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;
020
021import org.apache.reef.annotations.Unstable;
022import org.apache.reef.exception.evaluator.ServiceException;
023
024/**
025 * Similar to {@link Iterable}, this is an interface for objects that can return
026 * {@link Accumulator}s.
027 *
028 * @param <T> The type accumulated.
029 */
030@Unstable
031public interface Accumulable<T> {
032  /**
033   * Returns a new Accumulator.
034   *
035   * @return the new {@link Accumulator}
036   * @throws ServiceException
037   */
038  Accumulator<T> accumulator() throws ServiceException;
039}