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/*
 * Hibernate, Relational Persistence for Idiomatic Java
 *
 * Copyright (c) 2008, Red Hat Middleware LLC 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 Middleware LLC.
 *
 * 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;

import java.util.Comparator;

import org.hibernate.cache.access.SoftLock;

/**
 * Implementors manage transactional access to cached data. Transactions
 * pass in a timestamp indicating transaction start time. Two different
 * implementation patterns are provided for.
    *
  • A transaction-aware cache implementation might be wrapped by a * "synchronous" concurrency strategy, where updates to the cache are written * to the cache inside the transaction.
  • *
  • A non transaction-aware cache would be wrapped by an "asynchronous" * concurrency strategy, where items are merely "soft locked" during the * transaction and then updated during the "after transaction completion" * phase; the soft lock is not an actual lock on the database row - * only upon the cached representation of the item.
  • *
*

* In terms of entity caches, the expected call sequences are:

    *
  • DELETES : {@link #lock} -> {@link #evict} -> {@link #release}
  • *
  • UPDATES : {@link #lock} -> {@link #update} -> {@link #afterUpdate}
  • *
  • INSERTS : {@link #insert} -> {@link #afterInsert}
  • *
*

* In terms of collection caches, all modification actions actually just * invalidate the entry(s). The call sequence here is: * {@link #lock} -> {@link #evict} -> {@link #release} *

* Note that, for an asynchronous cache, cache invalidation must be a two * step process (lock->release, or lock-afterUpdate), since this is the only * way to guarantee consistency with the database for a nontransactional cache * implementation. For a synchronous cache, cache invalidation is a single * step process (evict, or update). Hence, this interface defines a three * step process, to cater for both models. *

* Note that query result caching does not go through a concurrency strategy; they * are managed directly against the underlying {@link Cache cache regions}. * * @deprecated As of 3.3; see for details. */ public interface CacheConcurrencyStrategy { /** * Attempt to retrieve an object from the cache. Mainly used in attempting * to resolve entities/collections from the second level cache. * * @param key * @param txTimestamp a timestamp prior to the transaction start time * @return the cached object or null * @throws CacheException */ public Object get(Object key, long txTimestamp) throws CacheException; /** * Attempt to cache an object, after loading from the database. * * @param key * @param value * @param txTimestamp a timestamp prior to the transaction start time * @param version the item version number * @param versionComparator a comparator used to compare version numbers * @param minimalPut indicates that the cache should avoid a put is the item is already cached * @return true if the object was successfully cached * @throws CacheException */ public boolean put( Object key, Object value, long txTimestamp, Object version, Comparator versionComparator, boolean minimalPut) 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 release(), to release the * lock. Concurrency strategies which do not support client-visible * locks may silently return null. * * @param key * @param version * @throws CacheException */ public SoftLock lock(Object key, Object version) throws CacheException; /** * Called after an item has become stale (before the transaction completes). * This method is used by "synchronous" concurrency strategies. */ public void evict(Object key) throws CacheException; /** * Called after an item has been updated (before the transaction completes), * instead of calling evict(). * This method is used by "synchronous" concurrency strategies. */ public boolean update(Object key, Object value, Object currentVersion, Object previousVersion) throws CacheException; /** * Called after an item has been inserted (before the transaction completes), * instead of calling evict(). * This method is used by "synchronous" concurrency strategies. */ public boolean insert(Object key, Object value, Object currentVersion) 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. * @param key * @throws CacheException */ public void release(Object key, SoftLock lock) throws CacheException; /** * Called after an item has been updated (after the transaction completes), * instead of calling release(). * This method is used by "asynchronous" concurrency strategies. */ public boolean afterUpdate(Object key, Object value, Object version, SoftLock lock) throws CacheException; /** * Called after an item has been inserted (after the transaction completes), * instead of calling release(). * This method is used by "asynchronous" concurrency strategies. */ public boolean afterInsert(Object key, Object value, Object version) throws CacheException; /** * Evict an item from the cache immediately (without regard for transaction * isolation). * @param key * @throws CacheException */ public void remove(Object key) throws CacheException; /** * Evict all items from the cache immediately. * @throws CacheException */ public void clear() throws CacheException; /** * Clean up all resources. */ public void destroy(); /** * Set the underlying cache implementation. * @param cache */ public void setCache(Cache cache); /** * Get the cache region name */ public String getRegionName(); /** * Get the wrapped cache implementation */ public Cache getCache(); }





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