code: func (a *AggMetric) SyncChunkSaveState(ts uint32) {
  	a.Lock()
  	defer a.Unlock()
  	if ts > a.lastSaveFinish {
  		a.lastSaveFinish = ts
  	}
  	if ts > a.lastSaveStart {
  		a.lastSaveStart = ts
  	}
  	log.Debugf("AM: metric %s at chunk T0=%d has been saved.", a.key, ts)
  }
docs: // Sync the saved state of a chunk by its T0.