code: func (do *Domain) mustReload() (exitLoop bool) {
  	for {
  		err := do.Reload()
  		if err == nil {
  			logutil.Logger(context.Background()).Info("mustReload succeed")
  			return false
  		}
  
  		logutil.Logger(context.Background()).Info("reload the schema failed", zap.Error(err))
  		// If the domain is closed, we returns immediately.
  		select {
  		case <-do.exit:
  			logutil.Logger(context.Background()).Info("domain is closed")
  			return true
  		default:
  		}
  
  		time.Sleep(200 * time.Millisecond)
  	}
  }
docs: // mustReload tries to Reload the schema, it returns until it's successful or the domain is closed.
  // it returns false when it is successful, returns true when the domain is closed.