View Javadoc

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.util;
21  
22  import java.io.IOException;
23  
24  import org.apache.commons.logging.Log;
25  import org.apache.commons.logging.LogFactory;
26  import org.apache.hadoop.classification.InterfaceAudience;
27  import org.apache.hadoop.classification.InterfaceStability;
28  import org.apache.hadoop.conf.Configuration;
29  import org.apache.hadoop.conf.Configured;
30  import org.apache.hadoop.fs.FileSystem;
31  import org.apache.hadoop.fs.Path;
32  import org.apache.hadoop.hbase.TableName;
33  import org.apache.hadoop.hbase.HBaseConfiguration;
34  import org.apache.hadoop.hbase.HConstants;
35  import org.apache.hadoop.hbase.HRegionInfo;
36  import org.apache.hadoop.hbase.HTableDescriptor;
37  import org.apache.hadoop.hbase.MasterNotRunningException;
38  import org.apache.hadoop.hbase.ZooKeeperConnectionException;
39  import org.apache.hadoop.hbase.client.Delete;
40  import org.apache.hadoop.hbase.client.Get;
41  import org.apache.hadoop.hbase.client.HBaseAdmin;
42  import org.apache.hadoop.hbase.client.Result;
43  import org.apache.hadoop.hbase.regionserver.HRegion;
44  import org.apache.hadoop.hbase.regionserver.wal.HLog;
45  import org.apache.hadoop.io.WritableComparator;
46  import org.apache.hadoop.util.GenericOptionsParser;
47  import org.apache.hadoop.util.Tool;
48  import org.apache.hadoop.util.ToolRunner;
49  
50  import com.google.common.base.Preconditions;
51  
52  /**
53   * Utility that can merge any two regions in the same table: adjacent,
54   * overlapping or disjoint.
55   */
56  @InterfaceAudience.Public
57  @InterfaceStability.Evolving
58  public class Merge extends Configured implements Tool {
59    static final Log LOG = LogFactory.getLog(Merge.class);
60    private Path rootdir;
61    private volatile MetaUtils utils;
62    private TableName tableName;               // Name of table
63    private volatile byte [] region1;        // Name of region 1
64    private volatile byte [] region2;        // Name of region 2
65    private volatile HRegionInfo mergeInfo;
66  
67    /** default constructor */
68    public Merge() {
69      super();
70    }
71  
72    /**
73     * @param conf configuration
74     */
75    public Merge(Configuration conf) {
76      this.mergeInfo = null;
77      setConf(conf);
78    }
79  
80    public int run(String[] args) throws Exception {
81      if (parseArgs(args) != 0) {
82        return -1;
83      }
84  
85      // Verify file system is up.
86      FileSystem fs = FileSystem.get(getConf());              // get DFS handle
87      LOG.info("Verifying that file system is available...");
88      try {
89        FSUtils.checkFileSystemAvailable(fs);
90      } catch (IOException e) {
91        LOG.fatal("File system is not available", e);
92        return -1;
93      }
94  
95      // Verify HBase is down
96      LOG.info("Verifying that HBase is not running...");
97      try {
98        HBaseAdmin.checkHBaseAvailable(getConf());
99        LOG.fatal("HBase cluster must be off-line, and is not. Aborting.");
100       return -1;
101     } catch (ZooKeeperConnectionException zkce) {
102       // If no zk, presume no master.
103     } catch (MasterNotRunningException e) {
104       // Expected. Ignore.
105     }
106 
107     // Initialize MetaUtils and and get the root of the HBase installation
108 
109     this.utils = new MetaUtils(getConf());
110     this.rootdir = FSUtils.getRootDir(getConf());
111     try {
112       mergeTwoRegions();
113       return 0;
114     } catch (IOException e) {
115       LOG.fatal("Merge failed", e);
116       return -1;
117 
118     } finally {
119       if (this.utils != null) {
120         this.utils.shutdown();
121       }
122     }
123   }
124 
125   /** @return HRegionInfo for merge result */
126   HRegionInfo getMergedHRegionInfo() {
127     return this.mergeInfo;
128   }
129 
130   /*
131    * Merges two regions from a user table.
132    */
133   private void mergeTwoRegions() throws IOException {
134     LOG.info("Merging regions " + Bytes.toStringBinary(this.region1) + " and " +
135         Bytes.toStringBinary(this.region2) + " in table " + this.tableName);
136     HRegion meta = this.utils.getMetaRegion();
137     Get get = new Get(region1);
138     get.addColumn(HConstants.CATALOG_FAMILY, HConstants.REGIONINFO_QUALIFIER);
139     Result result1 =  meta.get(get);
140     Preconditions.checkState(!result1.isEmpty(),
141         "First region cells can not be null");
142     HRegionInfo info1 = HRegionInfo.getHRegionInfo(result1);
143     if (info1 == null) {
144       throw new NullPointerException("info1 is null using key " +
145           Bytes.toStringBinary(region1) + " in " + meta);
146     }
147     get = new Get(region2);
148     get.addColumn(HConstants.CATALOG_FAMILY, HConstants.REGIONINFO_QUALIFIER);
149     Result result2 =  meta.get(get);
150     Preconditions.checkState(!result2.isEmpty(),
151         "Second region cells can not be null");
152     HRegionInfo info2 = HRegionInfo.getHRegionInfo(result2);
153     if (info2 == null) {
154       throw new NullPointerException("info2 is null using key " + meta);
155     }
156     HTableDescriptor htd = FSTableDescriptors.getTableDescriptorFromFs(FileSystem.get(getConf()),
157       this.rootdir, this.tableName);
158     HRegion merged = merge(htd, meta, info1, info2);
159 
160     LOG.info("Adding " + merged.getRegionInfo() + " to " +
161         meta.getRegionInfo());
162 
163     HRegion.addRegionToMETA(meta, merged);
164     merged.close();
165   }
166 
167   /*
168    * Actually merge two regions and update their info in the meta region(s)
169    * Returns HRegion object for newly merged region
170    */
171   private HRegion merge(final HTableDescriptor htd, HRegion meta,
172                         HRegionInfo info1, HRegionInfo info2)
173   throws IOException {
174     if (info1 == null) {
175       throw new IOException("Could not find " + Bytes.toStringBinary(region1) + " in " +
176           Bytes.toStringBinary(meta.getRegionName()));
177     }
178     if (info2 == null) {
179       throw new IOException("Could not find " + Bytes.toStringBinary(region2) + " in " +
180           Bytes.toStringBinary(meta.getRegionName()));
181     }
182     HRegion merged = null;
183     HLog log = utils.getLog();
184     HRegion r1 = HRegion.openHRegion(info1, htd, log, getConf());
185     try {
186       HRegion r2 = HRegion.openHRegion(info2, htd, log, getConf());
187       try {
188         merged = HRegion.merge(r1, r2);
189       } finally {
190         if (!r2.isClosed()) {
191           r2.close();
192         }
193       }
194     } finally {
195       if (!r1.isClosed()) {
196         r1.close();
197       }
198     }
199 
200     // Remove the old regions from meta.
201     // HRegion.merge has already deleted their files
202 
203     removeRegionFromMeta(meta, info1);
204     removeRegionFromMeta(meta, info2);
205 
206     this.mergeInfo = merged.getRegionInfo();
207     return merged;
208   }
209 
210   /*
211    * Removes a region's meta information from the passed <code>meta</code>
212    * region.
213    *
214    * @param meta hbase:meta HRegion to be updated
215    * @param regioninfo HRegionInfo of region to remove from <code>meta</code>
216    *
217    * @throws IOException
218    */
219   private void removeRegionFromMeta(HRegion meta, HRegionInfo regioninfo)
220   throws IOException {
221     if (LOG.isDebugEnabled()) {
222       LOG.debug("Removing region: " + regioninfo + " from " + meta);
223     }
224 
225     Delete delete  = new Delete(regioninfo.getRegionName(),
226         System.currentTimeMillis());
227     meta.delete(delete);
228   }
229 
230   /*
231    * Parse given arguments including generic arguments and assign table name and regions names.
232    *
233    * @param args the arguments to parse
234    *
235    * @throws IOException
236    */
237   private int parseArgs(String[] args) throws IOException {
238     GenericOptionsParser parser =
239       new GenericOptionsParser(getConf(), args);
240 
241     String[] remainingArgs = parser.getRemainingArgs();
242     if (remainingArgs.length != 3) {
243       usage();
244       return -1;
245     }
246     tableName = TableName.valueOf(remainingArgs[0]);
247 
248     region1 = Bytes.toBytesBinary(remainingArgs[1]);
249     region2 = Bytes.toBytesBinary(remainingArgs[2]);
250     int status = 0;
251     if (notInTable(tableName, region1) || notInTable(tableName, region2)) {
252       status = -1;
253     } else if (Bytes.equals(region1, region2)) {
254       LOG.error("Can't merge a region with itself");
255       status = -1;
256     }
257     return status;
258   }
259 
260   private boolean notInTable(final TableName tn, final byte [] rn) {
261     if (WritableComparator.compareBytes(tn.getName(), 0, tn.getName().length,
262         rn, 0, tn.getName().length) != 0) {
263       LOG.error("Region " + Bytes.toStringBinary(rn) + " does not belong to table " +
264         tn);
265       return true;
266     }
267     return false;
268   }
269 
270   private void usage() {
271     System.err
272         .println("For hadoop 0.21+, Usage: bin/hbase org.apache.hadoop.hbase.util.Merge "
273             + "[-Dfs.defaultFS=hdfs://nn:port] <table-name> <region-1> <region-2>\n");
274   }
275 
276   public static void main(String[] args) {
277     int status;
278     try {
279       status = ToolRunner.run(HBaseConfiguration.create(), new Merge(), args);
280     } catch (Exception e) {
281       LOG.error("exiting due to error", e);
282       status = -1;
283     }
284     System.exit(status);
285   }
286 }