/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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.apache.openjpa.ee;
import javax.transaction.TransactionManager;
import org.apache.openjpa.util.InternalException;
import org.osgi.framework.BundleActivator;
import org.osgi.framework.BundleContext;
import org.osgi.framework.Constants;
import org.osgi.framework.InvalidSyntaxException;
import org.osgi.framework.ServiceEvent;
import org.osgi.framework.ServiceListener;
import org.osgi.framework.ServiceReference;
/**
* <p>Implementation of the {@link ManagedRuntime} interface that listens
* for an OSGi service with interface <code>javax.transaction.TransactionManager</code>
* to create a {@link TransactionManager} for controlling transactions.</p>
*
* <p>The support for a transaction manager is usually activated inside an OSGi
* {@link BundleActivator} implementation using {@link #registerServiceListener(BundleContext)}
* and {@link #deregisterServiceListener(BundleContext)}.
* </p>
*/
public class OSGiManagedRuntime extends AbstractManagedRuntime {
/**
* a static instance, which is managed by the ServiceListener added to the bundle
* context by {@link #registerServiceListener(BundleContext)}.
*/
private static TransactionManager transactionManager;
private static ServiceReference serviceReference;
private static ServiceListener listener;
private static final class Listener implements ServiceListener {
final BundleContext bundleContext;
// avoid the garbage collection of the OSGiManagedRuntime class itself,
// by holding a reference to it.
final Class<OSGiManagedRuntime> clazzRef;
public Listener(BundleContext bundleContext) {
this.bundleContext = bundleContext;
this.clazzRef = OSGiManagedRuntime.class;
}
@Override
public void serviceChanged(ServiceEvent event) {
synchronized (this.clazzRef) {
switch (event.getType()) {
case ServiceEvent.REGISTERED:
OSGiManagedRuntime.serviceReference = event.getServiceReference();
OSGiManagedRuntime.transactionManager =
(TransactionManager) this.bundleContext.getService(OSGiManagedRuntime.serviceReference);
break;
case ServiceEvent.UNREGISTERING:
OSGiManagedRuntime.transactionManager = null;
OSGiManagedRuntime.serviceReference = null;
this.bundleContext.ungetService(event.getServiceReference());
break;
}
}
}
}
/**
* <p>Register a service listener to the given bundle context by
* {@link BundleContext#addServiceListener(ServiceListener,String)} with a filter
* expression of <code>(objectClass=javax.transaction.TransactionManager)</code>.</p>
*
* <p>The caller is responsible for calling
* {@link #deregisterServiceListener(BundleContext)}, when
* the bundle context is being stopped.</p>
*
* @param bundle The bundle, which is currently being started.
* @throws InvalidSyntaxException When the filter expression is invalid.
*/
public static synchronized void registerServiceListener(BundleContext bundleContext)
throws InvalidSyntaxException {
if (listener != null) {
throw new InternalException("Another OSGi service listener has already been registered.");
}
listener = new Listener(bundleContext);
bundleContext.addServiceListener(listener, "(" + Constants.OBJECTCLASS
+ "=javax.transaction.TransactionManager)");
serviceReference = bundleContext.getServiceReference("javax.transaction.TransactionManager");
if (serviceReference != null) {
transactionManager = (TransactionManager)bundleContext.getService(serviceReference);
}
}
/**
* Remove a service listener previously started inside {@link #registerServiceListener(BundleContext)}.
*
* @param bundleContext The bundle context to call
* {@link BundleContext#removeServiceListener(ServiceListener)} on.
*/
public static synchronized void deregisterServiceListener(BundleContext bundleContext) {
try {
if (serviceReference != null) {
bundleContext.ungetService(serviceReference);
transactionManager = null;
serviceReference = null;
}
}
finally {
// assure, that the service listener is removed, whatever happens above.
if (listener != null) {
bundleContext.removeServiceListener(listener);
listener = null;
}
}
}
/* (non-Javadoc)
* @see org.apache.openjpa.ee.ManagedRuntime#getTransactionManager()
*/
@Override
public TransactionManager getTransactionManager() throws Exception {
synchronized (OSGiManagedRuntime.class) {
if (transactionManager == null) {
throw new InternalException("No javax.transaction.TransactionManager " +
"service is currently registered as an OSGi service.");
}
return transactionManager;
}
}
/* (non-Javadoc)
*
* @see org.apache.openjpa.ee.ManagedRuntime#setRollbackOnly(java.lang.Throwable)
*/
@Override
public void setRollbackOnly(Throwable cause) throws Exception {
// there is no generic support for setting the rollback cause
getTransactionManager().getTransaction().setRollbackOnly();
}
/* (non-Javadoc)
* @see org.apache.openjpa.ee.ManagedRuntime#getRollbackCause()
*/
@Override
public Throwable getRollbackCause() throws Exception {
// there is no generic support for setting the rollback cause
return null;
}
}