dom/mdsal-dom-broker/src/main/java/org/opendaylight/mdsal/dom/broker/DOMNotificationRouter.java

   1 /*
   2  * Copyright (c) 2014 Cisco Systems, Inc. and others.  All rights reserved.
   3  *
   4  * This program and the accompanying materials are made available under the
   5  * terms of the Eclipse Public License v1.0 which accompanies this distribution,
   6  * and is available at http://www.eclipse.org/legal/epl-v10.html
   7  */
   8 package org.opendaylight.mdsal.dom.broker;
   9
  10 import static com.google.common.base.Preconditions.checkArgument;
  11
  12 import com.google.common.annotations.VisibleForTesting;
  13 import com.google.common.collect.ImmutableList;
  14 import com.google.common.collect.ImmutableMultimap;
  15 import com.google.common.collect.ImmutableMultimap.Builder;
  16 import com.google.common.collect.Multimap;
  17 import com.google.common.collect.Multimaps;
  18 import com.google.common.util.concurrent.ListenableFuture;
  19 import com.google.common.util.concurrent.ThreadFactoryBuilder;
  20 import com.lmax.disruptor.EventHandler;
  21 import com.lmax.disruptor.InsufficientCapacityException;
  22 import com.lmax.disruptor.PhasedBackoffWaitStrategy;
  23 import com.lmax.disruptor.WaitStrategy;
  24 import com.lmax.disruptor.dsl.Disruptor;
  25 import com.lmax.disruptor.dsl.ProducerType;
  26 import java.util.Collection;
  27 import java.util.List;
  28 import java.util.Set;
  29 import java.util.concurrent.ExecutorService;
  30 import java.util.concurrent.Executors;
  31 import java.util.concurrent.ScheduledFuture;
  32 import java.util.concurrent.ScheduledThreadPoolExecutor;
  33 import java.util.concurrent.TimeUnit;
  34 import org.opendaylight.mdsal.dom.api.DOMNotification;
  35 import org.opendaylight.mdsal.dom.api.DOMNotificationListener;
  36 import org.opendaylight.mdsal.dom.api.DOMNotificationPublishService;
  37 import org.opendaylight.mdsal.dom.api.DOMNotificationService;
  38 import org.opendaylight.mdsal.dom.spi.DOMNotificationSubscriptionListener;
  39 import org.opendaylight.mdsal.dom.spi.DOMNotificationSubscriptionListenerRegistry;
  40 import org.opendaylight.yangtools.concepts.AbstractListenerRegistration;
  41 import org.opendaylight.yangtools.concepts.ListenerRegistration;
  42 import org.opendaylight.yangtools.util.ListenerRegistry;
  43 import org.opendaylight.yangtools.util.concurrent.FluentFutures;
  44 import org.opendaylight.yangtools.yang.model.api.stmt.SchemaNodeIdentifier.Absolute;
  45 import org.slf4j.Logger;
  46 import org.slf4j.LoggerFactory;
  47
  48 /**
  49  * Joint implementation of {@link DOMNotificationPublishService} and {@link DOMNotificationService}. Provides
  50  * routing of notifications from publishers to subscribers.
  51  *
  52  *<p>
  53  * Internal implementation works by allocating a two-handler Disruptor. The first handler delivers notifications
  54  * to subscribed listeners and the second one notifies whoever may be listening on the returned future. Registration
  55  * state tracking is performed by a simple immutable multimap -- when a registration or unregistration occurs we
  56  * re-generate the entire map from scratch and set it atomically. While registrations/unregistrations synchronize
  57  * on this instance, notifications do not take any locks here.
  58  *
  59  *<p>
  60  * The fully-blocking {@link #publish(long, DOMNotification, Collection)}
  61  * and non-blocking {@link #offerNotification(DOMNotification)}
  62  * are realized using the Disruptor's native operations. The bounded-blocking {@link
  63  * #offerNotification(DOMNotification, long, TimeUnit)}
  64  * is realized by arming a background wakeup interrupt.
  65  */
  66 public class DOMNotificationRouter implements AutoCloseable, DOMNotificationPublishService,
  67         DOMNotificationService, DOMNotificationSubscriptionListenerRegistry {
  68
  69     private static final Logger LOG = LoggerFactory.getLogger(DOMNotificationRouter.class);
  70     private static final ListenableFuture<Void> NO_LISTENERS = FluentFutures.immediateNullFluentFuture();
  71     private static final WaitStrategy DEFAULT_STRATEGY = PhasedBackoffWaitStrategy.withLock(
  72             1L, 30L, TimeUnit.MILLISECONDS);
  73     private static final EventHandler<DOMNotificationRouterEvent> DISPATCH_NOTIFICATIONS =
  74         (event, sequence, endOfBatch) -> event.deliverNotification();
  75     private static final EventHandler<DOMNotificationRouterEvent> NOTIFY_FUTURE =
  76         (event, sequence, endOfBatch) -> event.setFuture();
  77
  78     private final ListenerRegistry<DOMNotificationSubscriptionListener> subscriptionListeners =
  79             ListenerRegistry.create();
  80     private final Disruptor<DOMNotificationRouterEvent> disruptor;
  81     private final ScheduledThreadPoolExecutor observer;
  82     private final ExecutorService executor;
  83
  84     private volatile Multimap<Absolute, AbstractListenerRegistration<? extends DOMNotificationListener>> listeners =
  85             ImmutableMultimap.of();
  86
  87     @VisibleForTesting
  88     DOMNotificationRouter(final int queueDepth, final WaitStrategy strategy) {
  89         observer = new ScheduledThreadPoolExecutor(1,
  90             new ThreadFactoryBuilder().setDaemon(true).setNameFormat("DOMNotificationRouter-observer-%d").build());
  91         executor = Executors.newCachedThreadPool(
  92             new ThreadFactoryBuilder().setDaemon(true).setNameFormat("DOMNotificationRouter-listeners-%d").build());
  93         disruptor = new Disruptor<>(DOMNotificationRouterEvent.FACTORY, queueDepth,
  94                 new ThreadFactoryBuilder().setNameFormat("DOMNotificationRouter-disruptor-%d").build(),
  95                 ProducerType.MULTI, strategy);
  96         disruptor.handleEventsWith(DISPATCH_NOTIFICATIONS);
  97         disruptor.after(DISPATCH_NOTIFICATIONS).handleEventsWith(NOTIFY_FUTURE);
  98         disruptor.start();
  99     }
 100
 101     public static DOMNotificationRouter create(final int queueDepth) {
 102         return new DOMNotificationRouter(queueDepth, DEFAULT_STRATEGY);
 103     }
 104
 105     public static DOMNotificationRouter create(final int queueDepth, final long spinTime, final long parkTime,
 106             final TimeUnit unit) {
 107         checkArgument(Long.lowestOneBit(queueDepth) == Long.highestOneBit(queueDepth),
 108                 "Queue depth %s is not power-of-two", queueDepth);
 109         return new DOMNotificationRouter(queueDepth, PhasedBackoffWaitStrategy.withLock(spinTime, parkTime, unit));
 110     }
 111
 112     @Override
 113     public synchronized <T extends DOMNotificationListener> ListenerRegistration<T> registerNotificationListener(
 114             final T listener, final Collection<Absolute> types) {
 115         final AbstractListenerRegistration<T> reg = new AbstractListenerRegistration<>(listener) {
 116             @Override
 117             protected void removeRegistration() {
 118                 synchronized (DOMNotificationRouter.this) {
 119                     replaceListeners(ImmutableMultimap.copyOf(Multimaps.filterValues(listeners,
 120                         input -> input != this)));
 121                 }
 122             }
 123         };
 124
 125         if (!types.isEmpty()) {
 126             final Builder<Absolute, AbstractListenerRegistration<? extends DOMNotificationListener>> b =
 127                     ImmutableMultimap.builder();
 128             b.putAll(listeners);
 129
 130             for (final Absolute t : types) {
 131                 b.put(t, reg);
 132             }
 133
 134             replaceListeners(b.build());
 135         }
 136
 137         return reg;
 138     }
 139
 140     /**
 141      * Swaps registered listeners and triggers notification update.
 142      *
 143      * @param newListeners is used to notify listenerTypes changed
 144      */
 145     private void replaceListeners(
 146             final Multimap<Absolute, AbstractListenerRegistration<? extends DOMNotificationListener>> newListeners) {
 147         listeners = newListeners;
 148         notifyListenerTypesChanged(newListeners.keySet());
 149     }
 150
 151     @SuppressWarnings("checkstyle:IllegalCatch")
 152     private void notifyListenerTypesChanged(final Set<Absolute> typesAfter) {
 153         final List<? extends DOMNotificationSubscriptionListener> listenersAfter =
 154                 subscriptionListeners.streamListeners().collect(ImmutableList.toImmutableList());
 155         executor.execute(() -> {
 156             for (final DOMNotificationSubscriptionListener subListener : listenersAfter) {
 157                 try {
 158                     subListener.onSubscriptionChanged(typesAfter);
 159                 } catch (final Exception e) {
 160                     LOG.warn("Uncaught exception during invoking listener {}", subListener, e);
 161                 }
 162             }
 163         });
 164     }
 165
 166     @Override
 167     public <L extends DOMNotificationSubscriptionListener> ListenerRegistration<L> registerSubscriptionListener(
 168             final L listener) {
 169         final Set<Absolute> initialTypes = listeners.keySet();
 170         executor.execute(() -> listener.onSubscriptionChanged(initialTypes));
 171         return subscriptionListeners.register(listener);
 172     }
 173
 174     private ListenableFuture<Void> publish(final long seq, final DOMNotification notification,
 175             final Collection<AbstractListenerRegistration<? extends DOMNotificationListener>> subscribers) {
 176         final DOMNotificationRouterEvent event = disruptor.get(seq);
 177         final ListenableFuture<Void> future = event.initialize(notification, subscribers);
 178         disruptor.getRingBuffer().publish(seq);
 179         return future;
 180     }
 181
 182     @Override
 183     public ListenableFuture<? extends Object> putNotification(final DOMNotification notification)
 184             throws InterruptedException {
 185         final Collection<AbstractListenerRegistration<? extends DOMNotificationListener>> subscribers =
 186                 listeners.get(notification.getType());
 187         if (subscribers.isEmpty()) {
 188             return NO_LISTENERS;
 189         }
 190
 191         final long seq = disruptor.getRingBuffer().next();
 192         return publish(seq, notification, subscribers);
 193     }
 194
 195     @SuppressWarnings("checkstyle:IllegalCatch")
 196     @VisibleForTesting
 197     ListenableFuture<? extends Object> tryPublish(final DOMNotification notification,
 198             final Collection<AbstractListenerRegistration<? extends DOMNotificationListener>> subscribers) {
 199         final long seq;
 200         try {
 201             seq = disruptor.getRingBuffer().tryNext();
 202         } catch (final InsufficientCapacityException e) {
 203             return DOMNotificationPublishService.REJECTED;
 204         }
 205
 206         return publish(seq, notification, subscribers);
 207     }
 208
 209     @Override
 210     public ListenableFuture<? extends Object> offerNotification(final DOMNotification notification) {
 211         final Collection<AbstractListenerRegistration<? extends DOMNotificationListener>> subscribers =
 212                 listeners.get(notification.getType());
 213         if (subscribers.isEmpty()) {
 214             return NO_LISTENERS;
 215         }
 216
 217         return tryPublish(notification, subscribers);
 218     }
 219
 220     @Override
 221     public ListenableFuture<? extends Object> offerNotification(final DOMNotification notification, final long timeout,
 222             final TimeUnit unit) throws InterruptedException {
 223         final Collection<AbstractListenerRegistration<? extends DOMNotificationListener>> subscribers =
 224                 listeners.get(notification.getType());
 225         if (subscribers.isEmpty()) {
 226             return NO_LISTENERS;
 227         }
 228         // Attempt to perform a non-blocking publish first
 229         final ListenableFuture<?> noBlock = tryPublish(notification, subscribers);
 230         if (!DOMNotificationPublishService.REJECTED.equals(noBlock)) {
 231             return noBlock;
 232         }
 233
 234         try {
 235             final Thread publishThread = Thread.currentThread();
 236             ScheduledFuture<?> timerTask = observer.schedule(publishThread::interrupt, timeout, unit);
 237             final ListenableFuture<?> withBlock = putNotification(notification);
 238             timerTask.cancel(true);
 239             if (observer.getQueue().size() > 50) {
 240                 observer.purge();
 241             }
 242             return withBlock;
 243         } catch (InterruptedException e) {
 244             return DOMNotificationPublishService.REJECTED;
 245         }
 246     }
 247
 248     @Override
 249     public void close() {
 250         disruptor.shutdown();
 251         observer.shutdown();
 252         executor.shutdown();
 253     }
 254
 255     @VisibleForTesting
 256     ExecutorService executor() {
 257         return executor;
 258     }
 259
 260     @VisibleForTesting
 261     ExecutorService observer() {
 262         return observer;
 263     }
 264
 265     @VisibleForTesting
 266     Multimap<Absolute, ?> listeners() {
 267         return listeners;
 268     }
 269
 270     @VisibleForTesting
 271     ListenerRegistry<DOMNotificationSubscriptionListener> subscriptionListeners() {
 272         return subscriptionListeners;
 273     }
 274 }