public static void createIndex()

in src/main/java/com/hadoop/compression/lzo/LzoIndex.java [207:281]
56 lines of code
10 McCabe index (conditional complexity)

  public static void createIndex(FileSystem fs, Path lzoFile)
  throws IOException {

    Configuration conf = fs.getConf();
    CompressionCodecFactory factory = new CompressionCodecFactory(conf);
    CompressionCodec codec = factory.getCodec(lzoFile);
    if (null == codec) {
      throw new IOException("Could not find codec for file " + lzoFile +
        " - you may need to add the LZO codec to your io.compression.codecs " +
        "configuration in core-site.xml");
    }
    ((Configurable) codec).setConf(conf);

    FSDataInputStream is = null;
    FSDataOutputStream os = null;
    Path outputFile = lzoFile.suffix(LZO_INDEX_SUFFIX);
    Path tmpOutputFile = lzoFile.suffix(LZO_TMP_INDEX_SUFFIX);

    // Track whether an exception was thrown or not, so we know to either
    // delete the tmp index file on failure, or rename it to the new index file on success.
    boolean indexingSucceeded = false;
    try {
      is = fs.open(lzoFile);
      os = fs.create(tmpOutputFile);
      LzopDecompressor decompressor = (LzopDecompressor) codec.createDecompressor();
      // Solely for reading the header
      codec.createInputStream(is, decompressor);
      int numCompressedChecksums = decompressor.getCompressedChecksumsCount();
      int numDecompressedChecksums = decompressor.getDecompressedChecksumsCount();

      while (true) {
        // read and ignore, we just want to get to the next int
        int uncompressedBlockSize = is.readInt();
        if (uncompressedBlockSize == 0) {
          break;
        } else if (uncompressedBlockSize < 0) {
          throw new EOFException();
        }

        int compressedBlockSize = is.readInt();
        if (compressedBlockSize <= 0) {
          throw new IOException("Could not read compressed block size");
        }

        // See LzopInputStream.getCompressedData
        boolean isUncompressedBlock = (uncompressedBlockSize == compressedBlockSize);
        int numChecksumsToSkip = isUncompressedBlock ?
            numDecompressedChecksums : numDecompressedChecksums + numCompressedChecksums;
        long pos = is.getPos();
        // write the pos of the block start
        os.writeLong(pos - 8);
        // seek to the start of the next block, skip any checksums
        is.seek(pos + compressedBlockSize + (4 * numChecksumsToSkip));
      }
      // If we're here, indexing was successful.
      indexingSucceeded = true;
    } finally {
      // Close any open streams.
      if (is != null) {
        is.close();
      }

      if (os != null) {
        os.close();
      }

      if (!indexingSucceeded) {
        // If indexing didn't succeed (i.e. an exception was thrown), clean up after ourselves.
        fs.delete(tmpOutputFile, false);
      } else {
        // Otherwise, rename filename.lzo.index.tmp to filename.lzo.index.
        fs.rename(tmpOutputFile, outputFile);
      }
    }
  }