/**
* 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.namenode;
import java.io.File;
import java.io.IOException;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.hdfs.server.common.Storage;
import org.apache.hadoop.hdfs.server.common.Storage.StorageDirectory;
import org.apache.hadoop.hdfs.server.common.StorageInfo;
import com.google.common.base.Preconditions;
abstract class NNUpgradeUtil {
private static final Log LOG = LogFactory.getLog(NNUpgradeUtil.class);
/**
* Return true if this storage dir can roll back to the previous storage
* state, false otherwise. The NN will refuse to run the rollback operation
* unless at least one JM or fsimage storage directory can roll back.
*
* @param storage the storage info for the current state
* @param prevStorage the storage info for the previous (unupgraded) state
* @param targetLayoutVersion the layout version we intend to roll back to
* @return true if this JM can roll back, false otherwise.
* @throws IOException in the event of error
*/
static boolean canRollBack(StorageDirectory sd, StorageInfo storage,
StorageInfo prevStorage, int targetLayoutVersion) throws IOException {
File prevDir = sd.getPreviousDir();
if (!prevDir.exists()) { // use current directory then
LOG.info("Storage directory " + sd.getRoot()
+ " does not contain previous fs state.");
// read and verify consistency with other directories
storage.readProperties(sd);
return false;
}
// read and verify consistency of the prev dir
prevStorage.readPreviousVersionProperties(sd);
if (prevStorage.getLayoutVersion() != targetLayoutVersion) {
throw new IOException(
"Cannot rollback to storage version " +
prevStorage.getLayoutVersion() +
" using this version of the NameNode, which uses storage version " +
targetLayoutVersion + ". " +
"Please use the previous version of HDFS to perform the rollback.");
}
return true;
}
/**
* Finalize the upgrade. The previous dir, if any, will be renamed and
* removed. After this is completed, rollback is no longer allowed.
*
* @param sd the storage directory to finalize
* @throws IOException in the event of error
*/
static void doFinalize(StorageDirectory sd) throws IOException {
File prevDir = sd.getPreviousDir();
if (!prevDir.exists()) { // already discarded
LOG.info("Directory " + prevDir + " does not exist.");
LOG.info("Finalize upgrade for " + sd.getRoot()+ " is not required.");
return;
}
LOG.info("Finalizing upgrade of storage directory " + sd.getRoot());
Preconditions.checkState(sd.getCurrentDir().exists(),
"Current directory must exist.");
final File tmpDir = sd.getFinalizedTmp();
// rename previous to tmp and remove
NNStorage.rename(prevDir, tmpDir);
NNStorage.deleteDir(tmpDir);
LOG.info("Finalize upgrade for " + sd.getRoot()+ " is complete.");
}
/**
* Perform any steps that must succeed across all storage dirs/JournalManagers
* involved in an upgrade before proceeding onto the actual upgrade stage. If
* a call to any JM's or local storage dir's doPreUpgrade method fails, then
* doUpgrade will not be called for any JM. The existing current dir is
* renamed to previous.tmp, and then a new, empty current dir is created.
*
* @param sd the storage directory to perform the pre-upgrade procedure.
* @throws IOException in the event of error
*/
static void doPreUpgrade(StorageDirectory sd) throws IOException {
LOG.info("Starting upgrade of storage directory " + sd.getRoot());
File curDir = sd.getCurrentDir();
File prevDir = sd.getPreviousDir();
File tmpDir = sd.getPreviousTmp();
Preconditions.checkState(curDir.exists(),
"Current directory must exist for preupgrade.");
Preconditions.checkState(!prevDir.exists(),
"Previous directory must not exist for preupgrade.");
Preconditions.checkState(!tmpDir.exists(),
"Previous.tmp directory must not exist for preupgrade."
+ "Consider restarting for recovery.");
// rename current to tmp
NNStorage.rename(curDir, tmpDir);
if (!curDir.mkdir()) {
throw new IOException("Cannot create directory " + curDir);
}
}
/**
* Perform the upgrade of the storage dir to the given storage info. The new
* storage info is written into the current directory, and the previous.tmp
* directory is renamed to previous.
*
* @param sd the storage directory to upgrade
* @param storage info about the new upgraded versions.
* @throws IOException in the event of error
*/
static void doUpgrade(StorageDirectory sd, Storage storage) throws
IOException {
LOG.info("Performing upgrade of storage directory " + sd.getRoot());
try {
// Write the version file, since saveFsImage only makes the
// fsimage_<txid>, and the directory is otherwise empty.
storage.writeProperties(sd);
File prevDir = sd.getPreviousDir();
File tmpDir = sd.getPreviousTmp();
Preconditions.checkState(!prevDir.exists(),
"previous directory must not exist for upgrade.");
Preconditions.checkState(tmpDir.exists(),
"previous.tmp directory must exist for upgrade.");
// rename tmp to previous
NNStorage.rename(tmpDir, prevDir);
} catch (IOException ioe) {
LOG.error("Unable to rename temp to previous for " + sd.getRoot(), ioe);
throw ioe;
}
}
/**
* Perform rollback of the storage dir to the previous state. The existing
* current dir is removed, and the previous dir is renamed to current.
*
* @param sd the storage directory to roll back.
* @throws IOException in the event of error
*/
static void doRollBack(StorageDirectory sd)
throws IOException {
File prevDir = sd.getPreviousDir();
if (!prevDir.exists()) {
return;
}
File tmpDir = sd.getRemovedTmp();
Preconditions.checkState(!tmpDir.exists(),
"removed.tmp directory must not exist for rollback."
+ "Consider restarting for recovery.");
// rename current to tmp
File curDir = sd.getCurrentDir();
Preconditions.checkState(curDir.exists(),
"Current directory must exist for rollback.");
NNStorage.rename(curDir, tmpDir);
// rename previous to current
NNStorage.rename(prevDir, curDir);
// delete tmp dir
NNStorage.deleteDir(tmpDir);
LOG.info("Rollback of " + sd.getRoot() + " is complete.");
}
}