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MasterGraphPartitioner 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.partition;
20  
21  import java.util.Collection;
22  
23  import org.apache.hadoop.io.Writable;
24  import org.apache.hadoop.io.WritableComparable;
25  import org.apache.giraph.worker.WorkerInfo;
26  
27  /**
28   * Determines how to divide the graph into partitions, how to manipulate
29   * partitions and then how to assign those partitions to workers.
30   *
31   * @param <I> Vertex index value
32   * @param <V> Vertex value
33   * @param <E> Edge value
34   */
35  @SuppressWarnings("rawtypes")
36  public interface MasterGraphPartitioner<I extends WritableComparable,
37      V extends Writable, E extends Writable> {
38    /**
39     * Set some initial partition owners for the graph. Guaranteed to be called
40     * prior to the graph being loaded (initial or restart).
41     *
42     * @param availableWorkerInfos Workers available for partition assignment
43     * @param maxWorkers Maximum number of workers
44     * @return Collection of generated partition owners.
45     */
46    Collection<PartitionOwner> createInitialPartitionOwners(
47        Collection<WorkerInfo> availableWorkerInfos, int maxWorkers);
48  
49    /**
50     * Sets partition owners for the graph.
51     * Used then loading from checkpoint.
52     * @param partitionOwners assigned partition owners.
53     */
54    void setPartitionOwners(Collection<PartitionOwner> partitionOwners);
55  
56    /**
57     * After the worker stats have been merged to a single list, the master can
58     * use this information to send commands to the workers for any
59     * {@link Partition} changes. This protocol is specific to the
60     * {@link MasterGraphPartitioner} implementation.
61     *
62     * @param allPartitionStatsList All partition stats from all workers.
63     * @param availableWorkers Workers available for partition assignment
64     * @param maxWorkers Maximum number of workers
65     * @param superstep Partition owners will be set for this superstep
66     * @return Collection of {@link PartitionOwner} objects that changed from
67     *         the previous superstep, empty list if no change.
68     */
69    Collection<PartitionOwner> generateChangedPartitionOwners(
70        Collection<PartitionStats> allPartitionStatsList,
71        Collection<WorkerInfo> availableWorkers,
72        int maxWorkers,
73        long superstep);
74  
75    /**
76     * Get current partition owners at this time.
77     *
78     * @return Collection of current {@link PartitionOwner} objects
79     */
80    Collection<PartitionOwner> getCurrentPartitionOwners();
81  
82    /**
83     * Instantiate the {@link PartitionStats} implementation used to read the
84     * worker stats
85     *
86     * @return Instantiated {@link PartitionStats} object
87     */
88    PartitionStats createPartitionStats();
89  }