org.springframework.transaction.interceptor.AbstractFallbackTransactionAttributeSource Maven / Gradle / Ivy
/*
* Copyright 2002-2005 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.transaction.interceptor;
import java.lang.reflect.Method;
import java.util.Collection;
import java.util.HashMap;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.aop.support.AopUtils;
/**
* Abstract implementation of TransactionAttributeSource that caches attributes
* for methods, and implements fallback policy of 1. most specific method;
* 2. target class attribute; 3. declaring method; 4. declaring class.
*
* Defaults to using class's transaction attribute if none is associated
* with the target method. Any transaction attribute associated with the
* target method completely overrides a class transaction attribute.
*
*
This implementation caches attributes by method after they are first used.
* If it's ever desirable to allow dynamic changing of transaction attributes
* (unlikely) caching could be made configurable. Caching is desirable because
* of the cost of evaluating rollback rules.
*
* @author Rod Johnson
* @author Juergen Hoeller
* @since 1.1
*/
public abstract class AbstractFallbackTransactionAttributeSource implements TransactionAttributeSource {
/**
* Canonical value held in cache to indicate no transaction attribute was
* found for this method, and we don't need to look again
*/
private final static Object NULL_TRANSACTION_ATTRIBUTE = new Object();
protected final Log logger = LogFactory.getLog(getClass());
/**
* Cache of TransactionAttributes, keyed by Method and target class
*/
private Map cache = new HashMap();
/**
* Return the transaction attribute for this method invocation.
* Defaults to the class's transaction attribute if no method
* attribute is found
* @param method method for the current invocation. Can't be null
* @param targetClass target class for this invocation. May be null.
* @return TransactionAttribute for this method, or null if the method is non-transactional
*/
public final TransactionAttribute getTransactionAttribute(Method method, Class targetClass) {
// First, see if we have a cached value
Object cacheKey = getCacheKey(method, targetClass);
Object cached = this.cache.get(cacheKey);
if (cached != null) {
// Value will either be canonical value indicating there is no transaction attribute,
// or an actual transaction attribute
if (cached == NULL_TRANSACTION_ATTRIBUTE) {
return null;
}
else {
return (TransactionAttribute) cached;
}
}
else {
// We need to work it out
TransactionAttribute txAtt = computeTransactionAttribute(method, targetClass);
// Put it in the cache
if (txAtt == null) {
this.cache.put(cacheKey, NULL_TRANSACTION_ATTRIBUTE);
}
else {
this.cache.put(cacheKey, txAtt);
}
return txAtt;
}
}
/**
* Determine a cache key for the given method and target class.
* Must not produce same key for overloaded methods.
* Must produce same key for different instances of the same method.
* @param method the method
* @param targetClass the target class (may be null)
* @return the cache key
*/
protected Object getCacheKey(Method method, Class targetClass) {
// TODO this works fine, but could consider making it faster in future:
// Method.toString() is relatively (although not disastrously) slow.
return targetClass + "." + method;
}
/**
* Same return as getTransactionAttribute method, but doesn't cache the result.
* getTransactionAttribute is a caching decorator for this method.
*/
private TransactionAttribute computeTransactionAttribute(Method method, Class targetClass) {
// The method may be on an interface, but we need attributes from the target class.
// The AopUtils class provides a convenience method for this. If the target class
// is null, the method will be unchanged.
Method specificMethod = AopUtils.getMostSpecificMethod(method, targetClass);
// First try is the method in the target class.
TransactionAttribute txAtt = findTransactionAttribute(findAllAttributes(specificMethod));
if (txAtt != null) {
return txAtt;
}
// Second try is the transaction attribute on the target class.
txAtt = findTransactionAttribute(findAllAttributes(specificMethod.getDeclaringClass()));
if (txAtt != null) {
return txAtt;
}
if (specificMethod != method ) {
// Fallback is to look at the original method.
txAtt = findTransactionAttribute(findAllAttributes(method));
if (txAtt != null) {
return txAtt;
}
// Last fallback is the class of the original method.
return findTransactionAttribute(findAllAttributes(method.getDeclaringClass()));
}
return null;
}
/**
* Subclasses should implement this to return all attributes for this method.
* We need all because of the need to analyze rollback rules.
* @param method the method to retrieve attributes for
* @return all attributes associated with this method.
* May return null.
*/
protected abstract Collection findAllAttributes(Method method);
/**
* Subclasses should implement this to return all attributes for this class.
* @param clazz class to retrieve attributes for
* @return all attributes associated with this class.
* May return null.
*/
protected abstract Collection findAllAttributes(Class clazz);
/**
* Return the transaction attribute, given this set of attributes
* attached to a method or class.
*
Protected rather than private as subclasses may want to customize
* how this is done: for example, returning a TransactionAttribute
* affected by the values of other attributes.
*
This implementation takes into account RollbackRuleAttributes,
* if the TransactionAttribute is a RuleBasedTransactionAttribute.
* Return null if it's not transactional.
* @param atts attributes attached to a method or class. May
* be null, in which case a null TransactionAttribute will be returned.
* @return TransactionAttribute configured transaction attribute, or null
* if none was found
*/
protected TransactionAttribute findTransactionAttribute(Collection atts) {
if (atts == null) {
return null;
}
TransactionAttribute txAttribute = null;
// Check whether there is a transaction attribute.
for (Iterator itr = atts.iterator(); itr.hasNext() && txAttribute == null; ) {
Object att = itr.next();
if (att instanceof TransactionAttribute) {
txAttribute = (TransactionAttribute) att;
}
}
// Check if we have a RuleBasedTransactionAttribute.
if (txAttribute instanceof RuleBasedTransactionAttribute) {
RuleBasedTransactionAttribute rbta = (RuleBasedTransactionAttribute) txAttribute;
// We really want value: bit of a hack.
List rollbackRules = new LinkedList();
for (Iterator it = atts.iterator(); it.hasNext(); ) {
Object att = it.next();
if (att instanceof RollbackRuleAttribute) {
if (logger.isDebugEnabled()) {
logger.debug("Found rollback rule: " + att);
}
rollbackRules.add(att);
}
}
// Repeatedly setting this isn't elegant, but it works.
rbta.setRollbackRules(rollbackRules);
}
return txAttribute;
}
}