keycache.h
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上传日期:2022-05-23
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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 */
- ulonglong global_cache_w_requests;/* number of write requests (write hits) */
- ulonglong global_cache_write; /* number of writes from cache to files */
- ulonglong global_cache_r_requests;/* number of read requests (read hits) */
- ulonglong global_cache_read; /* number of reads from files to 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 */