<?php
class Ec_Session_SaveHandler_Memcached implements Zend_Session_SaveHandler_Interface {
	const LIFETIME = 'lifetime';
	const OVERRIDE_LIFETIME = 'overrideLifetime';
	const MEMCACHED = 'memcached';
	protected $_lifetime = false;
	protected $_overrideLifetime = false;
	protected $_sessionSavePath;
	protected $_sessionName;
	protected $_memcached;
	/**
	 * Constructor
	 *
	 * $config is an instance of Zend_Config or an array of key/value pairs
	 * containing configuration options for
	 * Zend_Session_SaveHandler_Memcached . These are the configuration options
	 * for
	 * Zend_Session_SaveHandler_Memcached:
	 *
	 *
	 * sessionId => The id of the current session
	 * sessionName => The name of the current session
	 * sessionSavePath => The save path of the current session
	 *
	 * modified => (string) Session last modification time column
	 *
	 * lifetime => (integer) Session lifetime (optional; default:
	 * ini_get('session.gc_maxlifetime'))
	 *
	 * overrideLifetime => (boolean) Whether or not the lifetime of an existing
	 * session should be overridden
	 * (optional; default: false)
	 *
	 * @param $config Zend_Config|array
	 *       	 User-provided configuration
	 * @return void
	 * @throws Zend_Session_SaveHandler_Exception
	 */
	public function __construct($config) {
		if ($config instanceof Zend_Config) {
			$config = $config->toArray ();
		} else if (! is_array ( $config )) {
			/**
			 *
			 * @see Zend_Session_SaveHandler_Exception
			 */
			require_once 'Zend/Session/SaveHandler/Exception.php';
			
			throw new Zend_Session_SaveHandler_Exception ( '$config must be an instance of Zend_Config or array of key/value pairs containing ' . 'configuration options for Zend_Session_SaveHandler_Memcached .' );
		}
		
		foreach ( $config as $key => $value ) {
			do {
				switch ($key) {
					case self::MEMCACHED :
						$this->createMemcached ( $value );
						break;
					case self::LIFETIME :
						$this->setLifetime ( $value );
						break;
					case self::OVERRIDE_LIFETIME :
						$this->setOverrideLifetime ( $value );
						break;
					default :
						// unrecognized options passed to parent::__construct()
						break 2;
				}
				unset ( $config [$key] );
			} while ( false );
		}
	}
	
	/**
	 * 创建memcached连接对象
	 *
	 * @return void
	 */
	public function createMemcached($config) {
		$mc = new Memcache ();
		foreach ( $config as $value ) {
			$mc->addServer ( $value ['ip'], $value ['port'] );
		}
		$this->_memcached = $mc;
	}
	
	public function __destruct() {
		Zend_Session::writeClose ();
	}
	/**
	 * Set session lifetime and optional whether or not the lifetime of an
	 * existing session should be overridden
	 *
	 * $lifetime === false resets lifetime to session.gc_maxlifetime
	 *
	 * @param $lifetime int       	
	 * @param $overrideLifetime boolean
	 *       	 (optional)
	 * @return Zend_Session_SaveHandler_Memcached
	 */
	public function setLifetime($lifetime, $overrideLifetime = null) {
		if ($lifetime < 0) {
			/**
			 *
			 * @see Zend_Session_SaveHandler_Exception
			 */
			require_once 'Zend/Session/SaveHandler/Exception.php';
			throw new Zend_Session_SaveHandler_Exception ();
		} else if (empty ( $lifetime )) {
			$this->_lifetime = ( int ) ini_get ( 'session.gc_maxlifetime' );
		} else {
			$this->_lifetime = ( int ) $lifetime;
		}
		
		if ($overrideLifetime != null) {
			$this->setOverrideLifetime ( $overrideLifetime );
		}
		
		return $this;
	}
	/**
	 * Retrieve session lifetime
	 *
	 * @return int
	 */
	public function getLifetime() {
		return $this->_lifetime;
	}
	/**
	 * Set whether or not the lifetime of an existing session should be
	 * overridden
	 *
	 * @param $overrideLifetime boolean       	
	 * @return Zend_Session_SaveHandler_Memcached
	 */
	public function setOverrideLifetime($overrideLifetime) {
		$this->_overrideLifetime = ( boolean ) $overrideLifetime;
		
		return $this;
	}
	
	public function getOverrideLifetime() {
		return $this->_overrideLifetime;
	}
	/**
	 * Retrieve session lifetime considering
	 *
	 * @param $value array       	
	 * @return int
	 */
	public function open($save_path, $name) {
		$this->_sessionSavePath = $save_path;
		$this->_sessionName = $name;
		
		return true;
	}
	/**
	 * Retrieve session expiration time
	 *
	 * @param
	 *       	 * @param array $value
	 * @return int
	 */
	public function close() {
		return true;
	}
	
	public function read($id) {
		$return = '';
		
		$value = $this->_memcached->get ( $id ); // 获取数据
		
		if ($value) {
			if ($this->_getExpirationTime ( $value ) > time ()) {
				$return = $value ['data'];
			} else {
				$this->destroy ( $id );
			}
		}
		
		return $return;
	}
	
	public function write($id, $data) {
		$return = false;
		
		$insertDate = array ('modified' => time (), 'data' => ( string ) $data );
		
		$value = $this->_memcached->get ( $id ); // 获取数据
		
		if ($value) {
			$insertDate ['lifetime'] = $this->_getLifetime ( $value );
			
			if ($this->_memcached->replace ( $id, $insertDate )) {
				$return = true;
			}
		} else {
			$insertDate ['lifetime'] = $this->_lifetime;
			
			if ($this->_memcached->add ( $id, $insertDate, false, $this->_lifetime )) {
				$return = true;
			}
		}
		
		return $return;
	}
	
	public function destroy($id) {
		$return = false;
		
		if ($this->_memcached->delete ( $id )) {
			$return = true;
		}
		
		return $return;
	}
	
	public function gc($maxlifetime) {
		return true;
	}
	
	protected function _getLifetime($value) {
		$return = $this->_lifetime;
		
		if (! $this->_overrideLifetime) {
			$return = ( int ) $value ['lifetime'];
		}
		
		return $return;
	}
	
	protected function _getExpirationTime($value) {
		return ( int ) $value ['modified'] + $this->_getLifetime ( $value );
	}
}