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.runtime.common.driver;
020
021import org.apache.reef.annotations.Unstable;
022import org.apache.reef.annotations.audience.DriverSide;
023import org.apache.reef.annotations.audience.Private;
024import org.apache.reef.annotations.audience.RuntimeAuthor;
025
026import java.util.Set;
027
028/**
029 * A interface to preserve evaluators across driver restarts.
030 */
031@DriverSide
032@Private
033@RuntimeAuthor
034@Unstable
035public interface EvaluatorPreserver {
036  /**
037   * Called on driver restart when evaluators are to be recovered.
038   */
039  Set<String> recoverEvaluators();
040
041  /**
042   * Called when an evaluator is to be preserved.
043   */
044  void recordAllocatedEvaluator(final String id);
045
046  /**
047   * Called when an evaluator is to be removed.
048   * @param id
049   */
050  void recordRemovedEvaluator(final String id);
051}