289 lines
8.3 KiB
PHP
289 lines
8.3 KiB
PHP
<?php
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/**
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* StatusNet, the distributed open-source microblogging tool
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*
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* Cache interface plus default in-memory cache implementation
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*
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* PHP version 5
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*
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* LICENCE: This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Affero General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Affero General Public License for more details.
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*
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* You should have received a copy of the GNU Affero General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*
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* @category Cache
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* @package StatusNet
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* @author Evan Prodromou <evan@status.net>
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* @copyright 2009 StatusNet, Inc.
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* @license http://www.fsf.org/licensing/licenses/agpl-3.0.html GNU Affero General Public License version 3.0
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* @link http://status.net/
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*/
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/**
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* Interface for caching
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*
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* An abstract interface for caching. Because we originally used the
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* Memcache plugin directly, the interface uses a small subset of the
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* Memcache interface.
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*
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* @category Cache
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* @package StatusNet
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* @author Evan Prodromou <evan@status.net>
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* @copyright 2009 StatusNet, Inc.
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* @license http://www.fsf.org/licensing/licenses/agpl-3.0.html AGPL 3.0
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* @link http://status.net/
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*/
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class Cache
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{
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/**
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* @var array additional in-process cache for web requests;
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* disabled on CLI, unsafe for long-running daemons
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*/
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var $_items = array();
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var $_inlineCache = true;
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static $_inst = null;
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const COMPRESSED = 1;
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private function __construct() {
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// Potentially long-running daemons or maintenance scripts
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// should not use an in-process cache as it becomes out of
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// date.
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$this->_inlineCache = (php_sapi_name() != 'cli');
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}
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/**
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* Singleton constructor
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*
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* Use this to get the singleton instance of Cache.
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*
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* @return Cache cache object
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*/
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static function instance()
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{
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if (is_null(self::$_inst)) {
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self::$_inst = new Cache();
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}
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return self::$_inst;
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}
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/**
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* Create a cache key from input text
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*
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* Builds a cache key from input text. Helps to namespace
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* the cache area (if shared with other applications or sites)
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* and prevent conflicts.
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*
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* @param string $extra the real part of the key
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*
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* @return string full key
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*/
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static function key($extra)
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{
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$base_key = common_config('cache', 'base');
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if (empty($base_key)) {
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$base_key = self::keyize(common_config('site', 'name'));
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}
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return 'statusnet:' . $base_key . ':' . $extra;
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}
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/**
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* Create a cache key for data dependent on code
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*
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* For cache elements that are dependent on changes in code, this creates
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* a more-or-less fingerprint of the current running code and adds it to
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* the cache key. In the case of an upgrade of core, or addition or
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* removal of plugins, a new unique fingerprint is generated and used.
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*
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* There can still be problems with a) differences in versions of the
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* plugins and b) people running code between official versions. This is
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* usually a problem only for experienced users like developers, who know
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* how to clear their cache.
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*
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* For sites that run code between versions (like the status.net cloud),
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* there's an additional build number configuration setting.
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*
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* @param string $extra the real part of the key
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*
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* @return string full key
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*/
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static function codeKey($extra)
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{
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static $prefix = null;
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if (empty($prefix)) {
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$plugins = StatusNet::getActivePlugins();
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$names = array();
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foreach ($plugins as $plugin) {
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$names[] = $plugin[0];
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}
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$names = array_unique($names);
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asort($names);
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// Unique enough.
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$uniq = crc32(implode(',', $names));
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$build = common_config('site', 'build');
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$prefix = GNUSOCIAL_VERSION.':'.$build.':'.$uniq;
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}
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return Cache::key($prefix.':'.$extra);
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}
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/**
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* Make a string suitable for use as a key
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*
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* Useful for turning primary keys of tables into cache keys.
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*
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* @param string $str string to turn into a key
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*
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* @return string keyized string
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*/
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static function keyize($str)
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{
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$str = strtolower($str);
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$str = preg_replace('/\s/', '_', $str);
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return $str;
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}
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/**
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* Get a value associated with a key
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*
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* The value should have been set previously.
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*
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* @param string $key Lookup key
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*
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* @return string retrieved value or null if unfound
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*/
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function get($key)
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{
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$value = false;
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common_perf_counter('Cache::get', $key);
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if (Event::handle('StartCacheGet', array(&$key, &$value))) {
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if ($this->_inlineCache && array_key_exists($key, $this->_items)) {
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$value = unserialize($this->_items[$key]);
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}
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Event::handle('EndCacheGet', array($key, &$value));
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}
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return $value;
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}
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/**
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* Set the value associated with a key
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*
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* @param string $key The key to use for lookups
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* @param string $value The value to store
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* @param integer $flag Flags to use, may include Cache::COMPRESSED
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* @param integer $expiry Expiry value, mostly ignored
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*
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* @return boolean success flag
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*/
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function set($key, $value, $flag=null, $expiry=null)
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{
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$success = false;
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common_perf_counter('Cache::set', $key);
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if (Event::handle('StartCacheSet', array(&$key, &$value, &$flag,
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&$expiry, &$success))) {
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if ($this->_inlineCache) {
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$this->_items[$key] = serialize($value);
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}
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$success = true;
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Event::handle('EndCacheSet', array($key, $value, $flag,
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$expiry));
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}
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return $success;
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}
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/**
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* Atomically increment an existing numeric value.
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* Existing expiration time should remain unchanged, if any.
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*
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* @param string $key The key to use for lookups
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* @param int $step Amount to increment (default 1)
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*
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* @return mixed incremented value, or false if not set.
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*/
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function increment($key, $step=1)
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{
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$value = false;
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common_perf_counter('Cache::increment', $key);
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if (Event::handle('StartCacheIncrement', array(&$key, &$step, &$value))) {
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// Fallback is not guaranteed to be atomic,
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// and may original expiry value.
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$value = $this->get($key);
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if ($value !== false) {
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$value += $step;
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$ok = $this->set($key, $value);
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$got = $this->get($key);
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}
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Event::handle('EndCacheIncrement', array($key, $step, $value));
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}
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return $value;
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}
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/**
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* Delete the value associated with a key
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*
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* @param string $key Key to delete
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*
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* @return boolean success flag
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*/
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function delete($key)
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{
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$success = false;
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common_perf_counter('Cache::delete', $key);
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if (Event::handle('StartCacheDelete', array(&$key, &$success))) {
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if ($this->_inlineCache && array_key_exists($key, $this->_items)) {
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unset($this->_items[$key]);
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}
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$success = true;
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Event::handle('EndCacheDelete', array($key));
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}
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return $success;
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}
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/**
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* Close or reconnect any remote connections, such as to give
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* daemon processes a chance to reconnect on a fresh socket.
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*
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* @return boolean success flag
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*/
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function reconnect()
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{
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$success = false;
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if (Event::handle('StartCacheReconnect', array(&$success))) {
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$success = true;
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Event::handle('EndCacheReconnect', array());
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}
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return $success;
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}
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}
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