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author | Jeff King <peff@peff.net> | 2012-10-04 04:02:53 -0400 |
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committer | Junio C Hamano <gitster@pobox.com> | 2012-10-04 20:34:28 -0700 |
commit | 6c4a060d7d895c90610eb442cb4f910fe43ef13a (patch) | |
tree | 8d7a9e6e23919cc3d5eeb477145298d352cd6583 | |
parent | e6dbffa67b8e4c463a8fe18e8599b8623d7f0485 (diff) | |
download | git-6c4a060d7d895c90610eb442cb4f910fe43ef13a.tar.gz git-6c4a060d7d895c90610eb442cb4f910fe43ef13a.tar.xz |
peel_ref: check object type before loading
The point of peel_ref is to dereference tags; if the base
object is not a tag, then we can return early without even
loading the object into memory.
This patch accomplishes that by checking sha1_object_info
for the type. For a packed object, we can get away with just
looking in the pack index. For a loose object, we only need
to inflate the first couple of header bytes.
This is a bit of a gamble; if we do find a tag object, then
we will end up loading the content anyway, and the extra
lookup will have been wasteful. However, if it is not a tag
object, then we save loading the object entirely. Depending
on the ratio of non-tags to tags in the input, this can be a
minor win or minor loss.
However, it does give us one potential major win: if a ref
points to a large blob (e.g., via an unannotated tag), then
we can avoid looking at it entirely.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
-rw-r--r-- | refs.c | 11 |
1 files changed, 9 insertions, 2 deletions
@@ -1225,8 +1225,15 @@ int peel_ref(const char *refname, unsigned char *sha1) } fallback: - o = parse_object(base); - if (o && o->type == OBJ_TAG) { + o = lookup_unknown_object(base); + if (o->type == OBJ_NONE) { + int type = sha1_object_info(base, NULL); + if (type < 0) + return -1; + o->type = type; + } + + if (o->type == OBJ_TAG) { o = deref_tag_noverify(o); if (o) { hashcpy(sha1, o->sha1); |