mem-pool.c

   1 /*
   2  * Memory Pool implementation logic.
   3  */
   4
   5 #include "cache.h"
   6 #include "mem-pool.h"
   7
   8 #define BLOCK_GROWTH_SIZE 1024*1024 - sizeof(struct mp_block);
   9
  10 /*
  11  * Allocate a new mp_block and insert it after the block specified in
  12  * `insert_after`. If `insert_after` is NULL, then insert block at the
  13  * head of the linked list.
  14  */
  15 static struct mp_block *mem_pool_alloc_block(struct mem_pool *mem_pool, size_t block_alloc, struct mp_block *insert_after)
  16 {
  17         struct mp_block *p;
  18
  19         mem_pool->pool_alloc += sizeof(struct mp_block) + block_alloc;
  20         p = xmalloc(st_add(sizeof(struct mp_block), block_alloc));
  21
  22         p->next_free = (char *)p->space;
  23         p->end = p->next_free + block_alloc;
  24
  25         if (insert_after) {
  26                 p->next_block = insert_after->next_block;
  27                 insert_after->next_block = p;
  28         } else {
  29                 p->next_block = mem_pool->mp_block;
  30                 mem_pool->mp_block = p;
  31         }
  32
  33         return p;
  34 }
  35
  36 void mem_pool_init(struct mem_pool **mem_pool, size_t initial_size)
  37 {
  38         struct mem_pool *pool;
  39
  40         if (*mem_pool)
  41                 return;
  42
  43         pool = xcalloc(1, sizeof(*pool));
  44
  45         pool->block_alloc = BLOCK_GROWTH_SIZE;
  46
  47         if (initial_size > 0)
  48                 mem_pool_alloc_block(pool, initial_size, NULL);
  49
  50         *mem_pool = pool;
  51 }
  52
  53 void mem_pool_discard(struct mem_pool *mem_pool, int invalidate_memory)
  54 {
  55         struct mp_block *block, *block_to_free;
  56
  57         block = mem_pool->mp_block;
  58         while (block)
  59         {
  60                 block_to_free = block;
  61                 block = block->next_block;
  62
  63                 if (invalidate_memory)
  64                         memset(block_to_free->space, 0xDD, ((char *)block_to_free->end) - ((char *)block_to_free->space));
  65
  66                 free(block_to_free);
  67         }
  68
  69         free(mem_pool);
  70 }
  71
  72 void *mem_pool_alloc(struct mem_pool *mem_pool, size_t len)
  73 {
  74         struct mp_block *p = NULL;
  75         void *r;
  76
  77         /* round up to a 'uintmax_t' alignment */
  78         if (len & (sizeof(uintmax_t) - 1))
  79                 len += sizeof(uintmax_t) - (len & (sizeof(uintmax_t) - 1));
  80
  81         if (mem_pool->mp_block &&
  82             mem_pool->mp_block->end - mem_pool->mp_block->next_free >= len)
  83                 p = mem_pool->mp_block;
  84
  85         if (!p) {
  86                 if (len >= (mem_pool->block_alloc / 2))
  87                         return mem_pool_alloc_block(mem_pool, len, mem_pool->mp_block);
  88
  89                 p = mem_pool_alloc_block(mem_pool, mem_pool->block_alloc, NULL);
  90         }
  91
  92         r = p->next_free;
  93         p->next_free += len;
  94         return r;
  95 }
  96
  97 void *mem_pool_calloc(struct mem_pool *mem_pool, size_t count, size_t size)
  98 {
  99         size_t len = st_mult(count, size);
 100         void *r = mem_pool_alloc(mem_pool, len);
 101         memset(r, 0, len);
 102         return r;
 103 }
 104
 105 int mem_pool_contains(struct mem_pool *mem_pool, void *mem)
 106 {
 107         struct mp_block *p;
 108
 109         /* Check if memory is allocated in a block */
 110         for (p = mem_pool->mp_block; p; p = p->next_block)
 111                 if ((mem >= ((void *)p->space)) &&
 112                     (mem < ((void *)p->end)))
 113                         return 1;
 114
 115         return 0;
 116 }
 117
 118 void mem_pool_combine(struct mem_pool *dst, struct mem_pool *src)
 119 {
 120         struct mp_block *p;
 121
 122         /* Append the blocks from src to dst */
 123         if (dst->mp_block && src->mp_block) {
 124                 /*
 125                  * src and dst have blocks, append
 126                  * blocks from src to dst.
 127                  */
 128                 p = dst->mp_block;
 129                 while (p->next_block)
 130                         p = p->next_block;
 131
 132                 p->next_block = src->mp_block;
 133         } else if (src->mp_block) {
 134                 /*
 135                  * src has blocks, dst is empty.
 136                  */
 137                 dst->mp_block = src->mp_block;
 138         } else {
 139                 /* src is empty, nothing to do. */
 140         }
 141
 142         dst->pool_alloc += src->pool_alloc;
 143         src->pool_alloc = 0;
 144         src->mp_block = NULL;
 145 }