Revise ResolvableType.as for introspection performance

This revision limits serializability of derived interfaces, superclasses and type parameters, optimizing for introspection performance instead.

Issue: SPR-17070

Author: jhoeller

spring-beans/src/main/java/org/springframework/beans/factory/config/DependencyDescriptor.java

@@ -75,7 +75,7 @@ public class DependencyDescriptor extends InjectionPoint implements Serializable
 	private Class<?> containingClass;
 
 	@Nullable
-	private volatile ResolvableType resolvableType;
+	private transient volatile ResolvableType resolvableType;
 
 
 	/**

spring-core/src/main/java/org/springframework/core/ResolvableType.java

@@ -430,7 +430,8 @@ public ResolvableType as(Class<?> type) {
 		if (this == NONE) {
 			return NONE;
 		}
-		if (ObjectUtils.nullSafeEquals(resolve(), type)) {
+		Class<?> resolved = resolve();
+		if (resolved == null || resolved == type) {
 			return this;
 		}
 		for (ResolvableType interfaceType : getInterfaces()) {
@@ -445,6 +446,7 @@ public ResolvableType as(Class<?> type) {
 	/**
 	 * Return a {@link ResolvableType} representing the direct supertype of this type.
 	 * If no supertype is available this method returns {@link #NONE}.
+	 * <p>Note: The resulting {@link ResolvableType} instance may not be {@link Serializable}.
 	 * @see #getInterfaces()
 	 */
 	public ResolvableType getSuperType() {
@@ -454,7 +456,7 @@ public ResolvableType getSuperType() {
 		}
 		ResolvableType superType = this.superType;
 		if (superType == null) {
-			superType = forType(SerializableTypeWrapper.forGenericSuperclass(resolved), asVariableResolver());
+			superType = forType(resolved.getGenericSuperclass(), this);
 			this.superType = superType;
 		}
 		return superType;
@@ -464,16 +466,21 @@ public ResolvableType getSuperType() {
 	 * Return a {@link ResolvableType} array representing the direct interfaces
 	 * implemented by this type. If this type does not implement any interfaces an
 	 * empty array is returned.
+	 * <p>Note: The resulting {@link ResolvableType} instances may not be {@link Serializable}.
 	 * @see #getSuperType()
 	 */
 	public ResolvableType[] getInterfaces() {
 		Class<?> resolved = resolve();
-		if (resolved == null || ObjectUtils.isEmpty(resolved.getGenericInterfaces())) {
+		if (resolved == null) {
 			return EMPTY_TYPES_ARRAY;
 		}
 		ResolvableType[] interfaces = this.interfaces;
 		if (interfaces == null) {
-			interfaces = forTypes(SerializableTypeWrapper.forGenericInterfaces(resolved), asVariableResolver());
+			Type[] genericIfcs = resolved.getGenericInterfaces();
+			interfaces = new ResolvableType[genericIfcs.length];
+			for (int i = 0; i < genericIfcs.length; i++) {
+				interfaces[i] = forType(genericIfcs[i], this);
+			}
 			this.interfaces = interfaces;
 		}
 		return interfaces;
@@ -673,8 +680,11 @@ public ResolvableType[] getGenerics() {
 		ResolvableType[] generics = this.generics;
 		if (generics == null) {
 			if (this.type instanceof Class) {
-				Class<?> typeClass = (Class<?>) this.type;
-				generics = forTypes(SerializableTypeWrapper.forTypeParameters(typeClass), this.variableResolver);
+				Type[] typeParams = ((Class<?>) this.type).getTypeParameters();
+				generics = new ResolvableType[typeParams.length];
+				for (int i = 0; i < generics.length; i++) {
+					generics[i] = ResolvableType.forType(typeParams[i], this);
+				}
 			}
 			else if (this.type instanceof ParameterizedType) {
 				Type[] actualTypeArguments = ((ParameterizedType) this.type).getActualTypeArguments();
@@ -818,7 +828,7 @@ ResolvableType resolveType() {
 
 	@Nullable
 	private Type resolveBounds(Type[] bounds) {
-		if (ObjectUtils.isEmpty(bounds) || Object.class == bounds[0]) {
+		if (bounds.length == 0 || bounds[0] == Object.class) {
 			return null;
 		}
 		return bounds[0];
@@ -1309,17 +1319,9 @@ public static ResolvableType forArrayComponent(ResolvableType componentType) {
 		return new ResolvableType(arrayClass, null, null, componentType);
 	}
 
-	private static ResolvableType[] forTypes(Type[] types, @Nullable VariableResolver owner) {
-		ResolvableType[] result = new ResolvableType[types.length];
-		for (int i = 0; i < types.length; i++) {
-			result[i] = forType(types[i], owner);
-		}
-		return result;
-	}
-
 	/**
 	 * Return a {@link ResolvableType} for the specified {@link Type}.
-	 * Note: The resulting {@link ResolvableType} may not be {@link Serializable}.
+	 * <p>Note: The resulting {@link ResolvableType} instance may not be {@link Serializable}.
 	 * @param type the source type (potentially {@code null})
 	 * @return a {@link ResolvableType} for the specified {@link Type}
 	 * @see #forType(Type, ResolvableType)
@@ -1330,7 +1332,8 @@ public static ResolvableType forType(@Nullable Type type) {
 
 	/**
 	 * Return a {@link ResolvableType} for the specified {@link Type} backed by the given
-	 * owner type. Note: The resulting {@link ResolvableType} may not be {@link Serializable}.
+	 * owner type.
+	 * <p>Note: The resulting {@link ResolvableType} instance may not be {@link Serializable}.
 	 * @param type the source type or {@code null}
 	 * @param owner the owner type used to resolve variables
 	 * @return a {@link ResolvableType} for the specified {@link Type} and owner
@@ -1347,7 +1350,7 @@ public static ResolvableType forType(@Nullable Type type, @Nullable ResolvableTy
 
 	/**
 	 * Return a {@link ResolvableType} for the specified {@link ParameterizedTypeReference}.
-	 * Note: The resulting {@link ResolvableType} may not be {@link Serializable}.
+	 * <p>Note: The resulting {@link ResolvableType} instance may not be {@link Serializable}.
 	 * @param typeReference the reference to obtain the source type from
 	 * @return a {@link ResolvableType} for the specified {@link ParameterizedTypeReference}
 	 * @since 4.3.12

spring-core/src/main/java/org/springframework/core/SerializableTypeWrapper.java

@@ -41,9 +41,7 @@
  *
  * <p>{@link #forField(Field) Fields} or {@link #forMethodParameter(MethodParameter)
  * MethodParameters} can be used as the root source for a serializable type.
- * Alternatively the {@link #forGenericSuperclass(Class) superclass},
- * {@link #forGenericInterfaces(Class) interfaces} or {@link #forTypeParameters(Class)
- * type parameters} or a regular {@link Class} can also be used as source.
+ * Alternatively, a regular {@link Class} can also be used as source.
  *
  * <p>The returned type will either be a {@link Class} or a serializable proxy of
  * {@link GenericArrayType}, {@link ParameterizedType}, {@link TypeVariable} or
@@ -84,41 +82,6 @@ public static Type forMethodParameter(MethodParameter methodParameter) {
 		return forTypeProvider(new MethodParameterTypeProvider(methodParameter));
 	}
 
-	/**
-	 * Return a {@link Serializable} variant of {@link Class#getGenericSuperclass()}.
-	 */
-	@SuppressWarnings("serial")
-	@Nullable
-	public static Type forGenericSuperclass(final Class<?> type) {
-		return forTypeProvider(type::getGenericSuperclass);
-	}
-
-	/**
-	 * Return a {@link Serializable} variant of {@link Class#getGenericInterfaces()}.
-	 */
-	@SuppressWarnings("serial")
-	public static Type[] forGenericInterfaces(final Class<?> type) {
-		Type[] result = new Type[type.getGenericInterfaces().length];
-		for (int i = 0; i < result.length; i++) {
-			final int index = i;
-			result[i] = forTypeProvider(() -> type.getGenericInterfaces()[index]);
-		}
-		return result;
-	}
-
-	/**
-	 * Return a {@link Serializable} variant of {@link Class#getTypeParameters()}.
-	 */
-	@SuppressWarnings("serial")
-	public static Type[] forTypeParameters(final Class<?> type) {
-		Type[] result = new Type[type.getTypeParameters().length];
-		for (int i = 0; i < result.length; i++) {
-			final int index = i;
-			result[i] = forTypeProvider(() -> type.getTypeParameters()[index]);
-		}
-		return result;
-	}
-
 	/**
 	 * Unwrap the given type, effectively returning the original non-serializable type.
 	 * @param type the type to unwrap

spring-core/src/test/java/org/springframework/core/ResolvableTypeTests.java

@@ -1246,8 +1246,6 @@ public void serialize() throws Exception {
 		testSerialization(ResolvableType.forMethodReturnType(Methods.class.getMethod("charSequenceReturn")));
 		testSerialization(ResolvableType.forConstructorParameter(Constructors.class.getConstructor(List.class), 0));
 		testSerialization(ResolvableType.forField(Fields.class.getField("charSequenceList")).getGeneric());
-		testSerialization(ResolvableType.forField(Fields.class.getField("charSequenceList")).asCollection());
-		testSerialization(ResolvableType.forClass(ExtendsMap.class).getSuperType());
 		ResolvableType deserializedNone = testSerialization(ResolvableType.NONE);
 		assertThat(deserializedNone, sameInstance(ResolvableType.NONE));
 	}

spring-core/src/test/java/org/springframework/core/SerializableTypeWrapperTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 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.
@@ -27,7 +27,6 @@
 import java.lang.reflect.Type;
 import java.lang.reflect.TypeVariable;
 import java.lang.reflect.WildcardType;
-import java.util.ArrayList;
 import java.util.List;
 
 import org.junit.Test;
@@ -65,27 +64,6 @@ public void forConstructor() throws Exception {
 		assertSerializable(type);
 	}
 
-	@Test
-	public void forGenericSuperClass() throws Exception {
-		Type type = SerializableTypeWrapper.forGenericSuperclass(ArrayList.class);
-		assertThat(type.toString(), equalTo("java.util.AbstractList<E>"));
-		assertSerializable(type);
-	}
-
-	@Test
-	public void forGenericInterfaces() throws Exception {
-		Type type = SerializableTypeWrapper.forGenericInterfaces(List.class)[0];
-		assertThat(type.toString(), equalTo("java.util.Collection<E>"));
-		assertSerializable(type);
-	}
-
-	@Test
-	public void forTypeParameters() throws Exception {
-		Type type = SerializableTypeWrapper.forTypeParameters(List.class)[0];
-		assertThat(type.toString(), equalTo("E"));
-		assertSerializable(type);
-	}
-
 	@Test
 	public void classType() throws Exception {
 		Type type = SerializableTypeWrapper.forField(Fields.class.getField("classType"));