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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.coprocessor;
20  
21  import java.io.IOException;
22  
23  import org.apache.hadoop.classification.InterfaceAudience;
24  import org.apache.hadoop.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.regionserver.wal.WALEdit;
30  
31  /**
32   * An abstract class that implements WALObserver.
33   * By extending it, you can create your own WAL observer without
34   * overriding all abstract methods of WALObserver.
35   */
36  @InterfaceAudience.LimitedPrivate(HBaseInterfaceAudience.COPROC)
37  @InterfaceStability.Evolving
38  public class BaseWALObserver implements WALObserver {
39    @Override
40    public void start(CoprocessorEnvironment e) throws IOException { }
41  
42    @Override
43    public void stop(CoprocessorEnvironment e) throws IOException { }
44  
45    @Override
46    public boolean preWALWrite(ObserverContext<WALCoprocessorEnvironment> ctx, HRegionInfo info,
47        HLogKey logKey, WALEdit logEdit) throws IOException {
48      return false;
49    }
50  
51    @Override
52    public void postWALWrite(ObserverContext<WALCoprocessorEnvironment> ctx, HRegionInfo info,
53        HLogKey logKey, WALEdit logEdit) throws IOException { }
54  }