Additional caching for ResolvableTypes

Add additional caching to ResolvableTypes and SerializableTypeWrapper
in order to improve SpEL performance.

Issue: SPR-11388

Author: Phillip Webb

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

@@ -115,6 +115,12 @@ public final class ResolvableType implements Serializable {
 	 */
 	private final Class<?> resolved;
 
+	private ResolvableType superType;
+
+	private ResolvableType[] interfaces;
+
+	private ResolvableType[] generics;
+
 
 	/**
 	 * Private constructor used to create a new {@link ResolvableType} for resolution purposes.
@@ -360,7 +366,11 @@ public ResolvableType getSuperType() {
 		if (resolved == null || resolved.getGenericSuperclass() == null) {
 			return NONE;
 		}
-		return forType(SerializableTypeWrapper.forGenericSuperclass(resolved), asVariableResolver());
+		if (this.superType == null) {
+			this.superType = forType(SerializableTypeWrapper.forGenericSuperclass(resolved),
+					asVariableResolver());
+		}
+		return this.superType;
 	}
 
 	/**
@@ -374,7 +384,11 @@ public ResolvableType[] getInterfaces() {
 		if (resolved == null || ObjectUtils.isEmpty(resolved.getGenericInterfaces())) {
 			return EMPTY_TYPES_ARRAY;
 		}
-		return forTypes(SerializableTypeWrapper.forGenericInterfaces(resolved), asVariableResolver());
+		if (this.interfaces == null) {
+			this.interfaces = forTypes(SerializableTypeWrapper.forGenericInterfaces(resolved),
+					asVariableResolver());
+		}
+		return this.interfaces;
 	}
 
 	/**
@@ -551,19 +565,24 @@ public ResolvableType[] getGenerics() {
 		if (this == NONE) {
 			return EMPTY_TYPES_ARRAY;
 		}
-		if (this.type instanceof Class<?>) {
-			Class<?> typeClass = (Class<?>) this.type;
-			return forTypes(SerializableTypeWrapper.forTypeParameters(typeClass), this.variableResolver);
-		}
-		if (this.type instanceof ParameterizedType) {
-			Type[] actualTypeArguments = ((ParameterizedType) this.type).getActualTypeArguments();
-			ResolvableType[] generics = new ResolvableType[actualTypeArguments.length];
-			for (int i = 0; i < actualTypeArguments.length; i++) {
-				generics[i] = forType(actualTypeArguments[i], this.variableResolver);
+		if (this.generics == null) {
+			if (this.type instanceof Class<?>) {
+				Class<?> typeClass = (Class<?>) this.type;
+				this.generics = forTypes(SerializableTypeWrapper.forTypeParameters(typeClass), this.variableResolver);
+			}
+			else if (this.type instanceof ParameterizedType) {
+				Type[] actualTypeArguments = ((ParameterizedType) this.type).getActualTypeArguments();
+				ResolvableType[] generics = new ResolvableType[actualTypeArguments.length];
+				for (int i = 0; i < actualTypeArguments.length; i++) {
+					generics[i] = forType(actualTypeArguments[i], this.variableResolver);
+				}
+				this.generics = generics;
+			}
+			else {
+				this.generics = resolveType().getGenerics();
 			}
-			return generics;
 		}
-		return resolveType().getGenerics();
+		return this.generics;
 	}
 
 	/**

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

@@ -31,6 +31,7 @@
 import java.lang.reflect.WildcardType;
 
 import org.springframework.util.Assert;
+import org.springframework.util.ConcurrentReferenceHashMap;
 import org.springframework.util.ReflectionUtils;
 
 /**
@@ -63,6 +64,9 @@ abstract class SerializableTypeWrapper {
 	private static final Method GET_TYPE_PROVIDER_METHOD = ReflectionUtils.findMethod(
 			SerializableTypeProxy.class, "getTypeProvider");
 
+	private static final ConcurrentReferenceHashMap<Type, Type> cache =
+			new ConcurrentReferenceHashMap<Type, Type>(256);
+
 	/**
 	 * Return a {@link Serializable} variant of {@link Field#getGenericType()}.
 	 */
@@ -150,13 +154,19 @@ static Type forTypeProvider(final TypeProvider provider) {
 		if (provider.getType() instanceof Serializable || provider.getType() == null) {
 			return provider.getType();
 		}
+		Type cached = cache.get(provider.getType());
+		if(cached != null) {
+			return cached;
+		}
 		for (Class<?> type : SUPPORTED_SERIALIZABLE_TYPES) {
 			if (type.isAssignableFrom(provider.getType().getClass())) {
 				ClassLoader classLoader = provider.getClass().getClassLoader();
 				Class<?>[] interfaces = new Class<?>[] { type,
 					SerializableTypeProxy.class, Serializable.class };
 				InvocationHandler handler = new TypeProxyInvocationHandler(provider);
-				return (Type) Proxy.newProxyInstance(classLoader, interfaces, handler);
+				cached = (Type) Proxy.newProxyInstance(classLoader, interfaces, handler);
+				cache.put(provider.getType(), cached);
+				return cached;
 			}
 		}
 		throw new IllegalArgumentException("Unsupported Type class " + provider.getType().getClass().getName());

spring-expression/src/test/java/org/springframework/expression/spel/MapAccessTests.java

@@ -20,7 +20,6 @@
 import java.util.Map;
 
 import org.junit.Test;
-
 import org.springframework.expression.AccessException;
 import org.springframework.expression.EvaluationContext;
 import org.springframework.expression.Expression;
@@ -29,6 +28,11 @@
 import org.springframework.expression.TypedValue;
 import org.springframework.expression.spel.standard.SpelExpressionParser;
 import org.springframework.expression.spel.support.StandardEvaluationContext;
+import org.springframework.tests.Assume;
+import org.springframework.tests.TestGroup;
+import org.springframework.util.StopWatch;
+
+import static org.hamcrest.Matchers.*;
 
 import static org.junit.Assert.*;
 
@@ -96,6 +100,25 @@ public void testGetValueFromRootMap() {
 		assertEquals("value", expr.getValue(map));
 	}
 
+	@Test
+	public void testGetValuePerformance() throws Exception {
+		Assume.group(TestGroup.PERFORMANCE);
+		Map<String, String> map = new HashMap<String, String>();
+		map.put("key", "value");
+		EvaluationContext context = new StandardEvaluationContext(map);
+
+		ExpressionParser spelExpressionParser = new SpelExpressionParser();
+		Expression expr = spelExpressionParser.parseExpression("#root['key']");
+
+		StopWatch s = new StopWatch();
+		s.start();
+		for (int i = 0; i < 10000; i++) {
+			expr.getValue(context);
+		}
+		s.stop();
+		assertThat(s.getTotalTimeMillis(), lessThan(200L));
+	}
+
 
 	public static class TestBean {