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authorNicolas Pitre <nico@cam.org>2006-09-21 00:09:44 -0400
committerJunio C Hamano <junkio@cox.net>2006-09-27 00:12:00 -0700
commitbe6b19145f64f62790049c06320c35011f7312a7 (patch)
treef83948d0c994e2641e92d0953e1ef6aee4ff4db1 /builtin-pack-objects.c
parent53dda6ff6263a3f350514d9edae600468c946ed4 (diff)
downloadgit-be6b19145f64f62790049c06320c35011f7312a7.tar.gz
make git-pack-objects able to create deltas with offset to base
This is enabled with --delta-base-offset only, and doesn't work with pack data reuse yet. The idea is to allow for the fetch protocol to use an extension flag to notify the remote end that --delta-base-offset can be used with git-pack-objects. Eventually git-repack will always provide this flag. With this, all delta base objects are now pushed before deltas that depend on them. This is a requirements for OBJ_OFS_DELTA. This is not a requirement for OBJ_REF_DELTA but always doing so makes the code simpler. Signed-off-by: Nicolas Pitre <nico@cam.org> Signed-off-by: Junio C Hamano <junkio@cox.net>
Diffstat (limited to 'builtin-pack-objects.c')
-rw-r--r--builtin-pack-objects.c47
1 files changed, 33 insertions, 14 deletions
diff --git a/builtin-pack-objects.c b/builtin-pack-objects.c
index c62734a2a6..221264916d 100644
--- a/builtin-pack-objects.c
+++ b/builtin-pack-objects.c
@@ -60,6 +60,8 @@ static int non_empty;
static int no_reuse_delta;
static int local;
static int incremental;
+static int allow_ofs_delta;
+
static struct object_entry **sorted_by_sha, **sorted_by_type;
static struct object_entry *objects;
static int nr_objects, nr_alloc, nr_result;
@@ -334,9 +336,6 @@ static unsigned long write_object(struct sha1file *f,
enum object_type obj_type;
int to_reuse = 0;
- if (entry->preferred_base)
- return 0;
-
obj_type = entry->type;
if (! entry->in_pack)
to_reuse = 0; /* can't reuse what we don't have */
@@ -380,18 +379,35 @@ static unsigned long write_object(struct sha1file *f,
if (entry->delta) {
buf = delta_against(buf, size, entry);
size = entry->delta_size;
- obj_type = OBJ_REF_DELTA;
+ obj_type = (allow_ofs_delta && entry->delta->offset) ?
+ OBJ_OFS_DELTA : OBJ_REF_DELTA;
}
/*
* The object header is a byte of 'type' followed by zero or
- * more bytes of length. For deltas, the 20 bytes of delta
- * sha1 follows that.
+ * more bytes of length.
*/
hdrlen = encode_header(obj_type, size, header);
sha1write(f, header, hdrlen);
- if (entry->delta) {
- sha1write(f, entry->delta, 20);
+ if (obj_type == OBJ_OFS_DELTA) {
+ /*
+ * Deltas with relative base contain an additional
+ * encoding of the relative offset for the delta
+ * base from this object's position in the pack.
+ */
+ unsigned long ofs = entry->offset - entry->delta->offset;
+ unsigned pos = sizeof(header) - 1;
+ header[pos] = ofs & 127;
+ while (ofs >>= 7)
+ header[--pos] = 128 | (--ofs & 127);
+ sha1write(f, header + pos, sizeof(header) - pos);
+ hdrlen += sizeof(header) - pos;
+ } else if (obj_type == OBJ_REF_DELTA) {
+ /*
+ * Deltas with a base reference contain
+ * an additional 20 bytes for the base sha1.
+ */
+ sha1write(f, entry->delta->sha1, 20);
hdrlen += 20;
}
datalen = sha1write_compressed(f, buf, size);
@@ -413,7 +429,7 @@ static unsigned long write_object(struct sha1file *f,
reused_delta++;
reused++;
}
- if (obj_type == OBJ_REF_DELTA)
+ if (entry->delta)
written_delta++;
written++;
return hdrlen + datalen;
@@ -423,17 +439,16 @@ static unsigned long write_one(struct sha1file *f,
struct object_entry *e,
unsigned long offset)
{
- if (e->offset)
+ if (e->offset || e->preferred_base)
/* offset starts from header size and cannot be zero
* if it is written already.
*/
return offset;
- e->offset = offset;
- offset += write_object(f, e);
- /* if we are deltified, write out its base object. */
+ /* if we are deltified, write out its base object first. */
if (e->delta)
offset = write_one(f, e->delta, offset);
- return offset;
+ e->offset = offset;
+ return offset + write_object(f, e);
}
static void write_pack_file(void)
@@ -1484,6 +1499,10 @@ int cmd_pack_objects(int argc, const char **argv, const char *prefix)
no_reuse_delta = 1;
continue;
}
+ if (!strcmp("--delta-base-offset", arg)) {
+ allow_ofs_delta = no_reuse_delta = 1;
+ continue;
+ }
if (!strcmp("--stdout", arg)) {
pack_to_stdout = 1;
continue;