/*
* 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.ace.agent.impl;
import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.CopyOnWriteArrayList;
import java.util.concurrent.ScheduledExecutorService;
import org.apache.ace.agent.EventListener;
import org.apache.ace.agent.EventsHandler;
import org.osgi.framework.BundleContext;
import org.osgi.framework.ServiceReference;
import org.osgi.util.tracker.ServiceTracker;
import org.osgi.util.tracker.ServiceTrackerCustomizer;
/**
* Default thread-safe {@link EventsHandler} implementation that tracks external {@link EventListener.class} services.
* Agent handles can manages their own listeners directly using {@link #addListener(EventListener)} and
* {@link #removeListener(EventListener)}.
*/
public class EventsHandlerImpl extends ComponentBase implements EventsHandler {
private final CopyOnWriteArrayList<EventListener> m_listeners = new CopyOnWriteArrayList<EventListener>();
private final BundleContext m_bundleContext;
//
private volatile ServiceTracker m_tracker;
public EventsHandlerImpl(BundleContext bundleContext) throws Exception {
super("events");
m_bundleContext = bundleContext;
}
@Override
public void addListener(EventListener listener) {
m_listeners.addIfAbsent(listener);
}
@Override
public void postEvent(final String topic, Map<String, String> payload) {
// Make sure that the payload isn't changed while posting events...
final Map<String, String> eventPayload = new HashMap<String, String>(payload);
for (final EventListener listener : m_listeners) {
ScheduledExecutorService executor = getExecutorService();
if (executor.isShutdown()) {
logWarning("Cannot post event, executor is shut down!");
return;
}
executor.submit(new Runnable() {
@Override
public void run() {
try {
listener.handle(topic, eventPayload);
}
catch (Exception e) {
logWarning("Exception while posting event", e);
}
}
});
}
}
@Override
public void removeListener(EventListener listener) {
m_listeners.remove(listener);
}
@Override
public void sendEvent(String topic, Map<String, String> payload) {
// Make sure that the payload isn't changed while sending events...
final Map<String, String> eventPayload = new HashMap<String, String>(payload);
for (EventListener listener : m_listeners) {
try {
listener.handle(topic, eventPayload);
}
catch (Exception e) {
logWarning("Exception while sending event", e);
}
}
}
@Override
protected void onInit() throws Exception {
m_tracker = new ServiceTracker(m_bundleContext, EventListener.class.getName(), new ServiceTrackerCustomizer() {
@Override
public Object addingService(ServiceReference reference) {
Object service = m_bundleContext.getService(reference);
addListener((EventListener) service);
return service;
}
@Override
public void modifiedService(ServiceReference reference, Object service) {
}
@Override
public void removedService(ServiceReference reference, Object service) {
removeListener((EventListener) service);
}
});
m_tracker.open();
}
@Override
protected void onStop() throws Exception {
m_tracker.close();
m_listeners.clear();
}
}