001/*
002 * Copyright 2006-2007 the original author or authors.
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 *      https://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016
017package org.springframework.batch.core.partition;
018
019import org.springframework.batch.core.JobExecution;
020import org.springframework.batch.core.JobExecutionException;
021import org.springframework.batch.core.StepExecution;
022
023import java.util.Set;
024
025/**
026 * Strategy interface for generating input contexts for a partitioned step
027 * execution independent from the fabric they are going to run on.
028 * 
029 * @author Dave Syer
030 * @since 2.0
031 */
032public interface StepExecutionSplitter {
033
034        /**
035         * The name of the step configuration that will be executed remotely. Remote
036         * workers are going to execute a the same step for each execution context
037         * in the partition.
038         * @return the name of the step that will execute the business logic
039         */
040        String getStepName();
041
042        /**
043         * Partition the provided {@link StepExecution} into a set of parallel
044         * executable instances with the same parent {@link JobExecution}. The grid
045         * size will be treated as a hint for the size of the collection to be
046         * returned. It may or may not correspond to the physical size of an
047         * execution grid.<br>
048         * <br>
049         * 
050         * On a restart clients of the {@link StepExecutionSplitter} should expect
051         * it to reconstitute the state of the last failed execution and only return
052         * those executions that need to be restarted. Thus the grid size hint will
053         * be ignored on a restart.
054         * 
055         * @param stepExecution the {@link StepExecution} to be partitioned.
056         * @param gridSize a hint for the splitter if the size of the grid is known
057         * @return a set of {@link StepExecution} instances for remote processing
058         * 
059         * @throws JobExecutionException if the split cannot be made
060         */
061        Set<StepExecution> split(StepExecution stepExecution, int gridSize) throws JobExecutionException;
062
063}