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LongXorReduce xref
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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.giraph.reducers.impl;
20  
21  import java.io.DataInput;
22  import java.io.DataOutput;
23  import java.io.IOException;
24  import org.apache.giraph.reducers.ReduceSameTypeOperation;
25  import org.apache.hadoop.io.LongWritable;
26  
27  /**
28   * ReduceOperation that XORs (^) values together.
29   */
30  public class LongXorReduce extends ReduceSameTypeOperation<LongWritable> {
31    /**
32     * Long XOR, equivalent to l1 ^ l2
33     */
34    public static final LongXorReduce INSTANCE = new LongXorReduce();
35  
36    /** Constructor used for deserialization only */
37    public LongXorReduce() {
38    }
39  
40    @Override public LongWritable createInitialValue() {
41      return new LongWritable(0L);
42    }
43  
44    @Override public LongWritable reduce(LongWritable curValue,
45        LongWritable valueToReduce) {
46      curValue.set(curValue.get() ^ valueToReduce.get());
47      return curValue;
48    }
49  
50    @Override public void write(DataOutput out) throws IOException {
51    }
52  
53    @Override public void readFields(DataInput in) throws IOException {
54    }
55  }