code: @Override
    public FlatRow next() throws IOException {
      if (isConsumed) {
        return null;
      }
  
      try(Timer.Context ignored = resultsTimer.time()) {
        FlatRow result = responseQueueReader.getNextMergedRow();
        if (result != null) {
          resultsMeter.mark();
        } else {
          isConsumed = true;
        }
        return result;
      } catch(RuntimeException|IOException e) {
        isConsumed = true;
        throw e;
      }
    }
docs: {@inheritDoc}