/*
* 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.commons.classloader.impl;
import java.util.Hashtable;
import org.apache.sling.commons.classloader.DynamicClassLoaderManager;
import org.osgi.framework.BundleActivator;
import org.osgi.framework.BundleContext;
import org.osgi.framework.BundleEvent;
import org.osgi.framework.Constants;
import org.osgi.framework.ServiceRegistration;
import org.osgi.framework.SynchronousBundleListener;
import org.osgi.service.packageadmin.PackageAdmin;
import org.osgi.util.tracker.ServiceTracker;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* This activator registers the dynamic class loader manager.
* It listens for bundle events and reregisters the class loader manager
* if a bundle event for a used bundle occurs.
*/
public class Activator implements SynchronousBundleListener, BundleActivator {
/** Package admin service name */
private static String PACKAGE_ADMIN_NAME = PackageAdmin.class.getName();
/** The logger. */
private final Logger logger = LoggerFactory.getLogger(this.getClass());
/** A service tracker for the package admin. */
private ServiceTracker packageAdminTracker;
/** The service registration for the dynamic class loader manager. */
private ServiceRegistration serviceReg;
/** The dynamic class loader service factory. */
private DynamicClassLoaderManagerFactory service;
/** The bundle context. */
private BundleContext bundleContext;
/**
* @see org.osgi.framework.BundleActivator#start(org.osgi.framework.BundleContext)
*/
public void start(BundleContext context) {
this.bundleContext = context;
this.packageAdminTracker = new ServiceTracker(this.bundleContext, PACKAGE_ADMIN_NAME, null);
this.packageAdminTracker.open();
// register service
this.registerManagerFactory();
this.bundleContext.addBundleListener(this);
}
/**
* Register the dynamic class loader manager factory.
*/
protected void registerManagerFactory() {
final Hashtable<String, String> props = new Hashtable<String, String>();
props.put(Constants.SERVICE_DESCRIPTION, "Apache Sling Dynamic Class Loader Service");
props.put(Constants.SERVICE_VENDOR, "The Apache Software Foundation");
this.service = new DynamicClassLoaderManagerFactory(this.bundleContext,
(PackageAdmin)this.packageAdminTracker.getService());
this.serviceReg = this.bundleContext.registerService(new String[] {DynamicClassLoaderManager.class.getName()}, service, props);
}
/**
* Unregister the dynamic class loader manager factory.
*/
protected void unregisterManagerFactory() {
if ( this.serviceReg != null ) {
this.serviceReg.unregister();
this.serviceReg = null;
}
if ( this.service != null ) {
this.service = null;
}
}
/**
* @see org.osgi.framework.BundleActivator#stop(org.osgi.framework.BundleContext)
*/
public void stop(final BundleContext context) {
context.removeBundleListener(this);
this.unregisterManagerFactory();
if ( this.packageAdminTracker != null ) {
this.packageAdminTracker.close();
this.packageAdminTracker = null;
}
this.bundleContext = null;
}
/**
* @see org.osgi.framework.BundleListener#bundleChanged(org.osgi.framework.BundleEvent)
*/
public void bundleChanged(final BundleEvent event) {
synchronized ( this ) {
final boolean lazyBundle = event.getBundle().getHeaders().get( Constants.BUNDLE_ACTIVATIONPOLICY ) != null;
final boolean reload;
if ( ( event.getType() == BundleEvent.STARTED && !lazyBundle)
|| (event.getType() == BundleEvent.STARTING && lazyBundle) ) {
reload = this.service.hasUnresolvedPackages(event.getBundle());
if (reload) {
logger.debug("Dynamic Class Loader is reloaded because the new bundle '{}' provides previously unresolved packages", event.getBundle());
}
} else if ( event.getType() == BundleEvent.UNRESOLVED || event.getType() == BundleEvent.RESOLVED ) {
reload = this.service.isBundleUsed(event.getBundle().getBundleId());
if (reload) {
logger.debug("Dynamic Class Loader is reloaded because it has previously loaded classes from bundle '{}' which is no longer active", event.getBundle());
}
} else {
reload = false;
}
if ( reload ) {
this.unregisterManagerFactory();
this.registerManagerFactory();
}
}
}
}