/*
* JBoss, Home of Professional Open Source.
* Copyright 2014, Red Hat, Inc., and individual contributors
* as indicated by the @author tags. See the copyright.txt file in the
* distribution for a full listing of individual contributors.
*
* This is free software; you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as
* published by the Free Software Foundation; either version 2.1 of
* the License, or (at your option) any later version.
*
* This software is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this software; if not, write to the Free
* Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
* 02110-1301 USA, or see the FSF site: http://www.fsf.org.
*/
package org.jboss.as.controller.notification;
import java.util.Arrays;
import java.util.Queue;
import java.util.concurrent.ConcurrentLinkedQueue;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.locks.ReadWriteLock;
import java.util.concurrent.locks.ReentrantReadWriteLock;
import org.jboss.as.controller.logging.ControllerLogger;
import org.jboss.as.controller.registry.NotificationHandlerRegistration;
/**
* Provides implementation of the {@code NotificationSupport}.
*
* The {@code BlockingNotificationSupport} will fire the notifications and deliver them to the handlers on the current thread.
* Its {@code emit()} method will return after the notifications have all been delivered (and blocks the code execution until it is done).
*
* The {@code NonBlockingNotificationSupport} will fire the notifications in a separate thread (provided by its {@code
* executorService}.
* Its {@code emit()} method will return immediately and will not block the code execution.
*
* @author <a href="http://jmesnil.net/">Jeff Mesnil</a> (c) 2014 Red Hat inc.
*/
class NotificationSupports {
static class BlockingNotificationSupport implements NotificationSupport {
private final NotificationHandlerRegistration registry;
public BlockingNotificationSupport(NotificationHandlerRegistration registry) {
this.registry = registry;
}
@Override
public void emit(Notification... notifications) {
fireNotifications(registry, notifications);
}
@Override
public NotificationHandlerRegistration getNotificationRegistry() {
return registry;
}
}
static class NonBlockingNotificationSupport implements NotificationSupport {
private final NotificationHandlerRegistration registry;
private final ExecutorService executor;
/**
* Use a concurrent queue to put the notifications in it when {@code emit()} is called.
* The queue will be drained in a separate thread and the notifications effectively delivered to the handlers.
*
* This ensures that the notifications will be delivered in the same order they were emitted.
*/
private final Queue<Notification> queue = new ConcurrentLinkedQueue<Notification>();
/**
* use the lock's exclusive writeLock to ensure only one thread can drain the queue at a given time.
*/
private final ReadWriteLock lock = new ReentrantReadWriteLock();
public NonBlockingNotificationSupport(NotificationHandlerRegistration registry, ExecutorService executor) {
this.registry = registry;
this.executor = executor;
}
@Override
public synchronized void emit(Notification... notifications) {
queue.addAll(Arrays.asList(notifications));
executor.execute(new Runnable() {
@Override
public void run() {
lock.writeLock().lock();
try {
while (true) {
Notification notification = queue.poll();
if (notification == null) {
break;
}
fireNotifications(registry, notification);
}
} finally {
lock.writeLock().unlock();
}
}
});
}
@Override
public NotificationHandlerRegistration getNotificationRegistry() {
return registry;
}
}
private static void fireNotifications(NotificationHandlerRegistration registry, final Notification... notifications) {
for (Notification notification : notifications) {
try {
// each notification may have a different subset of handlers depending on their filters
for (NotificationHandler handler : registry.findMatchingNotificationHandlers(notification)) {
handler.handleNotification(notification);
}
} catch (Throwable t) {
ControllerLogger.ROOT_LOGGER.failedToEmitNotification(notification, t);
}
}
}
}