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<?php

/**

 * CakePHP(tm) : Rapid Development Framework (http://cakephp.org)

 * Copyright (c) Cake Software Foundation, Inc. (http://cakefoundation.org)

 *

 * Licensed under The MIT License

 * For full copyright and license information, please see the LICENSE.txt

 * Redistributions of files must retain the above copyright notice.

 *

 * @copyright     Copyright (c) Cake Software Foundation, Inc. (http://cakefoundation.org)

 * @link          http://cakephp.org CakePHP(tm) Project

 * @since         CakePHP(tm) v 2.5.0

 * @license       http://www.opensource.org/licenses/mit-license.php MIT License

 */

/**

 * Memcached storage engine for cache. Memcached has some limitations in the amount of

 * control you have over expire times far in the future. See MemcachedEngine::write() for

 * more information.

 *

 * Main advantage of this Memcached engine over the memcached engine is

 * support of binary protocol, and igbibnary serialization

 * (if memcached extension compiled with --enable-igbinary)

 * Compressed keys can also be incremented/decremented

 *

 * @package       Cake.Cache.Engine

 */

class MemcachedEngine extends CacheEngine {

/**

 * memcached wrapper.

 *

 * @var Memcache

 */

	protected $_Memcached = null;

/**

 * Settings

 *

 *  - servers = string or array of memcached servers, default => 127.0.0.1. If an

 *    array MemcacheEngine will use them as a pool.

 *  - compress = boolean, default => false

 *  - persistent = string The name of the persistent connection. All configurations using

 *    the same persistent value will share a single underlying connection.

 *  - serialize = string, default => php. The serializer engine used to serialize data.

 *    Available engines are php, igbinary and json. Beside php, the memcached extension

 *    must be compiled with the appropriate serializer support.

 *

 * @var array

 */

	public $settings = array();

/**

 * List of available serializer engines

 *

 * Memcached must be compiled with json and igbinary support to use these engines

 *

 * @var array

 */

	protected $_serializers = array(

		'igbinary' => Memcached::SERIALIZER_IGBINARY,

		'json' => Memcached::SERIALIZER_JSON,

		'php' => Memcached::SERIALIZER_PHP

	);

/**

 * Initialize the Cache Engine

 *

 * Called automatically by the cache frontend

 * To reinitialize the settings call Cache::engine('EngineName', [optional] settings = array());

 *

 * @param array $settings array of setting for the engine

 * @return bool True if the engine has been successfully initialized, false if not

 * @throws CacheException when you try use authentication without Memcached compiled with SASL support

 */

	public function init($settings = array()) {

		if (!class_exists('Memcached')) {

			return false;

		}

		if (!isset($settings['prefix'])) {

			$settings['prefix'] = Inflector::slug(APP_DIR) . '_';

		}

		if (defined('Memcached::HAVE_MSGPACK') && Memcached::HAVE_MSGPACK) {

			$this->_serializers['msgpack'] = Memcached::SERIALIZER_MSGPACK;

		}

		$settings += array(

			'engine' => 'Memcached',

			'servers' => array('127.0.0.1'),

			'compress' => false,

			'persistent' => false,

			'login' => null,

			'password' => null,

			'serialize' => 'php'

		);

		parent::init($settings);

		if (!is_array($this->settings['servers'])) {

			$this->settings['servers'] = array($this->settings['servers']);

		}

		if (isset($this->_Memcached)) {

			return true;

		}

		$this->_Memcached = new Memcached($this->settings['persistent'] ? (string)$this->settings['persistent'] : null);

		$this->_setOptions();

		if (count($this->_Memcached->getServerList())) {

			return true;

		}

		$servers = array();

		foreach ($this->settings['servers'] as $server) {

			$servers[] = $this->_parseServerString($server);

		}

		if (!$this->_Memcached->addServers($servers)) {

			return false;

		}

		if ($this->settings['login'] !== null && $this->settings['password'] !== null) {

			if (!method_exists($this->_Memcached, 'setSaslAuthData')) {

				throw new CacheException(

					__d('cake_dev', 'Memcached extension is not build with SASL support')

				);

			}

			$this->_Memcached->setSaslAuthData($this->settings['login'], $this->settings['password']);

		}

		return true;

	}

/**

 * Settings the memcached instance

 *

 * @throws CacheException when the Memcached extension is not built with the desired serializer engine

 * @return void

 */

	protected function _setOptions() {

		$this->_Memcached->setOption(Memcached::OPT_LIBKETAMA_COMPATIBLE, true);

		$serializer = strtolower($this->settings['serialize']);

		if (!isset($this->_serializers[$serializer])) {

			throw new CacheException(

				__d('cake_dev', '%s is not a valid serializer engine for Memcached', $serializer)

			);

		}

		if ($serializer !== 'php' && !constant('Memcached::HAVE_' . strtoupper($serializer))) {

			throw new CacheException(

				__d('cake_dev', 'Memcached extension is not compiled with %s support', $serializer)

			);

		}

		$this->_Memcached->setOption(Memcached::OPT_SERIALIZER, $this->_serializers[$serializer]);

		// Check for Amazon ElastiCache instance

		if (defined('Memcached::OPT_CLIENT_MODE') && defined('Memcached::DYNAMIC_CLIENT_MODE')) {

			$this->_Memcached->setOption(Memcached::OPT_CLIENT_MODE, Memcached::DYNAMIC_CLIENT_MODE);

		}

		$this->_Memcached->setOption(Memcached::OPT_COMPRESSION, (bool)$this->settings['compress']);

	}

/**

 * Parses the server address into the host/port. Handles both IPv6 and IPv4

 * addresses and Unix sockets

 *

 * @param string $server The server address string.

 * @return array Array containing host, port

 */

	protected function _parseServerString($server) {

		if ($server[0] === 'u') {

			return array($server, 0);

		}

		if (substr($server, 0, 1) === '[') {

			$position = strpos($server, ']:');

			if ($position !== false) {

				$position++;

			}

		} else {

			$position = strpos($server, ':');

		}

		$port = 11211;

		$host = $server;

		if ($position !== false) {

			$host = substr($server, 0, $position);

			$port = substr($server, $position + 1);

		}

		return array($host, (int)$port);

	}

/**

 * Write data for key into cache. When using memcached as your cache engine

 * remember that the Memcached pecl extension does not support cache expiry times greater

 * than 30 days in the future. Any duration greater than 30 days will be treated as never expiring.

 *

 * @param string $key Identifier for the data

 * @param mixed $value Data to be cached

 * @param int $duration How long to cache the data, in seconds

 * @return bool True if the data was successfully cached, false on failure

 * @see http://php.net/manual/en/memcache.set.php

 */

	public function write($key, $value, $duration) {

		if ($duration > 30 * DAY) {

			$duration = 0;

		}

		return $this->_Memcached->set($key, $value, $duration);

	}

/**

 * Read a key from the cache

 *

 * @param string $key Identifier for the data

 * @return mixed The cached data, or false if the data doesn't exist, has expired, or if there was an error fetching it

 */

	public function read($key) {

		return $this->_Memcached->get($key);

	}

/**

 * Increments the value of an integer cached key

 *

 * @param string $key Identifier for the data

 * @param int $offset How much to increment

 * @return New incremented value, false otherwise

 * @throws CacheException when you try to increment with compress = true

 */

	public function increment($key, $offset = 1) {

		return $this->_Memcached->increment($key, $offset);

	}

/**

 * Decrements the value of an integer cached key

 *

 * @param string $key Identifier for the data

 * @param int $offset How much to subtract

 * @return New decremented value, false otherwise

 * @throws CacheException when you try to decrement with compress = true

 */

	public function decrement($key, $offset = 1) {

		return $this->_Memcached->decrement($key, $offset);

	}

/**

 * Delete a key from the cache

 *

 * @param string $key Identifier for the data

 * @return bool True if the value was successfully deleted, false if it didn't exist or couldn't be removed

 */

	public function delete($key) {

		return $this->_Memcached->delete($key);

	}

/**

 * Delete all keys from the cache

 *

 * @param bool $check If true no deletes will occur and instead CakePHP will rely

 *   on key TTL values.

 * @return bool True if the cache was successfully cleared, false otherwise

 */

	public function clear($check) {

		if ($check) {

			return true;

		}

		$keys = $this->_Memcached->getAllKeys();

		foreach ($keys as $key) {

			if (strpos($key, $this->settings['prefix']) === 0) {

				$this->_Memcached->delete($key);

			}

		}

		return true;

	}

/**

 * Returns the `group value` for each of the configured groups

 * If the group initial value was not found, then it initializes

 * the group accordingly.

 *

 * @return array

 */

	public function groups() {

		if (empty($this->_compiledGroupNames)) {

			foreach ($this->settings['groups'] as $group) {

				$this->_compiledGroupNames[] = $this->settings['prefix'] . $group;

			}

		}

		$groups = $this->_Memcached->getMulti($this->_compiledGroupNames);

		if (count($groups) !== count($this->settings['groups'])) {

			foreach ($this->_compiledGroupNames as $group) {

				if (!isset($groups[$group])) {

					$this->_Memcached->set($group, 1, 0);

					$groups[$group] = 1;

				}

			}

			ksort($groups);

		}

		$result = array();

		$groups = array_values($groups);

		foreach ($this->settings['groups'] as $i => $group) {

			$result[] = $group . $groups[$i];

		}

		return $result;

	}

/**

 * Increments the group value to simulate deletion of all keys under a group

 * old values will remain in storage until they expire.

 *

 * @param string $group The group to clear.

 * @return bool success

 */

	public function clearGroup($group) {

		return (bool)$this->_Memcached->increment($this->settings['prefix'] . $group);

	}

}