code: @Override
      public void saveHWMark(long endOfPeriod) {
          if(getHWMark() < endOfPeriod) {
              try {
                  set(0, get(0), endOfPeriod);
              } catch(Exception e) {
                  _logger.error("Failed to saveHWMark " + endOfPeriod, e);
              }
          } else if(0 < endOfPeriod && endOfPeriod < getLWMark()) {
              try {
                  _entryManager.sync();
              } catch(Exception e) {
                  _logger.error("Failed to saveHWMark" + endOfPeriod, e);
              }
              _entryManager.setWaterMarks(endOfPeriod, endOfPeriod);
          }
      }
docs: Sync-up the high water mark to a given value.
  
  @param endOfPeriod