public function count(Zend_Queue $queue=null)
    {
        if ($queue === null) {
            $queue = $this->_queue;
        }

        $queueName = $queue->getName();

        if (!$this->isExists($queueName)) {
            require_once 'Zend/Queue/Exception.php';
            throw new Zend_Queue_Exception('Queue does not exist:' . $queueName);
        }

        if (!isset($this->_queueObjects[$queueName])) {
            $this->_queueObjects[$queueName] = new Rediska_Key_List($this->_getKeyName("queue_$queueName"), array('rediska' => $this->_rediska));
        }

        return count($this->_queueObjects[$queueName]);
    }