Subversion-Projekte lars-tiefland.prado

<?php

/**

 * TMemCache class file

 *

 * @author Qiang Xue <qiang.xue@gmail.com>

 * @author Carl G. Mathisen <carlgmathisen@gmail.com>

 * @link http://www.pradosoft.com/

 * @copyright Copyright © 2005-2008 PradoSoft

 * @license http://www.pradosoft.com/license/

 * @version $Id: TMemCache.php 2541 2008-10-21 15:05:13Z qiang.xue $

 * @package System.Caching

 */

/**

 * TMemCache class

 *

 * TMemCache implements a cache application module based on {@link http://www.danga.com/memcached/ memcached}.

 *

 * TMemCache can be configured with the Host and Port properties, which

 * specify the host and port of the memcache server to be used.

 * By default, they take the value 'localhost' and 11211, respectively.

 * These properties must be set before {@link init} is invoked.

 *

 * The following basic cache operations are implemented:

 * - {@link get} : retrieve the value with a key (if any) from cache

 * - {@link set} : store the value with a key into cache

 * - {@link add} : store the value only if cache does not have this key

 * - {@link delete} : delete the value with the specified key from cache

 * - {@link flush} : delete all values from cache

 *

 * Each value is associated with an expiration time. The {@link get} operation

 * ensures that any expired value will not be returned. The expiration time can

 * be specified by the number of seconds (maximum 60*60*24*30)

 * or a UNIX timestamp. A expiration time 0 represents never expire.

 *

 * By definition, cache does not ensure the existence of a value

 * even if it never expires. Cache is not meant to be an persistent storage.

 *

 * Also note, there is no security measure to protected data in memcache.

 * All data in memcache can be accessed by any process running in the system.

 *

 * To use this module, the memcache PHP extension must be loaded.

 *

 * Some usage examples of TMemCache are as follows,

 * <code>

 * $cache=new TMemCache;  // TMemCache may also be loaded as a Prado application module

 * $cache->init(null);

 * $cache->add('object',$object);

 * $object2=$cache->get('object');

 * </code>

 *

 * You can configure TMemCache two different ways. If you only need one memcache server

 * you may use the method as follows.

 * <code>

 * <module id="cache" class="System.Caching.TMemCache" Host="localhost" Port="11211" />

 * </code>

 *

 * If you want a more complex configuration, you may use the method as follows.

 * <code>

 * <module id="cache" classs="System.Caching.TMemCache">

 *     <server Host="localhost" Port="11211" Weight="1" Timeout="300" RetryInterval="15" />

 *     <server Host="anotherhost" Port="11211" Weight="1" Timeout="300" RetryInterval="15" />

 * </module>

 * </code>

 *

 * If loaded, TMemCache will register itself with {@link TApplication} as the

 * cache module. It can be accessed via {@link TApplication::getCache()}.

 *

 * TMemCache may be configured in application configuration file as follows

 * <code>

 * <module id="cache" class="System.Caching.TMemCache" Host="localhost" Port="11211" />

 * </code>

 * where {@link getHost Host} and {@link getPort Port} are configurable properties

 * of TMemCache.

 *

 * @author Qiang Xue <qiang.xue@gmail.com>

 * @version $Id: TMemCache.php 2541 2008-10-21 15:05:13Z qiang.xue $

 * @package System.Caching

 * @since 3.0

 */

class TMemCache extends TCache

{

	/**

	 * @var boolean if the module is initialized

	 */

	private $_initialized=false;

	/**

	 * @var Memcache the Memcache instance

	 */

	private $_cache=null;

	/**

	 * @var string a unique prefix used to identify this cache instance from the others

	 */

	private $_prefix=null;

	/**

	 * @var string host name of the memcache server

	 */

	private $_host='localhost';

	/**

	 * @var integer the port number of the memcache server

	 */

	private $_port=11211;

	/**

	 * @var boolean controls the use of a persistent connection. Default to true.

	 */

    private $_persistence = true;

    /**

     * @var integer number of buckets to create for this server which in turn control its

     * probability of it being selected. The probability is relative to the total weight

     * of all servers.

     */

    private $_weight = 1;

    private $_timeout = 360;

    private $_retryInterval = 15;

    private $_status = true;

    private $_failureCallback = null;

	/**

	 * @var array list of servers available

	 */

	private $_servers=array();

	/**

	 * Destructor.

	 * Disconnect the memcache server.

	 */

	public function __destruct()

	{

		if($this->_cache!==null)

			$this->_cache->close();

	}

	/**

	 * Initializes this module.

	 * This method is required by the IModule interface. It makes sure that

	 * UniquePrefix has been set, creates a Memcache instance and connects

	 * to the memcache server.

	 * @param TApplication Prado application, can be null

	 * @param TXmlElement configuration for this module, can be null

	 * @throws TConfigurationException if memcache extension is not installed or memcache sever connection fails

	 */

	public function init($config)

	{

		if(!extension_loaded('memcache'))

			throw new TConfigurationException('memcache_extension_required');

		$this->_cache=new Memcache;

		$this->loadConfig($config);

		if(count($this->_servers))

        {

            foreach($this->_servers as $server)

            {

                Prado::trace('Adding server '.$server['Host'].' from serverlist', 'System.Caching.TMemCache');

                if($this->_cache->addServer($server['Host'],$server['Port'],$server['Persistent'],

                    $server['Weight'],$server['Timeout'],$server['RetryInterval'])===false)

                    throw new TConfigurationException('memcache_connection_failed',$server['Host'],$server['Port']);

            }

        }

        else

        {

            Prado::trace('Adding server '.$this->_host, 'System.Caching.TMemCache');

            if($this->_cache->addServer($this->_host,$this->_port)===false)

                throw new TConfigurationException('memcache_connection_failed',$this->_host,$this->_port);

        }

		$this->_initialized=true;

		parent::init($config);

	}

    /**

	 * Loads configuration from an XML element

	 * @param TXmlElement configuration node

	 * @throws TConfigurationException if log route class or type is not specified

	 */

	private function loadConfig($xml)

	{

	    if($xml instanceof TXmlElement)

		{

    		foreach($xml->getElementsByTagName('server') as $serverConfig)

    		{

    			$properties=$serverConfig->getAttributes();

    			if(($host=$properties->remove('Host'))===null)

    				throw new TConfigurationException('memcache_serverhost_required');

    			if(($port=$properties->remove('Port'))===null)

        			throw new TConfigurationException('memcache_serverport_required');

        		if(!is_numeric($port))

        		    throw new TConfigurationException('memcache_serverport_invalid');

        		$server = array('Host'=>$host,'Port'=>$port,'Weight'=>1,'Timeout'=>1800,'RetryInterval'=>15,'Persistent'=>true);

        		$checks = array(

        		    'Weight'=>'memcache_serverweight_invalid',

        		    'Timeout'=>'memcache_servertimeout_invalid',

        		    'RetryInterval'=>'memcach_serverretryinterval_invalid'

        		);

        		foreach($checks as $property=>$exception)

        		{

        		    $value=$properties->remove($property);

        		    if($value!==null && is_numeric($value))

        		        $server[$property]=$value;

        		    else if($value!==null)

        		        throw new TConfigurationException($exception);

        		}

        		$server['Persistent']= TPropertyValue::ensureBoolean($properties->remove('Persistent'));

    			$this->_servers[]=$server;

    		}

	    }

	}

	/**

	 * @return string host name of the memcache server

	 */

	public function getHost()

	{

		return $this->_host;

	}

	/**

	 * @param string host name of the memcache server

	 * @throws TInvalidOperationException if the module is already initialized

	 */

	public function setHost($value)

	{

		if($this->_initialized)

			throw new TInvalidOperationException('memcache_host_unchangeable');

		else

			$this->_host=$value;

	}

	/**

	 * @return integer port number of the memcache server

	 */

	public function getPort()

	{

		return $this->_port;

	}

	/**

	 * @param integer port number of the memcache server

	 * @throws TInvalidOperationException if the module is already initialized

	 */

	public function setPort($value)

	{

		if($this->_initialized)

			throw new TInvalidOperationException('memcache_port_unchangeable');

		else

			$this->_port=TPropertyValue::ensureInteger($value);

	}

	/**

	 * Retrieves a value from cache with a specified key.

	 * This is the implementation of the method declared in the parent class.

	 * @param string a unique key identifying the cached value

	 * @return string the value stored in cache, false if the value is not in the cache or expired.

	 */

	protected function getValue($key)

	{

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

	}

	/**

	 * Stores a value identified by a key in cache.

	 * This is the implementation of the method declared in the parent class.

	 *

	 * @param string the key identifying the value to be cached

	 * @param string the value to be cached

	 * @param integer the number of seconds in which the cached value will expire. 0 means never expire.

	 * @return boolean true if the value is successfully stored into cache, false otherwise

	 */

	protected function setValue($key,$value,$expire)

	{

		return $this->_cache->set($key,$value,0,$expire);

	}

	/**

	 * Stores a value identified by a key into cache if the cache does not contain this key.

	 * This is the implementation of the method declared in the parent class.

	 *

	 * @param string the key identifying the value to be cached

	 * @param string the value to be cached

	 * @param integer the number of seconds in which the cached value will expire. 0 means never expire.

	 * @return boolean true if the value is successfully stored into cache, false otherwise

	 */

	protected function addValue($key,$value,$expire)

	{

		return $this->_cache->add($key,$value,0,$expire);

	}

	/**

	 * Deletes a value with the specified key from cache

	 * This is the implementation of the method declared in the parent class.

	 * @param string the key of the value to be deleted

	 * @return boolean if no error happens during deletion

	 */

	protected function deleteValue($key)

	{

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

	}

	/**

	 * Deletes all values from cache.

	 * Be careful of performing this operation if the cache is shared by multiple applications.

	 */

	public function flush()

	{

		return $this->_cache->flush();

	}

}