code: func (cm *ConnManager) Stop() {
  	if atomic.AddInt32(&cm.stop, 1) != 1 {
  		log.Warnf("Connection manager already stopped")
  		return
  	}
  
  	// Stop all the listeners.  There will not be any listeners if
  	// listening is disabled.
  	for _, listener := range cm.cfg.Listeners {
  		// Ignore the error since this is shutdown and there is no way
  		// to recover anyways.
  		_ = listener.Close()
  	}
  
  	close(cm.quit)
  	log.Trace("Connection manager stopped")
  }
docs: // Stop gracefully shuts down the connection manager.