<?php /** * StatusNet - the distributed open-source microblogging tool * Copyright (C) 2010, StatusNet, Inc. * * Extra level of caching, in memory * * PHP version 5 * * 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 2010 StatusNet, Inc. * @license http://www.fsf.org/licensing/licenses/agpl-3.0.html AGPL 3.0 * @link http://status.net/ */ if (!defined('STATUSNET')) { // This check helps protect against security problems; // your code file can't be executed directly from the web. exit(1); } /** * Extra level of caching * * This plugin adds an extra level of in-process caching to any regular * cache system like APC, XCache, or Memcache. * * Note that since most caching plugins return false for StartCache* * methods, you should add this plugin before them, i.e. * * addPlugin('InProcessCache'); * addPlugin('XCache'); * * @category Cache * @package StatusNet * @author Evan Prodromou <evan@status.net> * @copyright 2010 StatusNet, Inc. * @license http://www.fsf.org/licensing/licenses/agpl-3.0.html AGPL 3.0 * @link http://status.net/ */ class InProcessCachePlugin extends Plugin { private $_items = array(); private $_hits = array(); private $active; /** * Constructor checks if it's safe to use the in-process cache. * On CLI scripts, we'll disable ourselves to avoid data corruption * due to keeping stale data around. * * On web requests we'll roll the dice; they're short-lived so have * less chance of stale data. Race conditions are still possible, * so beware! */ function __construct() { parent::__construct(); $this->active = (PHP_SAPI != 'cli'); } /** * Get an item from the cache * * Called before other cache systems are called (iif this * plugin was loaded correctly, see class comment). If we * have the data, return it, and don't hit the other cache * systems. * * @param string &$key Key to fetch * @param mixed &$value Resulting value or false for miss * * @return boolean false if found, else true */ function onStartCacheGet(&$key, &$value) { if ($this->active && array_key_exists($key, $this->_items)) { $value = $this->_items[$key]; if (array_key_exists($key, $this->_hits)) { $this->_hits[$key]++; } else { $this->_hits[$key] = 1; } Event::handle('EndCacheGet', array($key, &$value)); return false; } return true; } /** * Called at the end of a cache get * * If we don't already have the data, we cache it. This * keeps us from having to call the external cache if the * key is requested again. * * @param string $key Key to fetch * @param mixed &$value Resulting value or false for miss * * @return boolean hook value, true */ function onEndCacheGet($key, &$value) { if ($this->active && (!array_key_exists($key, $this->_items) || $this->_items[$key] != $value)) { $this->_items[$key] = $value; } return true; } /** * Called at the end of setting a cache element * * Always set the cache element; may overwrite existing * data. * * @param string $key Key to fetch * @param mixed $value Resulting value or false for miss * @param integer $flag ignored * @param integer $expiry ignored * * @return boolean true */ function onEndCacheSet($key, $value, $flag, $expiry) { if ($this->active) { $this->_items[$key] = $value; } return true; } /** * Called at the end of deleting a cache element * * If stuff's deleted from the other cache, we * delete it too. * * @param string &$key Key to delete * @param boolean &$success Success flag; ignored * * @return boolean true */ function onStartCacheDelete(&$key, &$success) { if ($this->active && array_key_exists($key, $this->_items)) { unset($this->_items[$key]); } return true; } /** * Version info * * @param array &$versions Array of version blocks * * @return boolean true */ function onPluginVersion(&$versions) { $url = 'http://status.net/wiki/Plugin:InProcessCache'; $versions[] = array('name' => 'InProcessCache', 'version' => STATUSNET_VERSION, 'author' => 'Evan Prodromou', 'homepage' => $url, 'description' => _m('Additional in-process cache for plugins.')); return true; } /** * Cleanup function; called at end of process * * If the inprocess/stats config value is true, we dump * stats to the log file * * @return boolean true */ function cleanup() { if ($this->active && common_config('inprocess', 'stats')) { $this->log(LOG_INFO, "cache size: " . count($this->_items)); $sum = 0; foreach ($this->_hits as $hitcount) { $sum += $hitcount; } $this->log(LOG_INFO, $sum . " hits on " . count($this->_hits) . " keys"); } return true; } }