A Custom Session Handler

SessionHandler.php

define('SESSION_SAVE_PATH', dirname(realpath(__FILE__)).DIRECTORY_SEPARATOR.'sessions');

class MySessionHandler extends SessionHandler
{

    private $sessionName = 'MYSESS';
    private $sessionMaxLifeTime = 0;
    private $sessionHTTPOnly = true;
    private $sessionSecure = false;
    private $sessionPath = '/';
    private $sessionDomain = '.phpdev.com';
    private $sessionSavePath = SESSION_SAVE_PATH;

    private $cipherKey = 'WYCRYPT0K3Y@2016';
    private $cipherMode = MCRYPT_MODE_ECB;
    private $cipherAlgorithm = MCRYPT_BLOWFISH;

    private $ttl = 30;

    public function __construct()
    {

        ini_set('session.use_cookies', 1);
        ini_set('session.use_only_cookies', 1);
        ini_set('session.use_trans_sid', 0);
        ini_set('session.save_handler', 'files');

        session_name($this->sessionName);

        session_save_path($this->sessionSavePath);

        session_set_cookie_params(
            $this->sessionMaxLifeTime,
            $this->sessionPath,
            $this->sessionDomain,
            $this->sessionSecure,
            $this->sessionHTTPOnly
        );

        session_set_save_handler($this, true);
    }

    public function __get($key)
    {
        return false !== (isset($_SESSION[$key])) ?  $_SESSION[$key] : false;
    }

    public function __set($key, $data)
    {
        $_SESSION[$key] = $data;
    }

    public function __isset($key)
    {
        return isset($_SESSION[$key]);
    }

    public function read($id)
    {
        return mcrypt_decrypt($this->cipherAlgorithm, $this->cipherKey, parent::read($id), $this->cipherMode);
    }

    public function write($id, $data)
    {
        parent::write($id, mcrypt_encrypt($this->cipherAlgorithm, $this->cipherKey, $data, $this->cipherMode));
    }

    public function start()
    {
        if('' === session_id()) {
            if(session_start()) {
                $this->setStartTimeStamp();
                $this->checkSessionValidity();
            }
        }
        return false;
    }

    public function kill()
    {
        session_unset();
        setcookie(
            $this->sessionName, '', time() - 1000,
            $this->sessionPath, $this->sessionDomain, $this->sessionSecure,
            $this->sessionHTTPOnly
        );
        return session_destroy();
    }

    private function renewSession()
    {
        $this->renewTimeStamp();
        return session_regenerate_id(true);
    }

    private function setStartTimeStamp()
    {
        if(!isset($this->sessionStartTimeStamp)) {
            $this->renewTimeStamp();
        }
    }

    private function renewTimeStamp()
    {
        $this->sessionStartTimeStamp = time();
    }

    private function checkSessionValidity()
    {
        if((time() - $this->sessionStartTimeStamp) > ($this->ttl * 60)) {
            $this->renewSession();
        }
    }

    private function getId()
    {
        return session_id();
    }

    public function isFingerPrintValid()
    {
        if(!isset($this->fingerPrint)) {
            $userAgent = $_SERVER['HTTP_USER_AGENT'];
            $this->randomKey = mcrypt_create_iv(64);
            $this->fingerPrint = sha1($userAgent.$this->getId().$this->randomKey);
        }

        $fingerPrint = sha1($_SERVER['HTTP_USER_AGENT'].$this->getId().$this->randomKey);

        if($fingerPrint === $this->fingerPrint) {
            return true;
        }

        return false;
    }
}

$session = new MySessionHandler();
$session->start();
if(!$session->isFingerPrintValid()) {
    $session->kill();
}

I got this error

Warning: session_write_close(): Session callback expects true/false return value in Unknown on line 0
Warning: session_write_close(): Failed to write session data using user defined save handler. (session.save_path: /home/mohammed/Code/php/sessions) in Unknown on line 0

I googled the problem I found the solution
I added return true; to the write() method
now it works good