private function getKey()
    {
        if ($this->_key === null) {
            $this->_key = ftok(__FILE__, $this->id);
        }

        return $this->_key;
    }
private function getKey()
    {
        if ($this->_key === null) {
            $this->_key = ftok(__FILE__, $this->id);
        }

        return $this->_key;
    }
private function getKey ( ) { if ( $ this -> _key === null ) { $ this -> _key = ftok ( __FILE__ , $ this -> id ) ; } return $ this -> _key ; }
Return a number representing the current queue.
@return integer
Return a number representing the current queue .