code: private int getSeriesSize(String series) {
          synchronized (dataStoreLock) {
              if (dataStore == null) {
                  return 0;
              }
              if (seriesToBatch.containsKey(series)) {
                  return (int) seriesToBatch.get(series).getDataSize();
              } else {
                  return 0;
              }
          }
      }
docs: Returns the size of the data set in a particular series.
  
  @param series The series to query
  @return Size of the data set, or 0 if series does not exist.