code: protected void reportStorageOpTime(long startNs) {
          if(streamStats != null) {
              streamStats.reportStreamingScan(operation);
              streamStats.reportStorageTime(operation,
                                            Utils.elapsedTimeNs(startNs, System.nanoTime()));
          }
      }
docs: Helper method to track storage operations & time via StreamingStats.
  
  @param startNs