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.lmax.disruptor.EventHandler;
  20 import com.lmax.disruptor.InsufficientCapacityException;
  21 import com.lmax.disruptor.PhasedBackoffWaitStrategy;
  22 import com.lmax.disruptor.WaitStrategy;
  23 import com.lmax.disruptor.dsl.Disruptor;
  24 import com.lmax.disruptor.dsl.ProducerType;
  25 import java.util.Arrays;
  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.TimeUnit;
  32 import org.opendaylight.mdsal.dom.api.DOMNotification;
  33 import org.opendaylight.mdsal.dom.api.DOMNotificationListener;
  34 import org.opendaylight.mdsal.dom.api.DOMNotificationPublishService;
  35 import org.opendaylight.mdsal.dom.api.DOMNotificationService;
  36 import org.opendaylight.mdsal.dom.spi.DOMNotificationSubscriptionListener;
  37 import org.opendaylight.mdsal.dom.spi.DOMNotificationSubscriptionListenerRegistry;
  38 import org.opendaylight.yangtools.concepts.AbstractListenerRegistration;
  39 import org.opendaylight.yangtools.concepts.ListenerRegistration;
  40 import org.opendaylight.yangtools.util.ListenerRegistry;
  41 import org.opendaylight.yangtools.yang.model.api.SchemaPath;
  42 import org.slf4j.Logger;
  43 import org.slf4j.LoggerFactory;
  44
  45 /**
  46  * Joint implementation of {@link DOMNotificationPublishService} and {@link DOMNotificationService}. Provides
  47  * routing of notifications from publishers to subscribers.
  48  *
  49  *<p>
  50  * Internal implementation works by allocating a two-handler Disruptor. The first handler delivers notifications
  51  * to subscribed listeners and the second one notifies whoever may be listening on the returned future. Registration
  52  * state tracking is performed by a simple immutable multimap -- when a registration or unregistration occurs we
  53  * re-generate the entire map from scratch and set it atomically. While registrations/unregistrations synchronize
  54  * on this instance, notifications do not take any locks here.
  55  *
  56  *<p>
  57  * The fully-blocking {@link #publish(long, DOMNotification, Collection)}
  58  * and non-blocking {@link #offerNotification(DOMNotification)}
  59  * are realized using the Disruptor's native operations. The bounded-blocking {@link
  60  * #offerNotification(DOMNotification, long, TimeUnit)}
  61  * is realized by arming a background wakeup interrupt.
  62  */
  63 public final class DOMNotificationRouter implements AutoCloseable, DOMNotificationPublishService,
  64         DOMNotificationService, DOMNotificationSubscriptionListenerRegistry {
  65
  66     private static final Logger LOG = LoggerFactory.getLogger(DOMNotificationRouter.class);
  67     private static final ListenableFuture<Void> NO_LISTENERS = Futures.immediateFuture(null);
  68     private static final WaitStrategy DEFAULT_STRATEGY = PhasedBackoffWaitStrategy.withLock(
  69             1L, 30L, TimeUnit.MILLISECONDS);
  70     private static final EventHandler<DOMNotificationRouterEvent> DISPATCH_NOTIFICATIONS =
  71         (event, sequence, endOfBatch) -> event.deliverNotification();
  72     private static final EventHandler<DOMNotificationRouterEvent> NOTIFY_FUTURE =
  73         (event, sequence, endOfBatch) -> event.setFuture();
  74
  75     private final Disruptor<DOMNotificationRouterEvent> disruptor;
  76     private final ExecutorService executor;
  77     private volatile Multimap<SchemaPath, ListenerRegistration<? extends
  78             DOMNotificationListener>> listeners = ImmutableMultimap.of();
  79     private final ListenerRegistry<DOMNotificationSubscriptionListener> subscriptionListeners =
  80             ListenerRegistry.create();
  81
  82     @SuppressWarnings("unchecked")
  83     private DOMNotificationRouter(final ExecutorService executor, final int queueDepth, final WaitStrategy strategy) {
  84         this.executor = Preconditions.checkNotNull(executor);
  85
  86         disruptor = new Disruptor<>(DOMNotificationRouterEvent.FACTORY,
  87                 queueDepth, executor, ProducerType.MULTI, strategy);
  88         disruptor.handleEventsWith(DISPATCH_NOTIFICATIONS);
  89         disruptor.after(DISPATCH_NOTIFICATIONS).handleEventsWith(NOTIFY_FUTURE);
  90         disruptor.start();
  91     }
  92
  93     public static DOMNotificationRouter create(final int queueDepth) {
  94         final ExecutorService executor = Executors.newCachedThreadPool();
  95
  96         return new DOMNotificationRouter(executor, queueDepth, DEFAULT_STRATEGY);
  97     }
  98
  99     public static DOMNotificationRouter create(final int queueDepth, final long spinTime,
 100             final long parkTime, final TimeUnit unit) {
 101         final ExecutorService executor = Executors.newCachedThreadPool();
 102         final WaitStrategy strategy = PhasedBackoffWaitStrategy.withLock(spinTime, parkTime, unit);
 103
 104         return new DOMNotificationRouter(executor, queueDepth, strategy);
 105     }
 106
 107     @Override
 108     public synchronized <T extends DOMNotificationListener> ListenerRegistration<T> registerNotificationListener(
 109             final T listener, final Collection<SchemaPath> types) {
 110         final ListenerRegistration<T> reg = new AbstractListenerRegistration<T>(listener) {
 111             @Override
 112             protected void removeRegistration() {
 113                 synchronized (DOMNotificationRouter.this) {
 114                     replaceListeners(ImmutableMultimap.copyOf(Multimaps.filterValues(listeners,
 115                         input -> input != this)));
 116                 }
 117             }
 118         };
 119
 120         if (!types.isEmpty()) {
 121             final Builder<SchemaPath, ListenerRegistration<? extends DOMNotificationListener>> b =
 122                     ImmutableMultimap.builder();
 123             b.putAll(listeners);
 124
 125             for (final SchemaPath t : types) {
 126                 b.put(t, reg);
 127             }
 128
 129             replaceListeners(b.build());
 130         }
 131
 132         return reg;
 133     }
 134
 135     @Override
 136     public <T extends DOMNotificationListener> ListenerRegistration<T> registerNotificationListener(
 137             final T listener, final SchemaPath... types) {
 138         return registerNotificationListener(listener, Arrays.asList(types));
 139     }
 140
 141     /**
 142      * Swaps registered listeners and triggers notification update.
 143      *
 144      * @param newListeners is used to notify listenerTypes changed
 145      */
 146     private void replaceListeners(
 147             final Multimap<SchemaPath, ListenerRegistration<? extends DOMNotificationListener>> newListeners) {
 148         listeners = newListeners;
 149         notifyListenerTypesChanged(newListeners.keySet());
 150     }
 151
 152     @SuppressWarnings("checkstyle:IllegalCatch")
 153     private void notifyListenerTypesChanged(final Set<SchemaPath> typesAfter) {
 154         final List<ListenerRegistration<DOMNotificationSubscriptionListener>> listenersAfter =
 155                 ImmutableList.copyOf(subscriptionListeners.getListeners());
 156         executor.submit(() -> {
 157             for (final ListenerRegistration<DOMNotificationSubscriptionListener> subListener : listenersAfter) {
 158                 try {
 159                     subListener.getInstance().onSubscriptionChanged(typesAfter);
 160                 } catch (final Exception e) {
 161                     LOG.warn("Uncaught exception during invoking listener {}", subListener.getInstance(), e);
 162                 }
 163             }
 164         });
 165     }
 166
 167     @Override
 168     public <L extends DOMNotificationSubscriptionListener> ListenerRegistration<L> registerSubscriptionListener(
 169             final L listener) {
 170         final Set<SchemaPath> initialTypes = listeners.keySet();
 171         executor.submit(() -> listener.onSubscriptionChanged(initialTypes));
 172         return subscriptionListeners.registerWithType(listener);
 173     }
 174
 175     private ListenableFuture<Void> publish(final long seq, final DOMNotification notification,
 176             final Collection<ListenerRegistration<? extends DOMNotificationListener>> subscribers) {
 177         final DOMNotificationRouterEvent event = disruptor.get(seq);
 178         final ListenableFuture<Void> future = event.initialize(notification, subscribers);
 179         disruptor.getRingBuffer().publish(seq);
 180         return future;
 181     }
 182
 183     @Override
 184     public ListenableFuture<? extends Object> putNotification(final DOMNotification notification)
 185             throws InterruptedException {
 186         final Collection<ListenerRegistration<? extends DOMNotificationListener>> subscribers =
 187                 listeners.get(notification.getType());
 188         if (subscribers.isEmpty()) {
 189             return NO_LISTENERS;
 190         }
 191
 192         final long seq = disruptor.getRingBuffer().next();
 193         return publish(seq, notification, subscribers);
 194     }
 195
 196     @SuppressWarnings("checkstyle:IllegalCatch")
 197     private ListenableFuture<? extends Object> tryPublish(final DOMNotification notification,
 198             final Collection<ListenerRegistration<? 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<ListenerRegistration<? 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<ListenerRegistration<? extends DOMNotificationListener>> subscribers =
 224                 listeners.get(notification.getType());
 225         if (subscribers.isEmpty()) {
 226             return NO_LISTENERS;
 227         }
 228
 229         // Attempt to perform a non-blocking publish first
 230         final ListenableFuture<? extends Object> noBlock = tryPublish(notification, subscribers);
 231         if (!DOMNotificationPublishService.REJECTED.equals(noBlock)) {
 232             return noBlock;
 233         }
 234
 235         /*
 236          * FIXME: we need a background thread, which will watch out for blocking too long. Here
 237          *        we will arm a tasklet for it and synchronize delivery of interrupt properly.
 238          */
 239         throw new UnsupportedOperationException("Not implemented yet");
 240     }
 241
 242     @Override
 243     public void close() {
 244         disruptor.shutdown();
 245         executor.shutdown();
 246     }
 247
 248     @VisibleForTesting
 249     ExecutorService executor() {
 250         return executor;
 251     }
 252
 253     @VisibleForTesting
 254     Multimap<SchemaPath, ?> listeners() {
 255         return listeners;
 256     }
 257
 258     @VisibleForTesting
 259     ListenerRegistry<DOMNotificationSubscriptionListener> subscriptionListeners() {
 260         return subscriptionListeners;
 261     }
 262
 263 }