LazySingletonAspectInstanceFactoryDecorator uses shared singleton mutex

Issue: SPR-14241

spring-aop/src/main/java/org/springframework/aop/aspectj/annotation/BeanFactoryAspectInstanceFactory.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2015 the original author or authors.
+ * Copyright 2002-2016 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.
@@ -82,12 +82,9 @@ public class BeanFactoryAspectInstanceFactory implements MetadataAwareAspectInst
 
 	@Override
 	public ClassLoader getAspectClassLoader() {
-		if (this.beanFactory instanceof ConfigurableBeanFactory) {
+		return (this.beanFactory instanceof ConfigurableBeanFactory ?
-			return ((ConfigurableBeanFactory) this.beanFactory).getBeanClassLoader();
+				((ConfigurableBeanFactory) this.beanFactory).getBeanClassLoader() :
-		}
+				ClassUtils.getDefaultClassLoader());
-		else {
-			return ClassUtils.getDefaultClassLoader();
-		}
 	}
 
 	@Override
@@ -95,6 +92,12 @@ public class BeanFactoryAspectInstanceFactory implements MetadataAwareAspectInst
 		return this.aspectMetadata;
 	}
 
+	@Override
+	public Object getAspectCreationMutex() {
+		return (this.beanFactory instanceof ConfigurableBeanFactory ?
+				((ConfigurableBeanFactory) this.beanFactory).getSingletonMutex() : this);
+	}
+
 	/**
 	 * Determine the order for this factory's target aspect, either
 	 * an instance-specific order expressed through implementing the

spring-aop/src/main/java/org/springframework/aop/aspectj/annotation/LazySingletonAspectInstanceFactoryDecorator.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2015 the original author or authors.
+ * Copyright 2002-2016 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.
@@ -46,9 +46,9 @@ public class LazySingletonAspectInstanceFactoryDecorator implements MetadataAwar
 
 
 	@Override
-	public synchronized Object getAspectInstance() {
+	public Object getAspectInstance() {
 		if (this.materialized == null) {
-			synchronized (this) {
+			synchronized (this.maaif.getAspectCreationMutex()) {
 				if (this.materialized == null) {
 					this.materialized = this.maaif.getAspectInstance();
 				}
@@ -71,6 +71,11 @@ public class LazySingletonAspectInstanceFactoryDecorator implements MetadataAwar
 		return this.maaif.getAspectMetadata();
 	}
 
+	@Override
+	public Object getAspectCreationMutex() {
+		return this.maaif.getAspectCreationMutex();
+	}
+
 	@Override
 	public int getOrder() {
 		return this.maaif.getOrder();

spring-aop/src/main/java/org/springframework/aop/aspectj/annotation/MetadataAwareAspectInstanceFactory.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2007 the original author or authors.
+ * Copyright 2002-2016 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.
@@ -39,4 +39,11 @@ public interface MetadataAwareAspectInstanceFactory extends AspectInstanceFactor
 	 */
 	AspectMetadata getAspectMetadata();
 
+	/**
+	 * Return the best possible creation mutex for this factory.
+	 * @return the mutex object (never {@code null})
+	 * @since 4.3
+	 */
+	Object getAspectCreationMutex();
+
 }

spring-aop/src/main/java/org/springframework/aop/aspectj/annotation/SimpleMetadataAwareAspectInstanceFactory.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2014 the original author or authors.
+ * Copyright 2002-2016 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.
@@ -50,6 +50,11 @@ public class SimpleMetadataAwareAspectInstanceFactory extends SimpleAspectInstan
 		return this.metadata;
 	}
 
+	@Override
+	public Object getAspectCreationMutex() {
+		return this;
+	}
+
 	@Override
 	protected int getOrderForAspectClass(Class<?> aspectClass) {
 		return OrderUtils.getOrder(aspectClass, Ordered.LOWEST_PRECEDENCE);

spring-aop/src/main/java/org/springframework/aop/aspectj/annotation/SingletonMetadataAwareAspectInstanceFactory.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2015 the original author or authors.
+ * Copyright 2002-2016 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.
@@ -55,6 +55,11 @@ public class SingletonMetadataAwareAspectInstanceFactory extends SingletonAspect
 		return this.metadata;
 	}
 
+	@Override
+	public Object getAspectCreationMutex() {
+		return this;
+	}
+
 	@Override
 	protected int getOrderForAspectClass(Class<?> aspectClass) {
 		return OrderUtils.getOrder(aspectClass, Ordered.LOWEST_PRECEDENCE);

spring-aop/src/test/java/org/springframework/aop/aspectj/annotation/AbstractAspectJAdvisorFactoryTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2015 the original author or authors.
+ * Copyright 2002-2016 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.
@@ -693,6 +693,11 @@ public abstract class AbstractAspectJAdvisorFactoryTests {
 			return new AspectMetadata(PerTypeWithinAspect.class, "perTypeWithin");
 		}
 
+		@Override
+		public Object getAspectCreationMutex() {
+			return this;
+		}
+
 		@Override
 		public int getOrder() {
 			return Ordered.LOWEST_PRECEDENCE;