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keycache.h
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keycache.h
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/* Copyright (C) 2003 MySQL AB
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; either version 2 of the License, or
(at your option) any later version.
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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */
/* Key cache variable structures */
#ifndef _keycache_h
#define _keycache_h
C_MODE_START
/* declare structures that is used by st_key_cache */
struct st_block_link;
typedef struct st_block_link BLOCK_LINK;
struct st_keycache_page;
typedef struct st_keycache_page KEYCACHE_PAGE;
struct st_hash_link;
typedef struct st_hash_link HASH_LINK;
/* info about requests in a waiting queue */
typedef struct st_keycache_wqueue
{
struct st_my_thread_var *last_thread; /* circular list of waiting threads */
} KEYCACHE_WQUEUE;
#define CHANGED_BLOCKS_HASH 128 /* must be power of 2 */
/*
The key cache structure
It also contains read-only statistics parameters.
*/
typedef struct st_key_cache
{
my_bool key_cache_inited;
my_bool resize_in_flush; /* true during flush of resize operation */
my_bool can_be_used; /* usage of cache for read/write is allowed */
uint key_cache_shift;
ulong key_cache_mem_size; /* specified size of the cache memory */
uint key_cache_block_size; /* size of the page buffer of a cache block */
ulong min_warm_blocks; /* min number of warm blocks; */
ulong age_threshold; /* age threshold for hot blocks */
ulonglong keycache_time; /* total number of block link operations */
uint hash_entries; /* max number of entries in the hash table */
int hash_links; /* max number of hash links */
int hash_links_used; /* number of hash links currently used */
int disk_blocks; /* max number of blocks in the cache */
ulong blocks_used; /* maximum number of concurrently used blocks */
ulong blocks_unused; /* number of currently unused blocks */
ulong blocks_changed; /* number of currently dirty blocks */
ulong warm_blocks; /* number of blocks in warm sub-chain */
ulong cnt_for_resize_op; /* counter to block resize operation */
long blocks_available; /* number of blocks available in the LRU chain */
HASH_LINK **hash_root; /* arr. of entries into hash table buckets */
HASH_LINK *hash_link_root; /* memory for hash table links */
HASH_LINK *free_hash_list; /* list of free hash links */
BLOCK_LINK *free_block_list; /* list of free blocks */
BLOCK_LINK *block_root; /* memory for block links */
byte HUGE_PTR *block_mem; /* memory for block buffers */
BLOCK_LINK *used_last; /* ptr to the last block of the LRU chain */
BLOCK_LINK *used_ins; /* ptr to the insertion block in LRU chain */
pthread_mutex_t cache_lock; /* to lock access to the cache structure */
KEYCACHE_WQUEUE resize_queue; /* threads waiting during resize operation */
KEYCACHE_WQUEUE waiting_for_hash_link; /* waiting for a free hash link */
KEYCACHE_WQUEUE waiting_for_block; /* requests waiting for a free block */
BLOCK_LINK *changed_blocks[CHANGED_BLOCKS_HASH]; /* hash for dirty file bl.*/
BLOCK_LINK *file_blocks[CHANGED_BLOCKS_HASH]; /* hash for other file bl.*/
/*
The following variables are and variables used to hold parameters for
initializing the key cache.
*/
ulonglong param_buff_size; /* size the memory allocated for the cache */
ulong param_block_size; /* size of the blocks in the key cache */
ulong param_division_limit; /* min. percentage of warm blocks */
ulong param_age_threshold; /* determines when hot block is downgraded */
/* Statistics variables. These are reset in reset_key_cache_counters(). */
ulong global_blocks_changed; /* number of currently dirty blocks */
ulong global_cache_w_requests;/* number of write requests (write hits) */
ulong global_cache_write; /* number of writes from the cache to files */
ulong global_cache_r_requests;/* number of read requests (read hits) */
ulong global_cache_read; /* number of reads from files to the cache */
int blocks; /* max number of blocks in the cache */
my_bool in_init; /* Set to 1 in MySQL during init/resize */
} KEY_CACHE;
/* The default key cache */
extern KEY_CACHE dflt_key_cache_var, *dflt_key_cache;
extern int init_key_cache(KEY_CACHE *keycache, uint key_cache_block_size,
ulong use_mem, uint division_limit,
uint age_threshold);
extern int resize_key_cache(KEY_CACHE *keycache, uint key_cache_block_size,
ulong use_mem, uint division_limit,
uint age_threshold);
extern void change_key_cache_param(KEY_CACHE *keycache, uint division_limit,
uint age_threshold);
extern byte *key_cache_read(KEY_CACHE *keycache,
File file, my_off_t filepos, int level,
byte *buff, uint length,
uint block_length,int return_buffer);
extern int key_cache_insert(KEY_CACHE *keycache,
File file, my_off_t filepos, int level,
byte *buff, uint length);
extern int key_cache_write(KEY_CACHE *keycache,
File file, my_off_t filepos, int level,
byte *buff, uint length,
uint block_length,int force_write);
extern int flush_key_blocks(KEY_CACHE *keycache,
int file, enum flush_type type);
extern void end_key_cache(KEY_CACHE *keycache, my_bool cleanup);
/* Functions to handle multiple key caches */
extern my_bool multi_keycache_init(void);
extern void multi_keycache_free(void);
extern KEY_CACHE *multi_key_cache_search(byte *key, uint length);
extern my_bool multi_key_cache_set(const byte *key, uint length,
KEY_CACHE *key_cache);
extern void multi_key_cache_change(KEY_CACHE *old_data,
KEY_CACHE *new_data);
extern int reset_key_cache_counters(const char *name,
KEY_CACHE *key_cache);
C_MODE_END
#endif /* _keycache_h */