Share internal StandardExecutionContext delegates

This commit makes sure that the per-operation execution context for
caching and event listening does not recreate the default internal
delegates, but rather get initialized with a shared state.

This reduces the number of instances created per operation execution,
reducing the GC pressure as a result. This also makes sure that any
cache, such as the one in StandardTypeLocator, is reused.

Closes gh-31617

spring-context/src/main/java/org/springframework/cache/interceptor/CacheAspectSupport.java

@@ -47,11 +47,13 @@ import org.springframework.beans.factory.annotation.BeanFactoryAnnotationUtils;
 import org.springframework.cache.Cache;
 import org.springframework.cache.CacheManager;
 import org.springframework.context.expression.AnnotatedElementKey;
+import org.springframework.context.expression.BeanFactoryResolver;
 import org.springframework.core.BridgeMethodResolver;
 import org.springframework.core.KotlinDetector;
 import org.springframework.core.ReactiveAdapter;
 import org.springframework.core.ReactiveAdapterRegistry;
 import org.springframework.expression.EvaluationContext;
+import org.springframework.expression.spel.support.StandardEvaluationContext;
 import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.ClassUtils;
@@ -99,7 +101,10 @@ public abstract class CacheAspectSupport extends AbstractCacheInvoker
 
 	private final Map<CacheOperationCacheKey, CacheOperationMetadata> metadataCache = new ConcurrentHashMap<>(1024);
 
-	private final CacheOperationExpressionEvaluator evaluator = new CacheOperationExpressionEvaluator();
+	private final StandardEvaluationContext originalEvaluationContext = new StandardEvaluationContext();
+
+	private final CacheOperationExpressionEvaluator evaluator = new CacheOperationExpressionEvaluator(
+			new CacheEvaluationContextFactory(this.originalEvaluationContext));
 
 	@Nullable
 	private final ReactiveCachingHandler reactiveCachingHandler;
@@ -222,6 +227,7 @@ public abstract class CacheAspectSupport extends AbstractCacheInvoker
 	@Override
 	public void setBeanFactory(BeanFactory beanFactory) {
 		this.beanFactory = beanFactory;
+		this.originalEvaluationContext.setBeanResolver(new BeanFactoryResolver(beanFactory));
 	}
 
 
@@ -852,7 +858,7 @@ public abstract class CacheAspectSupport extends AbstractCacheInvoker
 
 		private EvaluationContext createEvaluationContext(@Nullable Object result) {
 			return evaluator.createEvaluationContext(this.caches, this.metadata.method, this.args,
-					this.target, this.metadata.targetClass, this.metadata.targetMethod, result, beanFactory);
+					this.target, this.metadata.targetClass, this.metadata.targetMethod, result);
 		}
 
 		protected Collection<? extends Cache> getCaches() {

spring-context/src/main/java/org/springframework/cache/interceptor/CacheEvaluationContextFactory.java

@@ -0,0 +1,73 @@
+/*
+ * 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.
+ * You may obtain a copy of the License at
+ *
+ *      https://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 org.springframework.cache.interceptor;
+
+import java.lang.reflect.Method;
+import java.util.function.Supplier;
+
+import org.springframework.core.DefaultParameterNameDiscoverer;
+import org.springframework.core.ParameterNameDiscoverer;
+import org.springframework.expression.spel.support.StandardEvaluationContext;
+import org.springframework.lang.Nullable;
+import org.springframework.util.function.SingletonSupplier;
+
+/**
+ * A factory for {@link CacheEvaluationContext} that makes sure that internal
+ * delegates are reused.
+ *
+ * @author Stephane Nicoll
+ * @since 6.1.1
+ */
+class CacheEvaluationContextFactory {
+
+	private final StandardEvaluationContext originalContext;
+
+	@Nullable
+	private Supplier<ParameterNameDiscoverer> parameterNameDiscoverer;
+
+	CacheEvaluationContextFactory(StandardEvaluationContext originalContext) {
+		this.originalContext = originalContext;
+	}
+
+	public void setParameterNameDiscoverer(Supplier<ParameterNameDiscoverer> parameterNameDiscoverer) {
+		this.parameterNameDiscoverer = parameterNameDiscoverer;
+	}
+
+	public ParameterNameDiscoverer getParameterNameDiscoverer() {
+		if (this.parameterNameDiscoverer == null) {
+			this.parameterNameDiscoverer = SingletonSupplier.of(new DefaultParameterNameDiscoverer());
+		}
+		return this.parameterNameDiscoverer.get();
+	}
+
+	/**
+	 * Creates a {@link CacheEvaluationContext} for the specified operation.
+	 * @param rootObject the {@code root} object to use for the context
+	 * @param targetMethod the target cache {@link Method}
+	 * @param args the arguments of the method invocation
+	 * @return a context suitable for this cache operation
+	 */
+	public CacheEvaluationContext forOperation(CacheExpressionRootObject rootObject,
+			Method targetMethod, Object[] args) {
+
+		CacheEvaluationContext evaluationContext = new CacheEvaluationContext(
+				rootObject, targetMethod, args, getParameterNameDiscoverer());
+		this.originalContext.applyDelegatesTo(evaluationContext);
+		return evaluationContext;
+	}
+
+}

spring-context/src/main/java/org/springframework/cache/interceptor/CacheOperationExpressionEvaluator.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2018 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.
@@ -21,10 +21,8 @@ import java.util.Collection;
 import java.util.Map;
 import java.util.concurrent.ConcurrentHashMap;
 
-import org.springframework.beans.factory.BeanFactory;
 import org.springframework.cache.Cache;
 import org.springframework.context.expression.AnnotatedElementKey;
-import org.springframework.context.expression.BeanFactoryResolver;
 import org.springframework.context.expression.CachedExpressionEvaluator;
 import org.springframework.expression.EvaluationContext;
 import org.springframework.expression.Expression;
@@ -67,6 +65,13 @@ class CacheOperationExpressionEvaluator extends CachedExpressionEvaluator {
 
 	private final Map<ExpressionKey, Expression> unlessCache = new ConcurrentHashMap<>(64);
 
+	private final CacheEvaluationContextFactory evaluationContextFactory;
+
+	public CacheOperationExpressionEvaluator(CacheEvaluationContextFactory evaluationContextFactory) {
+		super();
+		this.evaluationContextFactory = evaluationContextFactory;
+		this.evaluationContextFactory.setParameterNameDiscoverer(this::getParameterNameDiscoverer);
+	}
 
 	/**
 	 * Create an {@link EvaluationContext}.
@@ -81,21 +86,18 @@ class CacheOperationExpressionEvaluator extends CachedExpressionEvaluator {
 	 */
 	public EvaluationContext createEvaluationContext(Collection<? extends Cache> caches,
 			Method method, Object[] args, Object target, Class<?> targetClass, Method targetMethod,
-			@Nullable Object result, @Nullable BeanFactory beanFactory) {
+			@Nullable Object result) {
 
 		CacheExpressionRootObject rootObject = new CacheExpressionRootObject(
 				caches, method, args, target, targetClass);
-		CacheEvaluationContext evaluationContext = new CacheEvaluationContext(
-				rootObject, targetMethod, args, getParameterNameDiscoverer());
+		CacheEvaluationContext evaluationContext = this.evaluationContextFactory
+				.forOperation(rootObject, targetMethod, args);
 		if (result == RESULT_UNAVAILABLE) {
 			evaluationContext.addUnavailableVariable(RESULT_VARIABLE);
 		}
 		else if (result != NO_RESULT) {
 			evaluationContext.setVariable(RESULT_VARIABLE, result);
 		}
-		if (beanFactory != null) {
-			evaluationContext.setBeanResolver(new BeanFactoryResolver(beanFactory));
-		}
 		return evaluationContext;
 	}
 

spring-context/src/main/java/org/springframework/context/event/ApplicationListenerMethodAdapter.java

@@ -262,7 +262,7 @@ public class ApplicationListenerMethodAdapter implements GenericApplicationListe
 		if (StringUtils.hasText(condition)) {
 			Assert.notNull(this.evaluator, "EventExpressionEvaluator must not be null");
 			return this.evaluator.condition(
-					condition, event, this.targetMethod, this.methodKey, args, this.applicationContext);
+					condition, event, this.targetMethod, this.methodKey, args);
 		}
 		return true;
 	}

spring-context/src/main/java/org/springframework/context/event/EventExpressionEvaluator.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 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.
@@ -20,14 +20,13 @@ import java.lang.reflect.Method;
 import java.util.Map;
 import java.util.concurrent.ConcurrentHashMap;
 
-import org.springframework.beans.factory.BeanFactory;
 import org.springframework.context.ApplicationEvent;
 import org.springframework.context.expression.AnnotatedElementKey;
-import org.springframework.context.expression.BeanFactoryResolver;
 import org.springframework.context.expression.CachedExpressionEvaluator;
 import org.springframework.context.expression.MethodBasedEvaluationContext;
+import org.springframework.expression.EvaluationContext;
 import org.springframework.expression.Expression;
-import org.springframework.lang.Nullable;
+import org.springframework.expression.spel.support.StandardEvaluationContext;
 
 /**
  * Utility class for handling SpEL expression parsing for application events.
@@ -41,23 +40,32 @@ class EventExpressionEvaluator extends CachedExpressionEvaluator {
 
 	private final Map<ExpressionKey, Expression> conditionCache = new ConcurrentHashMap<>(64);
 
+	private final StandardEvaluationContext originalEvaluationContext;
+
+	EventExpressionEvaluator(StandardEvaluationContext originalEvaluationContext) {
+		this.originalEvaluationContext = originalEvaluationContext;
+	}
 
 	/**
 	 * Determine if the condition defined by the specified expression evaluates
 	 * to {@code true}.
 	 */
 	public boolean condition(String conditionExpression, ApplicationEvent event, Method targetMethod,
-			AnnotatedElementKey methodKey, Object[] args, @Nullable BeanFactory beanFactory) {
-
-		EventExpressionRootObject root = new EventExpressionRootObject(event, args);
-		MethodBasedEvaluationContext evaluationContext = new MethodBasedEvaluationContext(
-				root, targetMethod, args, getParameterNameDiscoverer());
-		if (beanFactory != null) {
-			evaluationContext.setBeanResolver(new BeanFactoryResolver(beanFactory));
-		}
+			AnnotatedElementKey methodKey, Object[] args) {
 
+		EventExpressionRootObject rootObject = new EventExpressionRootObject(event, args);
+		EvaluationContext evaluationContext = createEvaluationContext(rootObject, targetMethod, args);
 		return (Boolean.TRUE.equals(getExpression(this.conditionCache, methodKey, conditionExpression).getValue(
 				evaluationContext, Boolean.class)));
 	}
 
+	private EvaluationContext createEvaluationContext(EventExpressionRootObject rootObject,
+			Method method, Object[] args) {
+
+		MethodBasedEvaluationContext evaluationContext = new MethodBasedEvaluationContext(rootObject,
+				method, args, getParameterNameDiscoverer());
+		this.originalEvaluationContext.applyDelegatesTo(evaluationContext);
+		return evaluationContext;
+	}
+
 }

spring-context/src/main/java/org/springframework/context/event/EventListenerMethodProcessor.java

@@ -39,10 +39,12 @@ import org.springframework.context.ApplicationContext;
 import org.springframework.context.ApplicationContextAware;
 import org.springframework.context.ApplicationListener;
 import org.springframework.context.ConfigurableApplicationContext;
+import org.springframework.context.expression.BeanFactoryResolver;
 import org.springframework.core.MethodIntrospector;
 import org.springframework.core.annotation.AnnotatedElementUtils;
 import org.springframework.core.annotation.AnnotationAwareOrderComparator;
 import org.springframework.core.annotation.AnnotationUtils;
+import org.springframework.expression.spel.support.StandardEvaluationContext;
 import org.springframework.lang.Nullable;
 import org.springframework.stereotype.Component;
 import org.springframework.util.Assert;
@@ -75,6 +77,8 @@ public class EventListenerMethodProcessor
 	@Nullable
 	private List<EventListenerFactory> eventListenerFactories;
 
+	private final StandardEvaluationContext originalEvaluationContext;
+
 	@Nullable
 	private final EventExpressionEvaluator evaluator;
 
@@ -82,7 +86,8 @@ public class EventListenerMethodProcessor
 
 
 	public EventListenerMethodProcessor() {
-		this.evaluator = new EventExpressionEvaluator();
+		this.originalEvaluationContext = new StandardEvaluationContext();
+		this.evaluator = new EventExpressionEvaluator(this.originalEvaluationContext);
 	}
 
 	@Override
@@ -95,6 +100,7 @@ public class EventListenerMethodProcessor
 	@Override
 	public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) {
 		this.beanFactory = beanFactory;
+		this.originalEvaluationContext.setBeanResolver(new BeanFactoryResolver(this.beanFactory));
 
 		Map<String, EventListenerFactory> beans = beanFactory.getBeansOfType(EventListenerFactory.class, false, false);
 		List<EventListenerFactory> factories = new ArrayList<>(beans.values());