3 * StatusNet, the distributed open-source microblogging tool
5 * Cache interface plus default in-memory cache implementation
9 * LICENCE: This program is free software: you can redistribute it and/or modify
10 * it under the terms of the GNU Affero General Public License as published by
11 * the Free Software Foundation, either version 3 of the License, or
12 * (at your option) any later version.
14 * This program is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 * GNU Affero General Public License for more details.
19 * You should have received a copy of the GNU Affero General Public License
20 * along with this program. If not, see <http://www.gnu.org/licenses/>.
24 * @author Evan Prodromou <evan@status.net>
25 * @copyright 2009 StatusNet, Inc.
26 * @license http://www.fsf.org/licensing/licenses/agpl-3.0.html GNU Affero General Public License version 3.0
27 * @link http://status.net/
31 * Interface for caching
33 * An abstract interface for caching. Because we originally used the
34 * Memcache plugin directly, the interface uses a small subset of the
39 * @author Evan Prodromou <evan@status.net>
40 * @copyright 2009 StatusNet, Inc.
41 * @license http://www.fsf.org/licensing/licenses/agpl-3.0.html AGPL 3.0
42 * @link http://status.net/
47 var $_items = array();
53 * Singleton constructor
55 * Use this to get the singleton instance of Cache.
57 * @return Cache cache object
60 static function instance()
62 if (is_null(self::$_inst)) {
63 self::$_inst = new Cache();
70 * Create a cache key from input text
72 * Builds a cache key from input text. Helps to namespace
73 * the cache area (if shared with other applications or sites)
74 * and prevent conflicts.
76 * @param string $extra the real part of the key
78 * @return string full key
81 static function key($extra)
83 $base_key = common_config('cache', 'base');
85 if (empty($base_key)) {
86 $base_key = common_keyize(common_config('site', 'name'));
89 return 'statusnet:' . $base_key . ':' . $extra;
93 * Make a string suitable for use as a key
95 * Useful for turning primary keys of tables into cache keys.
97 * @param string $str string to turn into a key
99 * @return string keyized string
102 static function keyize($str)
104 $str = strtolower($str);
105 $str = preg_replace('/\s/', '_', $str);
110 * Get a value associated with a key
112 * The value should have been set previously.
114 * @param string $key Lookup key
116 * @return string retrieved value or null if unfound
123 if (Event::handle('StartCacheGet', array(&$key, &$value))) {
124 if (array_key_exists($key, $this->_items)) {
125 $value = unserialize($this->_items[$key]);
127 Event::handle('EndCacheGet', array($key, &$value));
134 * Set the value associated with a key
136 * @param string $key The key to use for lookups
137 * @param string $value The value to store
138 * @param integer $flag Flags to use, may include Cache::COMPRESSED
139 * @param integer $expiry Expiry value, mostly ignored
141 * @return boolean success flag
144 function set($key, $value, $flag=null, $expiry=null)
148 if (Event::handle('StartCacheSet', array(&$key, &$value, &$flag,
149 &$expiry, &$success))) {
151 $this->_items[$key] = serialize($value);
155 Event::handle('EndCacheSet', array($key, $value, $flag,
163 * Atomically increment an existing numeric value.
164 * Existing expiration time should remain unchanged, if any.
166 * @param string $key The key to use for lookups
167 * @param int $step Amount to increment (default 1)
169 * @return mixed incremented value, or false if not set.
171 function increment($key, $step=1)
174 if (Event::handle('StartCacheIncrement', array(&$key, &$step, &$value))) {
175 // Fallback is not guaranteed to be atomic,
176 // and may original expiry value.
177 $value = $this->get($key);
178 if ($value !== false) {
180 $ok = $this->set($key, $value);
181 $got = $this->get($key);
183 Event::handle('EndCacheIncrement', array($key, $step, $value));
189 * Delete the value associated with a key
191 * @param string $key Key to delete
193 * @return boolean success flag
196 function delete($key)
200 if (Event::handle('StartCacheDelete', array(&$key, &$success))) {
201 if (array_key_exists($key, $this->_items)) {
202 unset($this->_items[$key]);
205 Event::handle('EndCacheDelete', array($key));
212 * Close or reconnect any remote connections, such as to give
213 * daemon processes a chance to reconnect on a fresh socket.
215 * @return boolean success flag
222 if (Event::handle('StartCacheReconnect', array(&$success))) {
224 Event::handle('EndCacheReconnect', array());