Predis\PubSub\AbstractConsumer::ping PHP Метод

PING the server with an optional payload that will be echoed as a PONG message in the pub/sub loop.

public ping ( string $payload = null )
$payload	string	Optional PING payload.

    public function ping($payload = null)
    {
        $this->writeRequest('PING', array($payload));
    }

AbstractConsumer