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HashPartitionerFactory 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  package org.apache.giraph.partition;
19  
20  import org.apache.hadoop.io.Writable;
21  import org.apache.hadoop.io.WritableComparable;
22  
23  /**
24   * Divides the vertices into partitions by their hash code using a simple
25   * round-robin hash for great balancing if given a random hash code.
26   *
27   * @param <I> Vertex id value
28   * @param <V> Vertex value
29   * @param <E> Edge value
30   */
31  public class HashPartitionerFactory<I extends WritableComparable,
32      V extends Writable, E extends Writable>
33      extends GraphPartitionerFactory<I, V, E> {
34  
35    @Override
36    public int getPartition(I id, int partitionCount, int workerCount) {
37      return Math.abs(id.hashCode() % partitionCount);
38    }
39  
40    @Override
41    public int getWorker(int partition, int partitionCount, int workerCount) {
42      return partition % workerCount;
43    }
44  }