Revisit internal caching arrangements.

Introduce caching and reduce allocations on hot code paths.

Closes: #4818
Original Pull Request: #4819

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/convert/DefaultMongoTypeMapper.java

@@ -171,6 +171,7 @@ public class DefaultMongoTypeMapper extends DefaultTypeMapper<Bson> implements M
 			this.typeKey = typeKey;
 		}
 
+		@Override
 		public Alias readAliasFrom(Bson source) {
 
 			if (source instanceof List) {

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/convert/MappingMongoConverter.java

@@ -27,6 +27,7 @@ import java.util.List;
 import java.util.Map;
 import java.util.Optional;
 import java.util.Set;
+import java.util.function.BiPredicate;
 import java.util.function.Predicate;
 import java.util.stream.Collectors;
 
@@ -130,6 +131,23 @@ public class MappingMongoConverter extends AbstractMongoConverter
 	private static final String INCOMPATIBLE_TYPES = "Cannot convert %1$s of type %2$s into an instance of %3$s; Implement a custom Converter<%2$s, %3$s> and register it with the CustomConversions; Parent object was: %4$s";
 	private static final String INVALID_TYPE_TO_READ = "Expected to read Document %s into type %s but didn't find a PersistentEntity for the latter";
 
+	private static final BiPredicate<MongoPersistentEntity<?>, MongoPersistentProperty> PROPERTY_FILTER = (e,
+			property) -> {
+
+		if (property.isIdProperty()) {
+			return false;
+		}
+
+		if (e.isCreatorArgument(property)) {
+			return false;
+		}
+
+		if (!property.isReadable()) {
+			return false;
+		}
+		return true;
+	};
+
 	public static final TypeInformation<Bson> BSON = TypeInformation.of(Bson.class);
 
 	protected static final Log LOGGER = LogFactory.getLog(MappingMongoConverter.class);
@@ -368,7 +386,7 @@ public class MappingMongoConverter extends AbstractMongoConverter
 					evaluator, spELContext);
 
 			readProperties(context, entity, convertingAccessor, documentAccessor, valueProvider, evaluator,
-					Predicates.isTrue());
+					(mongoPersistentProperties, mongoPersistentProperty) -> true);
 			return (R) projectionFactory.createProjection(mappedType.getType(), accessor.getBean());
 		}
 
@@ -518,6 +536,23 @@ public class MappingMongoConverter extends AbstractMongoConverter
 				parameterProvider);
 	}
 
+	class EvaluatingDocumentAccessor extends DocumentAccessor implements ValueExpressionEvaluator {
+
+		/**
+		 * Creates a new {@link DocumentAccessor} for the given {@link Document}.
+		 *
+		 * @param document must be a {@link Document} effectively, must not be {@literal null}.
+		 */
+		public EvaluatingDocumentAccessor(Bson document) {
+			super(document);
+		}
+
+		@Override
+		public <T> T evaluate(String expression) {
+			return expressionEvaluatorFactory.create(getDocument()).evaluate(expression);
+		}
+	}
+
 	private <S> S read(ConversionContext context, MongoPersistentEntity<S> entity, Document bson) {
 
 		S existing = context.findContextualEntity(entity, bson);
@@ -525,19 +560,18 @@ public class MappingMongoConverter extends AbstractMongoConverter
 			return existing;
 		}
 
-		ValueExpressionEvaluator evaluator = expressionEvaluatorFactory.create(bson);
-		DocumentAccessor documentAccessor = new DocumentAccessor(bson);
-
+		EvaluatingDocumentAccessor documentAccessor = new EvaluatingDocumentAccessor(bson);
 		InstanceCreatorMetadata<MongoPersistentProperty> instanceCreatorMetadata = entity.getInstanceCreatorMetadata();
 
 		ParameterValueProvider<MongoPersistentProperty> provider = instanceCreatorMetadata != null
-				&& instanceCreatorMetadata.hasParameters() ? getParameterProvider(context, entity, documentAccessor, evaluator)
+				&& instanceCreatorMetadata.hasParameters()
+						? getParameterProvider(context, entity, documentAccessor, documentAccessor)
 						: NoOpParameterValueProvider.INSTANCE;
 
 		EntityInstantiator instantiator = instantiators.getInstantiatorFor(entity);
 		S instance = instantiator.createInstance(entity, provider);
 
-		return populateProperties(context, entity, documentAccessor, evaluator, instance);
+		return populateProperties(context, entity, documentAccessor, documentAccessor, instance);
 	}
 
 	private <S> S populateProperties(ConversionContext context, MongoPersistentEntity<S> entity,
@@ -559,9 +593,7 @@ public class MappingMongoConverter extends AbstractMongoConverter
 		MongoDbPropertyValueProvider valueProvider = new MongoDbPropertyValueProvider(contextToUse, documentAccessor,
 				evaluator, spELContext);
 
-		Predicate<MongoPersistentProperty> propertyFilter = isIdentifier(entity).or(isConstructorArgument(entity))
-				.or(Predicates.negate(PersistentProperty::isReadable)).negate();
-		readProperties(contextToUse, entity, accessor, documentAccessor, valueProvider, evaluator, propertyFilter);
+		readProperties(contextToUse, entity, accessor, documentAccessor, valueProvider, evaluator, PROPERTY_FILTER);
 
 		return accessor.getBean();
 	}
@@ -606,13 +638,13 @@ public class MappingMongoConverter extends AbstractMongoConverter
 	private void readProperties(ConversionContext context, MongoPersistentEntity<?> entity,
 			PersistentPropertyAccessor<?> accessor, DocumentAccessor documentAccessor,
 			MongoDbPropertyValueProvider valueProvider, ValueExpressionEvaluator evaluator,
-			Predicate<MongoPersistentProperty> propertyFilter) {
+			BiPredicate<MongoPersistentEntity<?>, MongoPersistentProperty> propertyFilter) {
 
 		DbRefResolverCallback callback = null;
 
 		for (MongoPersistentProperty prop : entity) {
 
-			if (!propertyFilter.test(prop)) {
+			if (!propertyFilter.test(entity, prop)) {
 				continue;
 			}
 
@@ -1943,10 +1975,6 @@ public class MappingMongoConverter extends AbstractMongoConverter
 		MongoDbPropertyValueProvider(ConversionContext context, DocumentAccessor accessor,
 				ValueExpressionEvaluator evaluator, SpELContext spELContext) {
 
-			Assert.notNull(context, "ConversionContext must no be null");
-			Assert.notNull(accessor, "DocumentAccessor must no be null");
-			Assert.notNull(evaluator, "ValueExpressionEvaluator must not be null");
-
 			this.context = context;
 			this.accessor = accessor;
 			this.evaluator = evaluator;
@@ -2359,9 +2387,6 @@ public class MappingMongoConverter extends AbstractMongoConverter
 		public <S extends Object> S convert(Object source, TypeInformation<? extends S> typeHint,
 				ConversionContext context) {
 
-			Assert.notNull(source, "Source must not be null");
-			Assert.notNull(typeHint, "TypeInformation must not be null");
-
 			if (conversions.hasCustomReadTarget(source.getClass(), typeHint.getType())) {
 				return (S) elementConverter.convert(source, typeHint);
 			}

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/mapping/CachingMongoPersistentProperty.java

@@ -30,6 +30,8 @@ import org.springframework.lang.Nullable;
  */
 public class CachingMongoPersistentProperty extends BasicMongoPersistentProperty {
 
+	private final Lazy<Boolean> isEntity = Lazy.of(super::isEntity);
+	private final Lazy<Boolean> isUnwrapped = Lazy.of(super::isUnwrapped);
 	private final Lazy<Boolean> isIdProperty = Lazy.of(super::isIdProperty);
 	private final Lazy<Boolean> isAssociation = Lazy.of(super::isAssociation);
 	private final Lazy<DBRef> dbref = Lazy.of(super::getDBRef);
@@ -58,6 +60,16 @@ public class CachingMongoPersistentProperty extends BasicMongoPersistentProperty
 		super(property, owner, simpleTypeHolder, fieldNamingStrategy);
 	}
 
+	@Override
+	public boolean isEntity() {
+		return isEntity.get();
+	}
+
+	@Override
+	public boolean isUnwrapped() {
+		return isUnwrapped.get();
+	}
+
 	@Override
 	public boolean isIdProperty() {
 		return isIdProperty.get();

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/mapping/FieldName.java

@@ -25,7 +25,11 @@ import org.springframework.util.ObjectUtils;
  * @author Christoph Strobl
  * @since 4.2
  */
-public record FieldName(String name, Type type) {
+public record FieldName(String name, Type type, String[] parts) {
+
+	public FieldName(String name, Type type) {
+		this(name, type, name.split("\\."));
+	}
 
 	private static final String ID_KEY = "_id";
 
@@ -65,7 +69,7 @@ public record FieldName(String name, Type type) {
 			return new String[] { name };
 		}
 
-		return name.split("\\.");
+		return parts;
 	}
 
 	/**