content: /*
   * Licensed to the Apache Software Foundation (ASF) under one
   * or more contributor license agreements.  See the NOTICE file
   * distributed with this work for additional information
   * regarding copyright ownership.  The ASF licenses this file
   * to you under the Apache License, Version 2.0 (the
   * "License"); you may not use this file except in compliance
   * with the License.  You may obtain a copy of the License at
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing,
   * software distributed under the License is distributed on an
   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
   * KIND, either express or implied.  See the License for the
   * specific language governing permissions and limitations
   * under the License.
   */
  
  package com.aliyun.odps.graph;
  
  import java.io.IOException;
  
  import com.aliyun.odps.conf.Configuration;
  import com.aliyun.odps.io.WritableComparable;
  
  /**
   * 分区类，决定 {@link Vertex} 由哪个 Worker 负责.
   *
   * 可以通过{@link GraphJob#setPartitionerClass(Class)}方法自定义分区类，否则使用默认的分区类
   * HashPartitioner
   *
   * @param <VERTEX_ID>
   *     Vertex ID 类型
   */
  @SuppressWarnings({"rawtypes"})
  public abstract class Partitioner<VERTEX_ID extends WritableComparable> {
  
    /**
     * 此方法会在分区类对象被new出来后立即调用，传入运行时的{@link JobConf}对象
     *
     * @param conf
     *     运行时的JobConf对象
     */
    public void configure(Configuration conf) throws IOException {
    }
  
    /**
     * 给定 Vertex ID 和 Worker 个数，计算该 Vertex 由哪个 Worker 负责.
     *
     * <p>
     * 此方法通常实现为对 Vertex ID 的某个哈希函数，默认的分区类 HashPartitioner
     * </p>
     *
     * @param vertexId
     *     待分区的 Vertex ID
     * @param numWorkers
     *     分区数，既 Worker 个数
     * @return 分区序号，必须是 0 到 numWorkers-1
     */
    public abstract int getPartition(VERTEX_ID vertexId, int numWorkers);
  
  }
  