/*
* Copyright 2011 JBoss 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 org.drools.persistence.jpa;
import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import org.drools.persistence.TransactionManager;
import org.kie.api.runtime.Environment;
import org.kie.api.runtime.EnvironmentName;
import org.kie.api.runtime.KieSession;
/**
* This class manages {@link JpaPersistenceContext} objects, and the underlying persistence context ({@link EntityManager})
* instances for a persistent {@link KieSession} and other infrastructure classes that use persistence in KIE projects.
* </p>
* (For reference in the following documentation: the {@link EntityManager} is the class used to represent a persistence context)
* </p>
* There are 2 issues to take into account when looking at or modifying the code here: <ol>
* <li>One of the features made available here is the ability for the user to supply their own (Command Scoped) persistence
* context for use by the {@link KieSession}</li>
* <li>However, significant race-conditions arise when a Command Scoped persistence context is used in one persistent
* {@link KieSession} by multiple threads. In other words, when multiple threads call operations on a Singleton persistent
* {@link KieSession}.</li>
* </ol>
*
* This class uses {@link ThreadLocal} instances for two things:<ol>
* <li>The internal Command Scoped {@link EntityManager} instance.</li>
* <li></li>
* </ol>
*/
public abstract class AbstractPersistenceContextManager {
protected final Environment env;
protected final EntityManagerFactory emf;
protected final TransactionManager txm;
protected volatile EntityManager appScopedEntityManager;
protected volatile EntityManager cmdScopedEntityManager;
protected volatile boolean internalAppScopedEntityManagerFlag;
protected volatile boolean internalCmdScopedEntityManagerFlag;
public AbstractPersistenceContextManager(Environment env) {
this.env = env;
this.emf = ( EntityManagerFactory ) env.get( EnvironmentName.ENTITY_MANAGER_FACTORY );
this.txm = ( TransactionManager ) env.get(EnvironmentName.TRANSACTION_MANAGER);
}
public EntityManager getApplicationScopedEntityManager() {
if ( this.appScopedEntityManager == null ) {
// Use the App scoped EntityManager if the user has provided it, and it is open.
this.appScopedEntityManager = (EntityManager) this.env.get( EnvironmentName.APP_SCOPED_ENTITY_MANAGER );
if ( this.appScopedEntityManager != null && !this.appScopedEntityManager.isOpen() ) {
throw new RuntimeException("Provided APP_SCOPED_ENTITY_MANAGER is not open");
}
if ( this.appScopedEntityManager == null ) {
internalAppScopedEntityManagerFlag = true;
this.appScopedEntityManager = this.emf.createEntityManager();
this.env.set( EnvironmentName.APP_SCOPED_ENTITY_MANAGER, this.appScopedEntityManager );
if (txm.getStatus() == TransactionManager.STATUS_ACTIVE) {
this.txm.putResource(EnvironmentName.APP_SCOPED_ENTITY_MANAGER, this.appScopedEntityManager );
}
} else {
internalAppScopedEntityManagerFlag = false;
}
}
return appScopedEntityManager;
}
public EntityManager getCommandScopedEntityManager() {
// first check if there is already cmd scoped entity manager as transactional resource
EntityManager cmdScopedEntityManager = getInternalCommandScopedEntityManager();
if ( cmdScopedEntityManager == null) {
cmdScopedEntityManager = (EntityManager) env.get( EnvironmentName.CMD_SCOPED_ENTITY_MANAGER );
if (cmdScopedEntityManager != null) {
this.txm.putResource(EnvironmentName.CMD_SCOPED_ENTITY_MANAGER, cmdScopedEntityManager );
}
if ( cmdScopedEntityManager == null) {
internalCmdScopedEntityManagerFlag = true;
cmdScopedEntityManager = this.emf.createEntityManager(); // no need to call joinTransaction as it will do so if one already exists
this.env.set( EnvironmentName.CMD_SCOPED_ENTITY_MANAGER, cmdScopedEntityManager );
this.txm.putResource(EnvironmentName.CMD_SCOPED_ENTITY_MANAGER, cmdScopedEntityManager );
} else {
internalCmdScopedEntityManagerFlag = false;
}
}
cmdScopedEntityManager.joinTransaction();
if (this.appScopedEntityManager != null) {
this.appScopedEntityManager.joinTransaction();
}
return cmdScopedEntityManager;
}
public void endCommandScopedEntityManager() {
EntityManager cmdScopedEntityManager = getInternalCommandScopedEntityManager();
if ( this.internalCmdScopedEntityManagerFlag ) {
if (cmdScopedEntityManager != null && cmdScopedEntityManager.isOpen()) {
cmdScopedEntityManager.clear();
}
this.env.set( EnvironmentName.CMD_SCOPED_ENTITY_MANAGER, null );
}
}
public void dispose() {
if ( this.internalAppScopedEntityManagerFlag ) {
if ( this.appScopedEntityManager != null && this.appScopedEntityManager.isOpen() ) {
this.appScopedEntityManager.close();
}
this.internalAppScopedEntityManagerFlag = false;
this.env.set( EnvironmentName.APP_SCOPED_ENTITY_MANAGER, null );
this.appScopedEntityManager = null;
}
if ( this.internalCmdScopedEntityManagerFlag ) {
EntityManager cmdScopedEntityManager = getInternalCommandScopedEntityManager();
if ( cmdScopedEntityManager != null && cmdScopedEntityManager.isOpen() ) {
cmdScopedEntityManager.close();
}
this.env.set( EnvironmentName.CMD_SCOPED_ENTITY_MANAGER, null );
this.txm.putResource(EnvironmentName.CMD_SCOPED_ENTITY_MANAGER, null );
this.internalCmdScopedEntityManagerFlag = false;
}
}
protected EntityManager getInternalCommandScopedEntityManager() {
return (EntityManager) txm.getResource(EnvironmentName.CMD_SCOPED_ENTITY_MANAGER);
}
}