1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
|
/* 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; 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */
/* Key cache variable structures */
#ifndef PLUGIN_MYISAM_KEYCACHE_H
#define PLUGIN_MYISAM_KEYCACHE_H
enum flush_type
{
FLUSH_KEEP, /* flush block and keep it in the cache */
FLUSH_RELEASE, /* flush block and remove it from the cache */
FLUSH_IGNORE_CHANGED, /* remove block from the cache */
/*
* As my_disable_flush_pagecache_blocks is always 0, the following option
* is strictly equivalent to FLUSH_KEEP
* */
FLUSH_FORCE_WRITE
};
/* 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;
namespace drizzled
{
namespace internal
{
typedef uint64_t my_off_t;
struct st_my_thread_var;
}
/* info about requests in a waiting queue */
typedef struct st_keycache_wqueue
{
drizzled::internal::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
{
bool key_cache_inited;
bool in_resize; /* true during resize operation */
bool resize_in_flush; /* true during flush of resize operation */
bool can_be_used; /* usage of cache for read/write is allowed */
uint32_t hash_entries; /* max number of entries in the hash table */
uint32_t key_cache_mem_size; /* specified size of the cache memory */
uint32_t key_cache_block_size; /* size of the page buffer of a cache block */
int disk_blocks; /* max number of blocks in the cache */
ulong min_warm_blocks; /* min number of warm blocks; */
ulong age_threshold; /* age threshold for hot blocks */
uint64_t keycache_time; /* total number of block link operations */
int hash_links; /* max number of hash links */
int hash_links_used; /* number of hash links currently used */
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 */
unsigned char *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 */
/*
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.
*/
uint32_t param_buff_size; /* size the memory allocated for the cache */
uint32_t param_block_size; /* size of the blocks in the key cache */
uint32_t param_division_limit; /* min. percentage of warm blocks */
uint32_t param_age_threshold; /* determines when hot block is downgraded */
int blocks; /* max number of blocks in the cache */
/* Statistics variables. These are reset in reset_key_cache_counters(). */
ulong global_blocks_changed; /* number of currently dirty blocks */
uint64_t global_cache_w_requests;/* number of write requests (write hits) */
uint64_t global_cache_write; /* number of writes from cache to files */
uint64_t global_cache_r_requests;/* number of read requests (read hits) */
uint64_t global_cache_read; /* number of reads from files to cache */
bool in_init; /* Set to 1 in MySQL during init/resize */
} KEY_CACHE;
} /* namespace drizzled */
/* The default key cache */
extern drizzled::KEY_CACHE dflt_key_cache_var, *dflt_key_cache;
extern int init_key_cache(drizzled::KEY_CACHE *keycache, uint32_t key_cache_block_size,
size_t use_mem, uint32_t division_limit,
uint32_t age_threshold);
extern int resize_key_cache(drizzled::KEY_CACHE *keycache, uint32_t key_cache_block_size,
size_t use_mem, uint32_t division_limit,
uint32_t age_threshold);
extern unsigned char *key_cache_read(drizzled::KEY_CACHE *keycache,
int file, drizzled::internal::my_off_t filepos, int level,
unsigned char *buff, uint32_t length,
uint32_t block_length,int return_buffer);
extern int key_cache_insert(drizzled::KEY_CACHE *keycache,
int file, drizzled::internal::my_off_t filepos, int level,
unsigned char *buff, uint32_t length);
extern int key_cache_write(drizzled::KEY_CACHE *keycache,
int file, drizzled::internal::my_off_t filepos, int level,
unsigned char *buff, uint32_t length,
uint32_t block_length,int force_write);
extern int flush_key_blocks(drizzled::KEY_CACHE *keycache,
int file, enum flush_type type);
extern void end_key_cache(drizzled::KEY_CACHE *keycache, bool cleanup);
extern void reset_key_cache_counters();
/*
Next highest power of two
SYNOPSIS
my_round_up_to_next_power()
v Value to check
RETURN
Next or equal power of 2
Note: 0 will return 0
NOTES
Algorithm by Sean Anderson, according to:
http://graphics.stanford.edu/~seander/bithacks.html
(Orignal code public domain)
Comments shows how this works with 01100000000000000000000000001011
*/
static inline uint32_t my_round_up_to_next_power(uint32_t v)
{
v--; /* 01100000000000000000000000001010 */
v|= v >> 1; /* 01110000000000000000000000001111 */
v|= v >> 2; /* 01111100000000000000000000001111 */
v|= v >> 4; /* 01111111110000000000000000001111 */
v|= v >> 8; /* 01111111111111111100000000001111 */
v|= v >> 16; /* 01111111111111111111111111111111 */
return v+1; /* 10000000000000000000000000000000 */
}
#endif /* PLUGIN_MYISAM_KEYCACHE_H */
|