/**
* Copyright 2003-2010 Terracotta, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package net.sf.ehcache.transaction.xa.commands;
import net.sf.ehcache.Element;
import net.sf.ehcache.store.ElementValueComparator;
import net.sf.ehcache.store.Store;
import net.sf.ehcache.transaction.SoftLock;
import net.sf.ehcache.transaction.SoftLockFactory;
import net.sf.ehcache.transaction.xa.OptimisticLockFailureException;
import net.sf.ehcache.transaction.xa.XidTransactionID;
/**
* @author Ludovic Orban
*/
public abstract class AbstractStoreCommand implements Command {
private final Element oldElement;
private final Element newElement;
private Element softLockedElement;
/**
* Create a Store Command
* @param oldElement the element in the underlying store at the time this command is created
* @param newElement the new element to put in the underlying store
*/
public AbstractStoreCommand(final Element oldElement, final Element newElement) {
this.newElement = newElement;
this.oldElement = oldElement;
}
/**
* Get the element in the underlying store at the time this command is created
* @return the old element
*/
protected Element getOldElement() {
return oldElement;
}
/**
* Get the new element to put in the underlying store
* @return the new element to put in the underlying store
*/
protected Element getNewElement() {
return newElement;
}
/**
* {@inheritDoc}
*/
public boolean prepare(Store store, SoftLockFactory softLockFactory, XidTransactionID transactionId,
ElementValueComparator comparator) {
Object objectKey = getObjectKey();
SoftLock softLock = softLockFactory.createSoftLock(transactionId, objectKey, newElement, oldElement);
softLockedElement = createElement(objectKey, softLock);
softLock.lock();
softLock.freeze();
if (oldElement == null) {
Element previousElement = store.putIfAbsent(softLockedElement);
if (previousElement != null) {
softLock.unfreeze();
softLock.unlock();
softLockedElement = null;
throw new OptimisticLockFailureException();
}
} else {
boolean replaced = store.replace(oldElement, softLockedElement, comparator);
if (!replaced) {
softLock.unfreeze();
softLock.unlock();
softLockedElement = null;
throw new OptimisticLockFailureException();
}
}
return true;
}
/**
* {@inheritDoc}
*/
public void rollback(Store store) {
if (oldElement == null) {
store.remove(getObjectKey());
} else {
store.put(oldElement);
}
SoftLock softLock = (SoftLock) softLockedElement.getObjectValue();
softLock.unfreeze();
softLock.unlock();
softLockedElement = null;
}
private Element createElement(Object key, SoftLock softLock) {
Element element = new Element(key, softLock);
element.setEternal(true);
return element;
}
}