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1   /**
2    *
3    * Licensed to the Apache Software Foundation (ASF) under one
4    * or more contributor license agreements.  See the NOTICE file
5    * distributed with this work for additional information
6    * regarding copyright ownership.  The ASF licenses this file
7    * to you under the Apache License, Version 2.0 (the
8    * "License"); you may not use this file except in compliance
9    * with the License.  You may obtain a copy of the License at
10   *
11   *     http://www.apache.org/licenses/LICENSE-2.0
12   *
13   * Unless required by applicable law or agreed to in writing, software
14   * distributed under the License is distributed on an "AS IS" BASIS,
15   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
16   * See the License for the specific language governing permissions and
17   * limitations under the License.
18   */
19  
20  package org.apache.hadoop.hbase.master.snapshot;
21  
22  import java.io.IOException;
23  import java.util.List;
24  import java.util.concurrent.CancellationException;
25  
26  import org.apache.commons.logging.Log;
27  import org.apache.commons.logging.LogFactory;
28  import org.apache.hadoop.classification.InterfaceAudience;
29  import org.apache.hadoop.fs.FileSystem;
30  import org.apache.hadoop.fs.Path;
31  import org.apache.hadoop.hbase.TableName;
32  import org.apache.hadoop.hbase.HRegionInfo;
33  import org.apache.hadoop.hbase.HTableDescriptor;
34  import org.apache.hadoop.hbase.NotAllMetaRegionsOnlineException;
35  import org.apache.hadoop.hbase.TableExistsException;
36  import org.apache.hadoop.hbase.catalog.CatalogTracker;
37  import org.apache.hadoop.hbase.errorhandling.ForeignException;
38  import org.apache.hadoop.hbase.errorhandling.ForeignExceptionDispatcher;
39  import org.apache.hadoop.hbase.master.MasterServices;
40  import org.apache.hadoop.hbase.master.MetricsSnapshot;
41  import org.apache.hadoop.hbase.master.SnapshotSentinel;
42  import org.apache.hadoop.hbase.master.handler.CreateTableHandler;
43  import org.apache.hadoop.hbase.monitoring.MonitoredTask;
44  import org.apache.hadoop.hbase.monitoring.TaskMonitor;
45  import org.apache.hadoop.hbase.protobuf.generated.HBaseProtos.SnapshotDescription;
46  import org.apache.hadoop.hbase.snapshot.ClientSnapshotDescriptionUtils;
47  import org.apache.hadoop.hbase.snapshot.RestoreSnapshotException;
48  import org.apache.hadoop.hbase.snapshot.RestoreSnapshotHelper;
49  import org.apache.hadoop.hbase.snapshot.SnapshotDescriptionUtils;
50  
51  import com.google.common.base.Preconditions;
52  
53  /**
54   * Handler to Clone a snapshot.
55   *
56   * <p>Uses {@link RestoreSnapshotHelper} to create a new table with the same
57   * content of the specified snapshot.
58   */
59  @InterfaceAudience.Private
60  public class CloneSnapshotHandler extends CreateTableHandler implements SnapshotSentinel {
61    private static final Log LOG = LogFactory.getLog(CloneSnapshotHandler.class);
62  
63    private final static String NAME = "Master CloneSnapshotHandler";
64  
65    private final SnapshotDescription snapshot;
66  
67    private final ForeignExceptionDispatcher monitor;
68    private final MetricsSnapshot metricsSnapshot = new MetricsSnapshot();
69    private final MonitoredTask status;
70  
71    private RestoreSnapshotHelper.RestoreMetaChanges metaChanges;
72  
73    private volatile boolean stopped = false;
74  
75    public CloneSnapshotHandler(final MasterServices masterServices,
76        final SnapshotDescription snapshot, final HTableDescriptor hTableDescriptor) {
77      super(masterServices, masterServices.getMasterFileSystem(), hTableDescriptor,
78        masterServices.getConfiguration(), null, masterServices);
79  
80      // Snapshot information
81      this.snapshot = snapshot;
82  
83      // Monitor
84      this.monitor = new ForeignExceptionDispatcher();
85      this.status = TaskMonitor.get().createStatus("Cloning  snapshot '" + snapshot.getName() +
86        "' to table " + hTableDescriptor.getTableName());
87    }
88  
89    @Override
90    public CloneSnapshotHandler prepare() throws NotAllMetaRegionsOnlineException,
91        TableExistsException, IOException {
92      return (CloneSnapshotHandler) super.prepare();
93    }
94  
95    /**
96     * Create the on-disk regions, using the tableRootDir provided by the CreateTableHandler.
97     * The cloned table will be created in a temp directory, and then the CreateTableHandler
98     * will be responsible to add the regions returned by this method to hbase:meta and do the assignment.
99     */
100   @Override
101   protected List<HRegionInfo> handleCreateHdfsRegions(final Path tableRootDir,
102       final TableName tableName) throws IOException {
103     status.setStatus("Creating regions for table: " + tableName);
104     FileSystem fs = fileSystemManager.getFileSystem();
105     Path rootDir = fileSystemManager.getRootDir();
106 
107     try {
108       // 1. Execute the on-disk Clone
109       Path snapshotDir = SnapshotDescriptionUtils.getCompletedSnapshotDir(snapshot, rootDir);
110       RestoreSnapshotHelper restoreHelper = new RestoreSnapshotHelper(conf, fs,
111           snapshot, snapshotDir, hTableDescriptor, tableRootDir, monitor, status);
112       metaChanges = restoreHelper.restoreHdfsRegions();
113 
114       // Clone operation should not have stuff to restore or remove
115       Preconditions.checkArgument(!metaChanges.hasRegionsToRestore(),
116           "A clone should not have regions to restore");
117       Preconditions.checkArgument(!metaChanges.hasRegionsToRemove(),
118           "A clone should not have regions to remove");
119 
120       // At this point the clone is complete. Next step is enabling the table.
121       String msg = "Clone snapshot="+ snapshot.getName() +" on table=" + tableName + " completed!";
122       LOG.info(msg);
123       status.setStatus(msg + " Waiting for table to be enabled...");
124 
125       // 2. let the CreateTableHandler add the regions to meta
126       return metaChanges.getRegionsToAdd();
127     } catch (Exception e) {
128       String msg = "clone snapshot=" + ClientSnapshotDescriptionUtils.toString(snapshot) +
129         " failed because " + e.getMessage();
130       LOG.error(msg, e);
131       IOException rse = new RestoreSnapshotException(msg, e, snapshot);
132 
133       // these handlers aren't futures so we need to register the error here.
134       this.monitor.receive(new ForeignException(NAME, rse));
135       throw rse;
136     }
137   }
138 
139   @Override
140   protected void addRegionsToMeta(final CatalogTracker ct, final List<HRegionInfo> regionInfos)
141       throws IOException {
142     super.addRegionsToMeta(ct, regionInfos);
143     metaChanges.updateMetaParentRegions(ct, regionInfos);
144   }
145 
146   @Override
147   protected void completed(final Throwable exception) {
148     this.stopped = true;
149     if (exception != null) {
150       status.abort("Snapshot '" + snapshot.getName() + "' clone failed because " +
151           exception.getMessage());
152     } else {
153       status.markComplete("Snapshot '"+ snapshot.getName() +"' clone completed and table enabled!");
154     }
155     metricsSnapshot.addSnapshotClone(status.getCompletionTimestamp() - status.getStartTime());
156     super.completed(exception);
157   }
158 
159   @Override
160   public boolean isFinished() {
161     return this.stopped;
162   }
163 
164   @Override
165   public long getCompletionTimestamp() {
166     return this.status.getCompletionTimestamp();
167   }
168 
169   @Override
170   public SnapshotDescription getSnapshot() {
171     return snapshot;
172   }
173 
174   @Override
175   public void cancel(String why) {
176     if (this.stopped) return;
177     this.stopped = true;
178     String msg = "Stopping clone snapshot=" + snapshot + " because: " + why;
179     LOG.info(msg);
180     status.abort(msg);
181     this.monitor.receive(new ForeignException(NAME, new CancellationException(why)));
182   }
183 
184   @Override
185   public ForeignException getExceptionIfFailed() {
186     return this.monitor.getException();
187   }
188 
189   @Override
190   public void rethrowExceptionIfFailed() throws ForeignException {
191     monitor.rethrowException();
192   }
193 }