(obj, sha1, quiet);
--
1.8.3.506.g4fdeee5
--
To unsubscribe from this list: send the line "unsubscribe git" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html