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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.regionserver.wal;
20  
21  import java.io.IOException;
22  
23  import org.apache.hadoop.classification.InterfaceAudience;
24  import org.apache.hadoop.conf.Configuration;
25  import org.apache.hadoop.fs.Path;
26  import org.apache.hadoop.hbase.HConstants;
27  import org.apache.hadoop.hbase.util.FSUtils;
28  
29  /**
30   * Context used by our wal dictionary compressor. Null if we're not to do our
31   * custom dictionary compression.
32   */
33  @InterfaceAudience.Private
34  public abstract class WriterBase implements HLog.Writer {
35  
36    protected CompressionContext compressionContext;
37  
38    public boolean initializeCompressionContext(Configuration conf, Path path) throws IOException {
39      boolean doCompress = conf.getBoolean(HConstants.ENABLE_WAL_COMPRESSION, false);
40      if (doCompress) {
41        try {
42          this.compressionContext = new CompressionContext(LRUDictionary.class,
43              FSUtils.isRecoveredEdits(path));
44        } catch (Exception e) {
45          throw new IOException("Failed to initiate CompressionContext", e);
46        }
47      }
48      return doCompress;
49    }
50  }