144 lines
6.8 KiB
C
144 lines
6.8 KiB
C
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/* Copyright (C) 2003 MySQL AB
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; version 2 of the License.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */
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/* Key cache variable structures */
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#ifndef _keycache_h
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#define _keycache_h
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C_MODE_START
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/* declare structures that is used by st_key_cache */
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struct st_block_link;
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typedef struct st_block_link BLOCK_LINK;
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struct st_keycache_page;
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typedef struct st_keycache_page KEYCACHE_PAGE;
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struct st_hash_link;
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typedef struct st_hash_link HASH_LINK;
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/* info about requests in a waiting queue */
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typedef struct st_keycache_wqueue
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{
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struct st_my_thread_var *last_thread; /* circular list of waiting threads */
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} KEYCACHE_WQUEUE;
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#define CHANGED_BLOCKS_HASH 128 /* must be power of 2 */
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/*
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The key cache structure
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It also contains read-only statistics parameters.
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*/
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typedef struct st_key_cache
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{
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my_bool key_cache_inited;
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my_bool in_resize; /* true during resize operation */
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my_bool resize_in_flush; /* true during flush of resize operation */
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my_bool can_be_used; /* usage of cache for read/write is allowed */
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size_t key_cache_mem_size; /* specified size of the cache memory */
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uint key_cache_block_size; /* size of the page buffer of a cache block */
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ulong min_warm_blocks; /* min number of warm blocks; */
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ulong age_threshold; /* age threshold for hot blocks */
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ulonglong keycache_time; /* total number of block link operations */
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uint hash_entries; /* max number of entries in the hash table */
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int hash_links; /* max number of hash links */
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int hash_links_used; /* number of hash links currently used */
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int disk_blocks; /* max number of blocks in the cache */
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ulong blocks_used; /* maximum number of concurrently used blocks */
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ulong blocks_unused; /* number of currently unused blocks */
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ulong blocks_changed; /* number of currently dirty blocks */
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ulong warm_blocks; /* number of blocks in warm sub-chain */
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ulong cnt_for_resize_op; /* counter to block resize operation */
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long blocks_available; /* number of blocks available in the LRU chain */
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HASH_LINK **hash_root; /* arr. of entries into hash table buckets */
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HASH_LINK *hash_link_root; /* memory for hash table links */
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HASH_LINK *free_hash_list; /* list of free hash links */
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BLOCK_LINK *free_block_list; /* list of free blocks */
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BLOCK_LINK *block_root; /* memory for block links */
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uchar HUGE_PTR *block_mem; /* memory for block buffers */
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BLOCK_LINK *used_last; /* ptr to the last block of the LRU chain */
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BLOCK_LINK *used_ins; /* ptr to the insertion block in LRU chain */
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pthread_mutex_t cache_lock; /* to lock access to the cache structure */
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KEYCACHE_WQUEUE resize_queue; /* threads waiting during resize operation */
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/*
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Waiting for a zero resize count. Using a queue for symmetry though
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only one thread can wait here.
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*/
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KEYCACHE_WQUEUE waiting_for_resize_cnt;
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KEYCACHE_WQUEUE waiting_for_hash_link; /* waiting for a free hash link */
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KEYCACHE_WQUEUE waiting_for_block; /* requests waiting for a free block */
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BLOCK_LINK *changed_blocks[CHANGED_BLOCKS_HASH]; /* hash for dirty file bl.*/
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BLOCK_LINK *file_blocks[CHANGED_BLOCKS_HASH]; /* hash for other file bl.*/
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/*
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The following variables are and variables used to hold parameters for
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initializing the key cache.
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*/
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ulonglong param_buff_size; /* size the memory allocated for the cache */
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ulong param_block_size; /* size of the blocks in the key cache */
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ulong param_division_limit; /* min. percentage of warm blocks */
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ulong param_age_threshold; /* determines when hot block is downgraded */
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/* Statistics variables. These are reset in reset_key_cache_counters(). */
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ulong global_blocks_changed; /* number of currently dirty blocks */
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ulonglong global_cache_w_requests;/* number of write requests (write hits) */
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ulonglong global_cache_write; /* number of writes from cache to files */
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ulonglong global_cache_r_requests;/* number of read requests (read hits) */
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ulonglong global_cache_read; /* number of reads from files to cache */
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int blocks; /* max number of blocks in the cache */
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my_bool in_init; /* Set to 1 in MySQL during init/resize */
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} KEY_CACHE;
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/* The default key cache */
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extern KEY_CACHE dflt_key_cache_var, *dflt_key_cache;
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extern int init_key_cache(KEY_CACHE *keycache, uint key_cache_block_size,
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size_t use_mem, uint division_limit,
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uint age_threshold);
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extern int resize_key_cache(KEY_CACHE *keycache, uint key_cache_block_size,
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size_t use_mem, uint division_limit,
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uint age_threshold);
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extern void change_key_cache_param(KEY_CACHE *keycache, uint division_limit,
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uint age_threshold);
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extern uchar *key_cache_read(KEY_CACHE *keycache,
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File file, my_off_t filepos, int level,
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uchar *buff, uint length,
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uint block_length,int return_buffer);
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extern int key_cache_insert(KEY_CACHE *keycache,
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File file, my_off_t filepos, int level,
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uchar *buff, uint length);
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extern int key_cache_write(KEY_CACHE *keycache,
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File file, my_off_t filepos, int level,
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uchar *buff, uint length,
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uint block_length,int force_write);
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extern int flush_key_blocks(KEY_CACHE *keycache,
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int file, enum flush_type type);
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extern void end_key_cache(KEY_CACHE *keycache, my_bool cleanup);
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/* Functions to handle multiple key caches */
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extern my_bool multi_keycache_init(void);
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extern void multi_keycache_free(void);
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extern KEY_CACHE *multi_key_cache_search(uchar *key, uint length);
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extern my_bool multi_key_cache_set(const uchar *key, uint length,
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KEY_CACHE *key_cache);
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extern void multi_key_cache_change(KEY_CACHE *old_data,
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KEY_CACHE *new_data);
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extern int reset_key_cache_counters(const char *name,
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KEY_CACHE *key_cache);
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C_MODE_END
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#endif /* _keycache_h */
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