/*
* Copyright 2002-2008 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.lang.reflect.Modifier;
import java.util.Map;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.core.BridgeMethodResolver;
import org.springframework.core.CollectionFactory;
import org.springframework.core.JdkVersion;
import org.springframework.util.ClassUtils;
import org.springframework.util.ObjectUtils;
/**
* Abstract implementation of {@link TransactionAttributeSource} that caches
* attributes for methods and implements a fallback policy: 1. specific target
* method; 2. target class; 3. declaring method; 4. declaring class/interface.
*
* <p>Defaults to using the target 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.
* If none found on the target class, the interface that the invoked method
* has been called through (in case of a JDK proxy) will be checked.
*
* <p>This implementation caches attributes by method after they are first used.
* If it is ever desirable to allow dynamic changing of transaction attributes
* (which is very 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();
/**
* Logger available to subclasses.
* <p>As this base class is not marked Serializable, the logger will be recreated
* after serialization - provided that the concrete subclass is Serializable.
*/
protected final Log logger = LogFactory.getLog(getClass());
/**
* Cache of TransactionAttributes, keyed by DefaultCacheKey (Method + target Class).
* <p>As this base class is not marked Serializable, the cache will be recreated
* after serialization - provided that the concrete subclass is Serializable.
*/
final Map attributeCache = CollectionFactory.createConcurrentMapIfPossible(16);
/**
* Determine the transaction attribute for this method invocation.
* <p>Defaults to the class's transaction attribute if no method attribute is found.
* @param method the method for the current invocation (never <code>null</code>)
* @param targetClass the target class for this invocation (may be <code>null</code>)
* @return TransactionAttribute for this method, or <code>null</code> if the method
* is not transactional
*/
public TransactionAttribute getTransactionAttribute(Method method, Class targetClass) {
// First, see if we have a cached value.
Object cacheKey = getCacheKey(method, targetClass);
Object cached = this.attributeCache.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.attributeCache.put(cacheKey, NULL_TRANSACTION_ATTRIBUTE);
}
else {
if (logger.isDebugEnabled()) {
logger.debug("Adding transactional method [" + method.getName() + "] with attribute [" + txAtt + "]");
}
this.attributeCache.put(cacheKey, txAtt);
}
return txAtt;
}
}
/**
* Determine a cache key for the given method and target class.
* <p>Must not produce same key for overloaded methods.
* Must produce same key for different instances of the same method.
* @param method the method (never <code>null</code>)
* @param targetClass the target class (may be <code>null</code>)
* @return the cache key (never <code>null</code>)
*/
protected Object getCacheKey(Method method, Class targetClass) {
return new DefaultCacheKey(method, targetClass);
}
/**
* Same signature as {@link #getTransactionAttribute}, but doesn't cache the result.
* {@link #getTransactionAttribute} is effectively a caching decorator for this method.
* @see #getTransactionAttribute
*/
private TransactionAttribute computeTransactionAttribute(Method method, Class targetClass) {
// Don't allow no-public methods as required.
if (allowPublicMethodsOnly() && !Modifier.isPublic(method.getModifiers())) {
return null;
}
// The method may be on an interface, but we need attributes from the target class.
// If the target class is null, the method will be unchanged.
Method specificMethod = ClassUtils.getMostSpecificMethod(method, targetClass);
// If we are dealing with method with generic parameters, find the original method.
if (JdkVersion.isAtLeastJava15()) {
specificMethod = BridgeMethodResolver.findBridgedMethod(specificMethod);
}
// First try is the method in the target class.
TransactionAttribute txAtt = findTransactionAttribute(specificMethod);
if (txAtt != null) {
return txAtt;
}
// Second try is the transaction attribute on the target class.
txAtt = findTransactionAttribute(specificMethod.getDeclaringClass());
if (txAtt != null) {
return txAtt;
}
if (specificMethod != method) {
// Fallback is to look at the original method.
txAtt = findTransactionAttribute(method);
if (txAtt != null) {
return txAtt;
}
// Last fallback is the class of the original method.
return findTransactionAttribute(method.getDeclaringClass());
}
return null;
}
/**
* Subclasses need to implement this to return the transaction attribute
* for the given method, if any.
* @param method the method to retrieve the attribute for
* @return all transaction attribute associated with this method
* (or <code>null</code> if none)
*/
protected abstract TransactionAttribute findTransactionAttribute(Method method);
/**
* Subclasses need to implement this to return the transaction attribute
* for the given class, if any.
* @param clazz the class to retrieve the attribute for
* @return all transaction attribute associated with this class
* (or <code>null</code> if none)
*/
protected abstract TransactionAttribute findTransactionAttribute(Class clazz);
/**
* Should only public methods be allowed to have transactional semantics?
* <p>The default implementation returns <code>false</code>.
*/
protected boolean allowPublicMethodsOnly() {
return false;
}
/**
* Default cache key for the TransactionAttribute cache.
*/
private static class DefaultCacheKey {
private final Method method;
private final Class targetClass;
public DefaultCacheKey(Method method, Class targetClass) {
this.method = method;
this.targetClass = targetClass;
}
public boolean equals(Object other) {
if (this == other) {
return true;
}
if (!(other instanceof DefaultCacheKey)) {
return false;
}
DefaultCacheKey otherKey = (DefaultCacheKey) other;
return (this.method.equals(otherKey.method) &&
ObjectUtils.nullSafeEquals(this.targetClass, otherKey.targetClass));
}
public int hashCode() {
return this.method.hashCode() * 29 + (this.targetClass != null ? this.targetClass.hashCode() : 0);
}
}
}