/* ********************************************************************** **
** Copyright notice **
** **
** (c) 2005-2009 RSSOwl Development Team **
** http://www.rssowl.org/ **
** **
** All rights reserved **
** **
** This program and the accompanying materials are made available under **
** the terms of the Eclipse Public License v1.0 which accompanies this **
** distribution, and is available at: **
** http://www.rssowl.org/legal/epl-v10.html **
** **
** A copy is found in the file epl-v10.html and important notices to the **
** license from the team is found in the textfile LICENSE.txt distributed **
** in this package. **
** **
** This copyright notice MUST APPEAR in all copies of the file! **
** **
** Contributors: **
** RSSOwl Development Team - initial API and implementation **
** **
** ********************************************************************** */
package org.rssowl.core.internal.persist.dao;
import org.eclipse.core.runtime.Assert;
import org.rssowl.core.internal.persist.service.DBHelper;
import org.rssowl.core.internal.persist.service.DBManager;
import org.rssowl.core.internal.persist.service.DatabaseEvent;
import org.rssowl.core.internal.persist.service.DatabaseListener;
import org.rssowl.core.persist.IEntity;
import org.rssowl.core.persist.IPersistable;
import org.rssowl.core.persist.dao.IPersistableDAO;
import org.rssowl.core.persist.service.PersistenceException;
import com.db4o.ObjectContainer;
import com.db4o.ext.Db4oException;
import com.db4o.query.Query;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.List;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReadWriteLock;
/**
* The base abstract class for all DAO to access entities from the database and
* store/update them.
*
* @param <T> any {@link IEntity}
*/
public abstract class AbstractPersistableDAO<T extends IPersistable> implements IPersistableDAO<T> {
protected final Class<? extends T> fEntityClass;
protected final boolean fSaveFully;
protected volatile ReadWriteLock fLock;
protected volatile Lock fWriteLock;
protected volatile Lock fReadLock;
protected volatile ObjectContainer fDb;
public AbstractPersistableDAO(Class<? extends T> entityClass, boolean saveFully) {
Assert.isNotNull(entityClass, "entityClass"); //$NON-NLS-1$
fEntityClass = entityClass;
fSaveFully = saveFully;
DBManager.getDefault().addEntityStoreListener(new DatabaseListener() {
public void databaseOpened(DatabaseEvent event) {
onDatabaseOpened(event);
}
public void databaseClosed(DatabaseEvent event) {
onDatabaseClosed(event);
}
});
}
/**
* Called when the database is opened.
*
* @param event
*/
protected void onDatabaseOpened(DatabaseEvent event) {
fDb = event.getObjectContainer();
fLock = event.getLock();
fWriteLock = fLock.writeLock();
fReadLock = fLock.readLock();
}
/**
* Called when the database is closed.
*
* @param event
*/
protected void onDatabaseClosed(@SuppressWarnings("unused")
DatabaseEvent event) {
fDb = null;
}
/*
* @see org.rssowl.core.persist.dao.IPersistableDAO#getEntityClass()
*/
public final Class<? extends T> getEntityClass() {
return fEntityClass;
}
protected final T getSingleResult(Query query) {
List<T> result = getList(query);
int resultSize = result.size();
if (resultSize == 0)
return null;
if (resultSize == 1)
return result.get(0);
throw new IllegalStateException("Expected a single result, but got: " + resultSize); //$NON-NLS-1$
}
@SuppressWarnings("unchecked")
protected final List<T> getList(Query query) {
return query.execute();
}
/*
* @see org.rssowl.core.model.internal.db4o.dao.PersistableDAO#loadAll()
*/
public Collection<T> loadAll() {
try {
List<? extends T> entities = fDb.query(fEntityClass);
activateAll(entities);
return new ArrayList<T>(entities);
} catch (Db4oException e) {
throw new PersistenceException(e);
}
}
protected final <C extends Collection<O>, O> C activateAll(C collection) {
for (O o : collection)
fDb.ext().activate(o, Integer.MAX_VALUE);
return collection;
}
/*
* @see org.rssowl.core.model.internal.db4o.dao.PersistableDAO#save(T)
*/
public T save(T object) {
saveAll(Collections.singletonList(object));
return object;
}
/*
* @see org.rssowl.core.model.internal.db4o.dao.PersistableDAO#saveAll(C)
*/
public void saveAll(Collection<T> objects) {
if (objects.isEmpty())
return;
try {
preSaveAll(objects);
fWriteLock.lock();
try {
for (T object : objects) {
preSave(object);
}
for (T object : objects) {
doSave(object);
}
preCommit();
fDb.commit();
} catch (Db4oException e) {
throw DBHelper.rollbackAndPE(fDb, e);
} finally {
fWriteLock.unlock();
}
DBHelper.cleanUpAndFireEvents();
} finally {
postSaveAll(objects);
}
}
protected void preSaveAll(@SuppressWarnings("unused")
Collection<T> objects) {
// Do nothing by default
}
protected void postSaveAll(@SuppressWarnings("unused")
Collection<T> objects) {
// Do nothing by default
}
protected void preSave(@SuppressWarnings("unused")
T persistable) {
// Do nothing by default
}
protected void doSave(T entity) {
if (fSaveFully)
fDb.ext().set(entity, Integer.MAX_VALUE);
else
fDb.set(entity);
}
/*
* @see org.rssowl.core.model.internal.db4o.dao.PersistableDAO#delete(T)
*/
public void delete(T object) {
deleteAll(Collections.singletonList(object));
}
protected void doDelete(T entity) {
fDb.delete(entity);
}
/*
* @see
* org.rssowl.core.model.internal.db4o.dao.PersistableDAO#deleteAll(java.util
* .Collection)
*/
public void deleteAll(Collection<T> objects) {
if (objects.isEmpty())
return;
fWriteLock.lock();
try {
for (T object : objects) {
preDelete(object);
}
for (T object : objects) {
doDelete(object);
}
preCommit();
fDb.commit();
} catch (Db4oException e) {
DBHelper.rollbackAndPE(fDb, e);
} finally {
fWriteLock.unlock();
}
DBHelper.cleanUpAndFireEvents();
}
protected void preCommit() {
DBHelper.preCommit(fDb);
}
protected void preDelete(@SuppressWarnings("unused")
T persistable) {
// Do nothing by default
}
/*
* @see org.rssowl.core.model.internal.db4o.dao.PersistableDAO#countAll()
*/
public long countAll() {
try {
List<? extends T> entities = fDb.query(fEntityClass);
return entities.size();
} catch (Db4oException e) {
throw new PersistenceException(e);
}
}
}