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, software
013     * distributed under the License is distributed on an "AS IS" BASIS,
014     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015     * See the License for the specific language governing permissions and
016     * limitations under the License.
017     */
018    package org.apache.hadoop.yarn.api.records;
019    
020    import java.util.List;
021    import java.util.Set;
022    
023    import org.apache.hadoop.classification.InterfaceAudience.Private;
024    import org.apache.hadoop.classification.InterfaceAudience.Public;
025    import org.apache.hadoop.classification.InterfaceStability.Evolving;
026    import org.apache.hadoop.classification.InterfaceStability.Unstable;
027    import org.apache.hadoop.yarn.api.protocolrecords.AllocateRequest;
028    import org.apache.hadoop.yarn.util.Records;
029    
030    /**
031     * Description of resources requested back by the <code>ResourceManager</code>.
032     * The <code>ApplicationMaster</code> (AM) can satisfy this request according
033     * to its own priorities to prevent containers from being forcibly killed by
034     * the platform.
035     * @see PreemptionMessage
036     */
037    @Public
038    @Evolving
039    public abstract class PreemptionContract {
040    
041      @Private
042      @Unstable
043      public static PreemptionContract newInstance(
044          List<PreemptionResourceRequest> req, Set<PreemptionContainer> containers) {
045        PreemptionContract contract = Records.newRecord(PreemptionContract.class);
046        contract.setResourceRequest(req);
047        contract.setContainers(containers);
048        return contract;
049      }
050    
051      /**
052       * If the AM releases resources matching these requests, then the {@link
053       * PreemptionContainer}s enumerated in {@link #getContainers()} should not be
054       * evicted from the cluster. Due to delays in propagating cluster state and
055       * sending these messages, there are conditions where satisfied contracts may
056       * not prevent the platform from killing containers.
057       * @return List of {@link PreemptionResourceRequest} to update the
058       * <code>ApplicationMaster</code> about resources requested back by the
059       * <code>ResourceManager</code>.
060       * @see AllocateRequest#setAskList(List)
061       */
062      @Public
063      @Evolving
064      public abstract List<PreemptionResourceRequest> getResourceRequest();
065    
066      @Private
067      @Unstable
068      public abstract void setResourceRequest(List<PreemptionResourceRequest> req);
069    
070      /**
071       * Assign the set of {@link PreemptionContainer} specifying which containers
072       * owned by the <code>ApplicationMaster</code> that may be reclaimed by the
073       * <code>ResourceManager</code>. If the AM prefers a different set of
074       * containers, then it may checkpoint or kill containers matching the
075       * description in {@link #getResourceRequest}.
076       * @return Set of containers at risk if the contract is not met.
077       */
078      @Public
079      @Evolving
080      public abstract Set<PreemptionContainer> getContainers();
081    
082    
083      @Private
084      @Unstable
085      public abstract void setContainers(Set<PreemptionContainer> containers);
086    
087    }