/** Get the record reader for the next chunk in this CombineFileSplit. */
  protected boolean initNextRecordReader() throws IOException {

    if (curReader != null) {
      curReader.close();
      curReader = null;
      if (idx > 0) {
        progress += split.getLength(idx - 1); // done processing so far
      }
    }

    // if all chunks have been processed, nothing more to do.
    if (idx == split.getNumPaths()) {
      return false;
    }

    // get a record reader for the idx-th chunk
    try {
      Configuration conf = context.getConfiguration();
      // setup some helper config variables.
      conf.set(MRJobConfig.MAP_INPUT_FILE, split.getPath(idx).toString());
      conf.setLong(MRJobConfig.MAP_INPUT_START, split.getOffset(idx));
      conf.setLong(MRJobConfig.MAP_INPUT_PATH, split.getLength(idx));

      curReader = rrConstructor.newInstance(new Object[] {split, context, Integer.valueOf(idx)});

      if (idx > 0) {
        // initialize() for the first RecordReader will be called by MapTask;
        // we're responsible for initializing subsequent RecordReaders.
        curReader.initialize(split, context);
      }
    } catch (Exception e) {
      throw new RuntimeException(e);
    }
    idx++;
    return true;
  }
 public void close() throws IOException {
   if (curReader != null) {
     curReader.close();
     curReader = null;
   }
 }