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midx: write object ids in a chunk
Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
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‎Documentation/technical/pack-format.txt‎

Lines changed: 4 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -302,6 +302,10 @@ CHUNK DATA:
302302
name. This is the only chunk not guaranteed to be a multiple of four
303303
bytes in length, so should be the last chunk for alignment reasons.
304304

305+
OID Lookup (ID: {'O', 'I', 'D', 'L'})
306+
The OIDs for all objects in the MIDX are stored in lexicographic
307+
order in this chunk.
308+
305309
(This section intentionally left incomplete.)
306310

307311
TRAILER:

‎midx.c‎

Lines changed: 44 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -18,9 +18,10 @@
1818
#define MIDX_HASH_LEN 20
1919
#define MIDX_MIN_SIZE (MIDX_HEADER_SIZE + MIDX_HASH_LEN)
2020

21-
#define MIDX_MAX_CHUNKS 1
21+
#define MIDX_MAX_CHUNKS 2
2222
#define MIDX_CHUNK_ALIGNMENT 4
2323
#define MIDX_CHUNKID_PACKNAMES 0x504e414d /* "PNAM" */
24+
#define MIDX_CHUNKID_OIDLOOKUP 0x4f49444c /* "OIDL" */
2425
#define MIDX_CHUNKLOOKUP_WIDTH (sizeof(uint32_t) + sizeof(uint64_t))
2526

2627
static char *get_midx_filename(const char *object_dir)
@@ -101,6 +102,10 @@ struct multi_pack_index *load_multi_pack_index(const char *object_dir)
101102
m->chunk_pack_names = m->data + chunk_offset;
102103
break;
103104

105+
case MIDX_CHUNKID_OIDLOOKUP:
106+
m->chunk_oid_lookup = m->data + chunk_offset;
107+
break;
108+
104109
case 0:
105110
die(_("terminating multi-pack-index chunk id appears earlier than expected"));
106111
break;
@@ -116,6 +121,8 @@ struct multi_pack_index *load_multi_pack_index(const char *object_dir)
116121

117122
if (!m->chunk_pack_names)
118123
die(_("multi-pack-index missing required pack-name chunk"));
124+
if (!m->chunk_oid_lookup)
125+
die(_("multi-pack-index missing required OID lookup chunk"));
119126

120127
m->pack_names = xcalloc(m->num_packs, sizeof(*m->pack_names));
121128

@@ -382,6 +389,32 @@ static size_t write_midx_pack_names(struct hashfile *f,
382389
return written;
383390
}
384391

392+
static size_t write_midx_oid_lookup(struct hashfile *f, unsigned char hash_len,
393+
struct pack_midx_entry *objects,
394+
uint32_t nr_objects)
395+
{
396+
struct pack_midx_entry *list = objects;
397+
uint32_t i;
398+
size_t written = 0;
399+
400+
for (i = 0; i < nr_objects; i++) {
401+
struct pack_midx_entry *obj = list++;
402+
403+
if (i < nr_objects - 1) {
404+
struct pack_midx_entry *next = list;
405+
if (oidcmp(&obj->oid, &next->oid) >= 0)
406+
BUG("OIDs not in order: %s >= %s",
407+
oid_to_hex(&obj->oid),
408+
oid_to_hex(&next->oid));
409+
}
410+
411+
hashwrite(f, obj->oid.hash, (int)hash_len);
412+
written += hash_len;
413+
}
414+
415+
return written;
416+
}
417+
385418
int write_midx_file(const char *object_dir)
386419
{
387420
unsigned char cur_chunk, num_chunks = 0;
@@ -428,17 +461,21 @@ int write_midx_file(const char *object_dir)
428461
FREE_AND_NULL(midx_name);
429462

430463
cur_chunk = 0;
431-
num_chunks = 1;
464+
num_chunks = 2;
432465

433466
written = write_midx_header(f, num_chunks, packs.nr);
434467

435468
chunk_ids[cur_chunk] = MIDX_CHUNKID_PACKNAMES;
436469
chunk_offsets[cur_chunk] = written + (num_chunks + 1) * MIDX_CHUNKLOOKUP_WIDTH;
437470

438471
cur_chunk++;
439-
chunk_ids[cur_chunk] = 0;
472+
chunk_ids[cur_chunk] = MIDX_CHUNKID_OIDLOOKUP;
440473
chunk_offsets[cur_chunk] = chunk_offsets[cur_chunk - 1] + packs.pack_name_concat_len;
441474

475+
cur_chunk++;
476+
chunk_ids[cur_chunk] = 0;
477+
chunk_offsets[cur_chunk] = chunk_offsets[cur_chunk - 1] + nr_entries * MIDX_HASH_LEN;
478+
442479
for (i = 0; i <= num_chunks; i++) {
443480
if (i && chunk_offsets[i] < chunk_offsets[i - 1])
444481
BUG("incorrect chunk offsets: %"PRIu64" before %"PRIu64,
@@ -468,6 +505,10 @@ int write_midx_file(const char *object_dir)
468505
written += write_midx_pack_names(f, packs.names, packs.nr);
469506
break;
470507

508+
case MIDX_CHUNKID_OIDLOOKUP:
509+
written += write_midx_oid_lookup(f, MIDX_HASH_LEN, entries, nr_entries);
510+
break;
511+
471512
default:
472513
BUG("trying to write unknown chunk id %"PRIx32,
473514
chunk_ids[i]);

‎midx.h‎

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -15,6 +15,7 @@ struct multi_pack_index {
1515
uint32_t num_objects;
1616

1717
const unsigned char *chunk_pack_names;
18+
const unsigned char *chunk_oid_lookup;
1819

1920
const char **pack_names;
2021
char object_dir[FLEX_ARRAY];

‎t/helper/test-read-midx.c‎

Lines changed: 2 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -22,6 +22,8 @@ static int read_midx_file(const char *object_dir)
2222

2323
if (m->chunk_pack_names)
2424
printf(" pack-names");
25+
if (m->chunk_oid_lookup)
26+
printf(" oid-lookup");
2527

2628
printf("\n");
2729

‎t/t5319-multi-pack-index.sh‎

Lines changed: 2 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -7,8 +7,8 @@ midx_read_expect () {
77
NUM_PACKS=$1
88
{
99
cat <<-EOF &&
10-
header: 4d494458 1 1 $NUM_PACKS
11-
chunks: pack-names
10+
header: 4d494458 1 2 $NUM_PACKS
11+
chunks: pack-names oid-lookup
1212
packs:
1313
EOF
1414
if test $NUM_PACKS -ge 1

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