nblair.pipeline.PipelineStepCallable.java Source code

Introduction

Here is the source code for nblair.pipeline.PipelineStepCallable.java

Source

/**
 *    Copyright 2012, Board of Regents of the University of Wisconsin System
 *
 *    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
 *
 *        http://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 nblair.pipeline;

import java.util.concurrent.Callable;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

/**
 * Abstract supertype for {@link Callable}s used in the {@link AbstractParallelPipelineStep}s.
 * 
 * @author Nicholas Blair
 */
public abstract class PipelineStepCallable<W> implements Callable<W> {

    protected final Log log = LogFactory.getLog(this.getClass());

    private final String stepName;
    private final PipelineStep<W> nextStep;
    private final W workUnit;

    /**
     * @param nextStep
     */
    public PipelineStepCallable(String stepName, PipelineStep<W> nextStep, W workUnit) {
        this.stepName = stepName;
        this.nextStep = nextStep;
        this.workUnit = workUnit;
    }

    /**
     * Updates the thread name, invokes {@link #doWork(Object)}, then calls {@link PipelineStep#accept(Object)} on
     * the next step.
     * Any {@link Exception} thrown by {@link #doWork(Object)} will be caught, logged, and rethrown.
     * 
     *  (non-Javadoc)
     * @see java.util.concurrent.Callable#call()
     * @return the workunit
     */
    @Override
    public final W call() throws Exception {
        final String originalThreadName = Thread.currentThread().getName();
        try {
            Thread.currentThread().setName(originalThreadName + "-" + stepName + "-" + idWorkUnit(workUnit));
            W result = doWork(workUnit);
            nextStep.accept(workUnit);
            return result;
        } catch (Exception e) {
            log.error(
                    "caught Exception in SyncStepCallable '" + stepName + "' for workUnit " + idWorkUnit(workUnit),
                    e);
            throw (e);
        } finally {
            Thread.currentThread().setName(originalThreadName);
        }
    }

    /**
     * 
     * @param workUnit
     * @return a {@link String} to 'uniquely' identify the workunit
     */
    public abstract String idWorkUnit(W workUnit);

    /**
     * Perform the actual work on the workunit.
     * 
     * @param workUnit
     * @return the workUnit
     * @throws Exception
     */
    public abstract W doWork(W workUnit) throws Exception;
}