Cache property TypeDescriptors

Attempt to improve performance by caching TypeDescriptors against bean
PropertyDescriptors in CachedIntrospectionResults.

This change is an attempt to fix the failing performance test case
`testPrototypeCreationWithOverriddenResourcePropertiesIsFastEnough` in
`AnnotationProcessorPerformanceTests`.

Author: Phillip Webb

spring-beans/src/main/java/org/springframework/beans/BeanWrapperImpl.java

@@ -490,18 +490,23 @@ private Object convertIfNecessary(String propertyName, Object oldValue, Object n
 	 * @throws TypeMismatchException if type conversion failed
 	 */
 	public Object convertForProperty(Object value, String propertyName) throws TypeMismatchException {
-		PropertyDescriptor pd = getCachedIntrospectionResults().getPropertyDescriptor(propertyName);
+		CachedIntrospectionResults cachedIntrospectionResults = getCachedIntrospectionResults();
+		PropertyDescriptor pd = cachedIntrospectionResults.getPropertyDescriptor(propertyName);
+		TypeDescriptor td = cachedIntrospectionResults.getTypeDescriptor(pd);
 		if (pd == null) {
 			throw new InvalidPropertyException(getRootClass(), this.nestedPath + propertyName,
 					"No property '" + propertyName + "' found");
 		}
-		return convertForProperty(propertyName, null, value, pd);
+		if (td == null) {
+			td = new TypeDescriptor(property(pd));
+			cachedIntrospectionResults.putTypeDescriptor(pd, td);
+		}
+		return convertForProperty(propertyName, null, value, pd, td);
 	}
 
-	private Object convertForProperty(String propertyName, Object oldValue, Object newValue, PropertyDescriptor pd)
+	private Object convertForProperty(String propertyName, Object oldValue, Object newValue, PropertyDescriptor pd, TypeDescriptor td)
 			throws TypeMismatchException {
-
-		return convertIfNecessary(propertyName, oldValue, newValue, pd.getPropertyType(), new TypeDescriptor(property(pd)));
+		return convertIfNecessary(propertyName, oldValue, newValue, pd.getPropertyType(), td);
 	}
 
 	private Property property(PropertyDescriptor pd) {
@@ -1107,7 +1112,7 @@ public Object run() throws Exception {
 								}
 							}
 						}
-						valueToApply = convertForProperty(propertyName, oldValue, originalValue, pd);
+						valueToApply = convertForProperty(propertyName, oldValue, originalValue, pd, new TypeDescriptor(property(pd)));
 					}
 					pv.getOriginalPropertyValue().conversionNecessary = (valueToApply != originalValue);
 				}

spring-beans/src/main/java/org/springframework/beans/CachedIntrospectionResults.java

@@ -22,6 +22,7 @@
 import java.beans.PropertyDescriptor;
 import java.lang.ref.Reference;
 import java.lang.ref.WeakReference;
+import java.util.HashMap;
 import java.util.HashSet;
 import java.util.Iterator;
 import java.util.LinkedHashMap;
@@ -32,6 +33,7 @@
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
+import org.springframework.core.convert.TypeDescriptor;
 import org.springframework.core.io.support.SpringFactoriesLoader;
 import org.springframework.util.ClassUtils;
 import org.springframework.util.StringUtils;
@@ -216,6 +218,9 @@ private static boolean isUnderneathClassLoader(ClassLoader candidate, ClassLoade
 	/** PropertyDescriptor objects keyed by property name String */
 	private final Map<String, PropertyDescriptor> propertyDescriptorCache;
 
+	/** TypeDescriptor objects keyed by PropertyDescriptor */
+	private final Map<PropertyDescriptor, TypeDescriptor> typeDescriptorCache;
+
 
 	/**
 	 * Create a new CachedIntrospectionResults instance for the given class.
@@ -273,6 +278,8 @@ private CachedIntrospectionResults(Class<?> beanClass) throws BeansException {
 				pd = buildGenericTypeAwarePropertyDescriptor(beanClass, pd);
 				this.propertyDescriptorCache.put(pd.getName(), pd);
 			}
+
+			this.typeDescriptorCache = new HashMap<PropertyDescriptor, TypeDescriptor>();
 		}
 		catch (IntrospectionException ex) {
 			throw new FatalBeanException("Failed to obtain BeanInfo for class [" + beanClass.getName() + "]", ex);
@@ -321,4 +328,12 @@ private PropertyDescriptor buildGenericTypeAwarePropertyDescriptor(Class<?> bean
 		}
 	}
 
+	TypeDescriptor getTypeDescriptor(PropertyDescriptor pd) {
+		return this.typeDescriptorCache.get(pd);
+	}
+
+	void putTypeDescriptor(PropertyDescriptor pd, TypeDescriptor td) {
+		this.typeDescriptorCache.put(pd, td);
+	}
+
 }