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1   /**
2    * Licensed to the Apache Software Foundation (ASF) under one
3    * or more contributor license agreements.  See the NOTICE file
4    * distributed with this work for additional information
5    * regarding copyright ownership.  The ASF licenses this file
6    * to you under the Apache License, Version 2.0 (the
7    * "License"); you may not use this file except in compliance
8    * with the License.  You may obtain a copy of the License at
9    *
10   *     http://www.apache.org/licenses/LICENSE-2.0
11   *
12   * Unless required by applicable law or agreed to in writing, software
13   * distributed under the License is distributed on an "AS IS" BASIS,
14   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15   * See the License for the specific language governing permissions and
16   * limitations under the License.
17   */
18  
19  package org.apache.hadoop.hbase.client;
20  
21  import java.util.Collection;
22  import java.util.Iterator;
23  
24  import org.apache.hadoop.hbase.classification.InterfaceAudience;
25  import org.apache.hadoop.hbase.HRegionInfo;
26  
27  /**
28   * Utility methods which contain the logic for regions and replicas.
29   */
30  @InterfaceAudience.Private
31  public class RegionReplicaUtil {
32  
33    /**
34     * The default replicaId for the region
35     */
36    static final int DEFAULT_REPLICA_ID = 0;
37  
38    /**
39     * Returns the HRegionInfo for the given replicaId. HRegionInfo's correspond to
40     * a range of a table, but more than one "instance" of the same range can be
41     * deployed which are differentiated by the replicaId.
42     * @param replicaId the replicaId to use
43     * @return an HRegionInfo object corresponding to the same range (table, start and
44     * end key), but for the given replicaId.
45     */
46    public static HRegionInfo getRegionInfoForReplica(HRegionInfo regionInfo, int replicaId) {
47      if (regionInfo.getReplicaId() == replicaId) {
48        return regionInfo;
49      }
50      HRegionInfo replicaInfo = new HRegionInfo(regionInfo.getTable(), regionInfo.getStartKey(),
51        regionInfo.getEndKey(), regionInfo.isSplit(), regionInfo.getRegionId(), replicaId);
52  
53      replicaInfo.setOffline(regionInfo.isOffline());
54      return replicaInfo;
55    }
56  
57    /**
58     * Returns the HRegionInfo for the default replicaId (0). HRegionInfo's correspond to
59     * a range of a table, but more than one "instance" of the same range can be
60     * deployed which are differentiated by the replicaId.
61     * @return an HRegionInfo object corresponding to the same range (table, start and
62     * end key), but for the default replicaId.
63     */
64    public static HRegionInfo getRegionInfoForDefaultReplica(HRegionInfo regionInfo) {
65      return getRegionInfoForReplica(regionInfo, DEFAULT_REPLICA_ID);
66    }
67  
68    /** @return true if this replicaId corresponds to default replica for the region */
69    public static boolean isDefaultReplica(int replicaId) {
70      return DEFAULT_REPLICA_ID == replicaId;
71    }
72  
73    /** @return true if this region is a default replica for the region */
74    public static boolean isDefaultReplica(HRegionInfo hri) {
75      return  hri.getReplicaId() == DEFAULT_REPLICA_ID;
76    }
77  
78    /**
79     * Removes the non-default replicas from the passed regions collection
80     * @param regions
81     */
82    public static void removeNonDefaultRegions(Collection<HRegionInfo> regions) {
83      Iterator<HRegionInfo> iterator = regions.iterator();
84      while (iterator.hasNext()) {
85        HRegionInfo hri = iterator.next();
86        if (!RegionReplicaUtil.isDefaultReplica(hri)) {
87          iterator.remove();
88        }
89      }
90    }
91  }