<?php /** * TMemCache class file * * @author Qiang Xue <qiang.xue@gmail.com> * @link http://www.pradosoft.com/ * @copyright Copyright © 2005 PradoSoft * @license http://www.pradosoft.com/license/ * @version $Revision: $ $Date: $ * @package System.Data */ /** * 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 replace} : store the value only if cache has 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> * * 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 * <module id="cache" type="System.Data.TMemCache" Host="localhost" Port=11211 /> * where {@link getHost Host} and {@link getPort Port} are configurable properties * of TMemCache. * * @author Qiang Xue <qiang.xue@gmail.com> * @version $Revision: $ $Date: $ * @package System.Data * @since 3.0 */ class TMemCache extends TModule implements ICache { /** * @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 $_port=11211; /** * Destructor. * Disconnect the memcache server. */ public function __destruct() { if($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'); $this->_cache=new Memcache; if($this->_cache->connect($this->_host,$this->_port)===false) throw new TConfigurationException('memcache_connection_failed',$this->_host,$this->_port); $application=$this->getApplication(); $this->_prefix=$application->getUniqueID(); $application->setCache($this); $this->_initialized=true; } /** * @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. * @return mixed the value stored in cache, false if the value is not in the cache or expired. */ public function get($key) { return $this->_cache->get($this->generateUniqueKey($key)); } /** * Stores a value identified by a key into cache. * If the cache already contains such a key, the existing value and * expiration time will be replaced with the new ones. * * Note, avoid using this method whenever possible. Database insertion is * very expensive. Try using {@link add} instead, which will not store the value * if the key is already in cache. * * @param string the key identifying the value to be cached * @param mixed the value to be cached * @param integer the expiration time of the value, * 0 means never expire, * a number less or equal than 60*60*24*30 means the number of seconds that the value will remain valid. * a number greater than 60*60*24*30 means a UNIX timestamp after which the value will expire. * @return boolean true if the value is successfully stored into cache, false otherwise */ public function set($key,$value,$expire=0) { return $this->_cache->set($this->generateUniqueKey($key),$value,0,$expire); } /** * Stores a value identified by a key into cache if the cache does not contain this key. * Nothing will be done if the cache already contains the key. * @param string the key identifying the value to be cached * @param mixed the value to be cached * @param integer the expiration time of the value, * 0 means never expire, * a number less or equal than 60*60*24*30 means the number of seconds that the value will remain valid. * a number greater than 60*60*24*30 means a UNIX timestamp after which the value will expire. * @return boolean true if the value is successfully stored into cache, false otherwise */ public function add($key,$value,$expiry=0) { return $this->_cache->add($this->generateUniqueKey($key),$value,0,$expiry); } /** * Stores a value identified by a key into cache only if the cache contains this key. * The existing value and expiration time will be overwritten with the new ones. * @param string the key identifying the value to be cached * @param mixed the value to be cached * @param integer the expiration time of the value, * 0 means never expire, * a number less or equal than 60*60*24*30 means the number of seconds that the value will remain valid. * a number greater than 60*60*24*30 means a UNIX timestamp after which the value will expire. * @return boolean true if the value is successfully stored into cache, false otherwise */ public function replace($key,$value,$expiry=0) { return $this->_cache->replace($this->generateUniqueKey($key),$value,0,$expiry); } /** * Deletes a value with the specified key from cache * @param string the key of the value to be deleted * @return boolean if no error happens during deletion */ public function delete($key) { return $this->_cache->delete($this->generateUniqueKey($key)); } /** * Deletes all values from cache. * Be careful of performing this operation if the cache is shared by multiple applications. */ public function flush() { return $this->_cache->flush(); } /** * Generates a unique key based on a given user key. * This method generates a unique key with the memcache. * The key is made unique by prefixing with a unique string that is supposed * to be unique among applications using the same memcache. * @param string user key * @param string a unique key */ protected function generateUniqueKey($key) { return md5($this->_prefix.$key); } } ?>