Java StartupOption.IMPORT属性代码示例

private static Collection<URI> getStorageDirs(Configuration conf,
                                              String propertyName) {
  Collection<String> dirNames = conf.getTrimmedStringCollection(propertyName);
  StartupOption startOpt = NameNode.getStartupOption(conf);
  if(startOpt == StartupOption.IMPORT) {
    // In case of IMPORT this will get rid of default directories 
    // but will retain directories specified in hdfs-site.xml
    // When importing image from a checkpoint, the name-node can
    // start with empty set of storage directories.
    Configuration cE = new HdfsConfiguration(false);
    cE.addResource("core-default.xml");
    cE.addResource("core-site.xml");
    cE.addResource("hdfs-default.xml");
    Collection<String> dirNames2 = cE.getTrimmedStringCollection(propertyName);
    dirNames.removeAll(dirNames2);
    if(dirNames.isEmpty())
      LOG.warn("!!! WARNING !!!" +
        "\n\tThe NameNode currently runs without persistent storage." +
        "\n\tAny changes to the file system meta-data may be lost." +
        "\n\tRecommended actions:" +
        "\n\t\t- shutdown and restart NameNode with configured \"" 
        + propertyName + "\" in hdfs-site.xml;" +
        "\n\t\t- use Backup Node as a persistent and up-to-date storage " +
        "of the file system meta-data.");
  } else if (dirNames.isEmpty()) {
    dirNames = Collections.singletonList(
        DFSConfigKeys.DFS_NAMENODE_EDITS_DIR_DEFAULT);
  }
  return Util.stringCollectionAsURIs(dirNames);
}
 

/**
 * For each storage directory, performs recovery of incomplete transitions
 * (eg. upgrade, rollback, checkpoint) and inserts the directory's storage
 * state into the dataDirStates map.
 * @param dataDirStates output of storage directory states
 * @return true if there is at least one valid formatted storage directory
 */
public static boolean recoverStorageDirs(StartupOption startOpt,
    NNStorage storage, Map<StorageDirectory, StorageState> dataDirStates)
    throws IOException {
  boolean isFormatted = false;
  // This loop needs to be over all storage dirs, even shared dirs, to make
  // sure that we properly examine their state, but we make sure we don't
  // mutate the shared dir below in the actual loop.
  for (Iterator<StorageDirectory> it = 
                    storage.dirIterator(); it.hasNext();) {
    StorageDirectory sd = it.next();
    StorageState curState;
    if (startOpt == StartupOption.METADATAVERSION) {
      /* All we need is the layout version. */
      storage.readProperties(sd);
      return true;
    }

    try {
      curState = sd.analyzeStorage(startOpt, storage);
      // sd is locked but not opened
      switch(curState) {
      case NON_EXISTENT:
        // name-node fails if any of the configured storage dirs are missing
        throw new InconsistentFSStateException(sd.getRoot(),
                    "storage directory does not exist or is not accessible.");
      case NOT_FORMATTED:
        break;
      case NORMAL:
        break;
      default:  // recovery is possible
        sd.doRecover(curState);
      }
      if (curState != StorageState.NOT_FORMATTED 
          && startOpt != StartupOption.ROLLBACK) {
        // read and verify consistency with other directories
        storage.readProperties(sd, startOpt);
        isFormatted = true;
      }
      if (startOpt == StartupOption.IMPORT && isFormatted)
        // import of a checkpoint is allowed only into empty image directories
        throw new IOException("Cannot import image from a checkpoint. " 
            + " NameNode already contains an image in " + sd.getRoot());
    } catch (IOException ioe) {
      sd.unlock();
      throw ioe;
    }
    dataDirStates.put(sd,curState);
  }
  return isFormatted;
}