/*******************************************************************************
* Copyright (c) 2011 Oracle. All rights reserved.
* This program and the accompanying materials are made available under the
* terms of the Eclipse Public License v1.0 and Eclipse Distribution License v. 1.0
* which accompanies this distribution.
* The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v10.html
* and the Eclipse Distribution License is available at
* http://www.eclipse.org/org/documents/edl-v10.php.
*
* Contributors:
* James Sutherland (Oracle) - initial API and implementation
******************************************************************************/
package org.eclipse.persistence.descriptors.partitioning;
import java.util.List;
import org.eclipse.persistence.descriptors.ClassDescriptor;
import org.eclipse.persistence.exceptions.QueryException;
import org.eclipse.persistence.internal.databaseaccess.Accessor;
import org.eclipse.persistence.internal.sessions.AbstractRecord;
import org.eclipse.persistence.internal.sessions.AbstractSession;
import org.eclipse.persistence.queries.DatabaseQuery;
import org.eclipse.persistence.sessions.server.ClientSession;
import org.eclipse.persistence.sessions.server.ConnectionPool;
import org.eclipse.persistence.sessions.server.ServerSession;
/**
* PUBLIC:
* A PartitioningPolicy is used to partition the data for a class across multiple difference databases
* or across a database cluster such as Oracle RAC.
* Partitioning can provide improved scalability by allowing multiple database machines to service requests.
* <p>
* If multiple partitions are used to process a single transaction, JTA should be used for proper XA transaction support.
* @author James Sutherland
* @since EclipseLink 2.2
*/
public abstract class PartitioningPolicy implements java.io.Serializable {
/** The persistent unit unique name for the policy. */
protected String name;
public abstract List<Accessor> getConnectionsForQuery(AbstractSession session, DatabaseQuery query, AbstractRecord arguments);
/**
* INTERNAL:
* Allow for the persist call to assign the partition.
*/
public void partitionPersist(AbstractSession session, Object object, ClassDescriptor descriptor) { }
/**
* INTERNAL:
* Initialize the policy.
*/
public void initialize(AbstractSession session) { }
/**
* INTERNAL:
* Convert all the class-name-based settings to actual class-based
* settings. This method is used when converting a project that has been built
* with class names to a project with classes.
*/
public void convertClassNamesToClasses(ClassLoader classLoader) { }
/**
* INTERNAL:
* Return an accessor from the pool.
*/
public Accessor acquireAccessor(String poolName, ServerSession session, DatabaseQuery query, boolean returnNullIfDead) {
ConnectionPool pool = session.getConnectionPool(poolName);
if (pool == null) {
throw QueryException.missingConnectionPool(poolName, query);
}
if (returnNullIfDead && pool.isDead()) {
return null;
}
return pool.acquireConnection();
}
/**
* INTERNAL:
* Return an accessor from the pool for the session.
* For a client session the accessor is stored for the duration of the transaction.
*/
public Accessor getAccessor(String poolName, AbstractSession session, DatabaseQuery query, boolean returnNullIfDead) {
Accessor accessor = null;
if (session.isClientSession()) {
ClientSession client = (ClientSession)session;
// If the client session is exclusive and has a connection then just use the existing connection.
if (client.isExclusiveIsolatedClientSession() && client.hasWriteConnection()) {
accessor = client.getWriteConnection();
} else {
accessor = client.getWriteConnections().get(poolName);
if (accessor == null) {
accessor = acquireAccessor(poolName, client.getParent(), query, returnNullIfDead);
// Assign a write connection for the duration of the transaction.
if (client.isExclusiveIsolatedClientSession() || session.isInTransaction()) {
accessor = client.addWriteConnection(poolName, accessor);
}
}
}
} else if (session.isServerSession()) {
accessor = acquireAccessor(poolName, (ServerSession)session, query, returnNullIfDead);
} else {
throw QueryException.partitioningNotSupported(session, query);
}
return accessor;
}
/**
* PUBLIC:
* Return the name of the policy.
* The name must be unique for the persistence unit.
* The name allows the policy to be shared among multiple descriptors, queries.
*/
public String getName() {
return name;
}
/**
* PUBLIC:
* Set the name of the policy.
* The name must be unique for the persistence unit.
* The name allows the policy to be shared among multiple descriptors, queries.
*/
public void setName(String name) {
this.name = name;
}
}