code: func (mc *CCacheMetric) nextTs(ts uint32) uint32 {
  	chunk := mc.chunks[ts]
  	return mc.nextTsCore(chunk.Itgen, chunk.Prev, chunk.Next)
  }
docs: // nextTs takes a chunk's ts and returns the ts of the next chunk. (guessing if necessary)
  // assumes we already have at least a read lock