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.Arrays;
  27 import java.util.Collection;
  28 import java.util.List;
  29 import java.util.Set;
  30 import java.util.concurrent.ExecutorService;
  31 import java.util.concurrent.Executors;
  32 import java.util.concurrent.ScheduledFuture;
  33 import java.util.concurrent.ScheduledThreadPoolExecutor;
  34 import java.util.concurrent.TimeUnit;
  35 import org.opendaylight.mdsal.dom.api.DOMNotification;
  36 import org.opendaylight.mdsal.dom.api.DOMNotificationListener;
  37 import org.opendaylight.mdsal.dom.api.DOMNotificationPublishService;
  38 import org.opendaylight.mdsal.dom.api.DOMNotificationService;
  39 import org.opendaylight.mdsal.dom.spi.DOMNotificationSubscriptionListener;
  40 import org.opendaylight.mdsal.dom.spi.DOMNotificationSubscriptionListenerRegistry;
  41 import org.opendaylight.yangtools.concepts.AbstractListenerRegistration;
  42 import org.opendaylight.yangtools.concepts.ListenerRegistration;
  43 import org.opendaylight.yangtools.util.ListenerRegistry;
  44 import org.opendaylight.yangtools.util.concurrent.FluentFutures;
  45 import org.opendaylight.yangtools.yang.model.api.SchemaPath;
  46 import org.slf4j.Logger;
  47 import org.slf4j.LoggerFactory;
  48
  49 /**
  50  * Joint implementation of {@link DOMNotificationPublishService} and {@link DOMNotificationService}. Provides
  51  * routing of notifications from publishers to subscribers.
  52  *
  53  *<p>
  54  * Internal implementation works by allocating a two-handler Disruptor. The first handler delivers notifications
  55  * to subscribed listeners and the second one notifies whoever may be listening on the returned future. Registration
  56  * state tracking is performed by a simple immutable multimap -- when a registration or unregistration occurs we
  57  * re-generate the entire map from scratch and set it atomically. While registrations/unregistrations synchronize
  58  * on this instance, notifications do not take any locks here.
  59  *
  60  *<p>
  61  * The fully-blocking {@link #publish(long, DOMNotification, Collection)}
  62  * and non-blocking {@link #offerNotification(DOMNotification)}
  63  * are realized using the Disruptor's native operations. The bounded-blocking {@link
  64  * #offerNotification(DOMNotification, long, TimeUnit)}
  65  * is realized by arming a background wakeup interrupt.
  66  */
  67 public class DOMNotificationRouter implements AutoCloseable, DOMNotificationPublishService,
  68         DOMNotificationService, DOMNotificationSubscriptionListenerRegistry {
  69
  70     private static final Logger LOG = LoggerFactory.getLogger(DOMNotificationRouter.class);
  71     private static final ListenableFuture<Void> NO_LISTENERS = FluentFutures.immediateNullFluentFuture();
  72     private static final WaitStrategy DEFAULT_STRATEGY = PhasedBackoffWaitStrategy.withLock(
  73             1L, 30L, TimeUnit.MILLISECONDS);
  74     private static final EventHandler<DOMNotificationRouterEvent> DISPATCH_NOTIFICATIONS =
  75         (event, sequence, endOfBatch) -> event.deliverNotification();
  76     private static final EventHandler<DOMNotificationRouterEvent> NOTIFY_FUTURE =
  77         (event, sequence, endOfBatch) -> event.setFuture();
  78
  79     private final ListenerRegistry<DOMNotificationSubscriptionListener> subscriptionListeners =
  80             ListenerRegistry.create();
  81     private final Disruptor<DOMNotificationRouterEvent> disruptor;
  82     private final ScheduledThreadPoolExecutor observer;
  83     private final ExecutorService executor;
  84
  85     private volatile Multimap<SchemaPath, ListenerRegistration<? extends DOMNotificationListener>> listeners =
  86             ImmutableMultimap.of();
  87
  88     @VisibleForTesting
  89     DOMNotificationRouter(final int queueDepth, final WaitStrategy strategy) {
  90         observer = new ScheduledThreadPoolExecutor(1,
  91             new ThreadFactoryBuilder().setDaemon(true).setNameFormat("DOMNotificationRouter-observer-%d").build());
  92         executor = Executors.newCachedThreadPool(
  93             new ThreadFactoryBuilder().setDaemon(true).setNameFormat("DOMNotificationRouter-listeners-%d").build());
  94         disruptor = new Disruptor<>(DOMNotificationRouterEvent.FACTORY, queueDepth,
  95                 new ThreadFactoryBuilder().setNameFormat("DOMNotificationRouter-disruptor-%d").build(),
  96                 ProducerType.MULTI, strategy);
  97         disruptor.handleEventsWith(DISPATCH_NOTIFICATIONS);
  98         disruptor.after(DISPATCH_NOTIFICATIONS).handleEventsWith(NOTIFY_FUTURE);
  99         disruptor.start();
 100     }
 101
 102     public static DOMNotificationRouter create(final int queueDepth) {
 103         return new DOMNotificationRouter(queueDepth, DEFAULT_STRATEGY);
 104     }
 105
 106     public static DOMNotificationRouter create(final int queueDepth, final long spinTime, final long parkTime,
 107             final TimeUnit unit) {
 108         checkArgument(Long.lowestOneBit(queueDepth) == Long.highestOneBit(queueDepth),
 109                 "Queue depth %s is not power-of-two", queueDepth);
 110         return new DOMNotificationRouter(queueDepth, PhasedBackoffWaitStrategy.withLock(spinTime, parkTime, unit));
 111     }
 112
 113     @Override
 114     public synchronized <T extends DOMNotificationListener> ListenerRegistration<T> registerNotificationListener(
 115             final T listener, final Collection<SchemaPath> types) {
 116         final ListenerRegistration<T> reg = new AbstractListenerRegistration<T>(listener) {
 117             @Override
 118             protected void removeRegistration() {
 119                 synchronized (DOMNotificationRouter.this) {
 120                     replaceListeners(ImmutableMultimap.copyOf(Multimaps.filterValues(listeners,
 121                         input -> input != this)));
 122                 }
 123             }
 124         };
 125
 126         if (!types.isEmpty()) {
 127             final Builder<SchemaPath, ListenerRegistration<? extends DOMNotificationListener>> b =
 128                     ImmutableMultimap.builder();
 129             b.putAll(listeners);
 130
 131             for (final SchemaPath t : types) {
 132                 b.put(t, reg);
 133             }
 134
 135             replaceListeners(b.build());
 136         }
 137
 138         return reg;
 139     }
 140
 141     @Override
 142     public <T extends DOMNotificationListener> ListenerRegistration<T> registerNotificationListener(
 143             final T listener, final SchemaPath... types) {
 144         return registerNotificationListener(listener, Arrays.asList(types));
 145     }
 146
 147     /**
 148      * Swaps registered listeners and triggers notification update.
 149      *
 150      * @param newListeners is used to notify listenerTypes changed
 151      */
 152     private void replaceListeners(
 153             final Multimap<SchemaPath, ListenerRegistration<? extends DOMNotificationListener>> newListeners) {
 154         listeners = newListeners;
 155         notifyListenerTypesChanged(newListeners.keySet());
 156     }
 157
 158     @SuppressWarnings("checkstyle:IllegalCatch")
 159     private void notifyListenerTypesChanged(final Set<SchemaPath> typesAfter) {
 160         final List<? extends DOMNotificationSubscriptionListener> listenersAfter =
 161                 subscriptionListeners.getRegistrations().stream().map(ListenerRegistration::getInstance)
 162                 .collect(ImmutableList.toImmutableList());
 163         executor.execute(() -> {
 164             for (final DOMNotificationSubscriptionListener subListener : listenersAfter) {
 165                 try {
 166                     subListener.onSubscriptionChanged(typesAfter);
 167                 } catch (final Exception e) {
 168                     LOG.warn("Uncaught exception during invoking listener {}", subListener, e);
 169                 }
 170             }
 171         });
 172     }
 173
 174     @Override
 175     public <L extends DOMNotificationSubscriptionListener> ListenerRegistration<L> registerSubscriptionListener(
 176             final L listener) {
 177         final Set<SchemaPath> initialTypes = listeners.keySet();
 178         executor.execute(() -> listener.onSubscriptionChanged(initialTypes));
 179         return subscriptionListeners.register(listener);
 180     }
 181
 182     private ListenableFuture<Void> publish(final long seq, final DOMNotification notification,
 183             final Collection<ListenerRegistration<? extends DOMNotificationListener>> subscribers) {
 184         final DOMNotificationRouterEvent event = disruptor.get(seq);
 185         final ListenableFuture<Void> future = event.initialize(notification, subscribers);
 186         disruptor.getRingBuffer().publish(seq);
 187         return future;
 188     }
 189
 190     @Override
 191     public ListenableFuture<? extends Object> putNotification(final DOMNotification notification)
 192             throws InterruptedException {
 193         final Collection<ListenerRegistration<? extends DOMNotificationListener>> subscribers =
 194                 listeners.get(notification.getType());
 195         if (subscribers.isEmpty()) {
 196             return NO_LISTENERS;
 197         }
 198
 199         final long seq = disruptor.getRingBuffer().next();
 200         return publish(seq, notification, subscribers);
 201     }
 202
 203     @SuppressWarnings("checkstyle:IllegalCatch")
 204     @VisibleForTesting
 205     ListenableFuture<? extends Object> tryPublish(final DOMNotification notification,
 206             final Collection<ListenerRegistration<? extends DOMNotificationListener>> subscribers) {
 207         final long seq;
 208         try {
 209             seq = disruptor.getRingBuffer().tryNext();
 210         } catch (final InsufficientCapacityException e) {
 211             return DOMNotificationPublishService.REJECTED;
 212         }
 213
 214         return publish(seq, notification, subscribers);
 215     }
 216
 217     @Override
 218     public ListenableFuture<? extends Object> offerNotification(final DOMNotification notification) {
 219         final Collection<ListenerRegistration<? extends DOMNotificationListener>> subscribers =
 220                 listeners.get(notification.getType());
 221         if (subscribers.isEmpty()) {
 222             return NO_LISTENERS;
 223         }
 224
 225         return tryPublish(notification, subscribers);
 226     }
 227
 228     @Override
 229     public ListenableFuture<? extends Object> offerNotification(final DOMNotification notification, final long timeout,
 230             final TimeUnit unit) throws InterruptedException {
 231         final Collection<ListenerRegistration<? extends DOMNotificationListener>> subscribers =
 232                 listeners.get(notification.getType());
 233         if (subscribers.isEmpty()) {
 234             return NO_LISTENERS;
 235         }
 236         // Attempt to perform a non-blocking publish first
 237         final ListenableFuture<?> noBlock = tryPublish(notification, subscribers);
 238         if (!DOMNotificationPublishService.REJECTED.equals(noBlock)) {
 239             return noBlock;
 240         }
 241
 242         try {
 243             final Thread publishThread = Thread.currentThread();
 244             ScheduledFuture<?> timerTask = observer.schedule(publishThread::interrupt, timeout, unit);
 245             final ListenableFuture<?> withBlock = putNotification(notification);
 246             timerTask.cancel(true);
 247             if (observer.getQueue().size() > 50) {
 248                 observer.purge();
 249             }
 250             return withBlock;
 251         } catch (InterruptedException e) {
 252             return DOMNotificationPublishService.REJECTED;
 253         }
 254     }
 255
 256     @Override
 257     public void close() {
 258         disruptor.shutdown();
 259         observer.shutdown();
 260         executor.shutdown();
 261     }
 262
 263     @VisibleForTesting
 264     ExecutorService executor() {
 265         return executor;
 266     }
 267
 268     @VisibleForTesting
 269     ExecutorService observer() {
 270         return observer;
 271     }
 272
 273     @VisibleForTesting
 274     Multimap<SchemaPath, ?> listeners() {
 275         return listeners;
 276     }
 277
 278     @VisibleForTesting
 279     ListenerRegistry<DOMNotificationSubscriptionListener> subscriptionListeners() {
 280         return subscriptionListeners;
 281     }
 282 }