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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  package org.apache.hadoop.hbase.coprocessor;
20  
21  import java.io.IOException;
22  import java.util.List;
23  
24  import org.apache.hadoop.hbase.Coprocessor;
25  import org.apache.hadoop.hbase.MetaMutationAnnotation;
26  import org.apache.hadoop.hbase.client.Mutation;
27  import org.apache.hadoop.hbase.regionserver.HRegion;
28  import org.apache.hadoop.hbase.replication.ReplicationEndpoint;
29  
30  public interface RegionServerObserver extends Coprocessor {
31  
32    /**
33     * Called before stopping region server.
34     * @param env An instance of RegionServerCoprocessorEnvironment
35     * @throws IOException Signals that an I/O exception has occurred.
36     */
37    void preStopRegionServer(
38      final ObserverContext<RegionServerCoprocessorEnvironment> env)
39      throws IOException;
40  
41    /**
42     * Called before the regions merge. 
43     * Call {@link org.apache.hadoop.hbase.coprocessor.ObserverContext#bypass()} to skip the merge.
44     * @throws IOException if an error occurred on the coprocessor
45     * @param ctx
46     * @param regionA
47     * @param regionB
48     * @throws IOException
49     */
50    void preMerge(final ObserverContext<RegionServerCoprocessorEnvironment> ctx,
51        final HRegion regionA, final HRegion regionB) throws IOException;
52  
53    /**
54     * called after the regions merge.
55     * @param c
56     * @param regionA
57     * @param regionB
58     * @param mergedRegion
59     * @throws IOException
60     */
61    void postMerge(final ObserverContext<RegionServerCoprocessorEnvironment> c,
62        final HRegion regionA, final HRegion regionB, final HRegion mergedRegion) throws IOException;
63  
64    /**
65     * This will be called before PONR step as part of regions merge transaction. Calling
66     * {@link org.apache.hadoop.hbase.coprocessor.ObserverContext#bypass()} rollback the merge
67     * @param ctx
68     * @param regionA
69     * @param regionB
70     * @param metaEntries mutations to execute on hbase:meta atomically with regions merge updates. 
71     *        Any puts or deletes to execute on hbase:meta can be added to the mutations.
72     * @throws IOException
73     */
74    void preMergeCommit(final ObserverContext<RegionServerCoprocessorEnvironment> ctx,
75        final HRegion regionA, final HRegion regionB,
76        @MetaMutationAnnotation List<Mutation> metaEntries) throws IOException;
77  
78    /**
79     * This will be called after PONR step as part of regions merge transaction.
80     * @param ctx
81     * @param regionA
82     * @param regionB
83     * @param mergedRegion
84     * @throws IOException
85     */
86    void postMergeCommit(final ObserverContext<RegionServerCoprocessorEnvironment> ctx,
87        final HRegion regionA, final HRegion regionB, final HRegion mergedRegion) throws IOException;
88  
89    /**
90     * This will be called before the roll back of the regions merge.
91     * @param ctx
92     * @param regionA
93     * @param regionB
94     * @throws IOException
95     */
96    void preRollBackMerge(final ObserverContext<RegionServerCoprocessorEnvironment> ctx,
97        final HRegion regionA, final HRegion regionB) throws IOException;
98  
99    /**
100    * This will be called after the roll back of the regions merge.
101    * @param ctx
102    * @param regionA
103    * @param regionB
104    * @throws IOException
105    */
106   void postRollBackMerge(final ObserverContext<RegionServerCoprocessorEnvironment> ctx,
107       final HRegion regionA, final HRegion regionB) throws IOException;
108 
109   /**
110    * This will be called before executing user request to roll a region server WAL.
111    * @param ctx An instance of ObserverContext
112    * @throws IOException Signals that an I/O exception has occurred.
113    */
114   void preRollWALWriterRequest(final ObserverContext<RegionServerCoprocessorEnvironment> ctx)
115       throws IOException;
116 
117   /**
118    * This will be called after executing user request to roll a region server WAL.
119    * @param ctx An instance of ObserverContext
120    * @throws IOException Signals that an I/O exception has occurred.
121    */
122   void postRollWALWriterRequest(final ObserverContext<RegionServerCoprocessorEnvironment> ctx)
123       throws IOException;
124 
125   /**
126    * This will be called after the replication endpoint is instantiated.
127    * @param ctx
128    * @param endpoint - the base endpoint for replication
129    * @return the endpoint to use during replication.
130    */
131   ReplicationEndpoint postCreateReplicationEndPoint(
132       ObserverContext<RegionServerCoprocessorEnvironment> ctx, ReplicationEndpoint endpoint);
133 
134 }