public static long toLong(byte[] bytes, int offset, final int length) {
    if (length != SIZEOF_LONG || offset + length > bytes.length) {
      throw explainWrongLengthOrOffset(bytes, offset, length, SIZEOF_LONG);
    }
    return ConverterHolder.BEST_CONVERTER.toLong(bytes, offset, length);
  }
Converts a byte array to a long value.
@param bytes  array of bytes
@param offset offset into array
@param length length of data (must be {@link #SIZEOF_LONG})
@return the long value
@throws IllegalArgumentException if length is not {@link #SIZEOF_LONG} or if there's not enough
                                 room in the array at the offset indicated.
hbase-common/src/main/java/org/apache/hadoop/hbase/util/Bytes.java