Reduce ProxyCallbackFilter to key-only role after class generation

Avoids memory leaks from ProxyCallbackFilter-contained Advisors.
Includes consistent ProxyCallbackFilter#equals/hashCode methods.

Closes gh-26266
Closes gh-30615

Author: jhoeller

spring-aop/src/main/java/org/springframework/aop/framework/AdvisedSupport.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2023 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.
@@ -22,6 +22,7 @@
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collection;
+import java.util.Collections;
 import java.util.List;
 import java.util.Map;
 import java.util.concurrent.ConcurrentHashMap;
@@ -32,6 +33,8 @@
 import org.springframework.aop.DynamicIntroductionAdvice;
 import org.springframework.aop.IntroductionAdvisor;
 import org.springframework.aop.IntroductionInfo;
+import org.springframework.aop.Pointcut;
+import org.springframework.aop.PointcutAdvisor;
 import org.springframework.aop.TargetSource;
 import org.springframework.aop.support.DefaultIntroductionAdvisor;
 import org.springframework.aop.support.DefaultPointcutAdvisor;
@@ -41,6 +44,7 @@
 import org.springframework.util.Assert;
 import org.springframework.util.ClassUtils;
 import org.springframework.util.CollectionUtils;
+import org.springframework.util.ObjectUtils;
 
 /**
  * Base class for AOP proxy configuration managers.
@@ -72,15 +76,13 @@ public class AdvisedSupport extends ProxyConfig implements Advised {
 
 
 	/** Package-protected to allow direct access for efficiency. */
-	@SuppressWarnings("serial")
 	TargetSource targetSource = EMPTY_TARGET_SOURCE;
 
 	/** Whether the Advisors are already filtered for the specific target class. */
 	private boolean preFiltered = false;
 
 	/** The AdvisorChainFactory to use. */
-	@SuppressWarnings("serial")
-	AdvisorChainFactory advisorChainFactory = new DefaultAdvisorChainFactory();
+	private AdvisorChainFactory advisorChainFactory;
 
 	/** Cache with Method as key and advisor chain List as value. */
 	private transient Map<MethodCacheKey, List<Object>> methodCache;
@@ -89,21 +91,22 @@ public class AdvisedSupport extends ProxyConfig implements Advised {
 	 * Interfaces to be implemented by the proxy. Held in List to keep the order
 	 * of registration, to create JDK proxy with specified order of interfaces.
 	 */
-	@SuppressWarnings("serial")
 	private List<Class<?>> interfaces = new ArrayList<>();
 
 	/**
 	 * List of Advisors. If an Advice is added, it will be wrapped
 	 * in an Advisor before being added to this List.
 	 */
-	@SuppressWarnings("serial")
 	private List<Advisor> advisors = new ArrayList<>();
 
+	private List<Advisor> advisorKey = this.advisors;
+
 
 	/**
 	 * No-arg constructor for use as a JavaBean.
 	 */
 	public AdvisedSupport() {
+		this.advisorChainFactory = DefaultAdvisorChainFactory.INSTANCE;
 		this.methodCache = new ConcurrentHashMap<>(32);
 	}
 
@@ -116,6 +119,15 @@ public AdvisedSupport(Class<?>... interfaces) {
 		setInterfaces(interfaces);
 	}
 
+	/**
+	 * Internal constructor for {@link #getConfigurationOnlyCopy()}.
+	 * @since 6.0.10
+	 */
+	private AdvisedSupport(AdvisorChainFactory advisorChainFactory, Map<MethodCacheKey, List<Object>> methodCache) {
+		this.advisorChainFactory = advisorChainFactory;
+		this.methodCache = methodCache;
+	}
+
 
 	/**
 	 * Set the given object as target.
@@ -520,15 +532,27 @@ protected void copyConfigurationFrom(AdvisedSupport other, TargetSource targetSo
 	 * replacing the TargetSource.
 	 */
 	AdvisedSupport getConfigurationOnlyCopy() {
-		AdvisedSupport copy = new AdvisedSupport();
+		AdvisedSupport copy = new AdvisedSupport(this.advisorChainFactory, this.methodCache);
 		copy.copyFrom(this);
 		copy.targetSource = EmptyTargetSource.forClass(getTargetClass(), getTargetSource().isStatic());
-		copy.advisorChainFactory = this.advisorChainFactory;
 		copy.interfaces = new ArrayList<>(this.interfaces);
 		copy.advisors = new ArrayList<>(this.advisors);
+		copy.advisorKey = new ArrayList<>(this.advisors.size());
+		for (Advisor advisor : this.advisors) {
+			copy.advisorKey.add(new AdvisorKeyEntry(advisor));
+		}
 		return copy;
 	}
 
+	void reduceToAdvisorKey() {
+		this.advisors = this.advisorKey;
+		this.methodCache = Collections.emptyMap();
+	}
+
+	Object getAdvisorKey() {
+		return this.advisorKey;
+	}
+
 
 	//---------------------------------------------------------------------
 	// Serialization support
@@ -604,4 +628,51 @@ public int compareTo(MethodCacheKey other) {
 		}
 	}
 
+
+	/**
+	 * Stub for an Advisor instance that is just needed for key purposes,
+	 * allowing for efficient equals and hashCode comparisons against the
+	 * advice class and the pointcut.
+	 * @since 6.0.10
+	 * @see #getConfigurationOnlyCopy()
+	 * @see #getAdvisorKey()
+	 */
+	private static class AdvisorKeyEntry implements Advisor {
+
+		private final Class<?> adviceType;
+
+		@Nullable
+		private String classFilterKey;
+
+		@Nullable
+		private String methodMatcherKey;
+
+		public AdvisorKeyEntry(Advisor advisor) {
+			this.adviceType = advisor.getAdvice().getClass();
+			if (advisor instanceof PointcutAdvisor pointcutAdvisor) {
+				Pointcut pointcut = pointcutAdvisor.getPointcut();
+				this.classFilterKey = ObjectUtils.identityToString(pointcut.getClassFilter());
+				this.methodMatcherKey = ObjectUtils.identityToString(pointcut.getMethodMatcher());
+			}
+		}
+
+		@Override
+		public Advice getAdvice() {
+			throw new UnsupportedOperationException();
+		}
+
+		@Override
+		public boolean equals(Object other) {
+			return (this == other || (other instanceof AdvisorKeyEntry otherEntry &&
+					this.adviceType == otherEntry.adviceType &&
+					ObjectUtils.nullSafeEquals(this.classFilterKey, otherEntry.classFilterKey) &&
+					ObjectUtils.nullSafeEquals(this.methodMatcherKey, otherEntry.methodMatcherKey)));
+		}
+
+		@Override
+		public int hashCode() {
+			return this.adviceType.hashCode();
+		}
+	}
+
 }

spring-aop/src/main/java/org/springframework/aop/framework/CglibAopProxy.java

@@ -26,14 +26,11 @@
 import java.util.Set;
 import java.util.WeakHashMap;
 
-import org.aopalliance.aop.Advice;
 import org.aopalliance.intercept.MethodInvocation;
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 
-import org.springframework.aop.Advisor;
 import org.springframework.aop.AopInvocationException;
-import org.springframework.aop.PointcutAdvisor;
 import org.springframework.aop.RawTargetAccess;
 import org.springframework.aop.TargetSource;
 import org.springframework.aop.support.AopUtils;
@@ -205,12 +202,21 @@ private Object buildProxy(@Nullable ClassLoader classLoader, boolean classOnly)
 				types[x] = callbacks[x].getClass();
 			}
 			// fixedInterceptorMap only populated at this point, after getCallbacks call above
-			enhancer.setCallbackFilter(new ProxyCallbackFilter(
-					this.advised.getConfigurationOnlyCopy(), this.fixedInterceptorMap, this.fixedInterceptorOffset));
+			ProxyCallbackFilter filter = new ProxyCallbackFilter(
+					this.advised.getConfigurationOnlyCopy(), this.fixedInterceptorMap, this.fixedInterceptorOffset);
+			enhancer.setCallbackFilter(filter);
 			enhancer.setCallbackTypes(types);
 
 			// Generate the proxy class and create a proxy instance.
-			return (classOnly ? createProxyClass(enhancer) : createProxyClassAndInstance(enhancer, callbacks));
+			// ProxyCallbackFilter has method introspection capability with Advisor access.
+			try {
+				return (classOnly ? createProxyClass(enhancer) : createProxyClassAndInstance(enhancer, callbacks));
+			}
+			finally {
+				// Reduce ProxyCallbackFilter to key-only state for its class cache role
+				// in the CGLIB$CALLBACK_FILTER field, not leaking any Advisor state...
+				filter.advised.reduceToAdvisorKey();
+			}
 		}
 		catch (CodeGenerationException | IllegalArgumentException ex) {
 			throw new AopConfigException("Could not generate CGLIB subclass of " + this.advised.getTargetClass() +
@@ -294,9 +300,9 @@ else if (logger.isDebugEnabled() && !Modifier.isPublic(mod) && !Modifier.isProte
 
 	private Callback[] getCallbacks(Class<?> rootClass) throws Exception {
 		// Parameters used for optimization choices...
-		boolean exposeProxy = this.advised.isExposeProxy();
-		boolean isFrozen = this.advised.isFrozen();
 		boolean isStatic = this.advised.getTargetSource().isStatic();
+		boolean isFrozen = this.advised.isFrozen();
+		boolean exposeProxy = this.advised.isExposeProxy();
 
 		// Choose an "aop" interceptor (used for AOP calls).
 		Callback aopInterceptor = new DynamicAdvisedInterceptor(this.advised);
@@ -776,7 +782,7 @@ public Object proceed() throws Throwable {
 	 */
 	private static class ProxyCallbackFilter implements CallbackFilter {
 
-		private final AdvisedSupport advised;
+		final AdvisedSupport advised;
 
 		private final Map<Method, Integer> fixedInterceptorMap;
 
@@ -857,9 +863,9 @@ public int accept(Method method) {
 			// Proxy is not yet available, but that shouldn't matter.
 			List<?> chain = this.advised.getInterceptorsAndDynamicInterceptionAdvice(method, targetClass);
 			boolean haveAdvice = !chain.isEmpty();
-			boolean exposeProxy = this.advised.isExposeProxy();
 			boolean isStatic = this.advised.getTargetSource().isStatic();
 			boolean isFrozen = this.advised.isFrozen();
+			boolean exposeProxy = this.advised.isExposeProxy();
 			if (haveAdvice || !isFrozen) {
 				// If exposing the proxy, then AOP_PROXY must be used.
 				if (exposeProxy) {
@@ -921,63 +927,18 @@ public boolean equals(@Nullable Object other) {
 				return false;
 			}
 			AdvisedSupport otherAdvised = otherCallbackFilter.advised;
-			if (this.advised.isFrozen() != otherAdvised.isFrozen()) {
-				return false;
-			}
-			if (this.advised.isExposeProxy() != otherAdvised.isExposeProxy()) {
-				return false;
-			}
-			if (this.advised.getTargetSource().isStatic() != otherAdvised.getTargetSource().isStatic()) {
-				return false;
-			}
-			if (!AopProxyUtils.equalsProxiedInterfaces(this.advised, otherAdvised)) {
-				return false;
-			}
-			// Advice instance identity is unimportant to the proxy class:
-			// All that matters is type and ordering.
-			if (this.advised.getAdvisorCount() != otherAdvised.getAdvisorCount()) {
-				return false;
-			}
-			Advisor[] thisAdvisors = this.advised.getAdvisors();
-			Advisor[] thatAdvisors = otherAdvised.getAdvisors();
-			for (int i = 0; i < thisAdvisors.length; i++) {
-				Advisor thisAdvisor = thisAdvisors[i];
-				Advisor thatAdvisor = thatAdvisors[i];
-				if (!equalsAdviceClasses(thisAdvisor, thatAdvisor)) {
-					return false;
-				}
-				if (!equalsPointcuts(thisAdvisor, thatAdvisor)) {
-					return false;
-				}
-			}
-			return true;
-		}
-
-		private static boolean equalsAdviceClasses(Advisor a, Advisor b) {
-			return (a.getAdvice().getClass() == b.getAdvice().getClass());
-		}
-
-		private static boolean equalsPointcuts(Advisor a, Advisor b) {
-			// If only one of the advisor (but not both) is PointcutAdvisor, then it is a mismatch.
-			// Takes care of the situations where an IntroductionAdvisor is used (see SPR-3959).
-			return (!(a instanceof PointcutAdvisor pointcutAdvisor1) ||
-					(b instanceof PointcutAdvisor pointcutAdvisor2 &&
-							ObjectUtils.nullSafeEquals(pointcutAdvisor1.getPointcut(), pointcutAdvisor2.getPointcut())));
+			return (this.advised.getAdvisorKey().equals(otherAdvised.getAdvisorKey()) &&
+					AopProxyUtils.equalsProxiedInterfaces(this.advised, otherAdvised) &&
+					ObjectUtils.nullSafeEquals(this.advised.getTargetClass(), otherAdvised.getTargetClass()) &&
+					this.advised.getTargetSource().isStatic() == otherAdvised.getTargetSource().isStatic() &&
+					this.advised.isFrozen() == otherAdvised.isFrozen() &&
+					this.advised.isExposeProxy() == otherAdvised.isExposeProxy() &&
+					this.advised.isOpaque() == otherAdvised.isOpaque());
 		}
 
 		@Override
 		public int hashCode() {
-			int hashCode = 0;
-			Advisor[] advisors = this.advised.getAdvisors();
-			for (Advisor advisor : advisors) {
-				Advice advice = advisor.getAdvice();
-				hashCode = 13 * hashCode + advice.getClass().hashCode();
-			}
-			hashCode = 13 * hashCode + (this.advised.isFrozen() ? 1 : 0);
-			hashCode = 13 * hashCode + (this.advised.isExposeProxy() ? 1 : 0);
-			hashCode = 13 * hashCode + (this.advised.isOptimize() ? 1 : 0);
-			hashCode = 13 * hashCode + (this.advised.isOpaque() ? 1 : 0);
-			return hashCode;
+			return this.advised.getAdvisorKey().hashCode();
 		}
 	}
 

spring-context/src/test/java/org/springframework/aop/framework/CglibProxyTests.java

@@ -28,13 +28,15 @@
 import org.springframework.aop.Pointcut;
 import org.springframework.aop.support.AopUtils;
 import org.springframework.aop.support.DefaultPointcutAdvisor;
+import org.springframework.aop.support.annotation.AnnotationMatchingPointcut;
 import org.springframework.aop.testfixture.advice.CountingBeforeAdvice;
 import org.springframework.aop.testfixture.interceptor.NopInterceptor;
 import org.springframework.beans.testfixture.beans.ITestBean;
 import org.springframework.beans.testfixture.beans.TestBean;
 import org.springframework.context.ApplicationContext;
 import org.springframework.context.ApplicationContextException;
 import org.springframework.context.support.ClassPathXmlApplicationContext;
+import org.springframework.lang.NonNull;
 import org.springframework.lang.Nullable;
 
 import static org.assertj.core.api.Assertions.assertThat;
@@ -304,6 +306,8 @@ public void testProxyAProxyWithAdditionalInterface() {
 		CglibAopProxy cglib = new CglibAopProxy(as);
 
 		ITestBean proxy1 = (ITestBean) cglib.getProxy();
+		ITestBean proxy1a = (ITestBean) cglib.getProxy();
+		assertThat(proxy1a.getClass()).isSameAs(proxy1.getClass());
 
 		mockTargetSource.setTarget(proxy1);
 		as = new AdvisedSupport(new Class<?>[]{});
@@ -313,6 +317,39 @@ public void testProxyAProxyWithAdditionalInterface() {
 
 		ITestBean proxy2 = (ITestBean) cglib.getProxy();
 		assertThat(proxy2).isInstanceOf(Serializable.class);
+		assertThat(proxy2.getClass()).isNotSameAs(proxy1.getClass());
+
+		ITestBean proxy2a = (ITestBean) cglib.getProxy();
+		assertThat(proxy2a).isInstanceOf(Serializable.class);
+		assertThat(proxy2a.getClass()).isSameAs(proxy2.getClass());
+
+		mockTargetSource.setTarget(proxy1);
+		as = new AdvisedSupport(new Class<?>[]{});
+		as.setTargetSource(mockTargetSource);
+		as.addAdvisor(new DefaultPointcutAdvisor(new AnnotationMatchingPointcut(Nullable.class), new NopInterceptor()));
+		cglib = new CglibAopProxy(as);
+
+		ITestBean proxy3 = (ITestBean) cglib.getProxy();
+		assertThat(proxy3).isInstanceOf(Serializable.class);
+		assertThat(proxy3.getClass()).isNotSameAs(proxy2.getClass());
+
+		ITestBean proxy3a = (ITestBean) cglib.getProxy();
+		assertThat(proxy3a).isInstanceOf(Serializable.class);
+		assertThat(proxy3a.getClass()).isSameAs(proxy3.getClass());
+
+		mockTargetSource.setTarget(proxy1);
+		as = new AdvisedSupport(new Class<?>[]{});
+		as.setTargetSource(mockTargetSource);
+		as.addAdvisor(new DefaultPointcutAdvisor(new AnnotationMatchingPointcut(NonNull.class), new NopInterceptor()));
+		cglib = new CglibAopProxy(as);
+
+		ITestBean proxy4 = (ITestBean) cglib.getProxy();
+		assertThat(proxy4).isInstanceOf(Serializable.class);
+		assertThat(proxy4.getClass()).isNotSameAs(proxy3.getClass());
+
+		ITestBean proxy4a = (ITestBean) cglib.getProxy();
+		assertThat(proxy4a).isInstanceOf(Serializable.class);
+		assertThat(proxy4a.getClass()).isSameAs(proxy4.getClass());
 	}
 
 	@Test