pack-objects.c

   1 #include "cache.h"
   2 #include "object.h"
   3 #include "pack.h"
   4 #include "pack-objects.h"
   5
   6 static uint32_t locate_object_entry_hash(struct packing_data *pdata,
   7                                          const unsigned char *sha1,
   8                                          int *found)
   9 {
  10         uint32_t i, hash, mask = (pdata->index_size - 1);
  11
  12         memcpy(&hash, sha1, sizeof(uint32_t));
  13         i = hash & mask;
  14
  15         while (pdata->index[i] > 0) {
  16                 uint32_t pos = pdata->index[i] - 1;
  17
  18                 if (!hashcmp(sha1, pdata->objects[pos].idx.sha1)) {
  19                         *found = 1;
  20                         return i;
  21                 }
  22
  23                 i = (i + 1) & mask;
  24         }
  25
  26         *found = 0;
  27         return i;
  28 }
  29
  30 static inline uint32_t closest_pow2(uint32_t v)
  31 {
  32         v = v - 1;
  33         v |= v >> 1;
  34         v |= v >> 2;
  35         v |= v >> 4;
  36         v |= v >> 8;
  37         v |= v >> 16;
  38         return v + 1;
  39 }
  40
  41 static void rehash_objects(struct packing_data *pdata)
  42 {
  43         uint32_t i;
  44         struct object_entry *entry;
  45
  46         pdata->index_size = closest_pow2(pdata->nr_objects * 3);
  47         if (pdata->index_size < 1024)
  48                 pdata->index_size = 1024;
  49
  50         free(pdata->index);
  51         pdata->index = xcalloc(pdata->index_size, sizeof(*pdata->index));
  52
  53         entry = pdata->objects;
  54
  55         for (i = 0; i < pdata->nr_objects; i++) {
  56                 int found;
  57                 uint32_t ix = locate_object_entry_hash(pdata, entry->idx.sha1, &found);
  58
  59                 if (found)
  60                         die("BUG: Duplicate object in hash");
  61
  62                 pdata->index[ix] = i + 1;
  63                 entry++;
  64         }
  65 }
  66
  67 struct object_entry *packlist_find(struct packing_data *pdata,
  68                                    const unsigned char *sha1,
  69                                    uint32_t *index_pos)
  70 {
  71         uint32_t i;
  72         int found;
  73
  74         if (!pdata->index_size)
  75                 return NULL;
  76
  77         i = locate_object_entry_hash(pdata, sha1, &found);
  78
  79         if (index_pos)
  80                 *index_pos = i;
  81
  82         if (!found)
  83                 return NULL;
  84
  85         return &pdata->objects[pdata->index[i] - 1];
  86 }
  87
  88 struct object_entry *packlist_alloc(struct packing_data *pdata,
  89                                     const unsigned char *sha1,
  90                                     uint32_t index_pos)
  91 {
  92         struct object_entry *new_entry;
  93
  94         if (pdata->nr_objects >= pdata->nr_alloc) {
  95                 pdata->nr_alloc = (pdata->nr_alloc  + 1024) * 3 / 2;
  96                 pdata->objects = xrealloc(pdata->objects,
  97                                           pdata->nr_alloc * sizeof(*new_entry));
  98         }
  99
 100         new_entry = pdata->objects + pdata->nr_objects++;
 101
 102         memset(new_entry, 0, sizeof(*new_entry));
 103         hashcpy(new_entry->idx.sha1, sha1);
 104
 105         if (pdata->index_size * 3 <= pdata->nr_objects * 4)
 106                 rehash_objects(pdata);
 107         else
 108                 pdata->index[index_pos] = pdata->nr_objects;
 109
 110         return new_entry;
 111 }