001    /*
002     * Licensed to the Apache Software Foundation (ASF) under one or more
003     * contributor license agreements. See the NOTICE file distributed with
004     * this work for additional information regarding copyright ownership.
005     * The ASF licenses this file to You under the Apache License, Version 2.0
006     * (the "License"); you may not use this file except in compliance with
007     * the License. You may obtain a copy of the License at
008     *
009     *      http://www.apache.org/licenses/LICENSE-2.0
010     *
011     * Unless required by applicable law or agreed to in writing, software
012     * distributed under the License is distributed on an "AS IS" BASIS,
013     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014     * See the License for the specific language governing permissions and
015     * limitations under the License.
016     */
017    
018    package org.apache.logging.log4j.core.osgi;
019    
020    import java.util.concurrent.atomic.AtomicReference;
021    
022    import org.apache.logging.log4j.Logger;
023    import org.apache.logging.log4j.core.config.plugins.util.PluginRegistry;
024    import org.apache.logging.log4j.core.util.Constants;
025    import org.apache.logging.log4j.status.StatusLogger;
026    import org.apache.logging.log4j.util.PropertiesUtil;
027    import org.osgi.framework.Bundle;
028    import org.osgi.framework.BundleActivator;
029    import org.osgi.framework.BundleContext;
030    import org.osgi.framework.BundleEvent;
031    import org.osgi.framework.SynchronousBundleListener;
032    import org.osgi.framework.wiring.BundleWiring;
033    
034    /**
035     * OSGi BundleActivator.
036     */
037    public final class Activator implements BundleActivator, SynchronousBundleListener {
038    
039        private static final Logger LOGGER = StatusLogger.getLogger();
040    
041        private final AtomicReference<BundleContext> context = new AtomicReference<BundleContext>();
042    
043        @Override
044        public void start(final BundleContext context) throws Exception {
045            // allow the user to override the default ContextSelector (e.g., by using BasicContextSelector for a global cfg)
046            if (PropertiesUtil.getProperties().getStringProperty(Constants.LOG4J_CONTEXT_SELECTOR) == null) {
047                System.setProperty(Constants.LOG4J_CONTEXT_SELECTOR, BundleContextSelector.class.getName());
048            }
049            if (this.context.compareAndSet(null, context)) {
050                context.addBundleListener(this);
051                // done after the BundleListener as to not miss any new bundle installs in the interim
052                scanInstalledBundlesForPlugins(context);
053            }
054        }
055    
056        private static void scanInstalledBundlesForPlugins(final BundleContext context) {
057            final Bundle[] bundles = context.getBundles();
058            for (final Bundle bundle : bundles) {
059                if (bundle.getState() == Bundle.ACTIVE) {
060                    // TODO: bundle state can change during this
061                    scanBundleForPlugins(bundle);
062                }
063            }
064        }
065    
066        private static void scanBundleForPlugins(final Bundle bundle) {
067            LOGGER.trace("Scanning bundle [{}] for plugins.", bundle.getSymbolicName());
068            PluginRegistry.getInstance().loadFromBundle(bundle.getBundleId(),
069                bundle.adapt(BundleWiring.class).getClassLoader());
070        }
071    
072        private static void stopBundlePlugins(final Bundle bundle) {
073            LOGGER.trace("Stopping bundle [{}] plugins.", bundle.getSymbolicName());
074            // TODO: plugin lifecycle code
075            PluginRegistry.getInstance().clearBundlePlugins(bundle.getBundleId());
076        }
077    
078        @Override
079        public void stop(final BundleContext context) throws Exception {
080            // not much can be done that isn't already automated by the framework
081            this.context.compareAndSet(context, null);
082            // TODO: shut down log4j
083        }
084    
085        @Override
086        public void bundleChanged(final BundleEvent event) {
087            switch (event.getType()) {
088                // FIXME: STARTING instead of STARTED?
089                case BundleEvent.STARTED:
090                    scanBundleForPlugins(event.getBundle());
091                    break;
092    
093                case BundleEvent.STOPPING:
094                    stopBundlePlugins(event.getBundle());
095                    break;
096    
097                default:
098                    break;
099            }
100        }
101    }