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 com.google.common.annotations.VisibleForTesting;
  11 import com.google.common.base.Preconditions;
  12 import com.google.common.collect.ImmutableList;
  13 import com.google.common.collect.ImmutableMultimap;
  14 import com.google.common.collect.ImmutableMultimap.Builder;
  15 import com.google.common.collect.Multimap;
  16 import com.google.common.collect.Multimaps;
  17 import com.google.common.util.concurrent.Futures;
  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.yang.model.api.SchemaPath;
  45 import org.slf4j.Logger;
  46 import org.slf4j.LoggerFactory;
  47
  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 = Futures.immediateFuture(null);
  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 Disruptor<DOMNotificationRouterEvent> disruptor;
  80     private final ExecutorService executor;
  81     private volatile Multimap<SchemaPath, ListenerRegistration<? extends
  82             DOMNotificationListener>> listeners = ImmutableMultimap.of();
  83     private final ListenerRegistry<DOMNotificationSubscriptionListener> subscriptionListeners =
  84             ListenerRegistry.create();
  85     private final ScheduledThreadPoolExecutor observer;
  86
  87     @SuppressWarnings("unchecked")
  88     @VisibleForTesting
  89     DOMNotificationRouter(final ExecutorService executor, final int queueDepth, final WaitStrategy strategy) {
  90         this.executor = Preconditions.checkNotNull(executor);
  91         this.observer = new ScheduledThreadPoolExecutor(1, new ThreadFactoryBuilder()
  92                 .setDaemon(true).setNameFormat("DOMNotificationRouter-%d").build());
  93         disruptor = new Disruptor<>(DOMNotificationRouterEvent.FACTORY,
  94                 queueDepth, executor, ProducerType.MULTI, strategy);
  95         disruptor.handleEventsWith(DISPATCH_NOTIFICATIONS);
  96         disruptor.after(DISPATCH_NOTIFICATIONS).handleEventsWith(NOTIFY_FUTURE);
  97         disruptor.start();
  98     }
  99
 100     public static DOMNotificationRouter create(final int queueDepth) {
 101         final ExecutorService executor = Executors.newCachedThreadPool();
 102
 103         return new DOMNotificationRouter(executor, queueDepth, DEFAULT_STRATEGY);
 104     }
 105
 106     public static DOMNotificationRouter create(final int queueDepth, final long spinTime,
 107             final long parkTime, final TimeUnit unit) {
 108         Preconditions.checkArgument(Long.lowestOneBit(queueDepth) == Long.highestOneBit(queueDepth),
 109                 "Queue depth %s is not power-of-two", queueDepth);
 110         final ExecutorService executor = Executors.newCachedThreadPool();
 111         final WaitStrategy strategy = PhasedBackoffWaitStrategy.withLock(spinTime, parkTime, unit);
 112
 113         return new DOMNotificationRouter(executor, queueDepth, strategy);
 114     }
 115
 116     @Override
 117     public synchronized <T extends DOMNotificationListener> ListenerRegistration<T> registerNotificationListener(
 118             final T listener, final Collection<SchemaPath> types) {
 119         final ListenerRegistration<T> reg = new AbstractListenerRegistration<T>(listener) {
 120             @Override
 121             protected void removeRegistration() {
 122                 synchronized (DOMNotificationRouter.this) {
 123                     replaceListeners(ImmutableMultimap.copyOf(Multimaps.filterValues(listeners,
 124                         input -> input != this)));
 125                 }
 126             }
 127         };
 128
 129         if (!types.isEmpty()) {
 130             final Builder<SchemaPath, ListenerRegistration<? extends DOMNotificationListener>> b =
 131                     ImmutableMultimap.builder();
 132             b.putAll(listeners);
 133
 134             for (final SchemaPath t : types) {
 135                 b.put(t, reg);
 136             }
 137
 138             replaceListeners(b.build());
 139         }
 140
 141         return reg;
 142     }
 143
 144     @Override
 145     public <T extends DOMNotificationListener> ListenerRegistration<T> registerNotificationListener(
 146             final T listener, final SchemaPath... types) {
 147         return registerNotificationListener(listener, Arrays.asList(types));
 148     }
 149
 150     /**
 151      * Swaps registered listeners and triggers notification update.
 152      *
 153      * @param newListeners is used to notify listenerTypes changed
 154      */
 155     private void replaceListeners(
 156             final Multimap<SchemaPath, ListenerRegistration<? extends DOMNotificationListener>> newListeners) {
 157         listeners = newListeners;
 158         notifyListenerTypesChanged(newListeners.keySet());
 159     }
 160
 161     @SuppressWarnings("checkstyle:IllegalCatch")
 162     private void notifyListenerTypesChanged(final Set<SchemaPath> typesAfter) {
 163         final List<ListenerRegistration<DOMNotificationSubscriptionListener>> listenersAfter =
 164                 ImmutableList.copyOf(subscriptionListeners.getListeners());
 165         executor.submit(() -> {
 166             for (final ListenerRegistration<DOMNotificationSubscriptionListener> subListener : listenersAfter) {
 167                 try {
 168                     subListener.getInstance().onSubscriptionChanged(typesAfter);
 169                 } catch (final Exception e) {
 170                     LOG.warn("Uncaught exception during invoking listener {}", subListener.getInstance(), e);
 171                 }
 172             }
 173         });
 174     }
 175
 176     @Override
 177     public <L extends DOMNotificationSubscriptionListener> ListenerRegistration<L> registerSubscriptionListener(
 178             final L listener) {
 179         final Set<SchemaPath> initialTypes = listeners.keySet();
 180         executor.submit(() -> listener.onSubscriptionChanged(initialTypes));
 181         return subscriptionListeners.registerWithType(listener);
 182     }
 183
 184     private ListenableFuture<Void> publish(final long seq, final DOMNotification notification,
 185             final Collection<ListenerRegistration<? extends DOMNotificationListener>> subscribers) {
 186         final DOMNotificationRouterEvent event = disruptor.get(seq);
 187         final ListenableFuture<Void> future = event.initialize(notification, subscribers);
 188         disruptor.getRingBuffer().publish(seq);
 189         return future;
 190     }
 191
 192     @Override
 193     public ListenableFuture<? extends Object> putNotification(final DOMNotification notification)
 194             throws InterruptedException {
 195         final Collection<ListenerRegistration<? extends DOMNotificationListener>> subscribers =
 196                 listeners.get(notification.getType());
 197         if (subscribers.isEmpty()) {
 198             return NO_LISTENERS;
 199         }
 200
 201         final long seq = disruptor.getRingBuffer().next();
 202         return publish(seq, notification, subscribers);
 203     }
 204
 205     @SuppressWarnings("checkstyle:IllegalCatch")
 206     @VisibleForTesting
 207     ListenableFuture<? extends Object> tryPublish(final DOMNotification notification,
 208             final Collection<ListenerRegistration<? extends DOMNotificationListener>> subscribers) {
 209         final long seq;
 210         try {
 211             seq = disruptor.getRingBuffer().tryNext();
 212         } catch (final InsufficientCapacityException e) {
 213             return DOMNotificationPublishService.REJECTED;
 214         }
 215
 216         return publish(seq, notification, subscribers);
 217     }
 218
 219     @Override
 220     public ListenableFuture<? extends Object> offerNotification(final DOMNotification notification) {
 221         final Collection<ListenerRegistration<? extends DOMNotificationListener>> subscribers =
 222                 listeners.get(notification.getType());
 223         if (subscribers.isEmpty()) {
 224             return NO_LISTENERS;
 225         }
 226
 227         return tryPublish(notification, subscribers);
 228     }
 229
 230     @Override
 231     public ListenableFuture<? extends Object> offerNotification(final DOMNotification notification, final long timeout,
 232             final TimeUnit unit) throws InterruptedException {
 233         final Collection<ListenerRegistration<? extends DOMNotificationListener>> subscribers =
 234                 listeners.get(notification.getType());
 235         if (subscribers.isEmpty()) {
 236             return NO_LISTENERS;
 237         }
 238         // Attempt to perform a non-blocking publish first
 239         final ListenableFuture<?> noBlock = tryPublish(notification, subscribers);
 240         if (!DOMNotificationPublishService.REJECTED.equals(noBlock)) {
 241             return noBlock;
 242         }
 243
 244         try {
 245             final Thread publishThread = Thread.currentThread();
 246             ScheduledFuture<?> timerTask = observer.schedule(publishThread::interrupt, timeout, unit);
 247             final ListenableFuture<?> withBlock = putNotification(notification);
 248             timerTask.cancel(true);
 249             if (observer.getQueue().size() > 50) {
 250                 observer.purge();
 251             }
 252             return withBlock;
 253         } catch (InterruptedException e) {
 254             return DOMNotificationPublishService.REJECTED;
 255         }
 256     }
 257
 258     @Override
 259     public void close() {
 260         observer.shutdown();
 261         disruptor.shutdown();
 262         executor.shutdown();
 263     }
 264
 265     @VisibleForTesting
 266     ExecutorService executor() {
 267         return executor;
 268     }
 269
 270     @VisibleForTesting
 271     Multimap<SchemaPath, ?> listeners() {
 272         return listeners;
 273     }
 274
 275     @VisibleForTesting
 276     ListenerRegistry<DOMNotificationSubscriptionListener> subscriptionListeners() {
 277         return subscriptionListeners;
 278     }
 279
 280 }