/*
* 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.installer.provider.file.impl;
import java.util.Dictionary;
import java.util.Hashtable;
import java.util.List;
import org.apache.sling.installer.api.OsgiInstaller;
import org.apache.sling.installer.api.UpdateHandler;
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;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* The <code>ServicesListener</code> listens for the required services
* and starts/stops the scanners based on the availability of the
* services.
*/
public class ServicesListener {
/** The logger. */
private final Logger logger = LoggerFactory.getLogger(this.getClass());
/** The name of the installer service. */
private static final String INSTALLER_SERVICE_NAME = OsgiInstaller.class.getName();
/** The bundle context. */
private final BundleContext bundleContext;
/** The listener for the installer. */
private final Listener installerListener;
/** The file installer. */
private final FileInstaller installer;
/** Service registration. */
private ServiceRegistration registration;
private boolean running = false;
public ServicesListener(final BundleContext bundleContext,
final List<ScanConfiguration> configs) {
this.bundleContext = bundleContext;
boolean writeBack = true;
final Object writeBackObj = Activator.getProp(this.bundleContext, Activator.KEY_WRITEBACK);
if ( writeBackObj != null && "false".equalsIgnoreCase(writeBackObj.toString())) {
writeBack = false;
}
this.installer = new FileInstaller(configs, writeBack);
this.installerListener = new Listener(INSTALLER_SERVICE_NAME);
this.installerListener.start();
}
public synchronized void notifyChange() {
final boolean shouldRun = this.installer.hasConfigurations();
if ( (shouldRun && !running) || (!shouldRun && running) ) {
final OsgiInstaller installer = (OsgiInstaller)this.installerListener.getService();
if ( installer != null&& !running ) {
logger.debug("Starting scanner");
this.startScanner(installer);
} else if ( running && installer == null ) {
logger.debug("Stopping scanner");
this.stopScanner();
}
}
}
/**
* Deactivate this listener.
*/
public void deactivate() {
this.installerListener.deactivate();
this.stopScanner();
}
/** Vendor of all registered services. */
public static final String VENDOR = "The Apache Software Foundation";
private void startScanner(final OsgiInstaller installer) {
if ( !running ) {
this.installer.start(installer);
final Dictionary<String, Object> props = new Hashtable<String, Object>();
props.put(Constants.SERVICE_DESCRIPTION, "Apache Sling File Installer Controller Service");
props.put(Constants.SERVICE_VENDOR, VENDOR);
props.put(UpdateHandler.PROPERTY_SCHEMES, this.installer.getSchemes());
this.registration = this.bundleContext.registerService(UpdateHandler.class.getName(),
this.installer, props);
running = true;
}
}
private void stopScanner() {
if ( running ) {
if ( this.registration != null ) {
this.registration.unregister();
this.registration = null;
}
this.installer.stop();
running = false;
}
}
protected final class Listener implements ServiceListener {
private final String serviceName;
private ServiceReference reference;
private Object service;
public Listener(final String serviceName) {
this.serviceName = serviceName;
}
public void start() {
this.retainService();
try {
bundleContext.addServiceListener(this, "("
+ Constants.OBJECTCLASS + "=" + serviceName + ")");
} catch (final InvalidSyntaxException ise) {
// this should really never happen
throw new RuntimeException("Unexpected exception occured.", ise);
}
}
public void deactivate() {
bundleContext.removeServiceListener(this);
}
public synchronized Object getService() {
return this.service;
}
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();
}
}
}
}
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.service == null ) {
this.retainService();
} else if ( event.getType() == ServiceEvent.UNREGISTERING && this.service != null ) {
this.releaseService();
}
}
}
}