@Override
    public void reserve(int byteCount) {
      switch (byteCount) {
      case 0:
        break;
      case 1:
        write(0);
        break;
      case 4:
        write(RESERVE_INT, 0, 4);
        break;
      default:
        for (int i = 0; i < byteCount; ++i) {
          write(0);
        }
      }
    }
Optimize for the common cases:
<ul>
  <li>Reserve 1 byte</li>
  <li>Reserve 1 int (4 bytes)</li>
</ul>
serde/src/java/org/apache/hadoop/hive/serde2/ByteStream.java