Connect to redis and assign the client to the RedisSession class
        so that it is globally available in this process.

        :param dict settings: The redis session configuration

def _redis_connect(cls, settings):
        """Connect to redis and assign the client to the RedisSession class
        so that it is globally available in this process.

        :param dict settings: The redis session configuration

        """
        if 'tornadoredis' not in globals():
            import tornadoredis
        kwargs = {'host': settings.get('host', cls.REDIS_HOST),
                  'port': settings.get('port', cls.REDIS_PORT),
                  'selected_db': settings.get('db', cls.REDIS_DB)}
        LOGGER.info('Connecting to %(host)s:%(port)s DB %(selected_db)s',
                    kwargs)
        cls._redis_client = tornadoredis.Client(**kwargs)
        cls._redis_client.connect()