Refresh cached value after unexpected mismatch (e.g. null vs non-null)

In addition to the previously addressed removal of bean definitions, this is able to deal with prototype factory methods returning non-null after null or also null after non-null. Stale cached values are getting refreshed rather than bypassed.

Closes gh-30794

(cherry picked from commit 0226580)

Author: jhoeller

spring-beans/src/main/java/org/springframework/beans/factory/annotation/AutowiredAnnotationBeanPostProcessor.java

@@ -594,7 +594,7 @@ private void registerDependentBeans(@Nullable String beanName, Set<String> autow
 	 * Resolve the specified cached method argument or field value.
 	 */
 	@Nullable
-	private Object resolvedCachedArgument(@Nullable String beanName, @Nullable Object cachedArgument) {
+	private Object resolveCachedArgument(@Nullable String beanName, @Nullable Object cachedArgument) {
 		if (cachedArgument instanceof DependencyDescriptor) {
 			DependencyDescriptor descriptor = (DependencyDescriptor) cachedArgument;
 			Assert.state(this.beanFactory != null, "No BeanFactory available");
@@ -629,10 +629,12 @@ protected void inject(Object bean, @Nullable String beanName, @Nullable Property
 			Object value;
 			if (this.cached) {
 				try {
-					value = resolvedCachedArgument(beanName, this.cachedFieldValue);
+					value = resolveCachedArgument(beanName, this.cachedFieldValue);
 				}
-				catch (NoSuchBeanDefinitionException ex) {
-					// Unexpected removal of target bean for cached argument -> re-resolve
+				catch (BeansException ex) {
+					// Unexpected target bean mismatch for cached argument -> re-resolve
+					this.cached = false;
+					logger.debug("Failed to resolve cached argument", ex);
 					value = resolveFieldValue(field, bean, beanName);
 				}
 			}
@@ -661,9 +663,8 @@ private Object resolveFieldValue(Field field, Object bean, @Nullable String bean
 			}
 			synchronized (this) {
 				if (!this.cached) {
-					Object cachedFieldValue = null;
 					if (value != null || this.required) {
-						cachedFieldValue = desc;
+						Object cachedFieldValue = desc;
 						registerDependentBeans(beanName, autowiredBeanNames);
 						if (value != null && autowiredBeanNames.size() == 1) {
 							String autowiredBeanName = autowiredBeanNames.iterator().next();
@@ -673,9 +674,13 @@ private Object resolveFieldValue(Field field, Object bean, @Nullable String bean
 										desc, autowiredBeanName, field.getType());
 							}
 						}
+						this.cachedFieldValue = cachedFieldValue;
+						this.cached = true;
+					}
+					else {
+						this.cachedFieldValue = null;
+						// cached flag remains false
 					}
-					this.cachedFieldValue = cachedFieldValue;
-					this.cached = true;
 				}
 			}
 			return value;
@@ -709,10 +714,12 @@ protected void inject(Object bean, @Nullable String beanName, @Nullable Property
 			Object[] arguments;
 			if (this.cached) {
 				try {
-					arguments = resolveCachedArguments(beanName);
+					arguments = resolveCachedArguments(beanName, this.cachedMethodArguments);
 				}
-				catch (NoSuchBeanDefinitionException ex) {
-					// Unexpected removal of target bean for cached argument -> re-resolve
+				catch (BeansException ex) {
+					// Unexpected target bean mismatch for cached argument -> re-resolve
+					this.cached = false;
+					logger.debug("Failed to resolve cached argument", ex);
 					arguments = resolveMethodArguments(method, bean, beanName);
 				}
 			}
@@ -731,14 +738,13 @@ protected void inject(Object bean, @Nullable String beanName, @Nullable Property
 		}
 
 		@Nullable
-		private Object[] resolveCachedArguments(@Nullable String beanName) {
-			Object[] cachedMethodArguments = this.cachedMethodArguments;
+		private Object[] resolveCachedArguments(@Nullable String beanName, @Nullable Object[] cachedMethodArguments) {
 			if (cachedMethodArguments == null) {
 				return null;
 			}
 			Object[] arguments = new Object[cachedMethodArguments.length];
 			for (int i = 0; i < arguments.length; i++) {
-				arguments[i] = resolvedCachedArgument(beanName, cachedMethodArguments[i]);
+				arguments[i] = resolveCachedArgument(beanName, cachedMethodArguments[i]);
 			}
 			return arguments;
 		}
@@ -771,7 +777,7 @@ private Object[] resolveMethodArguments(Method method, Object bean, @Nullable St
 			synchronized (this) {
 				if (!this.cached) {
 					if (arguments != null) {
-						DependencyDescriptor[] cachedMethodArguments = Arrays.copyOf(descriptors, arguments.length);
+						DependencyDescriptor[] cachedMethodArguments = Arrays.copyOf(descriptors, argumentCount);
 						registerDependentBeans(beanName, autowiredBeans);
 						if (autowiredBeans.size() == argumentCount) {
 							Iterator<String> it = autowiredBeans.iterator();
@@ -786,11 +792,12 @@ private Object[] resolveMethodArguments(Method method, Object bean, @Nullable St
 							}
 						}
 						this.cachedMethodArguments = cachedMethodArguments;
+						this.cached = true;
 					}
 					else {
 						this.cachedMethodArguments = null;
+						// cached flag remains false
 					}
-					this.cached = true;
 				}
 			}
 			return arguments;

spring-beans/src/test/java/org/springframework/beans/factory/annotation/AutowiredAnnotationBeanPostProcessorTests.java

@@ -154,6 +154,59 @@ public void testResourceInjectionWithNullBean() {
 		assertThat(bean.getTestBean3()).isNull();
 	}
 
+	@Test
+	void resourceInjectionWithSometimesNullBean() {
+		RootBeanDefinition bd = new RootBeanDefinition(OptionalResourceInjectionBean.class);
+		bd.setScope(BeanDefinition.SCOPE_PROTOTYPE);
+		bf.registerBeanDefinition("annotatedBean", bd);
+		RootBeanDefinition tb = new RootBeanDefinition(SometimesNullFactoryMethods.class);
+		tb.setFactoryMethodName("createTestBean");
+		tb.setScope(BeanDefinition.SCOPE_PROTOTYPE);
+		bf.registerBeanDefinition("testBean", tb);
+
+		SometimesNullFactoryMethods.active = false;
+		OptionalResourceInjectionBean bean = (OptionalResourceInjectionBean) bf.getBean("annotatedBean");
+		assertThat(bean.getTestBean()).isNull();
+		assertThat(bean.getTestBean2()).isNull();
+		assertThat(bean.getTestBean3()).isNull();
+
+		SometimesNullFactoryMethods.active = true;
+		bean = (OptionalResourceInjectionBean) bf.getBean("annotatedBean");
+		assertThat(bean.getTestBean()).isNotNull();
+		assertThat(bean.getTestBean2()).isNotNull();
+		assertThat(bean.getTestBean3()).isNotNull();
+
+		SometimesNullFactoryMethods.active = false;
+		bean = (OptionalResourceInjectionBean) bf.getBean("annotatedBean");
+		assertThat(bean.getTestBean()).isNull();
+		assertThat(bean.getTestBean2()).isNull();
+		assertThat(bean.getTestBean3()).isNull();
+
+		SometimesNullFactoryMethods.active = false;
+		bean = (OptionalResourceInjectionBean) bf.getBean("annotatedBean");
+		assertThat(bean.getTestBean()).isNull();
+		assertThat(bean.getTestBean2()).isNull();
+		assertThat(bean.getTestBean3()).isNull();
+
+		SometimesNullFactoryMethods.active = true;
+		bean = (OptionalResourceInjectionBean) bf.getBean("annotatedBean");
+		assertThat(bean.getTestBean()).isNotNull();
+		assertThat(bean.getTestBean2()).isNotNull();
+		assertThat(bean.getTestBean3()).isNotNull();
+
+		SometimesNullFactoryMethods.active = true;
+		bean = (OptionalResourceInjectionBean) bf.getBean("annotatedBean");
+		assertThat(bean.getTestBean()).isNotNull();
+		assertThat(bean.getTestBean2()).isNotNull();
+		assertThat(bean.getTestBean3()).isNotNull();
+
+		SometimesNullFactoryMethods.active = false;
+		bean = (OptionalResourceInjectionBean) bf.getBean("annotatedBean");
+		assertThat(bean.getTestBean()).isNull();
+		assertThat(bean.getTestBean2()).isNull();
+		assertThat(bean.getTestBean3()).isNull();
+	}
+
 	@Test
 	public void testExtendedResourceInjection() {
 		RootBeanDefinition bd = new RootBeanDefinition(TypedExtendedResourceInjectionBean.class);
@@ -3902,6 +3955,20 @@ public static NestedTestBean createNestedTestBean() {
 	}
 
 
+	public static class SometimesNullFactoryMethods {
+
+		public static boolean active = false;
+
+		public static TestBean createTestBean() {
+			return (active ? new TestBean() : null);
+		}
+
+		public static NestedTestBean createNestedTestBean() {
+			return (active ? new NestedTestBean() : null);
+		}
+	}
+
+
 	public static class ProvidedArgumentBean {
 
 		public ProvidedArgumentBean(String[] args) {