decorate.c

   1 /*
   2  * decorate.c - decorate a git object with some arbitrary
   3  * data.
   4  */
   5 #include "cache.h"
   6 #include "object.h"
   7 #include "decorate.h"
   8
   9 static unsigned int hash_obj(const struct object *obj, unsigned int n)
  10 {
  11         return sha1hash(get_object_hash(*obj)) % n;
  12 }
  13
  14 static void *insert_decoration(struct decoration *n, const struct object *base, void *decoration)
  15 {
  16         int size = n->size;
  17         struct object_decoration *hash = n->hash;
  18         unsigned int j = hash_obj(base, size);
  19
  20         while (hash[j].base) {
  21                 if (hash[j].base == base) {
  22                         void *old = hash[j].decoration;
  23                         hash[j].decoration = decoration;
  24                         return old;
  25                 }
  26                 if (++j >= size)
  27                         j = 0;
  28         }
  29         hash[j].base = base;
  30         hash[j].decoration = decoration;
  31         n->nr++;
  32         return NULL;
  33 }
  34
  35 static void grow_decoration(struct decoration *n)
  36 {
  37         int i;
  38         int old_size = n->size;
  39         struct object_decoration *old_hash = n->hash;
  40
  41         n->size = (old_size + 1000) * 3 / 2;
  42         n->hash = xcalloc(n->size, sizeof(struct object_decoration));
  43         n->nr = 0;
  44
  45         for (i = 0; i < old_size; i++) {
  46                 const struct object *base = old_hash[i].base;
  47                 void *decoration = old_hash[i].decoration;
  48
  49                 if (!decoration)
  50                         continue;
  51                 insert_decoration(n, base, decoration);
  52         }
  53         free(old_hash);
  54 }
  55
  56 /* Add a decoration pointer, return any old one */
  57 void *add_decoration(struct decoration *n, const struct object *obj,
  58                 void *decoration)
  59 {
  60         int nr = n->nr + 1;
  61
  62         if (nr > n->size * 2 / 3)
  63                 grow_decoration(n);
  64         return insert_decoration(n, obj, decoration);
  65 }
  66
  67 /* Lookup a decoration pointer */
  68 void *lookup_decoration(struct decoration *n, const struct object *obj)
  69 {
  70         unsigned int j;
  71
  72         /* nothing to lookup */
  73         if (!n->size)
  74                 return NULL;
  75         j = hash_obj(obj, n->size);
  76         for (;;) {
  77                 struct object_decoration *ref = n->hash + j;
  78                 if (ref->base == obj)
  79                         return ref->decoration;
  80                 if (!ref->base)
  81                         return NULL;
  82                 if (++j == n->size)
  83                         j = 0;
  84         }
  85 }