Function init_alloc_root

mysys/my_alloc.c:46–73

*/

void init_alloc_root(MEM_ROOT *mem_root, size_t block_size,
		     size_t pre_alloc_size __attribute__((unused)))
{
  DBUG_ENTER("init_alloc_root");
  DBUG_PRINT("enter",("root: 0x%lx", (long) mem_root));

  mem_root->free= mem_root->used= mem_root->pre_alloc= 0;
  mem_root->min_malloc= 32;
  mem_root->block_size= block_size - ALLOC_ROOT_MIN_BLOCK_SIZE;
  mem_root->error_handler= 0;
  mem_root->block_num= 4;			/* We shift this with >>2 */
  mem_root->first_block_usage= 0;

#if !(defined(HAVE_purify) && defined(EXTRA_DEBUG))
  if (pre_alloc_size)
  {
    if ((mem_root->free= mem_root->pre_alloc=
	 (USED_MEM*) my_malloc(pre_alloc_size+ ALIGN_SIZE(sizeof(USED_MEM)),
			       MYF(0))))
    {
      mem_root->free->size= pre_alloc_size+ALIGN_SIZE(sizeof(USED_MEM));
      mem_root->free->left= pre_alloc_size;
      mem_root->free->next= 0;
    }
  }
#endif
  DBUG_VOID_RETURN;
}

/** This is a no-op unless the build is debug or for Valgrind. */
#define TRASH_MEM(X) TRASH(((char*)(X) + ((X)->size-(X)->left)), (X)->left)