code: func (c *Cacher) Stop() {
  	c.stopLock.Lock()
  	if c.stopped {
  		// avoid stopping twice (note: cachers are shared with subresources)
  		c.stopLock.Unlock()
  		return
  	}
  	c.stopped = true
  	c.stopLock.Unlock()
  	close(c.stopCh)
  	c.stopWg.Wait()
  }
docs: // Stop implements the graceful termination.