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Filename : my_alloc.h
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/* Copyright (c) 2000, 2016, Oracle and/or its affiliates. All rights reserved.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; version 2 of the License.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA */

/* 
   Data structures for mysys/my_alloc.c (root memory allocator)
*/

#ifndef _my_alloc_h
#define _my_alloc_h

#define ALLOC_MAX_BLOCK_TO_DROP			4096
#define ALLOC_MAX_BLOCK_USAGE_BEFORE_DROP	10

/* PSI_memory_key */
#include "mysql/psi/psi_memory.h"

#ifdef __cplusplus
extern "C" {
#endif

typedef struct st_used_mem
{				   /* struct for once_alloc (block) */
  struct st_used_mem *next;	   /* Next block in use */
  unsigned int	left;		   /* memory left in block  */
  unsigned int	size;		   /* size of block */
} USED_MEM;


typedef struct st_mem_root
{
  USED_MEM *free;                  /* blocks with free memory in it */
  USED_MEM *used;                  /* blocks almost without free memory */
  USED_MEM *pre_alloc;             /* preallocated block */
  /* if block have less memory it will be put in 'used' list */
  size_t min_malloc;
  size_t block_size;               /* initial block size */
  unsigned int block_num;          /* allocated blocks counter */
  /* 
     first free block in queue test counter (if it exceed 
     MAX_BLOCK_USAGE_BEFORE_DROP block will be dropped in 'used' list)
  */
  unsigned int first_block_usage;

  /*
    Maximum amount of memory this mem_root can hold. A value of 0
    implies there is no limit.
  */
  size_t max_capacity;

  /* Allocated size for this mem_root */

  size_t allocated_size;

  /* Enable this for error reporting if capacity is exceeded */
  my_bool error_for_capacity_exceeded;

  void (*error_handler)(void);

  PSI_memory_key m_psi_key;
} MEM_ROOT;

#ifdef  __cplusplus
}
#endif

#endif