/**
*
* 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.hbase.master.snapshot;
import java.io.IOException;
import java.util.LinkedList;
import java.util.List;
import java.util.concurrent.CancellationException;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.hbase.HRegionInfo;
import org.apache.hadoop.hbase.HTableDescriptor;
import org.apache.hadoop.hbase.TableName;
import org.apache.hadoop.hbase.MetaTableAccessor;
import org.apache.hadoop.hbase.client.HConnection;
import org.apache.hadoop.hbase.errorhandling.ForeignException;
import org.apache.hadoop.hbase.errorhandling.ForeignExceptionDispatcher;
import org.apache.hadoop.hbase.executor.EventType;
import org.apache.hadoop.hbase.master.AssignmentManager;
import org.apache.hadoop.hbase.master.MasterFileSystem;
import org.apache.hadoop.hbase.master.MasterServices;
import org.apache.hadoop.hbase.master.MetricsSnapshot;
import org.apache.hadoop.hbase.master.RegionStates;
import org.apache.hadoop.hbase.master.SnapshotSentinel;
import org.apache.hadoop.hbase.master.handler.TableEventHandler;
import org.apache.hadoop.hbase.monitoring.MonitoredTask;
import org.apache.hadoop.hbase.monitoring.TaskMonitor;
import org.apache.hadoop.hbase.protobuf.generated.HBaseProtos.SnapshotDescription;
import org.apache.hadoop.hbase.snapshot.ClientSnapshotDescriptionUtils;
import org.apache.hadoop.hbase.snapshot.RestoreSnapshotException;
import org.apache.hadoop.hbase.snapshot.RestoreSnapshotHelper;
import org.apache.hadoop.hbase.snapshot.SnapshotDescriptionUtils;
import org.apache.hadoop.hbase.snapshot.SnapshotManifest;
/**
* Handler to Restore a snapshot.
*
* <p>Uses {@link RestoreSnapshotHelper} to replace the table content with the
* data available in the snapshot.
*/
@InterfaceAudience.Private
public class RestoreSnapshotHandler extends TableEventHandler implements SnapshotSentinel {
private static final Log LOG = LogFactory.getLog(RestoreSnapshotHandler.class);
private final HTableDescriptor hTableDescriptor;
private final SnapshotDescription snapshot;
private final ForeignExceptionDispatcher monitor;
private final MetricsSnapshot metricsSnapshot = new MetricsSnapshot();
private final MonitoredTask status;
private volatile boolean stopped = false;
public RestoreSnapshotHandler(final MasterServices masterServices,
final SnapshotDescription snapshot, final HTableDescriptor htd) throws IOException {
super(EventType.C_M_RESTORE_SNAPSHOT, htd.getTableName(), masterServices, masterServices);
// Snapshot information
this.snapshot = snapshot;
// Monitor
this.monitor = new ForeignExceptionDispatcher();
// Check table exists.
getTableDescriptor();
// This is the new schema we are going to write out as this modification.
this.hTableDescriptor = htd;
this.status = TaskMonitor.get().createStatus(
"Restoring snapshot '" + snapshot.getName() + "' to table "
+ hTableDescriptor.getTableName());
}
@Override
public RestoreSnapshotHandler prepare() throws IOException {
return (RestoreSnapshotHandler) super.prepare();
}
/**
* The restore table is executed in place.
* - The on-disk data will be restored - reference files are put in place without moving data
* - [if something fail here: you need to delete the table and re-run the restore]
* - hbase:meta will be updated
* - [if something fail here: you need to run hbck to fix hbase:meta entries]
* The passed in list gets changed in this method
*/
@Override
protected void handleTableOperation(List<HRegionInfo> hris) throws IOException {
MasterFileSystem fileSystemManager = masterServices.getMasterFileSystem();
HConnection conn = masterServices.getShortCircuitConnection();
FileSystem fs = fileSystemManager.getFileSystem();
Path rootDir = fileSystemManager.getRootDir();
TableName tableName = hTableDescriptor.getTableName();
try {
// 1. Update descriptor
this.masterServices.getTableDescriptors().add(hTableDescriptor);
// 2. Execute the on-disk Restore
LOG.debug("Starting restore snapshot=" + ClientSnapshotDescriptionUtils.toString(snapshot));
Path snapshotDir = SnapshotDescriptionUtils.getCompletedSnapshotDir(snapshot, rootDir);
SnapshotManifest manifest = SnapshotManifest.open(masterServices.getConfiguration(), fs,
snapshotDir, snapshot);
RestoreSnapshotHelper restoreHelper = new RestoreSnapshotHelper(
masterServices.getConfiguration(), fs, manifest,
this.hTableDescriptor, rootDir, monitor, status);
RestoreSnapshotHelper.RestoreMetaChanges metaChanges = restoreHelper.restoreHdfsRegions();
// 3. Forces all the RegionStates to be offline
//
// The AssignmentManager keeps all the region states around
// with no possibility to remove them, until the master is restarted.
// This means that a region marked as SPLIT before the restore will never be assigned again.
// To avoid having all states around all the regions are switched to the OFFLINE state,
// which is the same state that the regions will be after a delete table.
forceRegionsOffline(metaChanges);
// 4. Applies changes to hbase:meta
status.setStatus("Preparing to restore each region");
// 4.1 Removes the current set of regions from META
//
// By removing also the regions to restore (the ones present both in the snapshot
// and in the current state) we ensure that no extra fields are present in META
// e.g. with a simple add addRegionToMeta() the splitA and splitB attributes
// not overwritten/removed, so you end up with old informations
// that are not correct after the restore.
List<HRegionInfo> hrisToRemove = new LinkedList<HRegionInfo>();
if (metaChanges.hasRegionsToRemove()) hrisToRemove.addAll(metaChanges.getRegionsToRemove());
MetaTableAccessor.deleteRegions(conn, hrisToRemove);
// 4.2 Add the new set of regions to META
//
// At this point the old regions are no longer present in META.
// and the set of regions present in the snapshot will be written to META.
// All the information in hbase:meta are coming from the .regioninfo of each region present
// in the snapshot folder.
hris.clear();
if (metaChanges.hasRegionsToAdd()) hris.addAll(metaChanges.getRegionsToAdd());
MetaTableAccessor.addRegionsToMeta(conn, hris);
if (metaChanges.hasRegionsToRestore()) {
MetaTableAccessor.overwriteRegions(conn, metaChanges.getRegionsToRestore());
}
metaChanges.updateMetaParentRegions(this.server.getShortCircuitConnection(), hris);
// At this point the restore is complete. Next step is enabling the table.
LOG.info("Restore snapshot=" + ClientSnapshotDescriptionUtils.toString(snapshot) +
" on table=" + tableName + " completed!");
} catch (IOException e) {
String msg = "restore snapshot=" + ClientSnapshotDescriptionUtils.toString(snapshot)
+ " failed. Try re-running the restore command.";
LOG.error(msg, e);
monitor.receive(new ForeignException(masterServices.getServerName().toString(), e));
throw new RestoreSnapshotException(msg, e);
}
}
private void forceRegionsOffline(final RestoreSnapshotHelper.RestoreMetaChanges metaChanges) {
forceRegionsOffline(metaChanges.getRegionsToAdd());
forceRegionsOffline(metaChanges.getRegionsToRestore());
forceRegionsOffline(metaChanges.getRegionsToRemove());
}
private void forceRegionsOffline(final List<HRegionInfo> hris) {
AssignmentManager am = this.masterServices.getAssignmentManager();
RegionStates states = am.getRegionStates();
if (hris != null) {
for (HRegionInfo hri: hris) {
states.regionOffline(hri);
}
}
}
@Override
protected void completed(final Throwable exception) {
this.stopped = true;
if (exception != null) {
status.abort("Restore snapshot '" + snapshot.getName() + "' failed because " +
exception.getMessage());
} else {
status.markComplete("Restore snapshot '"+ snapshot.getName() +"'!");
}
metricsSnapshot.addSnapshotRestore(status.getCompletionTimestamp() - status.getStartTime());
super.completed(exception);
}
@Override
public boolean isFinished() {
return this.stopped;
}
@Override
public long getCompletionTimestamp() {
return this.status.getCompletionTimestamp();
}
@Override
public SnapshotDescription getSnapshot() {
return snapshot;
}
@Override
public void cancel(String why) {
if (this.stopped) return;
this.stopped = true;
String msg = "Stopping restore snapshot=" + ClientSnapshotDescriptionUtils.toString(snapshot)
+ " because: " + why;
LOG.info(msg);
CancellationException ce = new CancellationException(why);
this.monitor.receive(new ForeignException(masterServices.getServerName().toString(), ce));
}
@Override
public ForeignException getExceptionIfFailed() {
return this.monitor.getException();
}
@Override
public void rethrowExceptionIfFailed() throws ForeignException {
monitor.rethrowException();
}
}