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DBHomework/mysql_include/my_alloc.h

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2017-11-19 14:58:43 +08:00
/* 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;
void (*error_handler)(void);
PSI_memory_key m_psi_key;
} MEM_ROOT;
#ifdef __cplusplus
}
#endif
#endif