DATACMNS-332 - Performance improvements in conversion subsystem hotspots.

Added caching to DefaultTypeMapper, SimpleTypeInformationMapper, BasicPersistentEntity and PreferredConstructor as these seem to be performance hotspots on the reading side of object conversion.

src/main/java/org/springframework/data/convert/DefaultTypeMapper.java

@@ -19,6 +19,8 @@ import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collections;
 import java.util.List;
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
 
 import org.springframework.data.mapping.PersistentEntity;
 import org.springframework.data.mapping.context.MappingContext;
@@ -38,6 +40,7 @@ public class DefaultTypeMapper<S> implements TypeMapper<S> {
 
 	private final TypeAliasAccessor<S> accessor;
 	private final List<? extends TypeInformationMapper> mappers;
+	private final Map<Object, TypeInformation<?>> typeCache;
 
 	/**
 	 * Creates a new {@link DefaultTypeMapper} using the given {@link TypeAliasAccessor}. It will use a
@@ -84,6 +87,7 @@ public class DefaultTypeMapper<S> implements TypeMapper<S> {
 
 		this.mappers = Collections.unmodifiableList(mappers);
 		this.accessor = accessor;
+		this.typeCache = new ConcurrentHashMap<Object, TypeInformation<?>>();
 	}
 
 	/*
@@ -93,21 +97,37 @@ public class DefaultTypeMapper<S> implements TypeMapper<S> {
 	public TypeInformation<?> readType(S source) {
 
 		Assert.notNull(source);
-		Object alias = accessor.readAliasFrom(source);
 
-		if (alias == null) {
-			return null;
+		Object alias = accessor.readAliasFrom(source);
+		return alias == null ? null : getFromCacheOrCreate(alias);
+	}
+
+	/**
+	 * Tries to lookup a {@link TypeInformation} for the given alias from the cache and return it if found. If none is
+	 * found it'll consult the {@link TypeInformationMapper}s and cache the value found.
+	 * 
+	 * @param alias
+	 * @return
+	 */
+	private TypeInformation<?> getFromCacheOrCreate(Object alias) {
+
+		TypeInformation<?> typeInformation = typeCache.get(alias);
+
+		if (typeInformation != null) {
+			return typeInformation;
 		}
 
 		for (TypeInformationMapper mapper : mappers) {
-			TypeInformation<?> type = mapper.resolveTypeFrom(alias);
 
-			if (type != null) {
-				return type;
+			typeInformation = mapper.resolveTypeFrom(alias);
+
+			if (typeInformation != null) {
+				typeCache.put(alias, typeInformation);
+				return typeInformation;
 			}
 		}
 
-		return null;
+		return typeInformation;
 	}
 
 	/*

src/main/java/org/springframework/data/convert/SimpleTypeInformationMapper.java

@@ -15,6 +15,9 @@
  */
 package org.springframework.data.convert;
 
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+
 import org.springframework.data.util.ClassTypeInformation;
 import org.springframework.data.util.TypeInformation;
 import org.springframework.util.ClassUtils;
@@ -30,6 +33,7 @@ import org.springframework.util.StringUtils;
 public class SimpleTypeInformationMapper implements TypeInformationMapper {
 
 	public static final SimpleTypeInformationMapper INSTANCE = new SimpleTypeInformationMapper();
+	private static final Map<String, TypeInformation<?>> cache = new ConcurrentHashMap<String, TypeInformation<?>>();
 
 	/**
 	 * Returns the {@link TypeInformation} that shall be used when the given {@link String} value is found as type hint.
@@ -52,11 +56,23 @@ public class SimpleTypeInformationMapper implements TypeInformationMapper {
 			return null;
 		}
 
+		TypeInformation<?> information = cache.get(value);
+
+		if (information != null) {
+			return information;
+		}
+
 		try {
-			return ClassTypeInformation.from(ClassUtils.forName(value, null));
+			information = ClassTypeInformation.from(ClassUtils.forName(value, null));
 		} catch (ClassNotFoundException e) {
 			return null;
 		}
+
+		if (information != null) {
+			cache.put(value, information);
+		}
+
+		return information;
 	}
 
 	/**
@@ -67,7 +83,6 @@ public class SimpleTypeInformationMapper implements TypeInformationMapper {
 	 * @return the String representation to be stored or {@literal null} if no type information shall be stored.
 	 */
 	public String createAliasFor(TypeInformation<?> type) {
-
 		return type.getType().getName();
 	}
 }