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keycache.h
1 /* Copyright (c) 2003, 2010, Oracle and/or its affiliates. All rights reserved.
2 
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.
6 
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.
11 
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 */
15 
16 /* Key cache variable structures */
17 
18 #ifndef _keycache_h
19 #define _keycache_h
20 
21 #include "my_sys.h" /* flush_type */
22 
23 C_MODE_START
24 
25 /* declare structures that is used by st_key_cache */
26 
27 struct st_block_link;
28 typedef struct st_block_link BLOCK_LINK;
29 struct st_keycache_page;
30 typedef struct st_keycache_page KEYCACHE_PAGE;
31 struct st_hash_link;
32 typedef struct st_hash_link HASH_LINK;
33 
34 /* info about requests in a waiting queue */
35 typedef struct st_keycache_wqueue
36 {
37  struct st_my_thread_var *last_thread; /* circular list of waiting threads */
38 } KEYCACHE_WQUEUE;
39 
40 #define CHANGED_BLOCKS_HASH 128 /* must be power of 2 */
41 
42 /*
43  The key cache structure
44  It also contains read-only statistics parameters.
45 */
46 
47 typedef struct st_key_cache
48 {
49  my_bool key_cache_inited;
50  my_bool in_resize; /* true during resize operation */
51  my_bool resize_in_flush; /* true during flush of resize operation */
52  my_bool can_be_used; /* usage of cache for read/write is allowed */
53  size_t key_cache_mem_size; /* specified size of the cache memory */
54  uint key_cache_block_size; /* size of the page buffer of a cache block */
55  ulong min_warm_blocks; /* min number of warm blocks; */
56  ulong age_threshold; /* age threshold for hot blocks */
57  ulonglong keycache_time; /* total number of block link operations */
58  uint hash_entries; /* max number of entries in the hash table */
59  int hash_links; /* max number of hash links */
60  int hash_links_used; /* number of hash links currently used */
61  int disk_blocks; /* max number of blocks in the cache */
62  ulong blocks_used; /* maximum number of concurrently used blocks */
63  ulong blocks_unused; /* number of currently unused blocks */
64  ulong blocks_changed; /* number of currently dirty blocks */
65  ulong warm_blocks; /* number of blocks in warm sub-chain */
66  ulong cnt_for_resize_op; /* counter to block resize operation */
67  long blocks_available; /* number of blocks available in the LRU chain */
68  HASH_LINK **hash_root; /* arr. of entries into hash table buckets */
69  HASH_LINK *hash_link_root; /* memory for hash table links */
70  HASH_LINK *free_hash_list; /* list of free hash links */
71  BLOCK_LINK *free_block_list; /* list of free blocks */
72  BLOCK_LINK *block_root; /* memory for block links */
73  uchar *block_mem; /* memory for block buffers */
74  BLOCK_LINK *used_last; /* ptr to the last block of the LRU chain */
75  BLOCK_LINK *used_ins; /* ptr to the insertion block in LRU chain */
76  mysql_mutex_t cache_lock; /* to lock access to the cache structure */
77  KEYCACHE_WQUEUE resize_queue; /* threads waiting during resize operation */
78  /*
79  Waiting for a zero resize count. Using a queue for symmetry though
80  only one thread can wait here.
81  */
82  KEYCACHE_WQUEUE waiting_for_resize_cnt;
83  KEYCACHE_WQUEUE waiting_for_hash_link; /* waiting for a free hash link */
84  KEYCACHE_WQUEUE waiting_for_block; /* requests waiting for a free block */
85  BLOCK_LINK *changed_blocks[CHANGED_BLOCKS_HASH]; /* hash for dirty file bl.*/
86  BLOCK_LINK *file_blocks[CHANGED_BLOCKS_HASH]; /* hash for other file bl.*/
87 
88  /*
89  The following variables are and variables used to hold parameters for
90  initializing the key cache.
91  */
92 
93  ulonglong param_buff_size; /* size the memory allocated for the cache */
94  ulonglong param_block_size; /* size of the blocks in the key cache */
95  ulonglong param_division_limit; /* min. percentage of warm blocks */
96  ulonglong param_age_threshold; /* determines when hot block is downgraded */
97 
98  /* Statistics variables. These are reset in reset_key_cache_counters(). */
99  ulong global_blocks_changed; /* number of currently dirty blocks */
100  ulonglong global_cache_w_requests;/* number of write requests (write hits) */
101  ulonglong global_cache_write; /* number of writes from cache to files */
102  ulonglong global_cache_r_requests;/* number of read requests (read hits) */
103  ulonglong global_cache_read; /* number of reads from files to cache */
104 
105  int blocks; /* max number of blocks in the cache */
106  my_bool in_init; /* Set to 1 in MySQL during init/resize */
107 } KEY_CACHE;
108 
109 /* The default key cache */
110 extern KEY_CACHE dflt_key_cache_var, *dflt_key_cache;
111 
112 extern int init_key_cache(KEY_CACHE *keycache, uint key_cache_block_size,
113  size_t use_mem, uint division_limit,
114  uint age_threshold);
115 extern int resize_key_cache(KEY_CACHE *keycache, uint key_cache_block_size,
116  size_t use_mem, uint division_limit,
117  uint age_threshold);
118 extern void change_key_cache_param(KEY_CACHE *keycache, uint division_limit,
119  uint age_threshold);
120 extern uchar *key_cache_read(KEY_CACHE *keycache,
121  File file, my_off_t filepos, int level,
122  uchar *buff, uint length,
123  uint block_length,int return_buffer);
124 extern int key_cache_insert(KEY_CACHE *keycache,
125  File file, my_off_t filepos, int level,
126  uchar *buff, uint length);
127 extern int key_cache_write(KEY_CACHE *keycache,
128  File file, my_off_t filepos, int level,
129  uchar *buff, uint length,
130  uint block_length,int force_write);
131 extern int flush_key_blocks(KEY_CACHE *keycache,
132  int file, enum flush_type type);
133 extern void end_key_cache(KEY_CACHE *keycache, my_bool cleanup);
134 
135 /* Functions to handle multiple key caches */
136 extern my_bool multi_keycache_init(void);
137 extern void multi_keycache_free(void);
138 extern KEY_CACHE *multi_key_cache_search(uchar *key, uint length);
139 extern my_bool multi_key_cache_set(const uchar *key, uint length,
140  KEY_CACHE *key_cache);
141 extern void multi_key_cache_change(KEY_CACHE *old_data,
142  KEY_CACHE *new_data);
143 extern int reset_key_cache_counters(const char *name,
144  KEY_CACHE *key_cache);
145 C_MODE_END
146 #endif /* _keycache_h */