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Source code
001/*
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements.  See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership.  The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License.  You may obtain a copy of the License at
009 *
010 *   http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing,
013 * software distributed under the License is distributed on an
014 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
015 * KIND, either express or implied.  See the License for the
016 * specific language governing permissions and limitations
017 * under the License.
018 */
019package org.apache.reef.io.data.loading.api;
020
021import org.apache.hadoop.mapred.InputSplit;
022import org.apache.reef.annotations.Unstable;
023import org.apache.reef.annotations.audience.DriverSide;
024import org.apache.reef.driver.catalog.NodeDescriptor;
025import org.apache.reef.io.data.loading.impl.NumberedSplit;
026
027/**
028 * Interface that tracks the mapping between evaluators and the data partitions
029 * assigned to those evaluators. Its part of the implementation of a
030 * {@link org.apache.reef.io.data.loading.api.DataLoadingService} that uses the
031 * Hadoop {@link org.apache.hadoop.mapred.InputFormat} to partition the data and
032 * request resources accordingly
033 *
034 * @param <V>
035 */
036@DriverSide
037@Unstable
038public interface EvaluatorToPartitionStrategy<V extends InputSplit> {
039
040  /**
041   * Returns an input split for the given evaluator.
042   * @param nodeDescriptor
043   *      the node descriptor where the evaluator is running on
044   * @param evalId
045   *      the evaluator id
046   * @return
047   *      the numberedSplit
048   * @throws RuntimeException if no split could be allocated
049   */
050  NumberedSplit<V> getInputSplit(NodeDescriptor nodeDescriptor, String evalId);
051
052  /**
053   * Returns the total number of splits computed in this strategy.
054   * @return
055   *  the number of splits
056   */
057  int getNumberOfSplits();
058
059}