OpenCart 1.5 Non-Blocking Sessions

session.php

<?php
class Session {
    public $data = array();

	public function __construct() {
	    $this->data = new SessionData();
	}
	
	function getId() {
		return $this->data->getId();
	}
}

class SessionData implements ArrayAccess {
    private $data = array();
    protected $session_id;

    protected function openSession()
    {
        if (!session_id()) {
            ini_set('session.use_only_cookies', 'On');
            ini_set('session.use_trans_sid', 'Off');
            ini_set('session.cookie_httponly', 'On');

            session_set_cookie_params(0, '/');
            if (!empty($this->session_id)) {
                ini_set('session.cache_limiter', null);
            }
            session_start();
        } else {
            if (!empty($this->session_id)) {
                ini_set('session.cache_limiter', null);
            }
            session_start();
        }

        $this->data =& $_SESSION;
        $this->session_id = session_id();
    }

    protected function closeSession()
    {
        session_write_close();
    }

    public function offsetSet($offset, $value) {
        $this->openSession();
        if (is_null($offset)) {
            $this->data[] = $value;
        } else {
            $this->data[$offset] = $value;
        }
        $this->closeSession();
    }

    public function offsetExists($offset) {
        $this->openSession();
        $bool = isset($this->data[$offset]);
        $this->closeSession();
        return $bool;
    }

    public function offsetUnset($offset) {
        $this->openSession();
        unset($this->data[$offset]);
        $this->closeSession();
    }

    public function offsetGet($offset) {
        $this->openSession();
        $bool = isset($this->data[$offset]) ? $this->data[$offset] : null;
        $this->closeSession();
        return $bool;
    }

    function getId() {
        return $this->session_id;
    }
}
?>