/*
* Copyright 2006-2007 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
*
* 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 org.springframework.batch.core.step.item;
import java.util.Collection;
import org.apache.commons.logging.LogFactory;
import org.apache.commons.logging.Log;
import org.springframework.batch.classify.BinaryExceptionClassifier;
import org.springframework.batch.repeat.RepeatContext;
import org.springframework.batch.repeat.exception.ExceptionHandler;
import org.springframework.batch.repeat.support.RepeatSynchronizationManager;
import org.springframework.batch.retry.RetryCallback;
import org.springframework.batch.retry.RetryContext;
import org.springframework.batch.retry.RetryPolicy;
import org.springframework.batch.retry.listener.RetryListenerSupport;
/**
* An {@link ExceptionHandler} that is aware of the retry context so that it can
* distinguish between a fatal exception and one that can be retried. Delegates
* the actual exception handling to another {@link ExceptionHandler}.
*
* @author Dave Syer
*
*/
public class SimpleRetryExceptionHandler extends RetryListenerSupport implements ExceptionHandler {
/**
* Attribute key, whose existence signals an exhausted retry.
*/
private static final String EXHAUSTED = SimpleRetryExceptionHandler.class.getName() + ".RETRY_EXHAUSTED";
private static final Log logger = LogFactory.getLog(SimpleRetryExceptionHandler.class);
final private RetryPolicy retryPolicy;
final private ExceptionHandler exceptionHandler;
final private BinaryExceptionClassifier fatalExceptionClassifier;
/**
* Create an exception handler from its mandatory properties.
*
* @param retryPolicy the retry policy that will be under effect when an
* exception is encountered
* @param exceptionHandler the delegate to use if an exception actually
* needs to be handled
* @param fatalExceptionClasses
*/
public SimpleRetryExceptionHandler(RetryPolicy retryPolicy, ExceptionHandler exceptionHandler, Collection<Class<? extends Throwable>> fatalExceptionClasses) {
this.retryPolicy = retryPolicy;
this.exceptionHandler = exceptionHandler;
this.fatalExceptionClassifier = new BinaryExceptionClassifier(fatalExceptionClasses);
}
/**
* Check if the exception is going to be retried, and veto the handling if
* it is. If retry is exhausted or the exception is on the fatal list, then
* handle using the delegate.
*
* @see ExceptionHandler#handleException(org.springframework.batch.repeat.RepeatContext,
* java.lang.Throwable)
*/
public void handleException(RepeatContext context, Throwable throwable) throws Throwable {
// Only bother to check the delegate exception handler if we know that
// retry is exhausted
if (fatalExceptionClassifier.classify(throwable) || context.hasAttribute(EXHAUSTED)) {
logger.debug("Handled fatal exception");
exceptionHandler.handleException(context, throwable);
}
else {
logger.debug("Handled non-fatal exception", throwable);
}
}
/**
* If retry is exhausted set up some state in the context that can be used
* to signal that the exception should be handled.
*
* @see org.springframework.batch.retry.RetryListener#close(org.springframework.batch.retry.RetryContext,
* org.springframework.batch.retry.RetryCallback, java.lang.Throwable)
*/
public <T> void close(RetryContext context, RetryCallback<T> callback, Throwable throwable) {
if (!retryPolicy.canRetry(context)) {
logger.debug("Marking retry as exhausted: "+context);
getRepeatContext().setAttribute(EXHAUSTED, "true");
}
}
/**
* Get the parent context (the retry is in an inner "chunk" loop and we want
* the exception to be handled at the outer "step" level).
* @return the {@link RepeatContext} that should hold the exhausted flag.
*/
private RepeatContext getRepeatContext() {
RepeatContext context = RepeatSynchronizationManager.getContext();
if (context.getParent() != null) {
return context.getParent();
}
return context;
}
}
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