private static long getLongValue(final Cell cell) throws DoNotRetryIOException {
      int len = cell.getValueLength();
      if (len != Bytes.SIZEOF_LONG) {
        // throw DoNotRetryIOException instead of IllegalArgumentException
        throw new DoNotRetryIOException("Field is not a long, it's " + len + " bytes wide");
      }
      return PrivateCellUtil.getValueAsLong(cell);
    }
Returns Get the long out of the passed in Cell
hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/HRegion.java