Java tutorial
/** * * 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.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.TableName; import org.apache.hadoop.hbase.HRegionInfo; import org.apache.hadoop.hbase.HTableDescriptor; import org.apache.hadoop.hbase.NotAllMetaRegionsOnlineException; import org.apache.hadoop.hbase.TableExistsException; import org.apache.hadoop.hbase.catalog.CatalogTracker; import org.apache.hadoop.hbase.errorhandling.ForeignException; import org.apache.hadoop.hbase.errorhandling.ForeignExceptionDispatcher; import org.apache.hadoop.hbase.master.MasterServices; import org.apache.hadoop.hbase.master.MetricsSnapshot; import org.apache.hadoop.hbase.master.SnapshotSentinel; import org.apache.hadoop.hbase.master.handler.CreateTableHandler; 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; import com.google.common.base.Preconditions; /** * Handler to Clone a snapshot. * * <p>Uses {@link RestoreSnapshotHelper} to create a new table with the same * content of the specified snapshot. */ @InterfaceAudience.Private public class CloneSnapshotHandler extends CreateTableHandler implements SnapshotSentinel { private static final Log LOG = LogFactory.getLog(CloneSnapshotHandler.class); private final static String NAME = "Master CloneSnapshotHandler"; private final SnapshotDescription snapshot; private final ForeignExceptionDispatcher monitor; private final MetricsSnapshot metricsSnapshot = new MetricsSnapshot(); private final MonitoredTask status; private RestoreSnapshotHelper.RestoreMetaChanges metaChanges; private volatile boolean stopped = false; public CloneSnapshotHandler(final MasterServices masterServices, final SnapshotDescription snapshot, final HTableDescriptor hTableDescriptor) { super(masterServices, masterServices.getMasterFileSystem(), hTableDescriptor, masterServices.getConfiguration(), null, masterServices); // Snapshot information this.snapshot = snapshot; // Monitor this.monitor = new ForeignExceptionDispatcher(); this.status = TaskMonitor.get().createStatus( "Cloning snapshot '" + snapshot.getName() + "' to table " + hTableDescriptor.getTableName()); } @Override public CloneSnapshotHandler prepare() throws NotAllMetaRegionsOnlineException, TableExistsException, IOException { return (CloneSnapshotHandler) super.prepare(); } /** * Create the on-disk regions, using the tableRootDir provided by the CreateTableHandler. * The cloned table will be created in a temp directory, and then the CreateTableHandler * will be responsible to add the regions returned by this method to hbase:meta and do the assignment. */ @Override protected List<HRegionInfo> handleCreateHdfsRegions(final Path tableRootDir, final TableName tableName) throws IOException { status.setStatus("Creating regions for table: " + tableName); FileSystem fs = fileSystemManager.getFileSystem(); Path rootDir = fileSystemManager.getRootDir(); try { // 1. Execute the on-disk Clone Path snapshotDir = SnapshotDescriptionUtils.getCompletedSnapshotDir(snapshot, rootDir); SnapshotManifest manifest = SnapshotManifest.open(conf, fs, snapshotDir, snapshot); RestoreSnapshotHelper restoreHelper = new RestoreSnapshotHelper(conf, fs, manifest, hTableDescriptor, tableRootDir, monitor, status); metaChanges = restoreHelper.restoreHdfsRegions(); // Clone operation should not have stuff to restore or remove Preconditions.checkArgument(!metaChanges.hasRegionsToRestore(), "A clone should not have regions to restore"); Preconditions.checkArgument(!metaChanges.hasRegionsToRemove(), "A clone should not have regions to remove"); // At this point the clone is complete. Next step is enabling the table. String msg = "Clone snapshot=" + snapshot.getName() + " on table=" + tableName + " completed!"; LOG.info(msg); status.setStatus(msg + " Waiting for table to be enabled..."); // 2. let the CreateTableHandler add the regions to meta return metaChanges.getRegionsToAdd(); } catch (Exception e) { String msg = "clone snapshot=" + ClientSnapshotDescriptionUtils.toString(snapshot) + " failed because " + e.getMessage(); LOG.error(msg, e); IOException rse = new RestoreSnapshotException(msg, e, snapshot); // these handlers aren't futures so we need to register the error here. this.monitor.receive(new ForeignException(NAME, rse)); throw rse; } } @Override protected void addRegionsToMeta(final CatalogTracker ct, final List<HRegionInfo> regionInfos) throws IOException { super.addRegionsToMeta(ct, regionInfos); metaChanges.updateMetaParentRegions(ct, regionInfos); } @Override protected void completed(final Throwable exception) { this.stopped = true; if (exception != null) { status.abort("Snapshot '" + snapshot.getName() + "' clone failed because " + exception.getMessage()); } else { status.markComplete("Snapshot '" + snapshot.getName() + "' clone completed and table enabled!"); } metricsSnapshot.addSnapshotClone(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 clone snapshot=" + snapshot + " because: " + why; LOG.info(msg); status.abort(msg); this.monitor.receive(new ForeignException(NAME, new CancellationException(why))); } @Override public ForeignException getExceptionIfFailed() { return this.monitor.getException(); } @Override public void rethrowExceptionIfFailed() throws ForeignException { monitor.rethrowException(); } }