object-refs.c

   1 #include "cache.h"
   2 #include "object.h"
   3 #include "decorate.h"
   4
   5 int track_object_refs = 0;
   6
   7 static struct decoration ref_decorate;
   8
   9 struct object_refs *lookup_object_refs(struct object *base)
  10 {
  11         return lookup_decoration(&ref_decorate, base);
  12 }
  13
  14 static void add_object_refs(struct object *obj, struct object_refs *refs)
  15 {
  16         if (add_decoration(&ref_decorate, obj, refs))
  17                 die("object %s tried to add refs twice!", sha1_to_hex(obj->sha1));
  18 }
  19
  20 struct object_refs *alloc_object_refs(unsigned count)
  21 {
  22         struct object_refs *refs;
  23         size_t size = sizeof(*refs) + count*sizeof(struct object *);
  24
  25         refs = xcalloc(1, size);
  26         refs->count = count;
  27         return refs;
  28 }
  29
  30 static int compare_object_pointers(const void *a, const void *b)
  31 {
  32         const struct object * const *pa = a;
  33         const struct object * const *pb = b;
  34         if (*pa == *pb)
  35                 return 0;
  36         else if (*pa < *pb)
  37                 return -1;
  38         else
  39                 return 1;
  40 }
  41
  42 void set_object_refs(struct object *obj, struct object_refs *refs)
  43 {
  44         unsigned int i, j;
  45
  46         /* Do not install empty list of references */
  47         if (refs->count < 1) {
  48                 free(refs);
  49                 return;
  50         }
  51
  52         /* Sort the list and filter out duplicates */
  53         qsort(refs->ref, refs->count, sizeof(refs->ref[0]),
  54               compare_object_pointers);
  55         for (i = j = 1; i < refs->count; i++) {
  56                 if (refs->ref[i] != refs->ref[i - 1])
  57                         refs->ref[j++] = refs->ref[i];
  58         }
  59         if (j < refs->count) {
  60                 /* Duplicates were found - reallocate list */
  61                 size_t size = sizeof(*refs) + j*sizeof(struct object *);
  62                 refs->count = j;
  63                 refs = xrealloc(refs, size);
  64         }
  65
  66         for (i = 0; i < refs->count; i++)
  67                 refs->ref[i]->used = 1;
  68         add_object_refs(obj, refs);
  69 }
  70
  71 void mark_reachable(struct object *obj, unsigned int mask)
  72 {
  73         const struct object_refs *refs;
  74
  75         if (!track_object_refs)
  76                 die("cannot do reachability with object refs turned off");
  77         /* If we've been here already, don't bother */
  78         if (obj->flags & mask)
  79                 return;
  80         obj->flags |= mask;
  81         refs = lookup_object_refs(obj);
  82         if (refs) {
  83                 unsigned i;
  84                 for (i = 0; i < refs->count; i++)
  85                         mark_reachable(refs->ref[i], mask);
  86         }
  87 }