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midx: write object id fanout chunk

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Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Derrick Stolee
2018-07-12 15:39:31 -04:00
committed by Junio C Hamano
parent 0d5b3a5ef7
commit d7cacf29cc
5 changed files with 68 additions and 11 deletions
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53
midx.c
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@ -18,11 +18,13 @@
#define MIDX_HASH_LEN 20
#define MIDX_MIN_SIZE (MIDX_HEADER_SIZE + MIDX_HASH_LEN)
#define MIDX_MAX_CHUNKS 2
#define MIDX_MAX_CHUNKS 3
#define MIDX_CHUNK_ALIGNMENT 4
#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)
{
@ -102,6 +104,10 @@ struct multi_pack_index *load_multi_pack_index(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;
@ -121,9 +127,13 @@ struct multi_pack_index *load_multi_pack_index(const char *object_dir)
if (!m->chunk_pack_names)
die(_("multi-pack-index missing required pack-name chunk"));
if (!m->chunk_oid_fanout)
die(_("multi-pack-index missing required OID fanout chunk"));
if (!m->chunk_oid_lookup)
die(_("multi-pack-index missing required OID lookup chunk"));
m->num_objects = ntohl(m->chunk_oid_fanout[255]);
m->pack_names = xcalloc(m->num_packs, sizeof(*m->pack_names));
cur_pack_name = (const char *)m->chunk_pack_names;
@ -389,6 +399,35 @@ 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)
@ -461,7 +500,7 @@ int write_midx_file(const char *object_dir)
FREE_AND_NULL(midx_name);
cur_chunk = 0;
num_chunks = 2;
num_chunks = 3;
written = write_midx_header(f, num_chunks, packs.nr);
@ -469,9 +508,13 @@ int write_midx_file(const char *object_dir)
chunk_offsets[cur_chunk] = written + (num_chunks + 1) * MIDX_CHUNKLOOKUP_WIDTH;
cur_chunk++;
chunk_ids[cur_chunk] = MIDX_CHUNKID_OIDLOOKUP;
chunk_ids[cur_chunk] = MIDX_CHUNKID_OIDFANOUT;
chunk_offsets[cur_chunk] = chunk_offsets[cur_chunk - 1] + packs.pack_name_concat_len;
cur_chunk++;
chunk_ids[cur_chunk] = MIDX_CHUNKID_OIDLOOKUP;
chunk_offsets[cur_chunk] = chunk_offsets[cur_chunk - 1] + MIDX_CHUNK_FANOUT_SIZE;
cur_chunk++;
chunk_ids[cur_chunk] = 0;
chunk_offsets[cur_chunk] = chunk_offsets[cur_chunk - 1] + nr_entries * MIDX_HASH_LEN;
@ -505,6 +548,10 @@ int write_midx_file(const char *object_dir)
written += write_midx_pack_names(f, packs.names, packs.nr);
break;
case MIDX_CHUNKID_OIDFANOUT:
written += write_midx_oid_fanout(f, entries, nr_entries);
break;
case MIDX_CHUNKID_OIDLOOKUP:
written += write_midx_oid_lookup(f, MIDX_HASH_LEN, entries, nr_entries);
break;