/*
* 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.sling.launchpad.installer.impl;
import java.util.Dictionary;
import java.util.Hashtable;
import org.apache.sling.installer.api.OsgiInstaller;
import org.apache.sling.installer.api.event.InstallationListener;
import org.apache.sling.launchpad.api.LaunchpadContentProvider;
import org.apache.sling.launchpad.api.StartupHandler;
import org.apache.sling.settings.SlingSettingsService;
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;
import org.osgi.framework.ServiceRegistration;
/**
* The <code>ServicesListener</code> listens for the required services
* and starts the installation support if all services are available.
*/
public class ServicesListener {
/** The bundle context. */
private final BundleContext bundleContext;
/** The listener for the installer. */
private final Listener installerListener;
/** The listener for the provider. */
private final Listener providerListener;
/** The listener for the startup handler. */
private final Listener startupListener;
/** The listener for the settings service. */
private final Listener settingsListener;
/** The registration of the launchpad listener. */
private ServiceRegistration launchpadListenerReg;
/** Boolean marker to not reprocess things. */
private volatile boolean installed = false;
private LaunchpadListener launchpadListener;
/**
* Start listeners
*/
public ServicesListener(final BundleContext bundleContext) {
this.bundleContext = bundleContext;
this.installerListener = new Listener(OsgiInstaller.class.getName());
this.providerListener = new Listener(LaunchpadContentProvider.class.getName());
this.startupListener = new Listener(StartupHandler.class.getName());
this.settingsListener = new Listener(SlingSettingsService.class.getName());
this.startupListener.start();
this.installerListener.start();
this.providerListener.start();
this.settingsListener.start();
}
/**
* Notify of service changes from the listeners.
* If all services are available, register listener and pass resources
* to the OSGi installer.
*/
public synchronized void notifyChange() {
// check if all services are available
final OsgiInstaller installer = (OsgiInstaller)this.installerListener.getService();
final LaunchpadContentProvider lcp = (LaunchpadContentProvider)this.providerListener.getService();
final StartupHandler handler = (StartupHandler)this.startupListener.getService();
final SlingSettingsService settings = (SlingSettingsService)this.settingsListener.getService();
if ( installer != null && lcp != null && handler != null && settings != null ) {
if ( !this.installed ) {
this.installed = true;
this.launchpadListener = new LaunchpadListener(handler);
final Dictionary<String, Object> props = new Hashtable<String, Object>();
props.put(Constants.SERVICE_DESCRIPTION, "Apache Sling Launchpad Startup Listener");
props.put(Constants.SERVICE_VENDOR, "The Apache Software Foundation");
this.launchpadListenerReg = this.bundleContext.registerService(InstallationListener.class.getName(), launchpadListener, props);
LaunchpadConfigInstaller.install(installer, lcp, settings.getRunModes());
}
}
}
/**
* Deactivate this listener.
*/
public void deactivate() {
this.installerListener.deactivate();
this.providerListener.deactivate();
this.startupListener.deactivate();
this.settingsListener.deactivate();
if ( this.launchpadListenerReg != null ) {
this.launchpadListener.stop();
this.launchpadListenerReg.unregister();
this.launchpadListenerReg = null;
}
this.launchpadListener = null;
}
/**
* Helper class listening for service events for a defined service.
*/
protected final class Listener implements ServiceListener {
/** The name of the service. */
private final String serviceName;
/** The service reference. */
private volatile ServiceReference reference;
/** The service. */
private volatile Object service;
/**
* Constructor
*/
public Listener(final String serviceName) {
this.serviceName = serviceName;
}
/**
* Start the listener.
* First register a service listener and then check for the service.
*/
public void start() {
try {
bundleContext.addServiceListener(this, "("
+ Constants.OBJECTCLASS + "=" + serviceName + ")");
} catch (final InvalidSyntaxException ise) {
// this should really never happen
throw new RuntimeException("Unexpected exception occured.", ise);
}
this.retainService();
}
/**
* Unregister the listener.
*/
public void deactivate() {
bundleContext.removeServiceListener(this);
}
/**
* Return the service (if available)
*/
public synchronized Object getService() {
return this.service;
}
/**
* Try to get the service and notify the change.
*/
private synchronized void retainService() {
if ( this.reference == null ) {
this.reference = bundleContext.getServiceReference(this.serviceName);
if ( this.reference != null ) {
this.service = bundleContext.getService(this.reference);
if ( this.service == null ) {
this.reference = null;
} else {
notifyChange();
}
}
}
}
/**
* Try to release the service and notify the change.
*/
private synchronized void releaseService() {
if ( this.reference != null ) {
this.service = null;
bundleContext.ungetService(this.reference);
this.reference = null;
notifyChange();
}
}
/**
* @see org.osgi.framework.ServiceListener#serviceChanged(org.osgi.framework.ServiceEvent)
*/
public void serviceChanged(ServiceEvent event) {
if (event.getType() == ServiceEvent.REGISTERED) {
this.retainService();
} else if ( event.getType() == ServiceEvent.UNREGISTERING ) {
this.releaseService();
}
}
}
}