code: func (mc *CCacheMetric) generateKeys() {
  	keys := make([]uint32, 0, len(mc.chunks))
  	for k := range mc.chunks {
  		keys = append(keys, k)
  	}
  	sort.Sort(accnt.Uint32Asc(keys))
  	mc.keys = keys
  }
docs: // generateKeys generates sorted slice of all chunk timestamps
  // assumes we have at least read lock