public CompressionOutputStream createOutputStream()

in src/main/java/com/hadoop/compression/lzo/LzoCodec.java [114:149]

• 12 lines of code
• 3 McCabe index (conditional complexity)

  public CompressionOutputStream createOutputStream(OutputStream out,
      Compressor compressor) throws IOException {
    // Ensure native-lzo library is loaded & initialized
    if (!isNativeLzoLoaded(conf)) {
      throw new RuntimeException("native-lzo library not available");
    }

    /**
     * <b>https://www.oberhumer.com/opensource/lzo/lzofaq.php</b>
     *
     * How much can my data expand during compression ?
     * ================================================
     * LZO will expand incompressible data by a little amount.
     * I still haven't computed the exact values, but I suggest using
     * these formulas for a worst-case expansion calculation:
     *
     * Algorithm LZO1, LZO1A, LZO1B, LZO1C, LZO1F, LZO1X, LZO1Y, LZO1Z:
     * ----------------------------------------------------------------
     * output_block_size = input_block_size + (input_block_size / 16) + 64 + 3
     *
     * This is about 106% for a large block size.
     *
     * Algorithm LZO2A:
     * ----------------
     * output_block_size = input_block_size + (input_block_size / 8) + 128 + 3
     */

    // Create the lzo output-stream
    LzoCompressor.CompressionStrategy strategy = getCompressionStrategy(conf);
    int bufferSize = getBufferSize(conf);
    int compressionOverhead = strategy.name().contains("LZO1") ?
        (bufferSize >> 4) + 64 + 3 : (bufferSize >> 3) + 128 + 3;

    return new BlockCompressorStream(out, compressor, bufferSize,
        compressionOverhead);
  }