Edit File: keycache.h
/* Copyright (c) 2003, 2010, 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 */ /* Key cache variable structures */ #ifndef _keycache_h #define _keycache_h #include "my_sys.h" /* flush_type */ 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 in_resize; /* true during resize operation */ my_bool resize_in_flush; /* true during flush of resize operation */ my_bool can_be_used; /* usage of cache for read/write is allowed */ size_t 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 */ uchar *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 */ mysql_mutex_t cache_lock; /* to lock access to the cache structure */ KEYCACHE_WQUEUE resize_queue; /* threads waiting during resize operation */ /* Waiting for a zero resize count. Using a queue for symmetry though only one thread can wait here. */ KEYCACHE_WQUEUE waiting_for_resize_cnt; 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 */ ulonglong param_block_size; /* size of the blocks in the key cache */ ulonglong param_division_limit; /* min. percentage of warm blocks */ ulonglong 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, size_t use_mem, uint division_limit, uint age_threshold); extern int resize_key_cache(KEY_CACHE *keycache, uint key_cache_block_size, size_t use_mem, uint division_limit, uint age_threshold); extern void change_key_cache_param(KEY_CACHE *keycache, uint division_limit, uint age_threshold); extern uchar *key_cache_read(KEY_CACHE *keycache, File file, my_off_t filepos, int level, uchar *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, uchar *buff, uint length); extern int key_cache_write(KEY_CACHE *keycache, File file, my_off_t filepos, int level, uchar *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(uchar *key, uint length); extern my_bool multi_key_cache_set(const uchar *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 */
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