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1   /*
2    * Copyright 2010 The Apache Software Foundation
3    *
4    * Licensed to the Apache Software Foundation (ASF) under one
5    * or more contributor license agreements.  See the NOTICE file
6    * distributed with this work for additional information
7    * regarding copyright ownership.  The ASF licenses this file
8    * to you under the Apache License, Version 2.0 (the
9    * "License"); you may not use this file except in compliance
10   * with the License.  You may obtain a copy of the License at
11   *
12   *     http://www.apache.org/licenses/LICENSE-2.0
13   *
14   * Unless required by applicable law or agreed to in writing, software
15   * distributed under the License is distributed on an "AS IS" BASIS,
16   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
17   * See the License for the specific language governing permissions and
18   * limitations under the License.
19   */
20  package org.apache.hadoop.hbase.regionserver.wal;
21  
22  import org.apache.hadoop.fs.Path;
23  import org.apache.hadoop.hbase.HRegionInfo;
24  
25  /**
26   * Get notification of {@link HLog}/WAL log events. The invocations are inline
27   * so make sure your implementation is fast else you'll slow hbase.
28   */
29  public interface WALObserver {
30    /**
31     * The WAL was rolled.
32     * @param newFile the path to the new hlog
33     */
34    public void logRolled(Path newFile);
35  
36    /**
37     * A request was made that the WAL be rolled.
38     */
39    public void logRollRequested();
40  
41    /**
42     * The WAL is about to close.
43     */
44    public void logCloseRequested();
45  
46    /**
47    * Called before each write.
48    * @param info
49    * @param logKey
50    * @param logEdit
51    */
52   public void visitLogEntryBeforeWrite(HRegionInfo info, HLogKey logKey,
53     WALEdit logEdit);
54  }