org.springframework.batch.core.step.item.ChunkOrientedTasklet.java Source code

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Here is the source code for org.springframework.batch.core.step.item.ChunkOrientedTasklet.java

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/*
 * Copyright 2006-2013 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.batch.core.step.item;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.batch.core.StepContribution;
import org.springframework.batch.core.scope.context.ChunkContext;
import org.springframework.batch.core.step.tasklet.Tasklet;
import org.springframework.batch.repeat.RepeatStatus;

/**
 * A {@link Tasklet} implementing variations on read-process-write item
 * handling.
 *
 * @author Dave Syer
 *
 * @param <I> input item type
 */
public class ChunkOrientedTasklet<I> implements Tasklet {

    private static final String INPUTS_KEY = "INPUTS";

    private final ChunkProcessor<I> chunkProcessor;

    private final ChunkProvider<I> chunkProvider;

    private boolean buffering = true;

    private static Log logger = LogFactory.getLog(ChunkOrientedTasklet.class);

    public ChunkOrientedTasklet(ChunkProvider<I> chunkProvider, ChunkProcessor<I> chunkProcessor) {
        this.chunkProvider = chunkProvider;
        this.chunkProcessor = chunkProcessor;
    }

    /**
     * Flag to indicate that items should be buffered once read. Defaults to
     * true, which is appropriate for forward-only, non-transactional item
     * readers. Main (or only) use case for setting this flag to false is a
     * transactional JMS item reader.
     *
     * @param buffering indicator
     */
    public void setBuffering(boolean buffering) {
        this.buffering = buffering;
    }

    @Override
    public RepeatStatus execute(StepContribution contribution, ChunkContext chunkContext) throws Exception {

        @SuppressWarnings("unchecked")
        Chunk<I> inputs = (Chunk<I>) chunkContext.getAttribute(INPUTS_KEY);
        if (inputs == null) {
            inputs = chunkProvider.provide(contribution);
            if (buffering) {
                chunkContext.setAttribute(INPUTS_KEY, inputs);
            }
        }

        chunkProcessor.process(contribution, inputs);
        chunkProvider.postProcess(contribution, inputs);

        // Allow a message coming back from the processor to say that we
        // are not done yet
        if (inputs.isBusy()) {
            logger.debug("Inputs still busy");
            return RepeatStatus.CONTINUABLE;
        }

        chunkContext.removeAttribute(INPUTS_KEY);
        chunkContext.setComplete();

        if (logger.isDebugEnabled()) {
            logger.debug("Inputs not busy, ended: " + inputs.isEnd());
        }
        return RepeatStatus.continueIf(!inputs.isEnd());

    }

}