com.googlecode.ehcache.annotations.interceptor.EhCacheInterceptor Maven / Gradle / Ivy
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Provides a simple model for integrating Ehcache in a Spring project via annotations.
/**
* Copyright 2010 Nicholas Blair, Eric Dalquist
*
* 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 com.googlecode.ehcache.annotations.interceptor;
import java.io.Serializable;
import java.lang.reflect.Method;
import net.sf.ehcache.Ehcache;
import net.sf.ehcache.Element;
import net.sf.ehcache.constructs.blocking.CacheEntryFactory;
import net.sf.ehcache.constructs.blocking.SelfPopulatingCache;
import org.aopalliance.intercept.MethodInterceptor;
import org.aopalliance.intercept.MethodInvocation;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import com.googlecode.ehcache.annotations.AdviceType;
import com.googlecode.ehcache.annotations.CacheAttributeSource;
import com.googlecode.ehcache.annotations.Cacheable;
import com.googlecode.ehcache.annotations.CacheableAttribute;
import com.googlecode.ehcache.annotations.MethodAttribute;
import com.googlecode.ehcache.annotations.TriggersRemove;
import com.googlecode.ehcache.annotations.TriggersRemoveAttribute;
import com.googlecode.ehcache.annotations.When;
import com.googlecode.ehcache.annotations.key.CacheKeyGenerator;
/**
* Intercepter that handles invocations on methods annotated with {@link Cacheable} or {@link TriggersRemove}.
*
* @author Eric Dalquist
* @version $Revision: 427 $
*/
public class EhCacheInterceptor implements MethodInterceptor {
protected final Logger logger = LoggerFactory.getLogger(this.getClass());
private CacheAttributeSource cacheAttributeSource;
public void setCacheAttributeSource(CacheAttributeSource cacheableAttributeSource) {
this.cacheAttributeSource = cacheableAttributeSource;
}
/* (non-Javadoc)
* @see org.aopalliance.intercept.MethodInterceptor#invoke(org.aopalliance.intercept.MethodInvocation)
*/
public final Object invoke(final MethodInvocation methodInvocation) throws Throwable {
final Method method = methodInvocation.getMethod();
final Class targetClass = (methodInvocation.getThis() != null ? methodInvocation.getThis().getClass() : null);
final AdviceType adviceType = this.cacheAttributeSource.getAdviceType(method, targetClass);
switch (adviceType) {
case CACHE: {
final CacheableAttribute cacheableAttribute = this.cacheAttributeSource.getCacheableAttribute(method, targetClass);
if (cacheableAttribute == null) {
this.logger.warn("CacheAttributeSource.getAdviceType(Method, Class) returned CACHE but CacheAttributeSource.getCacheableAttribute(Method, Class) returned null. Method will be invoked directly with no Cachable advice. Method: {}, Class: {}", method, targetClass);
return methodInvocation.proceed();
}
return this.invokeCacheable(methodInvocation, cacheableAttribute);
}
case REMOVE: {
final TriggersRemoveAttribute triggersRemoveAttribute = this.cacheAttributeSource.getTriggersRemoveAttribute(method, targetClass);
if (triggersRemoveAttribute == null) {
this.logger.warn("CacheAttributeSource.getAdviceType(Method, Class) returned REMOVE but CacheAttributeSource.getTriggersRemoveAttribute(Method, Class) returned null. Method will be invoked directly with no TriggersFlush advice. Method: {}, Class: {}", method, targetClass);
return methodInvocation.proceed();
}
return this.invokeTriggersRemove(methodInvocation, triggersRemoveAttribute);
}
default: {
this.logger.trace("The method {} is not advised {}.", methodInvocation, adviceType);
return methodInvocation.proceed();
}
}
}
/**
* Called if the {@link MethodInvocation} is annotated with {@link Cacheable}.
*
* @param methodInvocation Original method invocation
* @param cacheableAttribute Information about the {@link Cacheable} annotation
* @return The result of the invocation or the cached result
* @throws Throwable exception thrown by the invocation or cached exception
*/
private Object invokeCacheable(final MethodInvocation methodInvocation, final CacheableAttribute cacheableAttribute) throws Throwable {
//Generate the cache key
final Serializable cacheKey = this.generateCacheKey(methodInvocation, cacheableAttribute);
this.checkForCachedException(cacheableAttribute, cacheKey);
//See if this is self-populating
if (cacheableAttribute.getEntryFactory() != null) {
return this.invokeSelfPopulatingCacheable(methodInvocation, cacheableAttribute, cacheKey);
}
//See if there is a cached result
final Ehcache cache = cacheableAttribute.getCache();
final Element element = cache.get(cacheKey);
if (element != null) {
return element.getObjectValue();
}
//No cached value or exception, proceed
final Object value;
try {
value = methodInvocation.proceed();
}
catch (Throwable t) {
this.cacheException(cacheableAttribute, cacheKey, t);
throw t;
}
//Cache and return the value
cache.put(new Element(cacheKey, value));
return value;
}
/**
* Handles invoking the advised method via a {@link SelfPopulatingCache}. The {@link MethodInvocation} is set into
* a {@link ThreadLocal} which is used by the {@link CacheEntryFactory} to create the object if needed.
*
* @param methodInvocation The advised invocation
* @param cacheableAttribute Configuration for the method invocation
* @param key The cache key for the invocation
* @return The result of the invocation or the cached result.
* @throws Throwable Exception from the invocation
*/
private Object invokeSelfPopulatingCacheable(final MethodInvocation methodInvocation, final CacheableAttribute cacheableAttribute, final Serializable key) throws Throwable {
final Ehcache cache = cacheableAttribute.getCache();
final ThreadLocal entryFactory = cacheableAttribute.getEntryFactory();
if (entryFactory == null) {
throw new IllegalArgumentException("CacheableAttribute.getEntryFactory() returned null");
}
entryFactory.set(methodInvocation);
final Element element;
try {
element = cache.get(key);
}
catch (Throwable t) {
Throwable cause = t.getCause();
this.cacheException(cacheableAttribute, key, cause);
throw cause;
}
finally {
entryFactory.remove();
}
//This should not occur, it would have to be from a coding error in this library or EhCache's APIs have changed
if (element == null) {
throw new IllegalStateException("the supposed SelfPopulatingCache returned null, which violates the contract it should always return an Element; perhaps the cache is not truly a SelfPopulatingCache?");
}
return element.getObjectValue();
}
/**
* Called if the {@link MethodInvocation} is annotated with {@link TriggersRemove}.
*
* @param methodInvocation Original method invocation
* @param triggersRemoveAttribute Information about the {@link TriggersRemove} annotation
* @return The result of the invocation
* @throws Throwable exception thrown by the invocation
*/
private Object invokeTriggersRemove(final MethodInvocation methodInvocation, final TriggersRemoveAttribute triggersRemoveAttribute) throws Throwable {
final Ehcache cache = triggersRemoveAttribute.getCache();
if(When.BEFORE_METHOD_INVOCATION.equals(triggersRemoveAttribute.when())) {
invokeCacheRemove(methodInvocation, triggersRemoveAttribute, cache);
return methodInvocation.proceed();
}
final Object methodInvocationResult = methodInvocation.proceed();
invokeCacheRemove(methodInvocation, triggersRemoveAttribute, cache);
return methodInvocationResult;
}
/**
* Call the ehcache remove function as prescribed by the {@link TriggersRemoveAttribute}.
*
* @param methodInvocation
* @param triggersRemoveAttribute
* @param cache
*/
private void invokeCacheRemove(final MethodInvocation methodInvocation,
final TriggersRemoveAttribute triggersRemoveAttribute,
final Ehcache cache) {
if (triggersRemoveAttribute.isRemoveAll()) {
cache.removeAll();
}
else {
final Serializable cacheKey = generateCacheKey(methodInvocation, triggersRemoveAttribute);
cache.remove(cacheKey);
}
}
/**
* Check if there is a cached exception for the key. If there is throw it.
*
* @param cacheableAttribute Configuration for the method invocation
* @param key The cache key for the method invocation
* @throws Throwable The cached throwable
*/
protected void checkForCachedException(final CacheableAttribute cacheableAttribute, final Serializable key) throws Throwable {
//Determine if exception caching is enabled
final Ehcache exceptionCache = cacheableAttribute.getExceptionCache();
if (exceptionCache != null) {
//See if there is a cached exception
final Element execptionElement = exceptionCache.get(key);
if (execptionElement != null) {
throw (Throwable)execptionElement.getObjectValue();
}
}
}
/**
* Checks {@link CacheableAttribute#getExceptionCache()}, if not null the exception will be cached.
*
* @param cacheableAttribute Configuration for the method invocation
* @param key Cache key for the invocation
* @param t The exception to cache
*/
protected void cacheException(final CacheableAttribute cacheableAttribute, final Serializable key, final Throwable t) {
final Ehcache exceptionCache = cacheableAttribute.getExceptionCache();
if (exceptionCache != null) {
exceptionCache.put(new Element(key, t));
}
}
/**
* Creates a {@link Serializable} cache key from the {@link MethodInvocation} and configuration attributes.
*
* @param methodInvocation Invocation to build the key for
* @param methodAttribute Configuration for the invoked method
* @return Generated cache key, must not return null.
*/
protected Serializable generateCacheKey(final MethodInvocation methodInvocation, final MethodAttribute methodAttribute) {
final CacheKeyGenerator cacheKeyGenerator = methodAttribute.getCacheKeyGenerator();
final Serializable cacheKey = cacheKeyGenerator.generateKey(methodInvocation);
this.logger.debug("Generated key '{}' for invocation: {}", cacheKey, methodInvocation);
return cacheKey;
}
}