code: func (c *Collector) RunPoller() {
  	for {
  		c.pollHost()
  		for _, m := range c.transform() {
  			c.MetricsChan <- m
  		}
  		time.Sleep(c.PollPeriod)
  	}
  }
docs: // RunPoller periodiclly polls the HTTP APIs of a Mesos agent. This function
  // should be run in its own goroutine.