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/*
* Hibernate, Relational Persistence for Idiomatic Java
*
* License: GNU Lesser General Public License (LGPL), version 2.1 or later.
* See the lgpl.txt file in the root directory or .
*/
package org.hibernate;
import org.hibernate.persister.entity.EntityPersister;
import org.hibernate.type.Type;
/**
* During a flush cycle, Hibernate needs to determine which of the entities associated with a {@link Session}
* are dirty, meaning modified. Dirty entities will be {@literal UPDATE}ed in the database.
*
* In some circumstances, the process of determining whether an entity is dirty can carry a significant overhead,
* since, by default, Hibernate must check each of the entity's attribute values one by one. Sometimes, an
* application already has knowledge of an entity's dirtiness and making use of that information would save some
* work. This contract allows the application to take over the task of determining if an entity is dirty.
*
* @see org.hibernate.cfg.AvailableSettings#CUSTOM_ENTITY_DIRTINESS_STRATEGY
* @see org.hibernate.cfg.Configuration#setCustomEntityDirtinessStrategy(CustomEntityDirtinessStrategy)
* @see org.hibernate.boot.SessionFactoryBuilder#applyCustomEntityDirtinessStrategy(CustomEntityDirtinessStrategy)
*
* @author Steve Ebersole
*/
public interface CustomEntityDirtinessStrategy {
/**
* Is this strategy capable of telling whether the given entity is dirty? A return of {@code true} means that
* {@link #isDirty} will be called next as the definitive means to determine whether the entity is dirty.
*
* @param entity The entity to be checked
* @param persister The persister corresponding to the given entity
* @param session The session from which this check originates.
*
* @return {@code true} indicates the dirty check can be done; {@code false} indicates it cannot.
*/
boolean canDirtyCheck(Object entity, EntityPersister persister, Session session);
/**
* The callback used by Hibernate to determine if the given entity is dirty. Only called if the previous
* {@link #canDirtyCheck} returned {@code true}
*
* @param entity The entity to check.
* @param persister The persister corresponding to the given entity
* @param session The session from which this check originates.
*
* @return {@code true} indicates the entity is dirty; {@code false} indicates the entity is not dirty.
*/
boolean isDirty(Object entity, EntityPersister persister, Session session);
/**
* Callback used by Hibernate to signal that the entity dirty flag should be cleared. Generally this
* happens after previous dirty changes were written to the database.
*
* @param entity The entity to reset
* @param persister The persister corresponding to the given entity
* @param session The session from which this call originates.
*/
void resetDirty(Object entity, EntityPersister persister, Session session);
/**
* Callback used to hook into Hibernate algorithm for determination of which attributes have changed. Applications
* wanting to hook in to this would call back into the given {@link DirtyCheckContext#doDirtyChecking}
* method, passing along an appropriate {@link AttributeChecker} implementation.
*
* @param entity The entity being checked
* @param persister The persister corresponding to the given entity
* @param session The session from which this call originates.
* @param dirtyCheckContext The callback context
*/
void findDirty(Object entity, EntityPersister persister, Session session, DirtyCheckContext dirtyCheckContext);
/**
* A callback to drive dirty checking. Handed to the {@link CustomEntityDirtinessStrategy#findDirty} method
* so that it can call back in to it if it wants to handle dirty checking rather than using Hibernate's default
* checking.
*
* @see CustomEntityDirtinessStrategy#findDirty
*/
@FunctionalInterface
interface DirtyCheckContext {
/**
* The callback to indicate that dirty checking (the dirty attribute determination phase) should be handled
* by the calling {@link CustomEntityDirtinessStrategy} using the given {@link AttributeChecker}.
*
* @param attributeChecker The delegate usable by the context for determining which attributes are dirty.
*/
void doDirtyChecking(AttributeChecker attributeChecker);
}
/**
* Responsible for identifying when attributes are dirty.
*/
@FunctionalInterface
interface AttributeChecker {
/**
* Do the attribute dirty check.
*
* @param attributeInformation Information about the attribute which is useful to help determine if it is
* dirty.
*
* @return {@code true} indicates the attribute value has changed; {@code false} indicates it has not.
*/
boolean isDirty(AttributeInformation attributeInformation);
}
/**
* Provides {@link AttributeChecker} with meta information about the attributes being checked.
*/
interface AttributeInformation {
/**
* Get a reference to the persister for the entity containing this attribute.
*
* @return The entity persister.
*/
EntityPersister getContainingPersister();
/**
* Many of Hibernate internals use arrays to define information about attributes. This value
* provides this index into those arrays for this particular attribute.
*
* It can be useful if needing to leverage those Hibernate internals.
*
* @return The attribute index.
*/
int getAttributeIndex();
/**
* Get the name of this attribute.
*
* @return The attribute name
*/
String getName();
/**
* Get the mapping type of this attribute.
*
* @return The mapping type.
*/
Type getType();
/**
* Get the current value of this attribute.
*
* @return The attributes current value
*/
Object getCurrentValue();
/**
* Get the loaded value of this attribute.
*
* NOTE : A call to this method may require hitting the database in cases where the loaded state is
* not known. In those cases the db hit is incurred only once per entity, not for each attribute.
*
* @return The attributes loaded value
*/
Object getLoadedValue();
}
}