/*
* 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.retry.interceptor;
import java.util.Arrays;
import org.aopalliance.intercept.MethodInterceptor;
import org.aopalliance.intercept.MethodInvocation;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.retry.RecoveryCallback;
import org.springframework.retry.RetryCallback;
import org.springframework.retry.RetryContext;
import org.springframework.retry.RetryOperations;
import org.springframework.retry.RetryState;
import org.springframework.retry.policy.NeverRetryPolicy;
import org.springframework.retry.support.DefaultRetryState;
import org.springframework.retry.support.RetryTemplate;
import org.springframework.util.Assert;
import org.springframework.util.ObjectUtils;
/**
* A {@link MethodInterceptor} that can be used to automatically retry calls to a method
* on a service if it fails. The argument to the service method is treated as an item to
* be remembered in case the call fails. So the retry operation is stateful, and the item
* that failed is tracked by its unique key (via {@link MethodArgumentsKeyGenerator})
* until the retry is exhausted, at which point the {@link MethodInvocationRecoverer} is
* called.<br/>
*
* The main use case for this is where the service is transactional, via a transaction
* interceptor on the interceptor chain. In this case the retry (and recovery on
* exhausted) always happens in a new transaction.<br/>
*
* The injected {@link RetryOperations} is used to control the number of retries. By
* default it will retry a fixed number of times, according to the defaults in
* {@link RetryTemplate}.<br/>
*
* @author Dave Syer
*/
public class StatefulRetryOperationsInterceptor implements MethodInterceptor {
private transient final Log logger = LogFactory.getLog(getClass());
private MethodArgumentsKeyGenerator keyGenerator;
private MethodInvocationRecoverer<?> recoverer;
private NewMethodArgumentsIdentifier newMethodArgumentsIdentifier;
private RetryOperations retryOperations;
public StatefulRetryOperationsInterceptor() {
RetryTemplate retryTemplate = new RetryTemplate();
retryTemplate.setRetryPolicy(new NeverRetryPolicy());
retryOperations = retryTemplate;
}
public void setRetryOperations(RetryOperations retryTemplate) {
Assert.notNull(retryTemplate, "'retryOperations' cannot be null.");
this.retryOperations = retryTemplate;
}
/**
* Public setter for the {@link MethodInvocationRecoverer} to use if the retry is
* exhausted. The recoverer should be able to return an object of the same type as the
* target object because its return value will be used to return to the caller in the
* case of a recovery.
* @param recoverer the {@link MethodInvocationRecoverer} to set
*/
public void setRecoverer(MethodInvocationRecoverer<?> recoverer) {
this.recoverer = recoverer;
}
public void setKeyGenerator(MethodArgumentsKeyGenerator keyGenerator) {
this.keyGenerator = keyGenerator;
}
/**
* Public setter for the {@link NewMethodArgumentsIdentifier}. Only set this if the
* arguments to the intercepted method can be inspected to find out if they have never
* been processed before.
* @param newMethodArgumentsIdentifier the {@link NewMethodArgumentsIdentifier} to set
*/
public void setNewItemIdentifier(NewMethodArgumentsIdentifier newMethodArgumentsIdentifier) {
this.newMethodArgumentsIdentifier = newMethodArgumentsIdentifier;
}
/**
* Wrap the method invocation in a stateful retry with the policy and other helpers
* provided. If there is a failure the exception will generally be re-thrown. The only
* time it is not re-thrown is when retry is exhausted and the recovery path is taken
* (though the {@link MethodInvocationRecoverer} provided if there is one). In that
* case the value returned from the method invocation will be the value returned by
* the recoverer (so the return type for that should be the same as the intercepted
* method).
* @see org.aopalliance.intercept.MethodInterceptor#invoke(org.aopalliance.intercept.MethodInvocation)
* @see MethodInvocationRecoverer#recover(Object[], Throwable)
*
*/
public Object invoke(final MethodInvocation invocation) throws Throwable {
if (logger.isDebugEnabled()) {
logger.debug("Executing proxied method in stateful retry: "
+ invocation.getStaticPart() + "("
+ ObjectUtils.getIdentityHexString(invocation) + ")");
}
Object[] args = invocation.getArguments();
Assert.state(args.length > 0, "Stateful retry applied to method that takes no arguments: "
+ invocation.getStaticPart());
Object arg = args;
if (args.length == 1) {
arg = args[0];
}
final Object item = arg;
RetryState retryState = new DefaultRetryState(
keyGenerator != null ? keyGenerator.getKey(args) : item,
newMethodArgumentsIdentifier != null && newMethodArgumentsIdentifier.isNew(args)
);
Object result = retryOperations.execute(new MethodInvocationRetryCallback(invocation),
recoverer != null ? new ItemRecovererCallback(args, recoverer) : null, retryState);
if (logger.isDebugEnabled()) {
logger.debug("Exiting proxied method in stateful retry with result: (" + result + ")");
}
return result;
}
/**
* @author Dave Syer
*
*/
private static final class MethodInvocationRetryCallback implements RetryCallback<Object, Throwable> {
private final MethodInvocation invocation;
private MethodInvocationRetryCallback(MethodInvocation invocation) {
this.invocation = invocation;
}
public Object doWithRetry(RetryContext context) throws Exception {
try {
return invocation.proceed();
}
catch (Exception e) {
throw e;
}
catch (Error e) {
throw e;
}
catch (Throwable e) {
throw new IllegalStateException(e);
}
}
}
/**
* @author Dave Syer
*
*/
private static final class ItemRecovererCallback implements RecoveryCallback<Object> {
private final Object[] args;
private final MethodInvocationRecoverer<?> recoverer;
/**
* @param args the item that failed.
*/
private ItemRecovererCallback(Object[] args, MethodInvocationRecoverer<?> recoverer) {
this.args = Arrays.asList(args).toArray();
this.recoverer = recoverer;
}
public Object recover(RetryContext context) {
return recoverer.recover(args, context.getLastThrowable());
}
}
}