On Thu, Jun 7, 2018 at 7:01 PM Derrick Stolee <stolee@xxxxxxxxx> wrote:
>
> Signed-off-by: Derrick Stolee <dstolee@xxxxxxxxxxxxx>
> ---
> Documentation/technical/pack-format.txt | 5 +++
> builtin/midx.c | 7 ++++
> midx.c | 56 +++++++++++++++++++++++--
> object-store.h | 2 +
> t/t5319-midx.sh | 11 +++--
> 5 files changed, 75 insertions(+), 6 deletions(-)
>
> diff --git a/Documentation/technical/pack-format.txt b/Documentation/technical/pack-format.txt
> index 2b37be7b33..29bf87283a 100644
> --- a/Documentation/technical/pack-format.txt
> +++ b/Documentation/technical/pack-format.txt
> @@ -296,6 +296,11 @@ CHUNK LOOKUP:
>
> CHUNK DATA:
>
> + Packfile Name Lookup (ID: {'P', 'L', 'O', 'O'}) (P * 4 bytes)
> + P * 4 bytes storing the offset in the packfile name chunk for
> + the null-terminated string containing the filename for the
> + ith packfile.
> +
Commit message is too light on this one. Why does this need to be
stored? Isn't the cost of rebuilding this in-core cheap?
Adding this chunk on disk in my opinion only adds more burden. Now you
have to verify that these offsets actually point to the right place.
> Packfile Names (ID: {'P', 'N', 'A', 'M'})
> Stores the packfile names as concatenated, null-terminated strings.
> Packfiles must be listed in lexicographic order for fast lookups by
> diff --git a/builtin/midx.c b/builtin/midx.c
> index fe56560853..3a261e9bbf 100644
> --- a/builtin/midx.c
> +++ b/builtin/midx.c
> @@ -16,6 +16,7 @@ static struct opts_midx {
>
> static int read_midx_file(const char *object_dir)
> {
> + uint32_t i;
> struct midxed_git *m = load_midxed_git(object_dir);
>
> if (!m)
> @@ -30,11 +31,17 @@ static int read_midx_file(const char *object_dir)
>
> printf("chunks:");
>
> + if (m->chunk_pack_lookup)
> + printf(" pack_lookup");
> if (m->chunk_pack_names)
> printf(" pack_names");
>
> printf("\n");
>
> + printf("packs:\n");
> + for (i = 0; i < m->num_packs; i++)
> + printf("%s\n", m->pack_names[i]);
> +
> printf("object_dir: %s\n", m->object_dir);
>
> return 0;
> diff --git a/midx.c b/midx.c
> index d4f4a01a51..923acda72e 100644
> --- a/midx.c
> +++ b/midx.c
> @@ -13,8 +13,9 @@
> #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_PACKLOOKUP 0x504c4f4f /* "PLOO" */
> #define MIDX_CHUNKID_PACKNAMES 0x504e414d /* "PNAM" */
> #define MIDX_CHUNKLOOKUP_WIDTH (sizeof(uint32_t) + sizeof(uint64_t))
>
> @@ -85,6 +86,10 @@ struct midxed_git *load_midxed_git(const char *object_dir)
> uint64_t chunk_offset = get_be64(m->data + 16 + MIDX_CHUNKLOOKUP_WIDTH * i);
>
> switch (chunk_id) {
> + case MIDX_CHUNKID_PACKLOOKUP:
> + m->chunk_pack_lookup = (uint32_t *)(m->data + chunk_offset);
> + break;
> +
> case MIDX_CHUNKID_PACKNAMES:
> m->chunk_pack_names = m->data + chunk_offset;
> break;
> @@ -102,9 +107,32 @@ struct midxed_git *load_midxed_git(const char *object_dir)
> }
> }
>
> + if (!m->chunk_pack_lookup)
> + die("MIDX missing required pack lookup chunk");
> if (!m->chunk_pack_names)
> die("MIDX missing required pack-name chunk");
>
> + m->pack_names = xcalloc(m->num_packs, sizeof(const char *));
> + for (i = 0; i < m->num_packs; i++) {
> + if (i) {
> + if (ntohl(m->chunk_pack_lookup[i]) <= ntohl(m->chunk_pack_lookup[i - 1])) {
> + error("MIDX pack lookup value %d before %d",
> + ntohl(m->chunk_pack_lookup[i - 1]),
> + ntohl(m->chunk_pack_lookup[i]));
> + goto cleanup_fail;
> + }
> + }
> +
> + m->pack_names[i] = (const char *)(m->chunk_pack_names + ntohl(m->chunk_pack_lookup[i]));
> +
> + if (i && strcmp(m->pack_names[i], m->pack_names[i - 1]) <= 0) {
> + error("MIDX pack names out of order: '%s' before '%s'",
> + m->pack_names[i - 1],
> + m->pack_names[i]);
> + goto cleanup_fail;
> + }
> + }
> +
> return m;
>
> cleanup_fail:
> @@ -162,6 +190,20 @@ static void sort_packs_by_name(char **pack_names, uint32_t nr_packs, uint32_t *p
> }
> }
>
> +static size_t write_midx_pack_lookup(struct hashfile *f,
> + char **pack_names,
> + uint32_t nr_packs)
> +{
> + uint32_t i, cur_len = 0;
> +
> + for (i = 0; i < nr_packs; i++) {
> + hashwrite_be32(f, cur_len);
> + cur_len += strlen(pack_names[i]) + 1;
> + }
> +
> + return sizeof(uint32_t) * (size_t)nr_packs;
> +}
> +
> static size_t write_midx_pack_names(struct hashfile *f,
> char **pack_names,
> uint32_t num_packs)
> @@ -275,13 +317,17 @@ 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, nr_packs);
>
> - chunk_ids[cur_chunk] = MIDX_CHUNKID_PACKNAMES;
> + chunk_ids[cur_chunk] = MIDX_CHUNKID_PACKLOOKUP;
> chunk_offsets[cur_chunk] = written + (num_chunks + 1) * MIDX_CHUNKLOOKUP_WIDTH;
>
> + cur_chunk++;
> + chunk_ids[cur_chunk] = MIDX_CHUNKID_PACKNAMES;
> + chunk_offsets[cur_chunk] = chunk_offsets[cur_chunk - 1] + nr_packs * sizeof(uint32_t);
> +
> cur_chunk++;
> chunk_ids[cur_chunk] = 0;
> chunk_offsets[cur_chunk] = chunk_offsets[cur_chunk - 1] + pack_name_concat_len;
> @@ -311,6 +357,10 @@ int write_midx_file(const char *object_dir)
> chunk_ids[i]);
>
> switch (chunk_ids[i]) {
> + case MIDX_CHUNKID_PACKLOOKUP:
> + written += write_midx_pack_lookup(f, pack_names, nr_packs);
> + break;
> +
> case MIDX_CHUNKID_PACKNAMES:
> written += write_midx_pack_names(f, pack_names, nr_packs);
> break;
> diff --git a/object-store.h b/object-store.h
> index 199cf4bd44..1ba50459ca 100644
> --- a/object-store.h
> +++ b/object-store.h
> @@ -100,8 +100,10 @@ struct midxed_git {
> uint32_t num_packs;
> uint32_t num_objects;
>
> + const uint32_t *chunk_pack_lookup;
> const unsigned char *chunk_pack_names;
>
> + const char **pack_names;
> char object_dir[FLEX_ARRAY];
> };
>
> diff --git a/t/t5319-midx.sh b/t/t5319-midx.sh
> index fdf4f84a90..a31c387c8f 100755
> --- a/t/t5319-midx.sh
> +++ b/t/t5319-midx.sh
> @@ -6,10 +6,15 @@ test_description='multi-pack-indexes'
> midx_read_expect() {
> NUM_PACKS=$1
> cat >expect <<- EOF
> - header: 4d494458 1 1 1 $NUM_PACKS
> - chunks: pack_names
> - object_dir: .
> + header: 4d494458 1 1 2 $NUM_PACKS
> + chunks: pack_lookup pack_names
> + packs:
> EOF
> + if [ $NUM_PACKS -ge 1 ]
> + then
> + ls pack/ | grep idx | sort >> expect
> + fi
> + printf "object_dir: .\n" >>expect &&
> git midx read --object-dir=. >actual &&
> test_cmp expect actual
> }
> --
> 2.18.0.rc1
>
--
Duy
