Use local copy set into volatile field instead of CopyOnWriteArrayList

Keep supporting legacy usage of Iterator.remove on getBeanPostProcessors result List in AbstractBeanFactoryBasedTargetSourceCreator and ScriptFactoryPostProcessor (and similarly designed integrations).

Issue: SPR-17286

spring-aop/src/main/java/org/springframework/aop/framework/autoproxy/target/AbstractBeanFactoryBasedTargetSourceCreator.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2012 the original author or authors.
+ * Copyright 2002-2018 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.
@@ -150,7 +150,7 @@ public abstract class AbstractBeanFactoryBasedTargetSourceCreator
 		// since those are only meant to apply to beans defined in the original factory.
 		for (Iterator<BeanPostProcessor> it = internalBeanFactory.getBeanPostProcessors().iterator(); it.hasNext();) {
 			if (it.next() instanceof AopInfrastructureBean) {
-				it.remove();
+				it.remove();  // effectively deprecated: use List.removeIf on Java 8+
 			}
 		}
 

spring-beans/src/main/java/org/springframework/beans/factory/support/AbstractBeanFactory.java

@@ -145,7 +145,7 @@ public abstract class AbstractBeanFactory extends FactoryBeanRegistrySupport imp
 	private final List<StringValueResolver> embeddedValueResolvers = new CopyOnWriteArrayList<StringValueResolver>();
 
 	/** BeanPostProcessors to apply in createBean */
-	private final List<BeanPostProcessor> beanPostProcessors = new CopyOnWriteArrayList<BeanPostProcessor>();
+	private volatile List<BeanPostProcessor> beanPostProcessors = new ArrayList<BeanPostProcessor>();
 
 	/** Indicates whether any InstantiationAwareBeanPostProcessors have been registered */
 	private volatile boolean hasInstantiationAwareBeanPostProcessors;
@@ -845,8 +845,12 @@ public abstract class AbstractBeanFactory extends FactoryBeanRegistrySupport imp
 	@Override
 	public void addBeanPostProcessor(BeanPostProcessor beanPostProcessor) {
 		Assert.notNull(beanPostProcessor, "BeanPostProcessor must not be null");
+		// Local copy set into volatile field, as an alternative to CopyOnWriteArrayList
+		// (which doesn't support Iterator.remove for our getBeanPostProcessors result List)
+		List<BeanPostProcessor> beanPostProcessors = new ArrayList<BeanPostProcessor>();
+		beanPostProcessors.addAll(this.beanPostProcessors);
 		// Remove from old position, if any
-		this.beanPostProcessors.remove(beanPostProcessor);
+		beanPostProcessors.remove(beanPostProcessor);
 		// Track whether it is instantiation/destruction aware
 		if (beanPostProcessor instanceof InstantiationAwareBeanPostProcessor) {
 			this.hasInstantiationAwareBeanPostProcessors = true;
@@ -855,7 +859,8 @@ public abstract class AbstractBeanFactory extends FactoryBeanRegistrySupport imp
 			this.hasDestructionAwareBeanPostProcessors = true;
 		}
 		// Add to end of list
-		this.beanPostProcessors.add(beanPostProcessor);
+		beanPostProcessors.add(beanPostProcessor);
+		this.beanPostProcessors = beanPostProcessors;
 	}
 
 	@Override

spring-context/src/main/java/org/springframework/scripting/support/ScriptFactoryPostProcessor.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2017 the original author or authors.
+ * Copyright 2002-2018 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.
@@ -136,8 +136,8 @@ import org.springframework.util.StringUtils;
  * @author Mark Fisher
  * @since 2.0
  */
-public class ScriptFactoryPostProcessor extends InstantiationAwareBeanPostProcessorAdapter implements
-		BeanClassLoaderAware, BeanFactoryAware, ResourceLoaderAware, DisposableBean, Ordered {
+public class ScriptFactoryPostProcessor extends InstantiationAwareBeanPostProcessorAdapter
+		implements BeanClassLoaderAware, BeanFactoryAware, ResourceLoaderAware, DisposableBean, Ordered {
 
 	/**
 	 * The {@link org.springframework.core.io.Resource}-style prefix that denotes
@@ -160,6 +160,7 @@ public class ScriptFactoryPostProcessor extends InstantiationAwareBeanPostProces
 
 	private static final String SCRIPTED_OBJECT_NAME_PREFIX = "scriptedObject.";
 
+
 	/** Logger available to subclasses */
 	protected final Log logger = LogFactory.getLog(getClass());
 
@@ -221,7 +222,7 @@ public class ScriptFactoryPostProcessor extends InstantiationAwareBeanPostProces
 		// since those are only meant to apply to beans defined in the original factory.
 		for (Iterator<BeanPostProcessor> it = this.scriptBeanFactory.getBeanPostProcessors().iterator(); it.hasNext();) {
 			if (it.next() instanceof AopInfrastructureBean) {
-				it.remove();
+				it.remove();  // effectively deprecated: use List.removeIf on Java 8+
 			}
 		}
 	}
@@ -236,6 +237,7 @@ public class ScriptFactoryPostProcessor extends InstantiationAwareBeanPostProces
 		return Integer.MIN_VALUE;
 	}
 
+
 	@Override
 	public Class<?> predictBeanType(Class<?> beanClass, String beanName) {
 		// We only apply special treatment to ScriptFactory implementations here.
@@ -274,8 +276,8 @@ public class ScriptFactoryPostProcessor extends InstantiationAwareBeanPostProces
 			if (ex instanceof BeanCreationException &&
 					((BeanCreationException) ex).getMostSpecificCause() instanceof BeanCurrentlyInCreationException) {
 				if (logger.isTraceEnabled()) {
-					logger.trace("Could not determine scripted object type for bean '" + beanName + "': "
-							+ ex.getMessage());
+					logger.trace("Could not determine scripted object type for bean '" + beanName + "': " +
+							ex.getMessage());
 				}
 			}
 			else {