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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.hbase.classification.InterfaceAudience;
24  import org.apache.hadoop.fs.Path;
25  import org.apache.hadoop.hbase.HRegionInfo;
26  import org.apache.hadoop.hbase.HTableDescriptor;
27  
28  import org.apache.hadoop.hbase.wal.WALKey;
29  
30  /**
31   * Get notification of WAL events. The invocations are inline
32   * so make sure your implementation is fast else you'll slow hbase.
33   */
34  @InterfaceAudience.Private
35  public interface WALActionsListener {
36  
37    /**
38     * The WAL is going to be rolled. The oldPath can be null if this is
39     * the first log file from the regionserver.
40     * @param oldPath the path to the old wal
41     * @param newPath the path to the new wal
42     */
43    void preLogRoll(Path oldPath, Path newPath) throws IOException;
44  
45    /**
46     * The WAL has been rolled. The oldPath can be null if this is
47     * the first log file from the regionserver.
48     * @param oldPath the path to the old wal
49     * @param newPath the path to the new wal
50     */
51    void postLogRoll(Path oldPath, Path newPath) throws IOException;
52  
53    /**
54     * The WAL is going to be archived.
55     * @param oldPath the path to the old wal
56     * @param newPath the path to the new wal
57     */
58    void preLogArchive(Path oldPath, Path newPath) throws IOException;
59  
60    /**
61     * The WAL has been archived.
62     * @param oldPath the path to the old wal
63     * @param newPath the path to the new wal
64     */
65    void postLogArchive(Path oldPath, Path newPath) throws IOException;
66  
67    /**
68     * A request was made that the WAL be rolled.
69     */
70    void logRollRequested();
71  
72    /**
73     * The WAL is about to close.
74     */
75    void logCloseRequested();
76  
77    /**
78    * Called before each write.
79    * @param info
80    * @param logKey
81    * @param logEdit
82    */
83    void visitLogEntryBeforeWrite(
84      HRegionInfo info, WALKey logKey, WALEdit logEdit
85    );
86  
87    /**
88     *
89     * @param htd
90     * @param logKey
91     * @param logEdit
92     * TODO: Retire this in favor of {@link #visitLogEntryBeforeWrite(HRegionInfo, WALKey, WALEdit)}
93     * It only exists to get scope when replicating.  Scope should be in the WALKey and not need
94     * us passing in a <code>htd</code>.
95     */
96    void visitLogEntryBeforeWrite(
97      HTableDescriptor htd, WALKey logKey, WALEdit logEdit
98    );
99  
100   /**
101    * For notification post append to the writer.  Used by metrics system at least.
102    * TODO: Combine this with above.
103    * @param entryLen approx length of cells in this append.
104    * @param elapsedTimeMillis elapsed time in milliseconds.
105    */
106   void postAppend(final long entryLen, final long elapsedTimeMillis);
107 
108   /**
109    * For notification post writer sync.  Used by metrics system at least.
110    * @param timeInNanos How long the filesystem sync took in nanoseconds.
111    * @param handlerSyncs How many sync handler calls were released by this call to filesystem
112    * sync.
113    */
114   void postSync(final long timeInNanos, final int handlerSyncs);
115 
116   static class Base implements WALActionsListener {
117     @Override
118     public void preLogRoll(Path oldPath, Path newPath) throws IOException {}
119 
120     @Override
121     public void postLogRoll(Path oldPath, Path newPath) throws IOException {}
122 
123     @Override
124     public void preLogArchive(Path oldPath, Path newPath) throws IOException {}
125 
126     @Override
127     public void postLogArchive(Path oldPath, Path newPath) throws IOException {}
128 
129     @Override
130     public void logRollRequested() {}
131 
132     @Override
133     public void logCloseRequested() {}
134 
135     @Override
136     public void visitLogEntryBeforeWrite(HRegionInfo info, WALKey logKey, WALEdit logEdit) {}
137 
138     @Override
139     public void visitLogEntryBeforeWrite(HTableDescriptor htd, WALKey logKey, WALEdit logEdit) {}
140 
141     @Override
142     public void postAppend(final long entryLen, final long elapsedTimeMillis) {}
143 
144     @Override
145     public void postSync(final long timeInNanos, final int handlerSyncs) {}
146   }
147 }