<?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 $_inst = null; const COMPRESSED = 1; /** * Singleton constructor * * Use this to get the singleton instance of Cache. * * @return Cache cache object */ static function instance() { if (is_null(self::$_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) { $value = false; if (Event::handle('StartCacheGet', array(&$key, &$value))) { if (array_key_exists($key, $this->_items)) { $value = unserialize($this->_items[$key]); } Event::handle('EndCacheGet', array($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, may include Cache::COMPRESSED * @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))) { $this->_items[$key] = serialize($value); $success = true; Event::handle('EndCacheSet', array($key, $value, $flag, $expiry)); } return $success; } /** * Atomically increment an existing numeric value. * Existing expiration time should remain unchanged, if any. * * @param string $key The key to use for lookups * @param int $step Amount to increment (default 1) * * @return mixed incremented value, or false if not set. */ function increment($key, $step=1) { $value = false; if (Event::handle('StartCacheIncrement', array(&$key, &$step, &$value))) { // Fallback is not guaranteed to be atomic, // and may original expiry value. $value = $this->get($key); if ($value !== false) { $value += $step; $ok = $this->set($key, $value); $got = $this->get($key); } Event::handle('EndCacheIncrement', array($key, $step, $value)); } return $value; } /** * 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, $this->_items)) { unset($this->_items[$key]); } $success = true; Event::handle('EndCacheDelete', array($key)); } return $success; } /** * Close or reconnect any remote connections, such as to give * daemon processes a chance to reconnect on a fresh socket. * * @return boolean success flag */ function reconnect() { $success = false; if (Event::handle('StartCacheReconnect', array(&$success))) { $success = true; Event::handle('EndCacheReconnect', array()); } return $success; } }