diff options
authorJeff King <>2013-03-17 08:38:57 (GMT)
committerJunio C Hamano <>2013-03-17 22:28:15 (GMT)
commit30b939c33ad5b8a9dfbe3fe5aafc36d89c40409f (patch)
parentf9b54e2630f4c839fbc4195693d66e790b09371b (diff)
fast-export: do not load blob objects twice
When fast-export wants to export a blob object, it first calls parse_object to get a "struct object" and check whether we have already shown the object. If we haven't shown it, we then use read_sha1_file to pull it from disk and write it out. That means we load each blob from disk twice: once for parse_object to find its type and check its sha1, and a second time when we actually output it. We can drop this to a single load by using lookup_object to check the SHOWN flag, and then checking the signature on and outputting a single buffer. This provides modest speedups on git.git (best-of-five, "git fast-export HEAD >/dev/null"): [before] [after] real 0m14.347s real 0m13.780s user 0m14.084s user 0m13.620s sys 0m0.208s sys 0m0.100s and somewhat more on more blob-heavy repos (this is a repository full of media files): [before] [after] real 0m52.236s real 0m44.451s user 0m50.568s user 0m43.000s sys 0m1.536s sys 0m1.284s Signed-off-by: Jeff King <> Signed-off-by: Junio C Hamano <>
1 files changed, 10 insertions, 6 deletions
diff --git a/builtin/fast-export.c b/builtin/fast-export.c
index 9e89925..ed29165 100644
--- a/builtin/fast-export.c
+++ b/builtin/fast-export.c
@@ -119,6 +119,7 @@ static void export_blob(const unsigned char *sha1)
enum object_type type;
char *buf;
struct object *object;
+ int eaten;
if (no_data)
@@ -126,16 +127,18 @@ static void export_blob(const unsigned char *sha1)
if (is_null_sha1(sha1))
- object = parse_object(sha1);
- if (!object)
- die ("Could not read blob %s", sha1_to_hex(sha1));
- if (object->flags & SHOWN)
+ object = lookup_object(sha1);
+ if (object && object->flags & SHOWN)
buf = read_sha1_file(sha1, &type, &size);
if (!buf)
die ("Could not read blob %s", sha1_to_hex(sha1));
+ if (check_sha1_signature(sha1, buf, size, typename(type)) < 0)
+ die("sha1 mismatch in blob %s", sha1_to_hex(sha1));
+ object = parse_object_buffer(sha1, type, size, buf, &eaten);
+ if (!object)
+ die("Could not read blob %s", sha1_to_hex(sha1));
@@ -147,7 +150,8 @@ static void export_blob(const unsigned char *sha1)
object->flags |= SHOWN;
- free(buf);
+ if (!eaten)
+ free(buf);
static int depth_first(const void *a_, const void *b_)