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   1 #ifndef COMMIT_SLAB_IMPL_H
   2 #define COMMIT_SLAB_IMPL_H
   3
   4 #define MAYBE_UNUSED __attribute__((__unused__))
   5
   6 #define implement_static_commit_slab(slabname, elemtype) \
   7         implement_commit_slab(slabname, elemtype, static MAYBE_UNUSED)
   8
   9 #define implement_shared_commit_slab(slabname, elemtype) \
  10         implement_commit_slab(slabname, elemtype, )
  11
  12 #define implement_commit_slab(slabname, elemtype, scope)                \
  13                                                                         \
  14 static int stat_ ##slabname## realloc;                                  \
  15                                                                         \
  16 scope void init_ ##slabname## _with_stride(struct slabname *s,          \
  17                                                    unsigned stride)     \
  18 {                                                                       \
  19         unsigned int elem_size;                                         \
  20         if (!stride)                                                    \
  21                 stride = 1;                                             \
  22         s->stride = stride;                                             \
  23         elem_size = sizeof(elemtype) * stride;                          \
  24         s->slab_size = COMMIT_SLAB_SIZE / elem_size;                    \
  25         s->slab_count = 0;                                              \
  26         s->slab = NULL;                                                 \
  27 }                                                                       \
  28                                                                         \
  29 scope void init_ ##slabname(struct slabname *s)                         \
  30 {                                                                       \
  31         init_ ##slabname## _with_stride(s, 1);                          \
  32 }                                                                       \
  33                                                                         \
  34 scope void clear_ ##slabname(struct slabname *s)                        \
  35 {                                                                       \
  36         unsigned int i;                                                 \
  37         for (i = 0; i < s->slab_count; i++)                             \
  38                 free(s->slab[i]);                                       \
  39         s->slab_count = 0;                                              \
  40         FREE_AND_NULL(s->slab);                                         \
  41 }                                                                       \
  42                                                                         \
  43 scope elemtype *slabname## _at_peek(struct slabname *s,                 \
  44                                                   const struct commit *c, \
  45                                                   int add_if_missing)   \
  46 {                                                                       \
  47         unsigned int nth_slab, nth_slot;                                \
  48                                                                         \
  49         nth_slab = c->index / s->slab_size;                             \
  50         nth_slot = c->index % s->slab_size;                             \
  51                                                                         \
  52         if (s->slab_count <= nth_slab) {                                \
  53                 unsigned int i;                                         \
  54                 if (!add_if_missing)                                    \
  55                         return NULL;                                    \
  56                 REALLOC_ARRAY(s->slab, nth_slab + 1);                   \
  57                 stat_ ##slabname## realloc++;                           \
  58                 for (i = s->slab_count; i <= nth_slab; i++)             \
  59                         s->slab[i] = NULL;                              \
  60                 s->slab_count = nth_slab + 1;                           \
  61         }                                                               \
  62         if (!s->slab[nth_slab]) {                                       \
  63                 if (!add_if_missing)                                    \
  64                         return NULL;                                    \
  65                 s->slab[nth_slab] = xcalloc(s->slab_size,               \
  66                                             sizeof(**s->slab) * s->stride);             \
  67         }                                                               \
  68         return &s->slab[nth_slab][nth_slot * s->stride];                \
  69 }                                                                       \
  70                                                                         \
  71 scope elemtype *slabname## _at(struct slabname *s,                      \
  72                                              const struct commit *c)    \
  73 {                                                                       \
  74         return slabname##_at_peek(s, c, 1);                             \
  75 }                                                                       \
  76                                                                         \
  77 scope elemtype *slabname## _peek(struct slabname *s,                    \
  78                                              const struct commit *c)    \
  79 {                                                                       \
  80         return slabname##_at_peek(s, c, 0);                             \
  81 }                                                                       \
  82                                                                         \
  83 struct slabname
  84
  85 /*
  86  * Note that this redundant forward declaration is required
  87  * to allow a terminating semicolon, which makes instantiations look
  88  * like function declarations.  I.e., the expansion of
  89  *
  90  *    implement_commit_slab(indegree, int, static);
  91  *
  92  * ends in 'struct indegree;'.  This would otherwise
  93  * be a syntax error according (at least) to ISO C.  It's hard to
  94  * catch because GCC silently parses it by default.
  95  */
  96
  97 #endif  /* COMMIT_SLAB_IMPL_H */