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
|
/*
Copyright (c) 2010, 2011, Monty Program 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1335 USA */
#ifndef SQL_EXPRESSION_CACHE_INCLUDED
#define SQL_EXPRESSION_CACHE_INCLUDED
#include "sql_select.h"
/**
Interface for expression cache
@note
Parameters of an expression cache interface are set on the creation of the
cache. They are passed when a cache object of the implementation class is
constructed. That's why they are not visible in this interface.
*/
extern ulong subquery_cache_miss, subquery_cache_hit;
class Expression_cache :public Sql_alloc
{
public:
enum result {ERROR, HIT, MISS};
Expression_cache()= default;
virtual ~Expression_cache() = default;
/**
Shall check the presence of expression value in the cache for a given
set of values of the expression parameters. Return the result of the
expression if it's found in the cache.
*/
virtual result check_value(Item **value)= 0;
/**
Shall put the value of an expression for given set of its parameters
into the expression cache
*/
virtual my_bool put_value(Item *value)= 0;
/**
Print cache parameters
*/
virtual void print(String *str, enum_query_type query_type)= 0;
/**
Is this cache initialized
*/
virtual bool is_inited()= 0;
/**
Initialize this cache
*/
virtual void init()= 0;
/**
Save this object's statistics into Expression_cache_tracker object
*/
virtual void update_tracker()= 0;
};
struct st_table_ref;
struct st_join_table;
class Item_field;
class Expression_cache_tracker :public Sql_alloc
{
public:
enum expr_cache_state {UNINITED, STOPPED, OK};
Expression_cache_tracker(Expression_cache *c) :
cache(c), hit(0), miss(0), state(UNINITED)
{}
private:
// This can be NULL if the cache is already deleted
Expression_cache *cache;
public:
ulong hit, miss;
enum expr_cache_state state;
static const char* state_str[3];
void set(ulong h, ulong m, enum expr_cache_state s)
{hit= h; miss= m; state= s;}
void detach_from_cache() { cache= NULL; }
void fetch_current_stats()
{
if (cache)
cache->update_tracker();
}
};
/**
Implementation of expression cache over a temporary table
*/
class Expression_cache_tmptable :public Expression_cache
{
public:
Expression_cache_tmptable(THD *thd, List<Item> &dependants, Item *value);
virtual ~Expression_cache_tmptable();
virtual result check_value(Item **value);
virtual my_bool put_value(Item *value);
void print(String *str, enum_query_type query_type);
bool is_inited() { return inited; };
void init();
void set_tracker(Expression_cache_tracker *st)
{
tracker= st;
update_tracker();
}
virtual void update_tracker()
{
if (tracker)
{
tracker->set(hit, miss, (inited ? (cache_table ?
Expression_cache_tracker::OK :
Expression_cache_tracker::STOPPED) :
Expression_cache_tracker::UNINITED));
}
}
private:
void disable_cache();
/* tmp table parameters */
TMP_TABLE_PARAM cache_table_param;
/* temporary table to store this cache */
TABLE *cache_table;
/* Thread handle for the temporary table */
THD *table_thd;
/* EXPALIN/ANALYZE statistics */
Expression_cache_tracker *tracker;
/* TABLE_REF for index lookup */
struct st_table_ref ref;
/* Cached result */
Item_field *cached_result;
/* List of parameter items */
List<Item> &items;
/* Value Item example */
Item *val;
/* hit/miss counters */
ulong hit, miss;
/* Set on if the object has been successfully initialized with init() */
bool inited;
};
#endif /* SQL_EXPRESSION_CACHE_INCLUDED */
|
