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SimpleRetryPolicy.java
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SimpleRetryPolicy.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
*
* 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.retry.policy;
import java.util.Collections;
import java.util.Map;
import org.springframework.classify.BinaryExceptionClassifier;
import org.springframework.retry.RetryContext;
import org.springframework.retry.RetryPolicy;
import org.springframework.retry.context.RetryContextSupport;
import org.springframework.util.ClassUtils;
/**
*
* Simple retry policy that retries a fixed number of times for a set of named
* exceptions (and subclasses). The number of attempts includes the initial try,
* so e.g.
*
* <pre>
* retryTemplate = new RetryTemplate(new SimpleRetryPolicy(3));
* retryTemplate.execute(callback);
* </pre>
*
* will execute the callback at least once, and as many as 3 times.
*
* @author Dave Syer
* @author Rob Harrop
* @author Gary Russell
*
*/
public class SimpleRetryPolicy implements RetryPolicy {
/**
* The default limit to the number of attempts for a new policy.
*/
public final static int DEFAULT_MAX_ATTEMPTS = 3;
private volatile int maxAttempts;
private BinaryExceptionClassifier retryableClassifier = new BinaryExceptionClassifier(false);
/**
* Create a {@link SimpleRetryPolicy} with the default number of retry
* attempts.
*/
public SimpleRetryPolicy() {
this(DEFAULT_MAX_ATTEMPTS, Collections
.<Class<? extends Throwable>, Boolean> singletonMap(Exception.class, true));
}
/**
* Create a {@link SimpleRetryPolicy} with the specified number of retry
* attempts.
*
* @param maxAttempts the maximum number of attempts
* @param retryableExceptions the map of exceptions that are retryable
*/
public SimpleRetryPolicy(int maxAttempts, Map<Class<? extends Throwable>, Boolean> retryableExceptions) {
this(maxAttempts, retryableExceptions, false);
}
/**
* Create a {@link SimpleRetryPolicy} with the specified number of retry
* attempts. If traverseCauses is true, the exception causes will be traversed until
* a match is found.
*
* @param maxAttempts the maximum number of attempts
* @param retryableExceptions the map of exceptions that are retryable
* @param traverseCauses is this clause traversable
*/
public SimpleRetryPolicy(int maxAttempts, Map<Class<? extends Throwable>, Boolean> retryableExceptions,
boolean traverseCauses) {
super();
this.maxAttempts = maxAttempts;
this.retryableClassifier = new BinaryExceptionClassifier(retryableExceptions);
this.retryableClassifier.setTraverseCauses(traverseCauses);
}
/**
* Set the number of attempts before retries are exhausted. Includes the initial
* attempt before the retries begin so, generally, will be {@code >= 1}. For example
* setting this property to 3 means 3 attempts total (initial + 2 retries).
*
* @param maxAttempts the maximum number of attempts including the initial attempt.
*/
public void setMaxAttempts(int maxAttempts) {
this.maxAttempts = maxAttempts;
}
/**
* The maximum number of attempts before failure.
*
* @return the maximum number of attempts
*/
public int getMaxAttempts() {
return this.maxAttempts;
}
/**
* Test for retryable operation based on the status.
*
* @see org.springframework.retry.RetryPolicy#canRetry(org.springframework.retry.RetryContext)
*
* @return true if the last exception was retryable and the number of
* attempts so far is less than the limit.
*/
@Override
public boolean canRetry(RetryContext context) {
Throwable t = context.getLastThrowable();
return (t == null || retryForException(t)) && context.getRetryCount() < maxAttempts;
}
/**
* @see org.springframework.retry.RetryPolicy#close(RetryContext)
*/
@Override
public void close(RetryContext status) {
}
/**
* Update the status with another attempted retry and the latest exception.
*
* @see RetryPolicy#registerThrowable(RetryContext, Throwable)
*/
@Override
public void registerThrowable(RetryContext context, Throwable throwable) {
SimpleRetryContext simpleContext = ((SimpleRetryContext) context);
simpleContext.registerThrowable(throwable);
}
/**
* Get a status object that can be used to track the current operation
* according to this policy. Has to be aware of the latest exception and the
* number of attempts.
*
* @see org.springframework.retry.RetryPolicy#open(RetryContext)
*/
@Override
public RetryContext open(RetryContext parent) {
return new SimpleRetryContext(parent);
}
@SuppressWarnings("serial")
private static class SimpleRetryContext extends RetryContextSupport {
public SimpleRetryContext(RetryContext parent) {
super(parent);
}
}
/**
* Delegates to an exception classifier.
*
* @param ex
* @return true if this exception or its ancestors have been registered as
* retryable.
*/
private boolean retryForException(Throwable ex) {
return retryableClassifier.classify(ex);
}
@Override
public String toString() {
return ClassUtils.getShortName(getClass()) + "[maxAttempts=" + maxAttempts + "]";
}
}