/**
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.hadoop.hdfs.server.common;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.RandomAccessFile;
import java.nio.channels.FileLock;
import java.nio.channels.OverlappingFileLockException;
import java.util.ArrayList;
import java.util.List;
import java.util.Iterator;
import java.util.Properties;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.hdfs.protocol.FSConstants;
import org.apache.hadoop.hdfs.server.common.HdfsConstants.NodeType;
import org.apache.hadoop.hdfs.server.common.HdfsConstants.StartupOption;
import org.apache.hadoop.fs.FileUtil;
/**
* Storage information file.
* <p>
* Local storage information is stored in a separate file VERSION.
* It contains type of the node,
* the storage layout version, the namespace id, and
* the fs state creation time.
* <p>
* Local storage can reside in multiple directories.
* Each directory should contain the same VERSION file as the others.
* During startup Hadoop servers (name-node and data-nodes) read their local
* storage information from them.
* <p>
* The servers hold a lock for each storage directory while they run so that
* other nodes were not able to startup sharing the same storage.
* The locks are released when the servers stop (normally or abnormally).
*
*/
public abstract class Storage extends StorageInfo {
public static final Log LOG = LogFactory.getLog(Storage.class.getName());
// Constants
// last layout version that did not suppot upgrades
protected static final int LAST_PRE_UPGRADE_LAYOUT_VERSION = -3;
// this corresponds to Hadoop-0.14.
public static final int LAST_UPGRADABLE_LAYOUT_VERSION = -7;
protected static final String LAST_UPGRADABLE_HADOOP_VERSION = "Hadoop-0.14";
/* this should be removed when LAST_UPGRADABLE_LV goes beyond -13.
* any upgrade code that uses this constant should also be removed. */
public static final int PRE_GENERATIONSTAMP_LAYOUT_VERSION = -13;
/** Layout versions of 203 release */
public static final int[] LAYOUT_VERSIONS_203 = {-19, -31};
private static final String STORAGE_FILE_LOCK = "in_use.lock";
protected static final String STORAGE_FILE_VERSION = "VERSION";
public static final String STORAGE_DIR_CURRENT = "current";
private static final String STORAGE_DIR_PREVIOUS = "previous";
private static final String STORAGE_TMP_REMOVED = "removed.tmp";
private static final String STORAGE_TMP_PREVIOUS = "previous.tmp";
private static final String STORAGE_TMP_FINALIZED = "finalized.tmp";
private static final String STORAGE_TMP_LAST_CKPT = "lastcheckpoint.tmp";
private static final String STORAGE_PREVIOUS_CKPT = "previous.checkpoint";
public enum StorageState {
NON_EXISTENT,
NOT_FORMATTED,
COMPLETE_UPGRADE,
RECOVER_UPGRADE,
COMPLETE_FINALIZE,
COMPLETE_ROLLBACK,
RECOVER_ROLLBACK,
COMPLETE_CHECKPOINT,
RECOVER_CHECKPOINT,
NORMAL;
}
/**
* An interface to denote storage directory type
* Implementations can define a type for storage directory by implementing
* this interface.
*/
public interface StorageDirType {
public StorageDirType getStorageDirType();
public boolean isOfType(StorageDirType type);
}
private NodeType storageType; // Type of the node using this storage
protected List<StorageDirectory> storageDirs = new ArrayList<StorageDirectory>();
private class DirIterator implements Iterator<StorageDirectory> {
StorageDirType dirType;
int prevIndex; // for remove()
int nextIndex; // for next()
DirIterator(StorageDirType dirType) {
this.dirType = dirType;
this.nextIndex = 0;
this.prevIndex = 0;
}
public boolean hasNext() {
if (storageDirs.isEmpty() || nextIndex >= storageDirs.size())
return false;
if (dirType != null) {
while (nextIndex < storageDirs.size()) {
if (getStorageDir(nextIndex).getStorageDirType().isOfType(dirType))
break;
nextIndex++;
}
if (nextIndex >= storageDirs.size())
return false;
}
return true;
}
public StorageDirectory next() {
StorageDirectory sd = getStorageDir(nextIndex);
prevIndex = nextIndex;
nextIndex++;
if (dirType != null) {
while (nextIndex < storageDirs.size()) {
if (getStorageDir(nextIndex).getStorageDirType().isOfType(dirType))
break;
nextIndex++;
}
}
return sd;
}
public void remove() {
nextIndex = prevIndex; // restore previous state
storageDirs.remove(prevIndex); // remove last returned element
hasNext(); // reset nextIndex to correct place
}
}
/**
* Return default iterator
* This iterator returns all entires of storageDirs
*/
public Iterator<StorageDirectory> dirIterator() {
return dirIterator(null);
}
/**
* Return iterator based on Storage Directory Type
* This iterator selects entires of storageDirs of type dirType and returns
* them via the Iterator
*/
public Iterator<StorageDirectory> dirIterator(StorageDirType dirType) {
return new DirIterator(dirType);
}
/**
* One of the storage directories.
*/
public class StorageDirectory {
File root; // root directory
FileLock lock; // storage lock
StorageDirType dirType; // storage dir type
public StorageDirectory(File dir) {
// default dirType is null
this(dir, null);
}
public StorageDirectory(File dir, StorageDirType dirType) {
this.root = dir;
this.lock = null;
this.dirType = dirType;
}
/**
* Get root directory of this storage
*/
public File getRoot() {
return root;
}
/**
* Get storage directory type
*/
public StorageDirType getStorageDirType() {
return dirType;
}
/**
* Read version file.
*
* @throws IOException if file cannot be read or contains inconsistent data
*/
public void read() throws IOException {
read(getVersionFile());
}
public void read(File from) throws IOException {
RandomAccessFile file = new RandomAccessFile(from, "rws");
FileInputStream in = null;
try {
in = new FileInputStream(file.getFD());
file.seek(0);
Properties props = new Properties();
props.load(in);
getFields(props, this);
} finally {
if (in != null) {
in.close();
}
file.close();
}
}
/**
* Write version file.
*
* @throws IOException
*/
public void write() throws IOException {
corruptPreUpgradeStorage(root);
write(getVersionFile());
}
public void write(File to) throws IOException {
Properties props = new Properties();
setFields(props, this);
RandomAccessFile file = new RandomAccessFile(to, "rws");
FileOutputStream out = null;
try {
file.seek(0);
out = new FileOutputStream(file.getFD());
/*
* If server is interrupted before this line,
* the version file will remain unchanged.
*/
props.store(out, null);
/*
* Now the new fields are flushed to the head of the file, but file
* length can still be larger then required and therefore the file can
* contain whole or corrupted fields from its old contents in the end.
* If server is interrupted here and restarted later these extra fields
* either should not effect server behavior or should be handled
* by the server correctly.
*/
file.setLength(out.getChannel().position());
} finally {
if (out != null) {
out.close();
}
file.close();
}
}
/**
* Clear and re-create storage directory.
* <p>
* Removes contents of the current directory and creates an empty directory.
*
* This does not fully format storage directory.
* It cannot write the version file since it should be written last after
* all other storage type dependent files are written.
* Derived storage is responsible for setting specific storage values and
* writing the version file to disk.
*
* @throws IOException
*/
public void clearDirectory() throws IOException {
File curDir = this.getCurrentDir();
if (curDir.exists())
if (!(FileUtil.fullyDelete(curDir)))
throw new IOException("Cannot remove current directory: " + curDir);
if (!curDir.mkdirs())
throw new IOException("Cannot create directory " + curDir);
}
/**
* Directory {@code current} contains latest files defining
* the file system meta-data.
*
* @return the directory path
*/
public File getCurrentDir() {
return new File(root, STORAGE_DIR_CURRENT);
}
/**
* File {@code VERSION} contains the following fields:
* <ol>
* <li>node type</li>
* <li>layout version</li>
* <li>namespaceID</li>
* <li>fs state creation time</li>
* <li>other fields specific for this node type</li>
* </ol>
* The version file is always written last during storage directory updates.
* The existence of the version file indicates that all other files have
* been successfully written in the storage directory, the storage is valid
* and does not need to be recovered.
*
* @return the version file path
*/
public File getVersionFile() {
return new File(new File(root, STORAGE_DIR_CURRENT), STORAGE_FILE_VERSION);
}
/**
* File {@code VERSION} from the {@code previous} directory.
*
* @return the previous version file path
*/
public File getPreviousVersionFile() {
return new File(new File(root, STORAGE_DIR_PREVIOUS), STORAGE_FILE_VERSION);
}
/**
* Directory {@code previous} contains the previous file system state,
* which the system can be rolled back to.
*
* @return the directory path
*/
public File getPreviousDir() {
return new File(root, STORAGE_DIR_PREVIOUS);
}
/**
* {@code previous.tmp} is a transient directory, which holds
* current file system state while the new state is saved into the new
* {@code current} during upgrade.
* If the saving succeeds {@code previous.tmp} will be moved to
* {@code previous}, otherwise it will be renamed back to
* {@code current} by the recovery procedure during startup.
*
* @return the directory path
*/
public File getPreviousTmp() {
return new File(root, STORAGE_TMP_PREVIOUS);
}
/**
* {@code removed.tmp} is a transient directory, which holds
* current file system state while the previous state is moved into
* {@code current} during rollback.
* If the moving succeeds {@code removed.tmp} will be removed,
* otherwise it will be renamed back to
* {@code current} by the recovery procedure during startup.
*
* @return the directory path
*/
public File getRemovedTmp() {
return new File(root, STORAGE_TMP_REMOVED);
}
/**
* {@code finalized.tmp} is a transient directory, which holds
* the {@code previous} file system state while it is being removed
* in response to the finalize request.
* Finalize operation will remove {@code finalized.tmp} when completed,
* otherwise the removal will resume upon the system startup.
*
* @return the directory path
*/
public File getFinalizedTmp() {
return new File(root, STORAGE_TMP_FINALIZED);
}
/**
* {@code lastcheckpoint.tmp} is a transient directory, which holds
* current file system state while the new state is saved into the new
* {@code current} during regular namespace updates.
* If the saving succeeds {@code lastcheckpoint.tmp} will be moved to
* {@code previous.checkpoint}, otherwise it will be renamed back to
* {@code current} by the recovery procedure during startup.
*
* @return the directory path
*/
public File getLastCheckpointTmp() {
return new File(root, STORAGE_TMP_LAST_CKPT);
}
/**
* {@code previous.checkpoint} is a directory, which holds the previous
* (before the last save) state of the storage directory.
* The directory is created as a reference only, it does not play role
* in state recovery procedures, and is recycled automatically,
* but it may be useful for manual recovery of a stale state of the system.
*
* @return the directory path
*/
public File getPreviousCheckpoint() {
return new File(root, STORAGE_PREVIOUS_CKPT);
}
/**
* Check consistency of the storage directory
*
* @param startOpt a startup option.
*
* @return state {@link StorageState} of the storage directory
* @throws InconsistentFSStateException if directory state is not
* consistent and cannot be recovered.
* @throws IOException
*/
public StorageState analyzeStorage(StartupOption startOpt) throws IOException {
assert root != null : "root is null";
String rootPath = root.getCanonicalPath();
try { // check that storage exists
if (!root.exists()) {
// storage directory does not exist
if (startOpt != StartupOption.FORMAT) {
LOG.info("Storage directory " + rootPath + " does not exist");
return StorageState.NON_EXISTENT;
}
LOG.info(rootPath + " does not exist. Creating...");
if (!root.mkdirs())
throw new IOException("Cannot create directory " + rootPath);
}
// or is inaccessible
if (!root.isDirectory()) {
LOG.info(rootPath + "is not a directory");
return StorageState.NON_EXISTENT;
}
if (!root.canWrite()) {
LOG.info("Cannot access storage directory " + rootPath);
return StorageState.NON_EXISTENT;
}
} catch(SecurityException ex) {
LOG.info("Cannot access storage directory " + rootPath, ex);
return StorageState.NON_EXISTENT;
}
this.lock(); // lock storage if it exists
if (startOpt == HdfsConstants.StartupOption.FORMAT)
return StorageState.NOT_FORMATTED;
if (startOpt != HdfsConstants.StartupOption.IMPORT) {
//make sure no conversion is required
checkConversionNeeded(this);
}
// check whether current directory is valid
File versionFile = getVersionFile();
boolean hasCurrent = versionFile.exists();
// check which directories exist
boolean hasPrevious = getPreviousDir().exists();
boolean hasPreviousTmp = getPreviousTmp().exists();
boolean hasRemovedTmp = getRemovedTmp().exists();
boolean hasFinalizedTmp = getFinalizedTmp().exists();
boolean hasCheckpointTmp = getLastCheckpointTmp().exists();
if (!(hasPreviousTmp || hasRemovedTmp
|| hasFinalizedTmp || hasCheckpointTmp)) {
// no temp dirs - no recovery
if (hasCurrent)
return StorageState.NORMAL;
if (hasPrevious)
throw new InconsistentFSStateException(root,
"version file in current directory is missing.");
return StorageState.NOT_FORMATTED;
}
if ((hasPreviousTmp?1:0) + (hasRemovedTmp?1:0)
+ (hasFinalizedTmp?1:0) + (hasCheckpointTmp?1:0) > 1)
// more than one temp dirs
throw new InconsistentFSStateException(root,
"too many temporary directories.");
// # of temp dirs == 1 should either recover or complete a transition
if (hasCheckpointTmp) {
return hasCurrent ? StorageState.COMPLETE_CHECKPOINT
: StorageState.RECOVER_CHECKPOINT;
}
if (hasFinalizedTmp) {
if (hasPrevious)
throw new InconsistentFSStateException(root,
STORAGE_DIR_PREVIOUS + " and " + STORAGE_TMP_FINALIZED
+ "cannot exist together.");
return StorageState.COMPLETE_FINALIZE;
}
if (hasPreviousTmp) {
if (hasPrevious)
throw new InconsistentFSStateException(root,
STORAGE_DIR_PREVIOUS + " and " + STORAGE_TMP_PREVIOUS
+ " cannot exist together.");
if (hasCurrent)
return StorageState.COMPLETE_UPGRADE;
return StorageState.RECOVER_UPGRADE;
}
assert hasRemovedTmp : "hasRemovedTmp must be true";
if (!(hasCurrent ^ hasPrevious))
throw new InconsistentFSStateException(root,
"one and only one directory " + STORAGE_DIR_CURRENT
+ " or " + STORAGE_DIR_PREVIOUS
+ " must be present when " + STORAGE_TMP_REMOVED
+ " exists.");
if (hasCurrent)
return StorageState.COMPLETE_ROLLBACK;
return StorageState.RECOVER_ROLLBACK;
}
/**
* Complete or recover storage state from previously failed transition.
*
* @param curState specifies what/how the state should be recovered
* @throws IOException
*/
public void doRecover(StorageState curState) throws IOException {
File curDir = getCurrentDir();
String rootPath = root.getCanonicalPath();
switch(curState) {
case COMPLETE_UPGRADE: // mv previous.tmp -> previous
LOG.info("Completing previous upgrade for storage directory "
+ rootPath);
rename(getPreviousTmp(), getPreviousDir());
return;
case RECOVER_UPGRADE: // mv previous.tmp -> current
LOG.info("Recovering storage directory " + rootPath
+ " from previous upgrade");
if (curDir.exists())
deleteDir(curDir);
rename(getPreviousTmp(), curDir);
return;
case COMPLETE_ROLLBACK: // rm removed.tmp
LOG.info("Completing previous rollback for storage directory "
+ rootPath);
deleteDir(getRemovedTmp());
return;
case RECOVER_ROLLBACK: // mv removed.tmp -> current
LOG.info("Recovering storage directory " + rootPath
+ " from previous rollback");
rename(getRemovedTmp(), curDir);
return;
case COMPLETE_FINALIZE: // rm finalized.tmp
LOG.info("Completing previous finalize for storage directory "
+ rootPath);
deleteDir(getFinalizedTmp());
return;
case COMPLETE_CHECKPOINT: // mv lastcheckpoint.tmp -> previous.checkpoint
LOG.info("Completing previous checkpoint for storage directory "
+ rootPath);
File prevCkptDir = getPreviousCheckpoint();
if (prevCkptDir.exists())
deleteDir(prevCkptDir);
rename(getLastCheckpointTmp(), prevCkptDir);
return;
case RECOVER_CHECKPOINT: // mv lastcheckpoint.tmp -> current
LOG.info("Recovering storage directory " + rootPath
+ " from failed checkpoint");
if (curDir.exists())
deleteDir(curDir);
rename(getLastCheckpointTmp(), curDir);
return;
default:
throw new IOException("Unexpected FS state: " + curState);
}
}
/**
* Lock storage to provide exclusive access.
*
* <p> Locking is not supported by all file systems.
* E.g., NFS does not consistently support exclusive locks.
*
* <p> If locking is supported we guarantee exculsive access to the
* storage directory. Otherwise, no guarantee is given.
*
* @throws IOException if locking fails
*/
public void lock() throws IOException {
this.lock = tryLock();
if (lock == null) {
String msg = "Cannot lock storage " + this.root
+ ". The directory is already locked.";
LOG.info(msg);
throw new IOException(msg);
}
}
/**
* Attempts to acquire an exclusive lock on the storage.
*
* @return A lock object representing the newly-acquired lock or
* <code>null</code> if storage is already locked.
* @throws IOException if locking fails.
*/
FileLock tryLock() throws IOException {
boolean deletionHookAdded = false;
File lockF = new File(root, STORAGE_FILE_LOCK);
if (!lockF.exists()) {
lockF.deleteOnExit();
deletionHookAdded = true;
}
RandomAccessFile file = new RandomAccessFile(lockF, "rws");
FileLock res = null;
try {
res = file.getChannel().tryLock();
} catch(OverlappingFileLockException oe) {
file.close();
return null;
} catch(IOException e) {
LOG.error("Cannot create lock on " + lockF, e);
file.close();
throw e;
}
if (res != null && !deletionHookAdded) {
// If the file existed prior to our startup, we didn't
// call deleteOnExit above. But since we successfully locked
// the dir, we can take care of cleaning it up.
lockF.deleteOnExit();
}
return res;
}
/**
* Unlock storage.
*
* @throws IOException
*/
public void unlock() throws IOException {
if (this.lock == null)
return;
this.lock.release();
lock.channel().close();
lock = null;
}
}
/**
* Create empty storage info of the specified type
*/
protected Storage(NodeType type) {
super();
this.storageType = type;
}
protected Storage(NodeType type, int nsID, long cT) {
super(FSConstants.LAYOUT_VERSION, nsID, cT);
this.storageType = type;
}
protected Storage(NodeType type, StorageInfo storageInfo) {
super(storageInfo);
this.storageType = type;
}
public int getNumStorageDirs() {
return storageDirs.size();
}
public StorageDirectory getStorageDir(int idx) {
return storageDirs.get(idx);
}
protected void addStorageDir(StorageDirectory sd) {
storageDirs.add(sd);
}
public abstract boolean isConversionNeeded(StorageDirectory sd) throws IOException;
/*
* Coversion is no longer supported. So this should throw exception if
* conversion is needed.
*/
private void checkConversionNeeded(StorageDirectory sd) throws IOException {
if (isConversionNeeded(sd)) {
//throw an exception
checkVersionUpgradable(0);
}
}
/**
* Checks if the upgrade from the given old version is supported. If
* no upgrade is supported, it throws IncorrectVersionException.
*
* @param oldVersion
*/
protected static void checkVersionUpgradable(int oldVersion)
throws IOException {
if (oldVersion > LAST_UPGRADABLE_LAYOUT_VERSION) {
String msg = "*********** Upgrade is not supported from this older" +
" version of storage to the current version." +
" Please upgrade to " + LAST_UPGRADABLE_HADOOP_VERSION +
" or a later version and then upgrade to current" +
" version. Old layout version is " +
(oldVersion == 0 ? "'too old'" : (""+oldVersion)) +
" and latest layout version this software version can" +
" upgrade from is " + LAST_UPGRADABLE_LAYOUT_VERSION +
". ************";
LOG.error(msg);
throw new IOException(msg);
}
}
/**
* Get common storage fields.
* Should be overloaded if additional fields need to be get.
*
* @param props
* @throws IOException
*/
protected void getFields(Properties props,
StorageDirectory sd
) throws IOException {
String sv, st, sid, sct;
sv = props.getProperty("layoutVersion");
st = props.getProperty("storageType");
sid = props.getProperty("namespaceID");
sct = props.getProperty("cTime");
if (sv == null || st == null || sid == null || sct == null)
throw new InconsistentFSStateException(sd.root,
"file " + STORAGE_FILE_VERSION + " is invalid.");
int rv = Integer.parseInt(sv);
NodeType rt = NodeType.valueOf(st);
int rid = Integer.parseInt(sid);
long rct = Long.parseLong(sct);
if (!storageType.equals(rt) ||
!((namespaceID == 0) || (rid == 0) || namespaceID == rid))
throw new InconsistentFSStateException(sd.root,
"is incompatible with others.");
if (rv < FSConstants.LAYOUT_VERSION) // future version
throw new IncorrectVersionException(rv, "storage directory "
+ sd.root.getCanonicalPath());
layoutVersion = rv;
storageType = rt;
namespaceID = rid;
cTime = rct;
}
/**
* Set common storage fields.
* Should be overloaded if additional fields need to be set.
*
* @param props
* @throws IOException
*/
protected void setFields(Properties props,
StorageDirectory sd
) throws IOException {
props.setProperty("layoutVersion", String.valueOf(layoutVersion));
props.setProperty("storageType", storageType.toString());
props.setProperty("namespaceID", String.valueOf(namespaceID));
props.setProperty("cTime", String.valueOf(cTime));
}
public static void rename(File from, File to) throws IOException {
if (!from.renameTo(to))
throw new IOException("Failed to rename "
+ from.getCanonicalPath() + " to " + to.getCanonicalPath());
}
protected static void deleteDir(File dir) throws IOException {
if (!FileUtil.fullyDelete(dir))
throw new IOException("Failed to delete " + dir.getCanonicalPath());
}
/**
* Write all data storage files.
* @throws IOException
*/
public void writeAll() throws IOException {
this.layoutVersion = FSConstants.LAYOUT_VERSION;
for (Iterator<StorageDirectory> it = storageDirs.iterator(); it.hasNext();) {
it.next().write();
}
}
/**
* Unlock all storage directories.
* @throws IOException
*/
public void unlockAll() throws IOException {
for (Iterator<StorageDirectory> it = storageDirs.iterator(); it.hasNext();) {
it.next().unlock();
}
}
/**
* Check whether underlying file system supports file locking.
*
* @return <code>true</code> if exclusive locks are supported or
* <code>false</code> otherwise.
* @throws IOException
* @see StorageDirectory#lock()
*/
public boolean isLockSupported(int idx) throws IOException {
StorageDirectory sd = storageDirs.get(idx);
FileLock firstLock = null;
FileLock secondLock = null;
try {
firstLock = sd.lock;
if(firstLock == null) {
firstLock = sd.tryLock();
if(firstLock == null)
return true;
}
secondLock = sd.tryLock();
if(secondLock == null)
return true;
} finally {
if(firstLock != null && firstLock != sd.lock) {
firstLock.release();
firstLock.channel().close();
}
if(secondLock != null) {
secondLock.release();
secondLock.channel().close();
}
}
return false;
}
public static String getRegistrationID(StorageInfo storage) {
return "NS-" + Integer.toString(storage.getNamespaceID())
+ "-" + Integer.toString(storage.getLayoutVersion())
+ "-" + Long.toString(storage.getCTime());
}
// Pre-upgrade version compatibility
protected abstract void corruptPreUpgradeStorage(File rootDir) throws IOException;
protected void writeCorruptedData(RandomAccessFile file) throws IOException {
final String messageForPreUpgradeVersion =
"\nThis file is INTENTIONALLY CORRUPTED so that versions\n"
+ "of Hadoop prior to 0.13 (which are incompatible\n"
+ "with this directory layout) will fail to start.\n";
file.seek(0);
file.writeInt(FSConstants.LAYOUT_VERSION);
org.apache.hadoop.io.UTF8.writeString(file, "");
file.writeBytes(messageForPreUpgradeVersion);
file.getFD().sync();
}
public static boolean is203LayoutVersion(int layoutVersion) {
for (int lv : LAYOUT_VERSIONS_203) {
if (lv == layoutVersion) {
return true;
}
}
return false;
}
}