TotalOrderPartitioner.java 文件源码

/**
 * Read the cut points from the given IFile.
 * @param fs The file system
 * @param p The path to read
 * @param keyClass The map output key class
 * @param job The job config
 * @throws IOException
 */
                               // matching key types enforced by passing in
@SuppressWarnings("unchecked") // map output key class
private K[] readPartitions(FileSystem fs, Path p, Class<K> keyClass,
    Configuration conf) throws IOException {
  SequenceFile.Reader reader = new SequenceFile.Reader(fs, p, conf);
  ArrayList<K> parts = new ArrayList<K>();
  K key = ReflectionUtils.newInstance(keyClass, conf);
  NullWritable value = NullWritable.get();
  try {
    while (reader.next(key, value)) {
      parts.add(key);
      key = ReflectionUtils.newInstance(keyClass, conf);
    }
    reader.close();
    reader = null;
  } finally {
    IOUtils.cleanup(LOG, reader);
  }
  return parts.toArray((K[])Array.newInstance(keyClass, parts.size()));
}