code: public long getDataSize() {
          long size = 0;
          synchronized (dataStoreLock) {
              for (DataStore b : dataBatches) {
                  size += b.getDataSize();
              }
          }
          return size;
      }
docs: Returns the size of all of the data in all the series.
  
  @return Size of the data store, or 0 if it has not been made yet.