/*
* Copyright (c) 2014 Cisco Systems, Inc. and others. All rights reserved.
*
* This program and the accompanying materials are made available under the
* terms of the Eclipse Public License v1.0 which accompanies this distribution,
* and is available at http://www.eclipse.org/legal/epl-v10.html
*/
package org.opendaylight.controller.md.sal.dom.broker.impl;
import com.google.common.base.Preconditions;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableMultimap;
import com.google.common.collect.ImmutableMultimap.Builder;
import com.google.common.collect.Multimap;
import com.google.common.collect.Multimaps;
import com.google.common.util.concurrent.Futures;
import com.google.common.util.concurrent.ListenableFuture;
import com.lmax.disruptor.EventHandler;
import com.lmax.disruptor.InsufficientCapacityException;
import com.lmax.disruptor.PhasedBackoffWaitStrategy;
import com.lmax.disruptor.WaitStrategy;
import com.lmax.disruptor.dsl.Disruptor;
import com.lmax.disruptor.dsl.ProducerType;
import java.util.Arrays;
import java.util.Collection;
import java.util.List;
import java.util.Set;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;
import org.opendaylight.controller.md.sal.dom.api.DOMNotification;
import org.opendaylight.controller.md.sal.dom.api.DOMNotificationListener;
import org.opendaylight.controller.md.sal.dom.api.DOMNotificationPublishService;
import org.opendaylight.controller.md.sal.dom.api.DOMNotificationService;
import org.opendaylight.controller.md.sal.dom.spi.DOMNotificationSubscriptionListener;
import org.opendaylight.controller.md.sal.dom.spi.DOMNotificationSubscriptionListenerRegistry;
import org.opendaylight.yangtools.concepts.AbstractListenerRegistration;
import org.opendaylight.yangtools.concepts.ListenerRegistration;
import org.opendaylight.yangtools.util.ListenerRegistry;
import org.opendaylight.yangtools.yang.model.api.SchemaPath;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* Joint implementation of {@link DOMNotificationPublishService} and {@link DOMNotificationService}. Provides
* routing of notifications from publishers to subscribers.
*
*
* Internal implementation works by allocating a two-handler Disruptor. The first handler delivers notifications
* to subscribed listeners and the second one notifies whoever may be listening on the returned future. Registration
* state tracking is performed by a simple immutable multimap -- when a registration or unregistration occurs we
* re-generate the entire map from scratch and set it atomically. While registrations/unregistrations synchronize
* on this instance, notifications do not take any locks here.
*
*
* The fully-blocking {@link #publish(long, DOMNotification, Collection)} and non-blocking
* {@link #offerNotification(DOMNotification)}
* are realized using the Disruptor's native operations. The bounded-blocking
* {@link #offerNotification(DOMNotification, long, TimeUnit)}
* is realized by arming a background wakeup interrupt.
*/
public final class DOMNotificationRouter implements AutoCloseable, DOMNotificationPublishService,
DOMNotificationService, DOMNotificationSubscriptionListenerRegistry {
private static final Logger LOG = LoggerFactory.getLogger(DOMNotificationRouter.class);
private static final ListenableFuture NO_LISTENERS = Futures.immediateFuture(null);
private static final WaitStrategy DEFAULT_STRATEGY = PhasedBackoffWaitStrategy
.withLock(1L, 30L, TimeUnit.MILLISECONDS);
private static final EventHandler DISPATCH_NOTIFICATIONS
= (event, sequence, endOfBatch) -> event.deliverNotification();
private static final EventHandler NOTIFY_FUTURE = (event, sequence, endOfBatch) -> event
.setFuture();
private final Disruptor disruptor;
private final ExecutorService executor;
private volatile Multimap> listeners
= ImmutableMultimap.of();
private final ListenerRegistry subscriptionListeners = ListenerRegistry
.create();
@SuppressWarnings("unchecked")
private DOMNotificationRouter(final ExecutorService executor, final int queueDepth, final WaitStrategy strategy) {
this.executor = Preconditions.checkNotNull(executor);
disruptor = new Disruptor<>(DOMNotificationRouterEvent.FACTORY, queueDepth, executor, ProducerType.MULTI,
strategy);
disruptor.handleEventsWith(DISPATCH_NOTIFICATIONS);
disruptor.after(DISPATCH_NOTIFICATIONS).handleEventsWith(NOTIFY_FUTURE);
disruptor.start();
}
public static DOMNotificationRouter create(final int queueDepth) {
final ExecutorService executor = Executors.newCachedThreadPool();
return new DOMNotificationRouter(executor, queueDepth, DEFAULT_STRATEGY);
}
public static DOMNotificationRouter create(final int queueDepth, final long spinTime, final long parkTime,
final TimeUnit unit) {
Preconditions.checkArgument(Long.lowestOneBit(queueDepth) == Long.highestOneBit(queueDepth),
"Queue depth %s is not power-of-two", queueDepth);
final ExecutorService executor = Executors.newCachedThreadPool();
final WaitStrategy strategy = PhasedBackoffWaitStrategy.withLock(spinTime, parkTime, unit);
return new DOMNotificationRouter(executor, queueDepth, strategy);
}
@Override
public synchronized ListenerRegistration registerNotificationListener(
final T listener, final Collection types) {
final ListenerRegistration reg = new AbstractListenerRegistration(listener) {
@Override
protected void removeRegistration() {
final ListenerRegistration me = this;
synchronized (DOMNotificationRouter.this) {
replaceListeners(ImmutableMultimap.copyOf(Multimaps.filterValues(listeners, input -> input != me)));
}
}
};
if (!types.isEmpty()) {
final Builder> b = ImmutableMultimap
.builder();
b.putAll(listeners);
for (final SchemaPath t : types) {
b.put(t, reg);
}
replaceListeners(b.build());
}
return reg;
}
@Override
public ListenerRegistration registerNotificationListener(final T listener,
final
SchemaPath...
types) {
return registerNotificationListener(listener, Arrays.asList(types));
}
/**
* Swaps registered listeners and triggers notification update.
*
* @param newListeners listeners
*/
private void replaceListeners(
final Multimap> newListeners) {
listeners = newListeners;
notifyListenerTypesChanged(newListeners.keySet());
}
@SuppressWarnings("checkstyle:IllegalCatch")
private void notifyListenerTypesChanged(final Set typesAfter) {
final List> listenersAfter = ImmutableList
.copyOf(subscriptionListeners.getListeners());
executor.submit(() -> {
for (final ListenerRegistration subListener : listenersAfter) {
try {
subListener.getInstance().onSubscriptionChanged(typesAfter);
} catch (final Exception e) {
LOG.warn("Uncaught exception during invoking listener {}", subListener.getInstance(), e);
}
}
});
}
@Override
public ListenerRegistration registerSubscriptionListener(
final L listener) {
final Set initialTypes = listeners.keySet();
executor.submit(() -> listener.onSubscriptionChanged(initialTypes));
return subscriptionListeners.registerWithType(listener);
}
private ListenableFuture publish(final long seq, final DOMNotification notification,
final Collection>
subscribers) {
final DOMNotificationRouterEvent event = disruptor.get(seq);
final ListenableFuture future = event.initialize(notification, subscribers);
disruptor.getRingBuffer().publish(seq);
return future;
}
@Override
public ListenableFuture> putNotification(final DOMNotification notification) throws InterruptedException {
final Collection> subscribers = listeners
.get(notification.getType());
if (subscribers.isEmpty()) {
return NO_LISTENERS;
}
final long seq = disruptor.getRingBuffer().next();
return publish(seq, notification, subscribers);
}
private ListenableFuture> tryPublish(final DOMNotification notification,
final Collection>
subscribers) {
final long seq;
try {
seq = disruptor.getRingBuffer().tryNext();
} catch (final InsufficientCapacityException e) {
return DOMNotificationPublishService.REJECTED;
}
return publish(seq, notification, subscribers);
}
@Override
public ListenableFuture> offerNotification(final DOMNotification notification) {
final Collection> subscribers = listeners
.get(notification.getType());
if (subscribers.isEmpty()) {
return NO_LISTENERS;
}
return tryPublish(notification, subscribers);
}
@Override
public ListenableFuture> offerNotification(final DOMNotification notification, final long timeout,
final TimeUnit unit) throws InterruptedException {
final Collection> subscribers = listeners
.get(notification.getType());
if (subscribers.isEmpty()) {
return NO_LISTENERS;
}
// Attempt to perform a non-blocking publish first
final ListenableFuture> noBlock = tryPublish(notification, subscribers);
if (!DOMNotificationPublishService.REJECTED.equals(noBlock)) {
return noBlock;
}
/*
* FIXME: we need a background thread, which will watch out for blocking too long. Here
* we will arm a tasklet for it and synchronize delivery of interrupt properly.
*/
throw new UnsupportedOperationException("Not implemented yet");
}
@Override
public void close() {
disruptor.shutdown();
executor.shutdown();
}
}