1 /* Copyright (c) 2003, 2015, Oracle and/or its affiliates. All rights reserved.
3 This program is free software; you can redistribute it and/or modify
4 it under the terms of the GNU General Public License as published by
5 the Free Software Foundation; version 2 of the License.
7 This program is distributed in the hope that it will be useful,
8 but WITHOUT ANY WARRANTY; without even the implied warranty of
9 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
10 GNU General Public License for more details.
12 You should have received a copy of the GNU General Public License
13 along with this program; if not, write to the Free Software
14 Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA */
16 /* Key cache variable structures */
21 #include "my_sys.h" /* flush_type */
25 /* declare structures that is used by st_key_cache */
28 typedef struct st_block_link BLOCK_LINK;
30 typedef struct st_hash_link HASH_LINK;
32 /* Thread specific variables */
33 typedef struct st_keycache_thread_var
36 struct st_keycache_thread_var *next,**prev;
38 } st_keycache_thread_var;
40 /* info about requests in a waiting queue */
41 typedef struct st_keycache_wqueue
43 st_keycache_thread_var *last_thread; /* circular list of waiting threads */
46 #define CHANGED_BLOCKS_HASH 128 /* must be power of 2 */
49 The key cache structure
50 It also contains read-only statistics parameters.
53 typedef struct st_key_cache
55 my_bool key_cache_inited;
56 my_bool in_resize; /* true during resize operation */
57 my_bool resize_in_flush; /* true during flush of resize operation */
58 my_bool can_be_used; /* usage of cache for read/write is allowed */
59 size_t key_cache_mem_size; /* specified size of the cache memory */
60 uint key_cache_block_size; /* size of the page buffer of a cache block */
61 ulonglong min_warm_blocks; /* min number of warm blocks; */
62 ulonglong age_threshold; /* age threshold for hot blocks */
63 ulonglong keycache_time; /* total number of block link operations */
64 uint hash_entries; /* max number of entries in the hash table */
65 int hash_links; /* max number of hash links */
66 int hash_links_used; /* number of hash links currently used */
67 int disk_blocks; /* max number of blocks in the cache */
68 ulong blocks_used; /* maximum number of concurrently used blocks */
69 ulong blocks_unused; /* number of currently unused blocks */
70 ulong blocks_changed; /* number of currently dirty blocks */
71 ulong warm_blocks; /* number of blocks in warm sub-chain */
72 ulong cnt_for_resize_op; /* counter to block resize operation */
73 long blocks_available; /* number of blocks available in the LRU chain */
74 HASH_LINK **hash_root; /* arr. of entries into hash table buckets */
75 HASH_LINK *hash_link_root; /* memory for hash table links */
76 HASH_LINK *free_hash_list; /* list of free hash links */
77 BLOCK_LINK *free_block_list; /* list of free blocks */
78 BLOCK_LINK *block_root; /* memory for block links */
79 uchar *block_mem; /* memory for block buffers */
80 BLOCK_LINK *used_last; /* ptr to the last block of the LRU chain */
81 BLOCK_LINK *used_ins; /* ptr to the insertion block in LRU chain */
82 mysql_mutex_t cache_lock; /* to lock access to the cache structure */
83 KEYCACHE_WQUEUE resize_queue; /* threads waiting during resize operation */
85 Waiting for a zero resize count. Using a queue for symmetry though
86 only one thread can wait here.
88 KEYCACHE_WQUEUE waiting_for_resize_cnt;
89 KEYCACHE_WQUEUE waiting_for_hash_link; /* waiting for a free hash link */
90 KEYCACHE_WQUEUE waiting_for_block; /* requests waiting for a free block */
91 BLOCK_LINK *changed_blocks[CHANGED_BLOCKS_HASH]; /* hash for dirty file bl.*/
92 BLOCK_LINK *file_blocks[CHANGED_BLOCKS_HASH]; /* hash for other file bl.*/
95 The following variables are and variables used to hold parameters for
96 initializing the key cache.
99 ulonglong param_buff_size; /* size the memory allocated for the cache */
100 ulonglong param_block_size; /* size of the blocks in the key cache */
101 ulonglong param_division_limit; /* min. percentage of warm blocks */
102 ulonglong param_age_threshold; /* determines when hot block is downgraded */
104 /* Statistics variables. These are reset in reset_key_cache_counters(). */
105 ulong global_blocks_changed; /* number of currently dirty blocks */
106 ulonglong global_cache_w_requests;/* number of write requests (write hits) */
107 ulonglong global_cache_write; /* number of writes from cache to files */
108 ulonglong global_cache_r_requests;/* number of read requests (read hits) */
109 ulonglong global_cache_read; /* number of reads from files to cache */
111 int blocks; /* max number of blocks in the cache */
112 my_bool in_init; /* Set to 1 in MySQL during init/resize */
115 /* The default key cache */
116 extern KEY_CACHE dflt_key_cache_var, *dflt_key_cache;
118 extern int init_key_cache(KEY_CACHE *keycache, ulonglong key_cache_block_size,
119 size_t use_mem, ulonglong division_limit,
120 ulonglong age_threshold);
121 extern int resize_key_cache(KEY_CACHE *keycache,
122 st_keycache_thread_var *thread_var,
123 ulonglong key_cache_block_size,
124 size_t use_mem, ulonglong division_limit,
125 ulonglong age_threshold);
126 extern uchar *key_cache_read(KEY_CACHE *keycache,
127 st_keycache_thread_var *thread_var,
128 File file, my_off_t filepos, int level,
129 uchar *buff, uint length,
130 uint block_length,int return_buffer);
131 extern int key_cache_insert(KEY_CACHE *keycache,
132 st_keycache_thread_var *thread_var,
133 File file, my_off_t filepos, int level,
134 uchar *buff, uint length);
135 extern int key_cache_write(KEY_CACHE *keycache,
136 st_keycache_thread_var *thread_var,
137 File file, my_off_t filepos, int level,
138 uchar *buff, uint length,
139 uint block_length,int force_write);
140 extern int flush_key_blocks(KEY_CACHE *keycache,
141 st_keycache_thread_var *thread_var,
142 int file, enum flush_type type);
143 extern void end_key_cache(KEY_CACHE *keycache, my_bool cleanup);
145 /* Functions to handle multiple key caches */
146 extern my_bool multi_keycache_init(void);
147 extern void multi_keycache_free(void);
148 extern KEY_CACHE *multi_key_cache_search(uchar *key, uint length);
149 extern my_bool multi_key_cache_set(const uchar *key, uint length,
150 KEY_CACHE *key_cache);
151 extern void multi_key_cache_change(KEY_CACHE *old_data,
152 KEY_CACHE *new_data);
153 extern int reset_key_cache_counters(const char *name,
154 KEY_CACHE *key_cache);
156 #endif /* _keycache_h */