/*
* 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.jackrabbit.oak.osgi;
import static com.google.common.base.Preconditions.checkNotNull;
import static com.google.common.base.Preconditions.checkState;
import static com.google.common.collect.Maps.newHashMap;
import java.io.Closeable;
import java.util.Map;
import javax.annotation.Nonnull;
import com.google.common.io.Closeables;
import com.google.common.io.Closer;
import org.apache.jackrabbit.oak.spi.commit.BackgroundObserver;
import org.apache.jackrabbit.oak.spi.commit.Observable;
import org.apache.jackrabbit.oak.spi.commit.Observer;
import org.apache.jackrabbit.oak.spi.whiteboard.WhiteboardExecutor;
import org.osgi.framework.BundleContext;
import org.osgi.framework.ServiceReference;
import org.osgi.util.tracker.ServiceTracker;
import org.osgi.util.tracker.ServiceTrackerCustomizer;
public class ObserverTracker implements ServiceTrackerCustomizer {
private final Map<ServiceReference, Closeable> subscriptions = newHashMap();
private final WhiteboardExecutor executor = new WhiteboardExecutor();
private final Observable observable;
private BundleContext bundleContext;
private ServiceTracker observerTracker;
public ObserverTracker(@Nonnull Observable observable) {
this.observable = checkNotNull(observable);
}
public void start(@Nonnull BundleContext bundleContext) {
checkState(this.bundleContext == null);
this.bundleContext = checkNotNull(bundleContext);
executor.start(new OsgiWhiteboard(bundleContext));
observerTracker = new ServiceTracker(bundleContext, Observer.class.getName(), this);
observerTracker.open();
}
public void stop() {
checkState(this.bundleContext != null);
observerTracker.close();
executor.stop();
}
//------------------------< ServiceTrackerCustomizer >----------------------
@Override
public Object addingService(ServiceReference reference) {
Object service = bundleContext.getService(reference);
if (service instanceof Observer) {
Closer subscription = Closer.create();
BackgroundObserver observer = subscription.register(
new BackgroundObserver((Observer) service, executor));
subscription.register(
observable.addObserver(observer));
subscriptions.put(reference, subscription);
return service;
} else {
bundleContext.ungetService(reference);
return null;
}
}
@Override
public void modifiedService(ServiceReference reference, Object service) {
// nothing to do
}
@Override
public void removedService(ServiceReference reference, Object service) {
if (subscriptions.containsKey(reference)) {
Closeables.closeQuietly(subscriptions.get(reference));
bundleContext.ungetService(reference);
}
}
}