midx: write object ids in a chunk
authorDerrick Stolee <stolee@gmail.com>
Thu, 12 Jul 2018 19:39:30 +0000 (15:39 -0400)
committerJunio C Hamano <gitster@pobox.com>
Fri, 20 Jul 2018 18:27:28 +0000 (11:27 -0700)
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Documentation/technical/pack-format.txt
midx.c
midx.h
t/helper/test-read-midx.c
t/t5319-multi-pack-index.sh

index 6c5a774..78ee048 100644 (file)
@@ -302,6 +302,10 @@ 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 Lookup (ID: {'O', 'I', 'D', 'L'})
+           The OIDs for all objects in the MIDX are stored in lexicographic
+           order in this chunk.
+
        (This section intentionally left incomplete.)
 
 TRAILER:
diff --git a/midx.c b/midx.c
index 29f8de5..3f113e1 100644 (file)
--- a/midx.c
+++ b/midx.c
 #define MIDX_HASH_LEN 20
 #define MIDX_MIN_SIZE (MIDX_HEADER_SIZE + MIDX_HASH_LEN)
 
-#define MIDX_MAX_CHUNKS 1
+#define MIDX_MAX_CHUNKS 2
 #define MIDX_CHUNK_ALIGNMENT 4
 #define MIDX_CHUNKID_PACKNAMES 0x504e414d /* "PNAM" */
+#define MIDX_CHUNKID_OIDLOOKUP 0x4f49444c /* "OIDL" */
 #define MIDX_CHUNKLOOKUP_WIDTH (sizeof(uint32_t) + sizeof(uint64_t))
 
 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)
                                m->chunk_pack_names = m->data + chunk_offset;
                                break;
 
+                       case MIDX_CHUNKID_OIDLOOKUP:
+                               m->chunk_oid_lookup = m->data + chunk_offset;
+                               break;
+
                        case 0:
                                die(_("terminating multi-pack-index chunk id appears earlier than expected"));
                                break;
@@ -116,6 +121,8 @@ 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_lookup)
+               die(_("multi-pack-index missing required OID lookup chunk"));
 
        m->pack_names = xcalloc(m->num_packs, sizeof(*m->pack_names));
 
@@ -382,6 +389,32 @@ static size_t write_midx_pack_names(struct hashfile *f,
        return written;
 }
 
+static size_t write_midx_oid_lookup(struct hashfile *f, unsigned char hash_len,
+                                   struct pack_midx_entry *objects,
+                                   uint32_t nr_objects)
+{
+       struct pack_midx_entry *list = objects;
+       uint32_t i;
+       size_t written = 0;
+
+       for (i = 0; i < nr_objects; i++) {
+               struct pack_midx_entry *obj = list++;
+
+               if (i < nr_objects - 1) {
+                       struct pack_midx_entry *next = list;
+                       if (oidcmp(&obj->oid, &next->oid) >= 0)
+                               BUG("OIDs not in order: %s >= %s",
+                                   oid_to_hex(&obj->oid),
+                                   oid_to_hex(&next->oid));
+               }
+
+               hashwrite(f, obj->oid.hash, (int)hash_len);
+               written += hash_len;
+       }
+
+       return written;
+}
+
 int write_midx_file(const char *object_dir)
 {
        unsigned char cur_chunk, num_chunks = 0;
@@ -428,7 +461,7 @@ int write_midx_file(const char *object_dir)
        FREE_AND_NULL(midx_name);
 
        cur_chunk = 0;
-       num_chunks = 1;
+       num_chunks = 2;
 
        written = write_midx_header(f, num_chunks, packs.nr);
 
@@ -436,9 +469,13 @@ 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] = 0;
+       chunk_ids[cur_chunk] = MIDX_CHUNKID_OIDLOOKUP;
        chunk_offsets[cur_chunk] = chunk_offsets[cur_chunk - 1] + packs.pack_name_concat_len;
 
+       cur_chunk++;
+       chunk_ids[cur_chunk] = 0;
+       chunk_offsets[cur_chunk] = chunk_offsets[cur_chunk - 1] + nr_entries * MIDX_HASH_LEN;
+
        for (i = 0; i <= num_chunks; i++) {
                if (i && chunk_offsets[i] < chunk_offsets[i - 1])
                        BUG("incorrect chunk offsets: %"PRIu64" before %"PRIu64,
@@ -468,6 +505,10 @@ int write_midx_file(const char *object_dir)
                                written += write_midx_pack_names(f, packs.names, packs.nr);
                                break;
 
+                       case MIDX_CHUNKID_OIDLOOKUP:
+                               written += write_midx_oid_lookup(f, MIDX_HASH_LEN, entries, nr_entries);
+                               break;
+
                        default:
                                BUG("trying to write unknown chunk id %"PRIx32,
                                    chunk_ids[i]);
diff --git a/midx.h b/midx.h
index 17b5617..4d3bcea 100644 (file)
--- a/midx.h
+++ b/midx.h
@@ -15,6 +15,7 @@ struct multi_pack_index {
        uint32_t num_objects;
 
        const unsigned char *chunk_pack_names;
+       const unsigned char *chunk_oid_lookup;
 
        const char **pack_names;
        char object_dir[FLEX_ARRAY];
index 76a60d7..de6d452 100644 (file)
@@ -22,6 +22,8 @@ static int read_midx_file(const char *object_dir)
 
        if (m->chunk_pack_names)
                printf(" pack-names");
+       if (m->chunk_oid_lookup)
+               printf(" oid-lookup");
 
        printf("\n");
 
index e8da082..4813610 100755 (executable)
@@ -7,8 +7,8 @@ midx_read_expect () {
        NUM_PACKS=$1
        {
                cat <<-EOF &&
-               header: 4d494458 1 1 $NUM_PACKS
-               chunks: pack-names
+               header: 4d494458 1 2 $NUM_PACKS
+               chunks: pack-names oid-lookup
                packs:
                EOF
                if test $NUM_PACKS -ge 1