@Override
  public final long readLong() throws IOException {
    if (readToBuff(8) < 0) {
      throw new EOFException();
    }
    int i1 = ((buff[0] & 0xff) << 24) | ((buff[1] & 0xff) << 16)
        | ((buff[2] & 0xff) << 8) | (buff[3] & 0xff);
    int i2 = ((buff[4] & 0xff) << 24) | ((buff[5] & 0xff) << 16)
        | ((buff[6] & 0xff) << 8) | (buff[7] & 0xff);

    return ((i1 & 0xffffffffL) << 32) | (i2 & 0xffffffffL);
  }
Reads a 64-bit <code>long</code> value from this stream.

@return the next <code>long</code> value from the source stream.

@throws IOException
          If a problem occurs reading from this DataInputStream.
ql/src/java/org/apache/hadoop/hive/ql/io/NonSyncDataInputBuffer.java