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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.codec.prefixtree.decode.timestamp;
20  
21  import org.apache.hadoop.classification.InterfaceAudience;
22  import org.apache.hadoop.hbase.codec.prefixtree.PrefixTreeBlockMeta;
23  import org.apache.hadoop.hbase.util.vint.UFIntTool;
24  
25  /**
26   * Given a block and its blockMeta, this will decode the MvccVersion for the i-th Cell in the block.
27   */
28  @InterfaceAudience.Private
29  public class MvccVersionDecoder {
30  
31    protected PrefixTreeBlockMeta blockMeta;
32    protected byte[] block;
33  
34  
35    /************** construct ***********************/
36  
37    public MvccVersionDecoder() {
38    }
39  
40    public void initOnBlock(PrefixTreeBlockMeta blockMeta, byte[] block) {
41      this.block = block;
42      this.blockMeta = blockMeta;
43    }
44  
45  
46    /************** methods *************************/
47  
48    public long getMvccVersion(int index) {
49      if (blockMeta.getMvccVersionIndexWidth() == 0) {//all mvccVersions in the block were identical
50        return blockMeta.getMinMvccVersion();
51      }
52      int startIndex = blockMeta.getAbsoluteMvccVersionOffset()
53          + blockMeta.getMvccVersionDeltaWidth() * index;
54      long delta = UFIntTool.fromBytes(block, startIndex, blockMeta.getMvccVersionDeltaWidth());
55      return blockMeta.getMinMvccVersion() + delta;
56    }
57  }