code: def _redis_watcher(state):
      
      conf = state.app.config
  
      r = redis.client.StrictRedis(
          host=conf.get('WAFFLE_REDIS_HOST', 'localhost'),
          port=conf.get('WAFFLE_REDIS_PORT', 6379))
  
      sub = r.pubsub(ignore_subscribe_messages=True)
      sub.subscribe(conf.get('WAFFLE_REDIS_CHANNEL', 'waffleconf'))
  
      while True:
          for msg in sub.listen():
              # Skip non-messages
              if not msg['type'] == 'message':
                  continue
  
              tstamp = float(msg['data'])
  
              # Compare timestamps and update config if needed
              if tstamp > state._tstamp:
                  state.update_conf()
                  state._tstamp = tstamp
docs: Listen to redis channel for a configuration update notifications.
  
      Arguments:
          state (_WaffleState): Object that contains reference to app and its
              configstore.