View Javadoc

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.coprocessor;
20  
21  import java.io.IOException;
22  
23  import org.apache.hadoop.hbase.classification.InterfaceAudience;
24  import org.apache.hadoop.hbase.classification.InterfaceStability;
25  import org.apache.hadoop.hbase.CoprocessorEnvironment;
26  import org.apache.hadoop.hbase.HBaseInterfaceAudience;
27  import org.apache.hadoop.hbase.HRegionInfo;
28  import org.apache.hadoop.hbase.regionserver.wal.HLogKey;
29  import org.apache.hadoop.hbase.wal.WALKey;
30  import org.apache.hadoop.hbase.regionserver.wal.WALEdit;
31  
32  /**
33   * An abstract class that implements WALObserver.
34   * By extending it, you can create your own WAL observer without
35   * overriding all abstract methods of WALObserver.
36   */
37  @InterfaceAudience.LimitedPrivate(HBaseInterfaceAudience.COPROC)
38  @InterfaceStability.Evolving
39  public class BaseWALObserver implements WALObserver {
40    @Override
41    public void start(CoprocessorEnvironment e) throws IOException { }
42  
43    @Override
44    public void stop(CoprocessorEnvironment e) throws IOException { }
45  
46    /**
47     * Implementers should override this method and leave the deprecated version as-is.
48     */
49    @Override
50    public boolean preWALWrite(ObserverContext<? extends WALCoprocessorEnvironment> ctx,
51        HRegionInfo info, WALKey logKey, WALEdit logEdit) throws IOException {
52      return false;
53    }
54  
55    @Override
56    public boolean preWALWrite(ObserverContext<WALCoprocessorEnvironment> ctx, HRegionInfo info,
57        HLogKey logKey, WALEdit logEdit) throws IOException {
58      return preWALWrite(ctx, info, (WALKey)logKey, logEdit);
59    }
60  
61    /**
62     * Implementers should override this method and leave the deprecated version as-is.
63     */
64    @Override
65    public void postWALWrite(ObserverContext<? extends WALCoprocessorEnvironment> ctx,
66        HRegionInfo info, WALKey logKey, WALEdit logEdit) throws IOException { }
67  
68    @Override
69    public void postWALWrite(ObserverContext<WALCoprocessorEnvironment> ctx, HRegionInfo info,
70        HLogKey logKey, WALEdit logEdit) throws IOException {
71      postWALWrite(ctx, info, (WALKey)logKey, logEdit);
72    }
73  }