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
|
<?php
/**
* Per-process memory cache for storing items.
*
* 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; either version 2 of the License, or
* (at your option) any later version.
*
* 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 02110-1301, USA.
* http://www.gnu.org/copyleft/gpl.html
*
* @file
* @ingroup Cache
*/
use Wikimedia\Assert\Assert;
/**
* Handles a simple LRU key/value map with a maximum number of entries
*
* Use ProcessCacheLRU if hierarchical purging is needed or objects can become stale
*
* @see ProcessCacheLRU
* @ingroup Cache
* @since 1.23
*/
class MapCacheLRU {
/** @var array */
protected $cache = array(); // (key => value)
protected $maxCacheKeys; // integer; max entries
/**
* @param int $maxKeys Maximum number of entries allowed (min 1).
* @throws Exception When $maxCacheKeys is not an int or =< 0.
*/
public function __construct( $maxKeys ) {
Assert::parameterType( 'integer', $maxKeys, '$maxKeys' );
Assert::parameter( $maxKeys >= 1, '$maxKeys', 'must be >= 1' );
$this->maxCacheKeys = $maxKeys;
}
/**
* Set a key/value pair.
* This will prune the cache if it gets too large based on LRU.
* If the item is already set, it will be pushed to the top of the cache.
*
* @param string $key
* @param mixed $value
* @return void
*/
public function set( $key, $value ) {
if ( array_key_exists( $key, $this->cache ) ) {
$this->ping( $key ); // push to top
} elseif ( count( $this->cache ) >= $this->maxCacheKeys ) {
reset( $this->cache );
$evictKey = key( $this->cache );
unset( $this->cache[$evictKey] );
}
$this->cache[$key] = $value;
}
/**
* Check if a key exists
*
* @param string $key
* @return bool
*/
public function has( $key ) {
return array_key_exists( $key, $this->cache );
}
/**
* Get the value for a key.
* This returns null if the key is not set.
* If the item is already set, it will be pushed to the top of the cache.
*
* @param string $key
* @return mixed
*/
public function get( $key ) {
if ( array_key_exists( $key, $this->cache ) ) {
$this->ping( $key ); // push to top
return $this->cache[$key];
} else {
return null;
}
}
/**
* @return array
* @since 1.25
*/
public function getAllKeys() {
return array_keys( $this->cache );
}
/**
* Clear one or several cache entries, or all cache entries
*
* @param string|array $keys
* @return void
*/
public function clear( $keys = null ) {
if ( $keys === null ) {
$this->cache = array();
} else {
foreach ( (array)$keys as $key ) {
unset( $this->cache[$key] );
}
}
}
/**
* Push an entry to the top of the cache
*
* @param string $key
*/
protected function ping( $key ) {
$item = $this->cache[$key];
unset( $this->cache[$key] );
$this->cache[$key] = $item;
}
}
|
