midx: use midx in approximate_object_count
[gitweb.git] / midx.c
diff --git a/midx.c b/midx.c
index 3f113e1bebbf74e639290d525c34b208e1bfc57f..bf2334acc6f2a2e7a81a977b3afc398f0f8d909e 100644 (file)
--- a/midx.c
+++ b/midx.c
@@ -1,10 +1,11 @@
 #include "cache.h"
+#include "config.h"
 #include "csum-file.h"
 #include "dir.h"
 #include "lockfile.h"
 #include "packfile.h"
 #include "object-store.h"
-#include "packfile.h"
+#include "sha1-lookup.h"
 #include "midx.h"
 
 #define MIDX_SIGNATURE 0x4d494458 /* "MIDX" */
 #define MIDX_HASH_LEN 20
 #define MIDX_MIN_SIZE (MIDX_HEADER_SIZE + MIDX_HASH_LEN)
 
-#define MIDX_MAX_CHUNKS 2
+#define MIDX_MAX_CHUNKS 5
 #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_CHUNKID_OBJECTOFFSETS 0x4f4f4646 /* "OOFF" */
+#define MIDX_CHUNKID_LARGEOFFSETS 0x4c4f4646 /* "LOFF" */
 #define MIDX_CHUNKLOOKUP_WIDTH (sizeof(uint32_t) + sizeof(uint64_t))
+#define MIDX_CHUNK_FANOUT_SIZE (sizeof(uint32_t) * 256)
+#define MIDX_CHUNK_OFFSET_WIDTH (2 * sizeof(uint32_t))
+#define MIDX_CHUNK_LARGE_OFFSET_WIDTH (sizeof(uint64_t))
+#define MIDX_LARGE_OFFSET_NEEDED 0x80000000
 
 static char *get_midx_filename(const char *object_dir)
 {
@@ -102,10 +110,22 @@ 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;
 
+                       case MIDX_CHUNKID_OBJECTOFFSETS:
+                               m->chunk_object_offsets = m->data + chunk_offset;
+                               break;
+
+                       case MIDX_CHUNKID_LARGEOFFSETS:
+                               m->chunk_large_offsets = m->data + chunk_offset;
+                               break;
+
                        case 0:
                                die(_("terminating multi-pack-index chunk id appears earlier than expected"));
                                break;
@@ -121,10 +141,17 @@ 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"));
+       if (!m->chunk_object_offsets)
+               die(_("multi-pack-index missing required object offsets chunk"));
+
+       m->num_objects = ntohl(m->chunk_oid_fanout[255]);
 
        m->pack_names = xcalloc(m->num_packs, sizeof(*m->pack_names));
+       m->packs = xcalloc(m->num_packs, sizeof(*m->packs));
 
        cur_pack_name = (const char *)m->chunk_pack_names;
        for (i = 0; i < m->num_packs; i++) {
@@ -152,6 +179,169 @@ struct multi_pack_index *load_multi_pack_index(const char *object_dir)
        return NULL;
 }
 
+static void close_midx(struct multi_pack_index *m)
+{
+       uint32_t i;
+       munmap((unsigned char *)m->data, m->data_len);
+       close(m->fd);
+       m->fd = -1;
+
+       for (i = 0; i < m->num_packs; i++) {
+               if (m->packs[i]) {
+                       close_pack(m->packs[i]);
+                       free(m->packs);
+               }
+       }
+       FREE_AND_NULL(m->packs);
+       FREE_AND_NULL(m->pack_names);
+}
+
+static int prepare_midx_pack(struct multi_pack_index *m, uint32_t pack_int_id)
+{
+       struct strbuf pack_name = STRBUF_INIT;
+
+       if (pack_int_id >= m->num_packs)
+               BUG("bad pack-int-id");
+
+       if (m->packs[pack_int_id])
+               return 0;
+
+       strbuf_addf(&pack_name, "%s/pack/%s", m->object_dir,
+                   m->pack_names[pack_int_id]);
+
+       m->packs[pack_int_id] = add_packed_git(pack_name.buf, pack_name.len, 1);
+       strbuf_release(&pack_name);
+       return !m->packs[pack_int_id];
+}
+
+int bsearch_midx(const struct object_id *oid, struct multi_pack_index *m, uint32_t *result)
+{
+       return bsearch_hash(oid->hash, m->chunk_oid_fanout, m->chunk_oid_lookup,
+                           MIDX_HASH_LEN, result);
+}
+
+struct object_id *nth_midxed_object_oid(struct object_id *oid,
+                                       struct multi_pack_index *m,
+                                       uint32_t n)
+{
+       if (n >= m->num_objects)
+               return NULL;
+
+       hashcpy(oid->hash, m->chunk_oid_lookup + m->hash_len * n);
+       return oid;
+}
+
+static off_t nth_midxed_offset(struct multi_pack_index *m, uint32_t pos)
+{
+       const unsigned char *offset_data;
+       uint32_t offset32;
+
+       offset_data = m->chunk_object_offsets + pos * MIDX_CHUNK_OFFSET_WIDTH;
+       offset32 = get_be32(offset_data + sizeof(uint32_t));
+
+       if (m->chunk_large_offsets && offset32 & MIDX_LARGE_OFFSET_NEEDED) {
+               if (sizeof(offset32) < sizeof(uint64_t))
+                       die(_("multi-pack-index stores a 64-bit offset, but off_t is too small"));
+
+               offset32 ^= MIDX_LARGE_OFFSET_NEEDED;
+               return get_be64(m->chunk_large_offsets + sizeof(uint64_t) * offset32);
+       }
+
+       return offset32;
+}
+
+static uint32_t nth_midxed_pack_int_id(struct multi_pack_index *m, uint32_t pos)
+{
+       return get_be32(m->chunk_object_offsets + pos * MIDX_CHUNK_OFFSET_WIDTH);
+}
+
+static int nth_midxed_pack_entry(struct multi_pack_index *m, struct pack_entry *e, uint32_t pos)
+{
+       uint32_t pack_int_id;
+       struct packed_git *p;
+
+       if (pos >= m->num_objects)
+               return 0;
+
+       pack_int_id = nth_midxed_pack_int_id(m, pos);
+
+       if (prepare_midx_pack(m, pack_int_id))
+               die(_("error preparing packfile from multi-pack-index"));
+       p = m->packs[pack_int_id];
+
+       /*
+       * We are about to tell the caller where they can locate the
+       * requested object.  We better make sure the packfile is
+       * still here and can be accessed before supplying that
+       * answer, as it may have been deleted since the MIDX was
+       * loaded!
+       */
+       if (!is_pack_valid(p))
+               return 0;
+
+       e->offset = nth_midxed_offset(m, pos);
+       e->p = p;
+
+       return 1;
+}
+
+int fill_midx_entry(const struct object_id *oid, struct pack_entry *e, struct multi_pack_index *m)
+{
+       uint32_t pos;
+
+       if (!bsearch_midx(oid, m, &pos))
+               return 0;
+
+       return nth_midxed_pack_entry(m, e, pos);
+}
+
+int midx_contains_pack(struct multi_pack_index *m, const char *idx_name)
+{
+       uint32_t first = 0, last = m->num_packs;
+
+       while (first < last) {
+               uint32_t mid = first + (last - first) / 2;
+               const char *current;
+               int cmp;
+
+               current = m->pack_names[mid];
+               cmp = strcmp(idx_name, current);
+               if (!cmp)
+                       return 1;
+               if (cmp > 0) {
+                       first = mid + 1;
+                       continue;
+               }
+               last = mid;
+       }
+
+       return 0;
+}
+
+int prepare_multi_pack_index_one(struct repository *r, const char *object_dir)
+{
+       struct multi_pack_index *m = r->objects->multi_pack_index;
+       struct multi_pack_index *m_search;
+       int config_value;
+
+       if (repo_config_get_bool(r, "core.multipackindex", &config_value) ||
+           !config_value)
+               return 0;
+
+       for (m_search = m; m_search; m_search = m_search->next)
+               if (!strcmp(object_dir, m_search->object_dir))
+                       return 1;
+
+       r->objects->multi_pack_index = load_multi_pack_index(object_dir);
+
+       if (r->objects->multi_pack_index) {
+               r->objects->multi_pack_index->next = m;
+               return 1;
+       }
+
+       return 0;
+}
+
 static size_t write_midx_header(struct hashfile *f,
                                unsigned char num_chunks,
                                uint32_t num_packs)
@@ -176,6 +366,7 @@ struct pack_list {
        uint32_t alloc_list;
        uint32_t alloc_names;
        size_t pack_name_concat_len;
+       struct multi_pack_index *m;
 };
 
 static void add_pack_to_midx(const char *full_path, size_t full_path_len,
@@ -184,6 +375,9 @@ static void add_pack_to_midx(const char *full_path, size_t full_path_len,
        struct pack_list *packs = (struct pack_list *)data;
 
        if (ends_with(file_name, ".idx")) {
+               if (packs->m && midx_contains_pack(packs->m, file_name))
+                       return;
+
                ALLOC_GROW(packs->list, packs->nr + 1, packs->alloc_list);
                ALLOC_GROW(packs->names, packs->nr + 1, packs->alloc_names);
 
@@ -269,6 +463,23 @@ static int midx_oid_compare(const void *_a, const void *_b)
        return a->pack_int_id - b->pack_int_id;
 }
 
+static int nth_midxed_pack_midx_entry(struct multi_pack_index *m,
+                                     uint32_t *pack_perm,
+                                     struct pack_midx_entry *e,
+                                     uint32_t pos)
+{
+       if (pos >= m->num_objects)
+               return 1;
+
+       nth_midxed_object_oid(&e->oid, m, pos);
+       e->pack_int_id = pack_perm[nth_midxed_pack_int_id(m, pos)];
+       e->offset = nth_midxed_offset(m, pos);
+
+       /* consider objects in midx to be from "old" packs */
+       e->pack_mtime = 0;
+       return 0;
+}
+
 static void fill_pack_entry(uint32_t pack_int_id,
                            struct packed_git *p,
                            uint32_t cur_object,
@@ -294,7 +505,8 @@ static void fill_pack_entry(uint32_t pack_int_id,
  * Copy only the de-duplicated entries (selected by most-recent modified time
  * of a packfile containing the object).
  */
-static struct pack_midx_entry *get_sorted_entries(struct packed_git **p,
+static struct pack_midx_entry *get_sorted_entries(struct multi_pack_index *m,
+                                                 struct packed_git **p,
                                                  uint32_t *perm,
                                                  uint32_t nr_packs,
                                                  uint32_t *nr_objects)
@@ -303,8 +515,9 @@ static struct pack_midx_entry *get_sorted_entries(struct packed_git **p,
        uint32_t alloc_fanout, alloc_objects, total_objects = 0;
        struct pack_midx_entry *entries_by_fanout = NULL;
        struct pack_midx_entry *deduplicated_entries = NULL;
+       uint32_t start_pack = m ? m->num_packs : 0;
 
-       for (cur_pack = 0; cur_pack < nr_packs; cur_pack++)
+       for (cur_pack = start_pack; cur_pack < nr_packs; cur_pack++)
                total_objects += p[cur_pack]->num_objects;
 
        /*
@@ -321,7 +534,23 @@ static struct pack_midx_entry *get_sorted_entries(struct packed_git **p,
        for (cur_fanout = 0; cur_fanout < 256; cur_fanout++) {
                uint32_t nr_fanout = 0;
 
-               for (cur_pack = 0; cur_pack < nr_packs; cur_pack++) {
+               if (m) {
+                       uint32_t start = 0, end;
+
+                       if (cur_fanout)
+                               start = ntohl(m->chunk_oid_fanout[cur_fanout - 1]);
+                       end = ntohl(m->chunk_oid_fanout[cur_fanout]);
+
+                       for (cur_object = start; cur_object < end; cur_object++) {
+                               ALLOC_GROW(entries_by_fanout, nr_fanout + 1, alloc_fanout);
+                               nth_midxed_pack_midx_entry(m, perm,
+                                                          &entries_by_fanout[nr_fanout],
+                                                          cur_object);
+                               nr_fanout++;
+                       }
+               }
+
+               for (cur_pack = start_pack; cur_pack < nr_packs; cur_pack++) {
                        uint32_t start = 0, end;
 
                        if (cur_fanout)
@@ -389,6 +618,35 @@ 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)
@@ -415,6 +673,56 @@ static size_t write_midx_oid_lookup(struct hashfile *f, unsigned char hash_len,
        return written;
 }
 
+static size_t write_midx_object_offsets(struct hashfile *f, int large_offset_needed,
+                                       struct pack_midx_entry *objects, uint32_t nr_objects)
+{
+       struct pack_midx_entry *list = objects;
+       uint32_t i, nr_large_offset = 0;
+       size_t written = 0;
+
+       for (i = 0; i < nr_objects; i++) {
+               struct pack_midx_entry *obj = list++;
+
+               hashwrite_be32(f, obj->pack_int_id);
+
+               if (large_offset_needed && obj->offset >> 31)
+                       hashwrite_be32(f, MIDX_LARGE_OFFSET_NEEDED | nr_large_offset++);
+               else if (!large_offset_needed && obj->offset >> 32)
+                       BUG("object %s requires a large offset (%"PRIx64") but the MIDX is not writing large offsets!",
+                           oid_to_hex(&obj->oid),
+                           obj->offset);
+               else
+                       hashwrite_be32(f, (uint32_t)obj->offset);
+
+               written += MIDX_CHUNK_OFFSET_WIDTH;
+       }
+
+       return written;
+}
+
+static size_t write_midx_large_offsets(struct hashfile *f, uint32_t nr_large_offset,
+                                      struct pack_midx_entry *objects, uint32_t nr_objects)
+{
+       struct pack_midx_entry *list = objects;
+       size_t written = 0;
+
+       while (nr_large_offset) {
+               struct pack_midx_entry *obj = list++;
+               uint64_t offset = obj->offset;
+
+               if (!(offset >> 31))
+                       continue;
+
+               hashwrite_be32(f, offset >> 32);
+               hashwrite_be32(f, offset & 0xffffffffUL);
+               written += 2 * sizeof(uint32_t);
+
+               nr_large_offset--;
+       }
+
+       return written;
+}
+
 int write_midx_file(const char *object_dir)
 {
        unsigned char cur_chunk, num_chunks = 0;
@@ -427,8 +735,9 @@ int write_midx_file(const char *object_dir)
        uint64_t written = 0;
        uint32_t chunk_ids[MIDX_MAX_CHUNKS + 1];
        uint64_t chunk_offsets[MIDX_MAX_CHUNKS + 1];
-       uint32_t nr_entries;
+       uint32_t nr_entries, num_large_offsets = 0;
        struct pack_midx_entry *entries = NULL;
+       int large_offsets_needed = 0;
 
        midx_name = get_midx_filename(object_dir);
        if (safe_create_leading_directories(midx_name)) {
@@ -437,16 +746,34 @@ int write_midx_file(const char *object_dir)
                          midx_name);
        }
 
+       packs.m = load_multi_pack_index(object_dir);
+
        packs.nr = 0;
-       packs.alloc_list = 16;
-       packs.alloc_names = 16;
+       packs.alloc_list = packs.m ? packs.m->num_packs : 16;
+       packs.alloc_names = packs.alloc_list;
        packs.list = NULL;
+       packs.names = NULL;
        packs.pack_name_concat_len = 0;
        ALLOC_ARRAY(packs.list, packs.alloc_list);
        ALLOC_ARRAY(packs.names, packs.alloc_names);
 
+       if (packs.m) {
+               for (i = 0; i < packs.m->num_packs; i++) {
+                       ALLOC_GROW(packs.list, packs.nr + 1, packs.alloc_list);
+                       ALLOC_GROW(packs.names, packs.nr + 1, packs.alloc_names);
+
+                       packs.list[packs.nr] = NULL;
+                       packs.names[packs.nr] = xstrdup(packs.m->pack_names[i]);
+                       packs.pack_name_concat_len += strlen(packs.names[packs.nr]) + 1;
+                       packs.nr++;
+               }
+       }
+
        for_each_file_in_pack_dir(object_dir, add_pack_to_midx, &packs);
 
+       if (packs.m && packs.nr == packs.m->num_packs)
+               goto cleanup;
+
        if (packs.pack_name_concat_len % MIDX_CHUNK_ALIGNMENT)
                packs.pack_name_concat_len += MIDX_CHUNK_ALIGNMENT -
                                              (packs.pack_name_concat_len % MIDX_CHUNK_ALIGNMENT);
@@ -454,14 +781,24 @@ int write_midx_file(const char *object_dir)
        ALLOC_ARRAY(pack_perm, packs.nr);
        sort_packs_by_name(packs.names, packs.nr, pack_perm);
 
-       entries = get_sorted_entries(packs.list, pack_perm, packs.nr, &nr_entries);
+       entries = get_sorted_entries(packs.m, packs.list, pack_perm, packs.nr, &nr_entries);
+
+       for (i = 0; i < nr_entries; i++) {
+               if (entries[i].offset > 0x7fffffff)
+                       num_large_offsets++;
+               if (entries[i].offset > 0xffffffff)
+                       large_offsets_needed = 1;
+       }
 
        hold_lock_file_for_update(&lk, midx_name, LOCK_DIE_ON_ERROR);
        f = hashfd(lk.tempfile->fd, lk.tempfile->filename.buf);
        FREE_AND_NULL(midx_name);
 
+       if (packs.m)
+               close_midx(packs.m);
+
        cur_chunk = 0;
-       num_chunks = 2;
+       num_chunks = large_offsets_needed ? 5 : 4;
 
        written = write_midx_header(f, num_chunks, packs.nr);
 
@@ -469,13 +806,29 @@ 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] = 0;
+       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] = MIDX_CHUNKID_OBJECTOFFSETS;
        chunk_offsets[cur_chunk] = chunk_offsets[cur_chunk - 1] + nr_entries * MIDX_HASH_LEN;
 
+       cur_chunk++;
+       chunk_offsets[cur_chunk] = chunk_offsets[cur_chunk - 1] + nr_entries * MIDX_CHUNK_OFFSET_WIDTH;
+       if (large_offsets_needed) {
+               chunk_ids[cur_chunk] = MIDX_CHUNKID_LARGEOFFSETS;
+
+               cur_chunk++;
+               chunk_offsets[cur_chunk] = chunk_offsets[cur_chunk - 1] +
+                                          num_large_offsets * MIDX_CHUNK_LARGE_OFFSET_WIDTH;
+       }
+
+       chunk_ids[cur_chunk] = 0;
+
        for (i = 0; i <= num_chunks; i++) {
                if (i && chunk_offsets[i] < chunk_offsets[i - 1])
                        BUG("incorrect chunk offsets: %"PRIu64" before %"PRIu64,
@@ -505,10 +858,22 @@ 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;
 
+                       case MIDX_CHUNKID_OBJECTOFFSETS:
+                               written += write_midx_object_offsets(f, large_offsets_needed, entries, nr_entries);
+                               break;
+
+                       case MIDX_CHUNKID_LARGEOFFSETS:
+                               written += write_midx_large_offsets(f, num_large_offsets, entries, nr_entries);
+                               break;
+
                        default:
                                BUG("trying to write unknown chunk id %"PRIx32,
                                    chunk_ids[i]);
@@ -523,6 +888,7 @@ int write_midx_file(const char *object_dir)
        finalize_hashfile(f, NULL, CSUM_FSYNC | CSUM_HASH_IN_STREAM);
        commit_lock_file(&lk);
 
+cleanup:
        for (i = 0; i < packs.nr; i++) {
                if (packs.list[i]) {
                        close_pack(packs.list[i]);
@@ -534,5 +900,7 @@ int write_midx_file(const char *object_dir)
        free(packs.list);
        free(packs.names);
        free(entries);
+       free(pack_perm);
+       free(midx_name);
        return 0;
 }