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.network.group.api.operators;
020
021import org.apache.reef.exception.evaluator.NetworkException;
022import org.apache.reef.wake.Identifier;
023
024import java.util.List;
025
026/**
027 * MPI AllGather Operator.
028 * <p>
029 * Each task applies this operator on an element of type T. The result will be
030 * a list of elements constructed using the elements all-gathered at each
031 * task.
032 */
033public interface AllGather<T> extends GroupCommOperator {
034
035  /**
036   * Apply the operation on element.
037   *
038   * @return List of all elements on which the operation was applied using default order
039   */
040  List<T> apply(T element) throws NetworkException,
041      InterruptedException;
042
043  /**
044   * Apply the operation on element.
045   *
046   * @return List of all elements on which the operation was applied using order specified
047   */
048  List<T> apply(T element, List<? extends Identifier> order)
049      throws NetworkException, InterruptedException;
050}