code: func (state *gbtWorkState) NotifyMempoolTx(lastUpdated time.Time) {
  	go func() {
  		state.Lock()
  		defer state.Unlock()
  
  		// No need to notify anything if no block templates have been generated
  		// yet.
  		if state.prevHash == nil || state.lastGenerated.IsZero() {
  			return
  		}
  
  		if time.Now().After(state.lastGenerated.Add(time.Second *
  			gbtRegenerateSeconds)) {
  
  			state.notifyLongPollers(state.prevHash, lastUpdated)
  		}
  	}()
  }
docs: // NotifyMempoolTx uses the new last updated time for the transaction memory
  // pool to notify any long poll clients with a new block template when their
  // existing block template is stale due to enough time passing and the contents
  // of the memory pool changing.