summaryrefslogtreecommitdiff
path: root/lib/cache.php
blob: 23657bbf348ec436d26b372432f72ce61dab1246 (plain)
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
186
187
<?php
/**
 * StatusNet, the distributed open-source microblogging tool
 *
 * Cache interface plus default in-memory cache implementation
 *
 * PHP version 5
 *
 * LICENCE: This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 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 Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 * @category  Cache
 * @package   StatusNet
 * @author    Evan Prodromou <evan@status.net>
 * @copyright 2009 StatusNet, Inc.
 * @license   http://www.fsf.org/licensing/licenses/agpl-3.0.html GNU Affero General Public License version 3.0
 * @link      http://status.net/
 */

/**
 * Interface for caching
 *
 * An abstract interface for caching. Because we originally used the
 * Memcache plugin directly, the interface uses a small subset of the
 * Memcache interface.
 *
 * @category  Cache
 * @package   StatusNet
 * @author    Evan Prodromou <evan@status.net>
 * @copyright 2009 StatusNet, Inc.
 * @license   http://www.fsf.org/licensing/licenses/agpl-3.0.html AGPL 3.0
 * @link      http://status.net/
 */

class Cache
{
    var $_items   = array();
    static $_inst = null;

    /**
     * Singleton constructor
     *
     * Use this to get the singleton instance of Cache.
     *
     * @return Cache cache object
     */

    static function instance()
    {
        if (is_null(self::$_inst)) {
            self::$_inst = new Cache();
        }

        return self::$_inst;
    }

    /**
     * Create a cache key from input text
     *
     * Builds a cache key from input text. Helps to namespace
     * the cache area (if shared with other applications or sites)
     * and prevent conflicts.
     *
     * @param string $extra the real part of the key
     *
     * @return string full key
     */

    static function key($extra)
    {
        $base_key = common_config('cache', 'base');

        if (empty($base_key)) {
            $base_key = common_keyize(common_config('site', 'name'));
        }

        return 'statusnet:' . $base_key . ':' . $extra;
    }

    /**
     * Make a string suitable for use as a key
     *
     * Useful for turning primary keys of tables into cache keys.
     *
     * @param string $str string to turn into a key
     *
     * @return string keyized string
     */

    static function keyize($str)
    {
        $str = strtolower($str);
        $str = preg_replace('/\s/', '_', $str);
        return $str;
    }

    /**
     * Get a value associated with a key
     *
     * The value should have been set previously.
     *
     * @param string $key Lookup key
     *
     * @return string retrieved value or null if unfound
     */

    function get($key)
    {
        $value = null;

        if (Event::handle('StartCacheGet', array(&$key, &$value))) {
            if (array_key_exists($key, $this->_items)) {
                common_log(LOG_INFO, 'Cache HIT for key ' . $key);
                $value = $this->_items[$key];
            } else {
                common_log(LOG_INFO, 'Cache MISS for key ' . $key);
            }
            Event::handle('EndCacheGet', array($key, &$value));
        }

        return $value;
    }

    /**
     * Set the value associated with a key
     *
     * @param string  $key    The key to use for lookups
     * @param string  $value  The value to store
     * @param integer $flag   Flags to use, mostly ignored
     * @param integer $expiry Expiry value, mostly ignored
     *
     * @return boolean success flag
     */

    function set($key, $value, $flag=null, $expiry=null)
    {
        $success = false;

        if (Event::handle('StartCacheSet', array(&$key, &$value, &$flag,
                                                 &$expiry, &$success))) {
            common_log(LOG_INFO, 'Setting cache value for key ' . $key);

            $this->_items[$key] = $value;

            $success = true;

            Event::handle('EndCacheSet', array($key, $value, $flag,
                                               $expiry));
        }

        return $success;
    }

    /**
     * Delete the value associated with a key
     *
     * @param string $key Key to delete
     *
     * @return boolean success flag
     */

    function delete($key)
    {
        $success = false;

        if (Event::handle('StartCacheDelete', array(&$key, &$success))) {
            if (array_key_exists($key, $this->_items[$key])) {
                common_log(LOG_INFO, 'Deleting cache value for key ' . $key);
                unset($this->_items[$key]);
            }
            $success = true;
            Event::handle('EndCacheDelete', array($key));
        }

        return $success;
    }
}