Signed-off-by: Derrick Stolee
---
Documentation/technical/pack-format.txt | 5 +++
builtin/midx.c | 4 +-
midx.c | 53 +++--
object-store.h | 1 +
t/t5319-midx.sh | 18 +
5 files changed, 69 insertions(+), 12 deletions(-)
diff --git a/Documentation/technical/pack-format.txt
b/Documentation/technical/pack-format.txt
index de9ac778b6..77e88f85e4 100644
--- a/Documentation/technical/pack-format.txt
+++ b/Documentation/technical/pack-format.txt
@@ -307,6 +307,11 @@ CHUNK DATA:
name. This is the only chunk not guaranteed to be a multiple of four
bytes in length, so should be the last chunk for alignment reasons.
+ OID Fanout (ID: {'O', 'I', 'D', 'F'}) (256 * 4 bytes)
+ The ith entry, F[i], stores the number of OIDs with first
+ byte at most i. Thus F[255] stores the total
+ number of objects (N).
+
OID Lookup (ID: {'O', 'I', 'D', 'L'}) (N * H bytes)
The OIDs for all objects in the MIDX are stored in lexicographic
order in this chunk.
diff --git a/builtin/midx.c b/builtin/midx.c
index 86edd30174..e1fd0e0de4 100644
--- a/builtin/midx.c
+++ b/builtin/midx.c
@@ -35,10 +35,12 @@ static int read_midx_file(const char *object_dir)
printf(" pack_lookup");
if (m->chunk_pack_names)
printf(" pack_names");
+ if (m->chunk_oid_fanout)
+ printf(" oid_fanout");
if (m->chunk_oid_lookup)
printf(" oid_lookup");
- printf("\n");
+ printf("\nnum_objects: %d\n", m->num_objects);
printf("packs:\n");
for (i = 0; i < m->num_packs; i++)
diff --git a/midx.c b/midx.c
index d06bc6876a..9458ced208 100644
--- a/midx.c
+++ b/midx.c
@@ -14,12 +14,14 @@
#define MIDX_HASH_LEN 20
#define MIDX_MIN_SIZE (MIDX_HEADER_SIZE + MIDX_HASH_LEN)
-#define MIDX_MAX_CHUNKS 3
+#define MIDX_MAX_CHUNKS 4
#define MIDX_CHUNK_ALIGNMENT 4
#define MIDX_CHUNKID_PACKLOOKUP 0x504c4f4f /* "PLOO" */
#define MIDX_CHUNKID_PACKNAMES 0x504e414d /* "PNAM" */
+#define MIDX_CHUNKID_OIDFANOUT 0x4f494446 /* "OIDF" */
#define MIDX_CHUNKID_OIDLOOKUP 0x4f49444c /* "OIDL" */
#define MIDX_CHUNKLOOKUP_WIDTH (sizeof(uint32_t) + sizeof(uint64_t))
+#define MIDX_CHUNK_FANOUT_SIZE (sizeof(uint32_t) * 256)
static char *get_midx_filename(const char *object_dir)
{
@@ -96,6 +98,10 @@ struct midxed_git *load_midxed_git(const char *object_dir)
m->chunk_pack_names = m->data + chunk_offset;
break;
+ case MIDX_CHUNKID_OIDFANOUT:
+ m->chunk_oid_fanout = (uint32_t *)(m->data +
chunk_offset);
+ break;
+
case MIDX_CHUNKID_OIDLOOKUP:
m->chunk_oid_lookup = m->data + chunk_offset;
break;
@@ -117,9 +123,13 @@ struct midxed_git *load_midxed_git(const char *object_dir)
die("MIDX missing required pack lookup chunk");
if (!m->chunk_pack_names)
die("MIDX missing required pack-name chunk");
+ if (!m->chunk_oid_fanout)
+ die("MIDX missing required OID fanout chunk");
if (!m->chunk_oid_lookup)
die("MIDX missing required OID lookup chunk");
+ m->num_objects = ntohl(m->chunk_oid_fanout[255]);
+
m->pack_names = xcalloc(m->num_packs, sizeof(const char *));
for (i = 0; i < m->num_packs; i++) {
if (i) {
@@ -377,6 +387,35 @@ static size_t write_midx_pack_names(struct hashfile *f,
return written;
}
+static size_t write_midx_oid_fanout(struct hashfile *f,
+ struct pack_midx_entry *objects,
+ uint32_t nr_objects)
+{
+ struct pack_midx_entry *list = objects;
+ struct pack_midx_entry *last = objects + nr_objects;
+ uint32_t count = 0;
+ uint32_t i;
+
+ /*
+ * Write the first-level table (the list is sorted,
+ * but we use a 256-entry lookup to be able to avoid
+ * having to do eight extra binary search iterations).
+ */
+ for (i = 0; i < 256; i++) {
+ struct pack_midx_entry *next = list;
+
+ while (next < last && next->oid.hash[0] == i) {
+ count++;
+ next++;
+ }
+
+ hashwrite_be32(f, count);
+ list = next;
+ }
+
+ return MIDX_CHUNK_FANOUT_SIZE;
+}
+
static size_t write_midx_oid_lookup(struct hashfile *f, unsigned char hash_len,
struct pack_midx_entry *objects,
uint32_t nr_objects)
@@ -489,7 +528,7 @@ int write_midx_file(const char *object_dir)
FREE_AND_NULL(midx_name);
