Fix SerializableTypeWrapper equals() performance

Change SerializableTypeWrapper proxies to directly call equals() methods
on the underlying Type, rather than possibly generating more wrappers.

This should help to improve performance, especially as the equals()
method is called many times when the ResolvableType cache is checked.

Issue: SPR-11335

Author: Phillip Webb

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2013 the original author or authors.
+ * Copyright 2002-2014 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.
@@ -57,6 +57,11 @@ abstract class SerializableTypeWrapper {
 	private static final Class<?>[] SUPPORTED_SERIALIZABLE_TYPES = {
 			GenericArrayType.class, ParameterizedType.class, TypeVariable.class, WildcardType.class};
 
+	private static final Method EQUALS_METHOD = ReflectionUtils.findMethod(Object.class,
+			"equals", Object.class);
+
+	private static final Method GET_TYPE_PROVIDER_METHOD = ReflectionUtils.findMethod(
+			SerializableTypeProxy.class, "getTypeProvider");
 
 	/**
 	 * Return a {@link Serializable} variant of {@link Field#getGenericType()}.
@@ -134,7 +139,8 @@ static Type forTypeProvider(final TypeProvider provider) {
 		for (Class<?> type : SUPPORTED_SERIALIZABLE_TYPES) {
 			if (type.isAssignableFrom(provider.getType().getClass())) {
 				ClassLoader classLoader = provider.getClass().getClassLoader();
-				Class<?>[] interfaces = new Class<?>[] { type, Serializable.class };
+				Class<?>[] interfaces = new Class<?>[] { type,
+					SerializableTypeProxy.class, Serializable.class };
 				InvocationHandler handler = new TypeProxyInvocationHandler(provider);
 				return (Type) Proxy.newProxyInstance(classLoader, interfaces, handler);
 			}
@@ -143,6 +149,19 @@ static Type forTypeProvider(final TypeProvider provider) {
 	}
 
 
+	/**
+	 * Additional interface implemented by the type proxy.
+	 */
+	static interface SerializableTypeProxy {
+
+		/**
+		 * Return the underlying type provider.
+		 */
+		TypeProvider getTypeProvider();
+
+	}
+
+
 	/**
 	 * A {@link Serializable} interface providing access to a {@link Type}.
 	 */
@@ -190,6 +209,17 @@ public TypeProxyInvocationHandler(TypeProvider provider) {
 
 		@Override
 		public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
+			if (GET_TYPE_PROVIDER_METHOD.equals(method)) {
+				return this.provider;
+			}
+			if (EQUALS_METHOD.equals(method)) {
+				Object other = args[0];
+				// Unwrap proxies for speed
+				while (other instanceof SerializableTypeProxy) {
+					other = ((SerializableTypeProxy) other).getTypeProvider().getType();
+				}
+				return this.provider.getType().equals(other);
+			}
 			if (Type.class.equals(method.getReturnType()) && args == null) {
 				return forTypeProvider(new MethodInvokeTypeProvider(this.provider, method, -1));
 			}