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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 http://www.gnu.org/licenses/lgpl-2.1.html
 */
package org.hibernate.cache.spi.access;

import java.io.Serializable;
import javax.persistence.Cache;

import org.hibernate.cache.CacheException;
import org.hibernate.cache.spi.DomainDataRegion;
import org.hibernate.engine.spi.SharedSessionContractImplementor;

/**
 * Base contract for accessing the underlying cached data for a particular
 * Navigable of the user's domain model in a transactionally ACID manner.
 *
 * @apiNote Note that the following methods are not considered "transactional"
 * in this sense : {@link #contains}, {@link #lockRegion}, {@link #unlockRegion},
 * {@link #evict}, {@link #evictAll}.  The semantics of these methods come
 * from JPA's {@link Cache} contract.
 *
 * @implSpec The "non transactional" methods noted in the `@apiNote` should
 * be implemented to ignore any locking.  In other words, if {@link #evict}
 * is called that item should be forcibly removed from the cache regardless of
 * whether anything has locked it.
 *
 * @author Steve Ebersole
 * @author Gail Badner
 */
public interface CachedDomainDataAccess {
	/**
	 * The region containing the data being accessed
	 */
	DomainDataRegion getRegion();

	/**
	 * The type of access implemented
	 */
	AccessType getAccessType();


	// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
	// Transactional

	/**
	 * Attempt to retrieve an object from the cache. Mainly used in attempting
	 * to resolve entities/collections from the second level cache.
	 *
	 * @param session Current session.
	 * @param key The key of the item to be retrieved.
	 *
	 * @return the cached data or {@code null}
	 *
	 * @throws CacheException Propagated from underlying cache provider
	 */
	Object get(SharedSessionContractImplementor session, Object key);

	/**
	 * Attempt to cache an object, afterQuery loading from the database.
	 *
	 * @param session Current session.
	 * @param key The item key
	 * @param value The item
	 * @param version the item version number
	 *
	 * @return {@code true} if the object was successfully cached
	 *
	 * @throws CacheException Propagated from underlying cache provider
	 */
	boolean putFromLoad(
			SharedSessionContractImplementor session,
			Object key,
			Object value,
			Object version);

	/**
	 * Attempt to cache an object, afterQuery loading from the database, explicitly
	 * specifying the minimalPut behavior.
	 *
	 * @param session Current session.
	 * @param key The item key
	 * @param value The item
	 * @param version the item version number
	 * @param minimalPutOverride Explicit minimalPut flag
	 *
	 * @return {@code true} if the object was successfully cached
	 *
	 * @throws CacheException Propagated from underlying cache provider
	 */
	boolean putFromLoad(
			SharedSessionContractImplementor session,
			Object key,
			Object value,
			Object version,
			boolean minimalPutOverride);

	/**
	 * We are going to attempt to update/delete the keyed object. This
	 * method is used by "asynchronous" concurrency strategies.
	 * 
	 * The returned object must be passed back to {@link #unlockItem}, to release the
	 * lock. Concurrency strategies which do not support client-visible
	 * locks may silently return null.
	 *
	 * @param session Current session.
	 * @param key The key of the item to lock
	 * @param version The item's current version value
	 *
	 * @return A representation of our lock on the item; or {@code null}.
	 *
	 * @throws CacheException Propagated from underlying cache provider
	 */
	SoftLock lockItem(SharedSessionContractImplementor session, Object key, Object version);

	/**
	 * Called when we have finished the attempted update/delete (which may or
	 * may not have been successful), after transaction completion.  This method
	 * is used by "asynchronous" concurrency strategies.
	 *
	 * @param session Current session.
	 * @param key The item key
	 * @param lock The lock previously obtained from {@link #lockItem}
	 *
	 * @throws CacheException Propagated from underlying cache provider
	 */
	void unlockItem(SharedSessionContractImplementor session, Object key, SoftLock lock);

	/**
	 * Called afterQuery an item has become stale (beforeQuery the transaction completes).
	 * This method is used by "synchronous" concurrency strategies.
	 *
	 * @param session Current session.
	 * @param key The key of the item to remove
	 *
	 * @throws CacheException Propagated from underlying cache provider
	 */
	void remove(SharedSessionContractImplementor session, Object key);

	/**
	 * Remove all data for this accessed type
	 *
	 * @throws CacheException Propagated from underlying cache provider
	 * @param session
	 */
	void removeAll(SharedSessionContractImplementor session);



	// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
	// Non-transactional

	/**
	 * Determine whether this region contains data for the given key.
	 * 

	 * The semantic here is whether the cache contains data visible for the
	 * current call context.  This should be viewed as a "best effort", meaning
	 * blocking should be avoid if possible.
	 *
	 * @param key The cache key
	 *
	 * @return True if the underlying cache contains corresponding data; false
	 * otherwise.
	 */
	boolean contains(Object key);

	/**
	 * Lock the entire region
	 *
	 * @return A representation of our lock on the item; or {@code null}.
	 *
	 * @throws CacheException Propagated from underlying cache provider
	 */
	SoftLock lockRegion();

	/**
	 * Called after we have finished the attempted invalidation of the entire
	 * region
	 *
	 * @param lock The lock previously obtained from {@link #lockRegion}
	 *
	 * @throws CacheException Propagated from underlying cache provider
	 */
	void unlockRegion(SoftLock lock);

	/**
	 * Forcibly evict an item from the cache immediately without regard for transaction
	 * isolation and/or locking.  This behavior is exactly Hibernate legacy behavior, but
	 * it is also required by JPA - so we cannot remove it.
	 * 

	 * Used from JPA's {@link javax.persistence.Cache#evict(Class, Object)}, as well as the
	 * Hibernate extension {@link org.hibernate.Cache#evictEntityData(Class, Serializable)}
	 * and {@link org.hibernate.Cache#evictEntityData(String, Serializable)}
	 *
	 * @param key The key of the item to remove
	 *
	 * @throws CacheException Propagated from underlying cache provider
	 */
	void evict(Object key);

	/**
	 * Forcibly evict all items from the cache immediately without regard for transaction
	 * isolation.  This behavior is exactly Hibernate legacy behavior, but it is also required
	 * by JPA - so we cannot remove it.
	 * 
	 * Used from our JPA impl of {@link Cache#evictAll()} as well as the Hibernate
	 * extensions {@link org.hibernate.Cache#evictEntityData(Class)},
	 * {@link org.hibernate.Cache#evictEntityData(String)} and
	 * {@link org.hibernate.Cache#evictEntityData()}
	 *
	 * @throws CacheException Propagated from underlying cache provider
	 */
	void evictAll();
}