runtime/executor/src/main/java/org/apache/nemo/runtime/executor/data/partitioner/Partitioner.java

/*
 * 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
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 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
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 */
package org.apache.nemo.runtime.executor.data.partitioner;

import java.io.Serializable;

/**
 * This interface represents the way of partitioning output data from a source task.
 * It takes an element and designates key of {@link org.apache.nemo.runtime.executor.data.partition.Partition}
 * to write the element, according to the number of destination tasks, the key of each element, etc.
 * @param <K> the key type of the partition to write.
 */
public interface Partitioner<K extends Serializable> {

  /**
   * Divides the output data from a task into multiple blocks.
   *
   * @param element        the output element from a source task.
   * @return the key of the partition in the block to write the element.
   */
   K partition(Object element);
}