pack-objects.c

   1 #include "cache.h"
   2 #include "object.h"
   3 #include "pack.h"
   4 #include "pack-objects.h"
   5 #include "packfile.h"
   6 #include "config.h"
   7
   8 static uint32_t locate_object_entry_hash(struct packing_data *pdata,
   9                                          const struct object_id *oid,
  10                                          int *found)
  11 {
  12         uint32_t i, mask = (pdata->index_size - 1);
  13
  14         i = oidhash(oid) & mask;
  15
  16         while (pdata->index[i] > 0) {
  17                 uint32_t pos = pdata->index[i] - 1;
  18
  19                 if (oideq(oid, &pdata->objects[pos].idx.oid)) {
  20                         *found = 1;
  21                         return i;
  22                 }
  23
  24                 i = (i + 1) & mask;
  25         }
  26
  27         *found = 0;
  28         return i;
  29 }
  30
  31 static inline uint32_t closest_pow2(uint32_t v)
  32 {
  33         v = v - 1;
  34         v |= v >> 1;
  35         v |= v >> 2;
  36         v |= v >> 4;
  37         v |= v >> 8;
  38         v |= v >> 16;
  39         return v + 1;
  40 }
  41
  42 static void rehash_objects(struct packing_data *pdata)
  43 {
  44         uint32_t i;
  45         struct object_entry *entry;
  46
  47         pdata->index_size = closest_pow2(pdata->nr_objects * 3);
  48         if (pdata->index_size < 1024)
  49                 pdata->index_size = 1024;
  50
  51         free(pdata->index);
  52         pdata->index = xcalloc(pdata->index_size, sizeof(*pdata->index));
  53
  54         entry = pdata->objects;
  55
  56         for (i = 0; i < pdata->nr_objects; i++) {
  57                 int found;
  58                 uint32_t ix = locate_object_entry_hash(pdata,
  59                                                        &entry->idx.oid,
  60                                                        &found);
  61
  62                 if (found)
  63                         BUG("Duplicate object in hash");
  64
  65                 pdata->index[ix] = i + 1;
  66                 entry++;
  67         }
  68 }
  69
  70 struct object_entry *packlist_find(struct packing_data *pdata,
  71                                    const struct object_id *oid)
  72 {
  73         uint32_t i;
  74         int found;
  75
  76         if (!pdata->index_size)
  77                 return NULL;
  78
  79         i = locate_object_entry_hash(pdata, oid, &found);
  80
  81         if (!found)
  82                 return NULL;
  83
  84         return &pdata->objects[pdata->index[i] - 1];
  85 }
  86
  87 static void prepare_in_pack_by_idx(struct packing_data *pdata)
  88 {
  89         struct packed_git **mapping, *p;
  90         int cnt = 0, nr = 1U << OE_IN_PACK_BITS;
  91
  92         ALLOC_ARRAY(mapping, nr);
  93         /*
  94          * oe_in_pack() on an all-zero'd object_entry
  95          * (i.e. in_pack_idx also zero) should return NULL.
  96          */
  97         mapping[cnt++] = NULL;
  98         for (p = get_all_packs(pdata->repo); p; p = p->next, cnt++) {
  99                 if (cnt == nr) {
 100                         free(mapping);
 101                         return;
 102                 }
 103                 p->index = cnt;
 104                 mapping[cnt] = p;
 105         }
 106         pdata->in_pack_by_idx = mapping;
 107 }
 108
 109 /*
 110  * A new pack appears after prepare_in_pack_by_idx() has been
 111  * run. This is likely a race.
 112  *
 113  * We could map this new pack to in_pack_by_idx[] array, but then we
 114  * have to deal with full array anyway. And since it's hard to test
 115  * this fall back code, just stay simple and fall back to using
 116  * in_pack[] array.
 117  */
 118 void oe_map_new_pack(struct packing_data *pack)
 119 {
 120         uint32_t i;
 121
 122         if (pack->in_pack)
 123                 BUG("packing_data has already been converted to pack array");
 124
 125         ALLOC_ARRAY(pack->in_pack, pack->nr_alloc);
 126
 127         for (i = 0; i < pack->nr_objects; i++)
 128                 pack->in_pack[i] = oe_in_pack(pack, pack->objects + i);
 129
 130         FREE_AND_NULL(pack->in_pack_by_idx);
 131 }
 132
 133 /* assume pdata is already zero'd by caller */
 134 void prepare_packing_data(struct repository *r, struct packing_data *pdata)
 135 {
 136         pdata->repo = r;
 137
 138         if (git_env_bool("GIT_TEST_FULL_IN_PACK_ARRAY", 0)) {
 139                 /*
 140                  * do not initialize in_pack_by_idx[] to force the
 141                  * slow path in oe_in_pack()
 142                  */
 143         } else {
 144                 prepare_in_pack_by_idx(pdata);
 145         }
 146
 147         pdata->oe_size_limit = git_env_ulong("GIT_TEST_OE_SIZE",
 148                                              1U << OE_SIZE_BITS);
 149         pdata->oe_delta_size_limit = git_env_ulong("GIT_TEST_OE_DELTA_SIZE",
 150                                                    1UL << OE_DELTA_SIZE_BITS);
 151         init_recursive_mutex(&pdata->odb_lock);
 152 }
 153
 154 struct object_entry *packlist_alloc(struct packing_data *pdata,
 155                                     const struct object_id *oid)
 156 {
 157         struct object_entry *new_entry;
 158
 159         if (pdata->nr_objects >= pdata->nr_alloc) {
 160                 pdata->nr_alloc = (pdata->nr_alloc  + 1024) * 3 / 2;
 161                 REALLOC_ARRAY(pdata->objects, pdata->nr_alloc);
 162
 163                 if (!pdata->in_pack_by_idx)
 164                         REALLOC_ARRAY(pdata->in_pack, pdata->nr_alloc);
 165                 if (pdata->delta_size)
 166                         REALLOC_ARRAY(pdata->delta_size, pdata->nr_alloc);
 167
 168                 if (pdata->tree_depth)
 169                         REALLOC_ARRAY(pdata->tree_depth, pdata->nr_alloc);
 170
 171                 if (pdata->layer)
 172                         REALLOC_ARRAY(pdata->layer, pdata->nr_alloc);
 173         }
 174
 175         new_entry = pdata->objects + pdata->nr_objects++;
 176
 177         memset(new_entry, 0, sizeof(*new_entry));
 178         oidcpy(&new_entry->idx.oid, oid);
 179
 180         if (pdata->index_size * 3 <= pdata->nr_objects * 4)
 181                 rehash_objects(pdata);
 182         else {
 183                 int found;
 184                 uint32_t pos = locate_object_entry_hash(pdata,
 185                                                         &new_entry->idx.oid,
 186                                                         &found);
 187                 if (found)
 188                         BUG("duplicate object inserted into hash");
 189                 pdata->index[pos] = pdata->nr_objects;
 190         }
 191
 192         if (pdata->in_pack)
 193                 pdata->in_pack[pdata->nr_objects - 1] = NULL;
 194
 195         if (pdata->tree_depth)
 196                 pdata->tree_depth[pdata->nr_objects - 1] = 0;
 197
 198         if (pdata->layer)
 199                 pdata->layer[pdata->nr_objects - 1] = 0;
 200
 201         return new_entry;
 202 }
 203
 204 void oe_set_delta_ext(struct packing_data *pdata,
 205                       struct object_entry *delta,
 206                       const struct object_id *oid)
 207 {
 208         struct object_entry *base;
 209
 210         ALLOC_GROW(pdata->ext_bases, pdata->nr_ext + 1, pdata->alloc_ext);
 211         base = &pdata->ext_bases[pdata->nr_ext++];
 212         memset(base, 0, sizeof(*base));
 213         oidcpy(&base->idx.oid, oid);
 214
 215         /* These flags mark that we are not part of the actual pack output. */
 216         base->preferred_base = 1;
 217         base->filled = 1;
 218
 219         delta->ext_base = 1;
 220         delta->delta_idx = base - pdata->ext_bases + 1;
 221 }