How to use

org.apache.hadoop.hdfs.server.namenode.SaveNamespaceContext

constructor

/**
 * Save FSimage in the legacy format. This is not for NN consumption,
 * but for tools like OIV.
 */
public void saveLegacyOIVImage(FSNamesystem source, String targetDir,
  Canceler canceler) throws IOException {
 FSImageCompression compression =
   FSImageCompression.createCompression(conf);
 long txid = getCorrectLastAppliedOrWrittenTxId();
 SaveNamespaceContext ctx = new SaveNamespaceContext(source, txid,
   canceler);
 FSImageFormat.Saver saver = new FSImageFormat.Saver(ctx);
 String imageFileName = NNStorage.getLegacyOIVImageFileName(txid);
 File imageFile = new File(targetDir, imageFileName);
 saver.save(imageFile, compression);
 archivalManager.purgeOldLegacyOIVImages(targetDir, txid);
}

 canceler = new Canceler();
SaveNamespaceContext ctx = new SaveNamespaceContext(
  source, txid, canceler);

/**
 * Save FSimage in the legacy format. This is not for NN consumption,
 * but for tools like OIV.
 */
public void saveLegacyOIVImage(FSNamesystem source, String targetDir,
  Canceler canceler) throws IOException {
 FSImageCompression compression =
   FSImageCompression.createCompression(conf);
 long txid = getCorrectLastAppliedOrWrittenTxId();
 SaveNamespaceContext ctx = new SaveNamespaceContext(source, txid,
   canceler);
 FSImageFormat.Saver saver = new FSImageFormat.Saver(ctx);
 String imageFileName = NNStorage.getLegacyOIVImageFileName(txid);
 File imageFile = new File(targetDir, imageFileName);
 saver.save(imageFile, compression);
 archivalManager.purgeOldLegacyOIVImages(targetDir, txid);
}

/**
 * Save FSimage in the legacy format. This is not for NN consumption,
 * but for tools like OIV.
 */
public void saveLegacyOIVImage(FSNamesystem source, String targetDir,
  Canceler canceler) throws IOException {
 FSImageCompression compression =
   FSImageCompression.createCompression(conf);
 long txid = getCorrectLastAppliedOrWrittenTxId();
 SaveNamespaceContext ctx = new SaveNamespaceContext(source, txid,
   canceler);
 FSImageFormat.Saver saver = new FSImageFormat.Saver(ctx);
 String imageFileName = NNStorage.getLegacyOIVImageFileName(txid);
 File imageFile = new File(targetDir, imageFileName);
 saver.save(imageFile, compression);
 archivalManager.purgeOldLegacyOIVImages(targetDir, txid);
}

 canceler = new Canceler();
SaveNamespaceContext ctx = new SaveNamespaceContext(
  source, txid, canceler);

 canceler = new Canceler();
SaveNamespaceContext ctx = new SaveNamespaceContext(
  source, txid, canceler);

/** Save the fsimage to a temp file */
private File saveFSImageToTempFile() throws IOException {
 SaveNamespaceContext context = new SaveNamespaceContext(fsn, txid,
   new Canceler());
 FSImageFormatProtobuf.Saver saver = new FSImageFormatProtobuf.Saver(context);
 FSImageCompression compression = FSImageCompression.createCompression(conf);
 File imageFile = getImageFile(testDir, txid);
 fsn.readLock();
 try {
  saver.save(imageFile, compression);
 } finally {
  fsn.readUnlock();
 }
 return imageFile;
}