<?php
/**
 * memcacheSessionHandler class
 * @class                       memcacheSessionHandler
 * @file                        memcacheSessionHandler.class.php
 * @brief                       This class is used to store session data with memcache, it store in json the session to be used more easily in Node.JS
 * @version                     0.1
 * @date                        2012-04-11
 * @author                      Deisss
 * @licence                     LGPLv3
 * This class is used to store session data with memcache, it store in json the session to be used more easily in Node.JS
 */
class memcacheSessionHandler implements \SessionHandlerInterface {
    private $host = "127.0.0.1";
    private $port = 11211;
    private $lifetime = 0;
    private $memcache = null;

    /**
     * Constructor
     */
    public function __construct(){
        $this->memcache = new Memcache;
        $this->memcache->connect($this->host, $this->port) or die("Error : Memcache is not ready");

        //session_set_save_handler(&$this, true);

        session_set_save_handler(
            array($this, "open"),
            array($this, "close"),
            array($this, "read"),
            array($this, "write"),
            array($this, "destroy"),
            array($this, "gc")
        );

    }

    /**
     * Destructor
     */
    public function __destruct(){
        session_write_close();
        $this->memcache->close();
    }

    /**
     * Open the session handler, set the lifetime ot session.gc_maxlifetime
     * @return boolean True if everything succeed
     */
    public function open($save_path, $session_name){
        $this->lifetime = ini_get('session.gc_maxlifetime');
        return true;
    }

    /**
     * Read the id
     * @param string $id The SESSID to search for
     * @return string The session saved previously
     */
    public function read($id){
        $tmp = $_SESSION;
        $_SESSION = json_decode($this->memcache->get("sessions/{$id}"), true);
        if(isset($_SESSION) && !empty($_SESSION) && $_SESSION != null){
            $new_data = session_encode();
            $_SESSION = $tmp;
            return $new_data;
        }else{
            return "";
        }
    }

    /**
     * Write the session data, convert to json before storing
     * @param string $id The SESSID to save
     * @param string $data The data to store, already serialized by PHP
     * @return boolean True if memcached was able to write the session data
     */
    public function write($id, $data){
        $tmp = $_SESSION;
        session_decode($data);
        $new_data = $_SESSION;
        $_SESSION = $tmp;
        return $this->memcache->set("sessions/{$id}", json_encode($new_data), 0, $this->lifetime);
    }

    /**
     * Delete object in session
     * @param string $id The SESSID to delete
     * @return boolean True if memcached was able delete session data
     */
    public function destroy($id){
        return $this->memcache->delete("sessions/{$id}");
    }

    /**
     * Close gc
     * @return boolean Always true
     */
    public function gc($maxlifetime){
        return true;
    }

    /**
     * Close session
     * @return boolean Always true
     */
    public function close(){
        return true;
    }
}

new memcacheSessionHandler();
?>

/* above is memcacheSessionHandler.class.php and next is your autoload.php, just load the memcacheSessionHandler.class.php file then do */
$handler = new memcacheSessionHandler();
session_set_save_handler($handler, true);

/* finally in php.ini I have the following */
extension=php_memcache.dll
[Memcache]
memcache.allow_failover = 1
memcache.max_failover_attempts=20
memcache.chunk_size =8192
memcache.default_port = 11211

/* so with memcached server/dameon running you'll now store your sessions to it instead of the default file. test.example
<?php
include_once(dirname(__FILE__).'/classes/autoload.php');
session_start();
$_SESSION['ID'] = 3;
?>