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 */
018package org.apache.hadoop.mapreduce.task.annotation;
019
020import java.lang.annotation.Documented;
021import java.lang.annotation.ElementType;
022import java.lang.annotation.Retention;
023import java.lang.annotation.RetentionPolicy;
024import java.lang.annotation.Target;
025
026import org.apache.hadoop.classification.InterfaceAudience;
027import org.apache.hadoop.classification.InterfaceStability;
028
029/**
030 * Contract representing to the framework that the task can be safely preempted
031 * and restarted between invocations of the user-defined function.
032 *
033 * This is often true when the result of a function does not rely on state
034 * derived from previous elements in the record stream, but the guarantee is
035 * left as an exercise to the implementor.
036 */
037@Documented
038@Target(ElementType.TYPE)
039@Retention(RetentionPolicy.RUNTIME)
040@InterfaceAudience.Public
041@InterfaceStability.Evolving
042public @interface Checkpointable { }