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, mask = (pdata->index_size - 1);
  11
  12         i = sha1hash(sha1) & mask;
  13
  14         while (pdata->index[i] > 0) {
  15                 uint32_t pos = pdata->index[i] - 1;
  16
  17                 if (!hashcmp(sha1, pdata->objects[pos].idx.sha1)) {
  18                         *found = 1;
  19                         return i;
  20                 }
  21
  22                 i = (i + 1) & mask;
  23         }
  24
  25         *found = 0;
  26         return i;
  27 }
  28
  29 static inline uint32_t closest_pow2(uint32_t v)
  30 {
  31         v = v - 1;
  32         v |= v >> 1;
  33         v |= v >> 2;
  34         v |= v >> 4;
  35         v |= v >> 8;
  36         v |= v >> 16;
  37         return v + 1;
  38 }
  39
  40 static void rehash_objects(struct packing_data *pdata)
  41 {
  42         uint32_t i;
  43         struct object_entry *entry;
  44
  45         pdata->index_size = closest_pow2(pdata->nr_objects * 3);
  46         if (pdata->index_size < 1024)
  47                 pdata->index_size = 1024;
  48
  49         free(pdata->index);
  50         pdata->index = xcalloc(pdata->index_size, sizeof(*pdata->index));
  51
  52         entry = pdata->objects;
  53
  54         for (i = 0; i < pdata->nr_objects; i++) {
  55                 int found;
  56                 uint32_t ix = locate_object_entry_hash(pdata, entry->idx.sha1, &found);
  57
  58                 if (found)
  59                         die("BUG: Duplicate object in hash");
  60
  61                 pdata->index[ix] = i + 1;
  62                 entry++;
  63         }
  64 }
  65
  66 struct object_entry *packlist_find(struct packing_data *pdata,
  67                                    const unsigned char *sha1,
  68                                    uint32_t *index_pos)
  69 {
  70         uint32_t i;
  71         int found;
  72
  73         if (!pdata->index_size)
  74                 return NULL;
  75
  76         i = locate_object_entry_hash(pdata, sha1, &found);
  77
  78         if (index_pos)
  79                 *index_pos = i;
  80
  81         if (!found)
  82                 return NULL;
  83
  84         return &pdata->objects[pdata->index[i] - 1];
  85 }
  86
  87 struct object_entry *packlist_alloc(struct packing_data *pdata,
  88                                     const unsigned char *sha1,
  89                                     uint32_t index_pos)
  90 {
  91         struct object_entry *new_entry;
  92
  93         if (pdata->nr_objects >= pdata->nr_alloc) {
  94                 pdata->nr_alloc = (pdata->nr_alloc  + 1024) * 3 / 2;
  95                 pdata->objects = xrealloc(pdata->objects,
  96                                           pdata->nr_alloc * sizeof(*new_entry));
  97         }
  98
  99         new_entry = pdata->objects + pdata->nr_objects++;
 100
 101         memset(new_entry, 0, sizeof(*new_entry));
 102         hashcpy(new_entry->idx.sha1, sha1);
 103
 104         if (pdata->index_size * 3 <= pdata->nr_objects * 4)
 105                 rehash_objects(pdata);
 106         else
 107                 pdata->index[index_pos] = pdata->nr_objects;
 108
 109         return new_entry;
 110 }