3 * StatusNet - the distributed open-source microblogging tool
4 * Copyright (C) 2010, StatusNet, Inc.
6 * Extra level of caching, in memory
10 * This program is free software: you can redistribute it and/or modify
11 * it under the terms of the GNU Affero General Public License as published by
12 * the Free Software Foundation, either version 3 of the License, or
13 * (at your option) any later version.
15 * This program is distributed in the hope that it will be useful,
16 * but WITHOUT ANY WARRANTY; without even the implied warranty of
17 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
18 * GNU Affero General Public License for more details.
20 * You should have received a copy of the GNU Affero General Public License
21 * along with this program. If not, see <http://www.gnu.org/licenses/>.
25 * @author Evan Prodromou <evan@status.net>
26 * @copyright 2010 StatusNet, Inc.
27 * @license http://www.fsf.org/licensing/licenses/agpl-3.0.html AGPL 3.0
28 * @link http://status.net/
31 if (!defined('STATUSNET')) {
32 // This check helps protect against security problems;
33 // your code file can't be executed directly from the web.
38 * Extra level of caching
40 * This plugin adds an extra level of in-process caching to any regular
41 * cache system like APC, XCache, or Memcache.
43 * Note that since most caching plugins return false for StartCache*
44 * methods, you should add this plugin before them, i.e.
46 * addPlugin('InProcessCache');
47 * addPlugin('XCache');
51 * @author Evan Prodromou <evan@status.net>
52 * @copyright 2010 StatusNet, Inc.
53 * @license http://www.fsf.org/licensing/licenses/agpl-3.0.html AGPL 3.0
54 * @link http://status.net/
57 class InProcessCachePlugin extends Plugin
59 private $_items = array();
60 private $_hits = array();
64 * Constructor checks if it's safe to use the in-process cache.
65 * On CLI scripts, we'll disable ourselves to avoid data corruption
66 * due to keeping stale data around.
68 * On web requests we'll roll the dice; they're short-lived so have
69 * less chance of stale data. Race conditions are still possible,
72 function __construct()
74 parent::__construct();
75 $this->active = (PHP_SAPI != 'cli');
79 * Get an item from the cache
81 * Called before other cache systems are called (iif this
82 * plugin was loaded correctly, see class comment). If we
83 * have the data, return it, and don't hit the other cache
86 * @param string &$key Key to fetch
87 * @param mixed &$value Resulting value or false for miss
89 * @return boolean false if found, else true
92 function onStartCacheGet(&$key, &$value)
94 if ($this->active && array_key_exists($key, $this->_items)) {
95 $value = $this->_items[$key];
96 if (array_key_exists($key, $this->_hits)) {
99 $this->_hits[$key] = 1;
101 Event::handle('EndCacheGet', array($key, &$value));
108 * Called at the end of a cache get
110 * If we don't already have the data, we cache it. This
111 * keeps us from having to call the external cache if the
112 * key is requested again.
114 * @param string $key Key to fetch
115 * @param mixed &$value Resulting value or false for miss
117 * @return boolean hook value, true
120 function onEndCacheGet($key, &$value)
122 if ($this->active && (!array_key_exists($key, $this->_items) ||
123 $this->_items[$key] != $value)) {
124 $this->_items[$key] = $value;
130 * Called at the end of setting a cache element
132 * Always set the cache element; may overwrite existing
135 * @param string $key Key to fetch
136 * @param mixed $value Resulting value or false for miss
137 * @param integer $flag ignored
138 * @param integer $expiry ignored
140 * @return boolean true
143 function onEndCacheSet($key, $value, $flag, $expiry)
146 $this->_items[$key] = $value;
152 * Called at the end of deleting a cache element
154 * If stuff's deleted from the other cache, we
157 * @param string &$key Key to delete
158 * @param boolean &$success Success flag; ignored
160 * @return boolean true
163 function onStartCacheDelete(&$key, &$success)
165 if ($this->active && array_key_exists($key, $this->_items)) {
166 unset($this->_items[$key]);
174 * @param array &$versions Array of version blocks
176 * @return boolean true
179 function onPluginVersion(&$versions)
181 $url = 'http://status.net/wiki/Plugin:InProcessCache';
183 $versions[] = array('name' => 'InProcessCache',
184 'version' => STATUSNET_VERSION,
185 'author' => 'Evan Prodromou',
188 _m('Additional in-process cache for plugins.'));
193 * Cleanup function; called at end of process
195 * If the inprocess/stats config value is true, we dump
196 * stats to the log file
198 * @return boolean true
203 if ($this->active && common_config('inprocess', 'stats')) {
204 $this->log(LOG_INFO, "cache size: " .
205 count($this->_items));
207 foreach ($this->_hits as $hitcount) {
210 $this->log(LOG_INFO, $sum . " hits on " .
211 count($this->_hits) . " keys");