/*
 * Hibernate, Relational Persistence for Idiomatic Java
 *
 * Copyright (c) 2011, Red Hat Inc. or third-party contributors as
 * indicated by the @author tags or express copyright attribution
 * statements applied by the authors.  All third-party contributions are
 * distributed under license by Red Hat Inc.
 *
 * This copyrighted material is made available to anyone wishing to use, modify,
 * copy, or redistribute it subject to the terms and conditions of the GNU
 * Lesser General Public License, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License
 * for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this distribution; if not, write to:
 * Free Software Foundation, Inc.
 * 51 Franklin Street, Fifth Floor
 * Boston, MA  02110-1301  USA
 */
package org.hibernate.cache.spi.access;

import org.hibernate.cache.CacheException;

Base access strategy for all regions.
Author:
Gail Badner/**
 * Base access strategy for all regions.
 *
 * @author Gail Badner
 */
public interface RegionAccessStrategy {
	
Attempt to retrieve an object from the cache. Mainly used in attempting
to resolve entities/collections from the second level cache.
Params:
key – The key of the item to be retrieved.
txTimestamp – a timestamp prior to the transaction start time
Throws:
CacheException – Propogated from underlying Region
Returns:
the cached object or null/**
	 * Attempt to retrieve an object from the cache. Mainly used in attempting
	 * to resolve entities/collections from the second level cache.
	 *
	 * @param key The key of the item to be retrieved.
	 * @param txTimestamp a timestamp prior to the transaction start time
	 * @return the cached object or <tt>null</tt>
	 * @throws org.hibernate.cache.CacheException Propogated from underlying {@link org.hibernate.cache.spi.Region}
	 */
	Object get(Object key, long txTimestamp) throws CacheException;

	
Attempt to cache an object, after loading from the database.
Params:
key – The item key
value – The item
txTimestamp – a timestamp prior to the transaction start time
version – the item version number
Throws:
CacheException – Propogated from underlying Region
Returns:
true if the object was successfully cached/**
	 * Attempt to cache an object, after loading from the database.
	 *
	 * @param key The item key
	 * @param value The item
	 * @param txTimestamp a timestamp prior to the transaction start time
	 * @param version the item version number
	 * @return <tt>true</tt> if the object was successfully cached
	 * @throws org.hibernate.cache.CacheException Propogated from underlying {@link org.hibernate.cache.spi.Region}
	 */
	boolean putFromLoad(
			Object key,
			Object value,
			long txTimestamp,
			Object version) throws CacheException;

	
Attempt to cache an object, after loading from the database, explicitly
specifying the minimalPut behavior.
Params:
key – The item key
value – The item
txTimestamp – a timestamp prior to the transaction start time
version – the item version number
minimalPutOverride – Explicit minimalPut flag
Throws:
CacheException – Propogated from underlying Region
Returns:
true if the object was successfully cached/**
	 * Attempt to cache an object, after loading from the database, explicitly
	 * specifying the minimalPut behavior.
	 *
	 * @param key The item key
	 * @param value The item
	 * @param txTimestamp a timestamp prior to the transaction start time
	 * @param version the item version number
	 * @param minimalPutOverride Explicit minimalPut flag
	 * @return <tt>true</tt> if the object was successfully cached
	 * @throws org.hibernate.cache.CacheException Propogated from underlying {@link org.hibernate.cache.spi.Region}
	 */
	boolean putFromLoad(
			Object key,
			Object value,
			long txTimestamp,
			Object version,
			boolean minimalPutOverride) throws CacheException;

	
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 unlockItem, to release the lock. Concurrency strategies which do not support client-visible locks may silently return null. 
Params:
key – The key of the item to lock
version – The item's current version value
Throws:
CacheException – Propogated from underlying Region
Returns:
A representation of our lock on the item; or null./**
	 * We are going to attempt to update/delete the keyed object. This
	 * method is used by "asynchronous" concurrency strategies.
	 * <p/>
	 * 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 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 null.
	 * @throws org.hibernate.cache.CacheException Propogated from underlying {@link org.hibernate.cache.spi.Region}
	 */
	SoftLock lockItem(Object key, Object version) throws CacheException;

	
Lock the entire region
Throws:
CacheException – Propogated from underlying Region
Returns:
A representation of our lock on the item; or null./**
	 * Lock the entire region
	 *
	 * @return A representation of our lock on the item; or null.
	 * @throws org.hibernate.cache.CacheException Propogated from underlying {@link org.hibernate.cache.spi.Region}
	 */
	SoftLock lockRegion() throws CacheException;

	
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.
Params:
key – The item key
lock – The lock previously obtained from lockItem
Throws:
CacheException – Propogated from underlying Region/**
	 * 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 key The item key
	 * @param lock The lock previously obtained from {@link #lockItem}
	 * @throws org.hibernate.cache.CacheException Propogated from underlying {@link org.hibernate.cache.spi.Region}
	 */
	void unlockItem(Object key, SoftLock lock) throws CacheException;

	
Called after we have finished the attempted invalidation of the entire
region
Params:
lock – The lock previously obtained from lockRegion
Throws:
CacheException – Propogated from underlying Region/**
	 * Called after we have finished the attempted invalidation of the entire
	 * region
	 *
	 * @param lock The lock previously obtained from {@link #lockRegion}
	 * @throws org.hibernate.cache.CacheException Propogated from underlying {@link org.hibernate.cache.spi.Region}
	 */
	void unlockRegion(SoftLock lock) throws CacheException;

	
Called after an item has become stale (before the transaction completes).
This method is used by "synchronous" concurrency strategies.
Params:
key – The key of the item to remove
Throws:
CacheException – Propogated from underlying Region/**
	 * Called after an item has become stale (before the transaction completes).
	 * This method is used by "synchronous" concurrency strategies.
	 *
	 * @param key The key of the item to remove
	 * @throws org.hibernate.cache.CacheException Propogated from underlying {@link org.hibernate.cache.spi.Region}
	 */
	void remove(Object key) throws CacheException;

	
Called to evict data from the entire region
Throws:
CacheException – Propogated from underlying Region/**
	 * Called to evict data from the entire region
	 *
	 * @throws org.hibernate.cache.CacheException Propogated from underlying {@link org.hibernate.cache.spi.Region}
	 */
	void removeAll() throws CacheException;

	
Forcibly evict an item from the cache immediately without regard for transaction
isolation.
Params:
key – The key of the item to remove
Throws:
CacheException – Propogated from underlying Region/**
	 * Forcibly evict an item from the cache immediately without regard for transaction
	 * isolation.
	 *
	 * @param key The key of the item to remove
	 * @throws org.hibernate.cache.CacheException Propogated from underlying {@link org.hibernate.cache.spi.Region}
	 */
	void evict(Object key) throws CacheException;

	
Forcibly evict all items from the cache immediately without regard for transaction
isolation.
Throws:
CacheException – Propogated from underlying Region/**
	 * Forcibly evict all items from the cache immediately without regard for transaction
	 * isolation.
	 *
	 * @throws org.hibernate.cache.CacheException Propogated from underlying {@link org.hibernate.cache.spi.Region}
	 */
	void evictAll() throws CacheException;
}