SnapshotIndexDeletionPolicy.java 文件源码

private void loadGenerations() throws IOException {
  FileSystem fileSystem = _path.getFileSystem(_configuration);
  FileStatus[] listStatus = fileSystem.listStatus(_path);
  SortedSet<FileStatus> existing = new TreeSet<FileStatus>(Arrays.asList(listStatus));
  if (existing.isEmpty()) {
    return;
  }
  FileStatus last = existing.last();
  Reader reader = new SequenceFile.Reader(fileSystem, last.getPath(), _configuration);
  Text key = new Text();
  LongWritable value = new LongWritable();
  while (reader.next(key, value)) {
    String name = key.toString();
    long gen = value.get();
    _namesToGenerations.put(name, gen);
    Set<String> names = _generationsToNames.get(gen);
    if (names == null) {
      names = Collections.newSetFromMap(new ConcurrentHashMap<String, Boolean>());
      _generationsToNames.put(gen, names);
    }
    names.add(name);
  }
  reader.close();
  existing.remove(last);
  cleanupOldFiles(fileSystem, existing);
}