opendaylight/md-sal/sal-dom-broker/src/main/java/org/opendaylight/controller/md/sal/dom/broker/impl/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.controller.md.sal.dom.broker.impl;
   9
  10 import com.google.common.base.Preconditions;
  11 import com.google.common.collect.ImmutableList;
  12 import com.google.common.collect.ImmutableMultimap;
  13 import com.google.common.collect.ImmutableMultimap.Builder;
  14 import com.google.common.collect.Multimap;
  15 import com.google.common.collect.Multimaps;
  16 import com.google.common.util.concurrent.Futures;
  17 import com.google.common.util.concurrent.ListenableFuture;
  18 import com.lmax.disruptor.EventHandler;
  19 import com.lmax.disruptor.InsufficientCapacityException;
  20 import com.lmax.disruptor.PhasedBackoffWaitStrategy;
  21 import com.lmax.disruptor.WaitStrategy;
  22 import com.lmax.disruptor.dsl.Disruptor;
  23 import com.lmax.disruptor.dsl.ProducerType;
  24 import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
  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.controller.md.sal.dom.api.DOMNotification;
  33 import org.opendaylight.controller.md.sal.dom.api.DOMNotificationListener;
  34 import org.opendaylight.controller.md.sal.dom.api.DOMNotificationPublishService;
  35 import org.opendaylight.controller.md.sal.dom.api.DOMNotificationService;
  36 import org.opendaylight.controller.md.sal.dom.spi.DOMNotificationSubscriptionListener;
  37 import org.opendaylight.controller.md.sal.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)} and non-blocking
  58  * {@link #offerNotification(DOMNotification)}
  59  * are realized using the Disruptor's native operations. The bounded-blocking
  60  * {@link #offerNotification(DOMNotification, long, TimeUnit)}
  61  * is realized by arming a background wakeup interrupt.
  62  */
  63 @SuppressFBWarnings(value = "NP_NONNULL_PARAM_VIOLATION", justification = "Void is the only allowed value")
  64 public final class DOMNotificationRouter implements AutoCloseable, DOMNotificationPublishService,
  65         DOMNotificationService, DOMNotificationSubscriptionListenerRegistry {
  66
  67     private static final Logger LOG = LoggerFactory.getLogger(DOMNotificationRouter.class);
  68     private static final ListenableFuture<Void> NO_LISTENERS = Futures.immediateFuture(null);
  69     private static final WaitStrategy DEFAULT_STRATEGY = PhasedBackoffWaitStrategy
  70             .withLock(1L, 30L, TimeUnit.MILLISECONDS);
  71     private static final EventHandler<DOMNotificationRouterEvent> DISPATCH_NOTIFICATIONS
  72             = (event, sequence, endOfBatch) -> event.deliverNotification();
  73     private static final EventHandler<DOMNotificationRouterEvent> NOTIFY_FUTURE = (event, sequence, endOfBatch) -> event
  74             .setFuture();
  75
  76     private final Disruptor<DOMNotificationRouterEvent> disruptor;
  77     private final ExecutorService executor;
  78     private volatile Multimap<SchemaPath, ListenerRegistration<? extends DOMNotificationListener>> listeners
  79             = ImmutableMultimap.of();
  80     private final ListenerRegistry<DOMNotificationSubscriptionListener> subscriptionListeners = ListenerRegistry
  81             .create();
  82
  83     @SuppressWarnings("unchecked")
  84     private DOMNotificationRouter(final ExecutorService executor, final int queueDepth, final WaitStrategy strategy) {
  85         this.executor = Preconditions.checkNotNull(executor);
  86
  87         disruptor = new Disruptor<>(DOMNotificationRouterEvent.FACTORY, queueDepth, executor, ProducerType.MULTI,
  88                                     strategy);
  89         disruptor.handleEventsWith(DISPATCH_NOTIFICATIONS);
  90         disruptor.after(DISPATCH_NOTIFICATIONS).handleEventsWith(NOTIFY_FUTURE);
  91         disruptor.start();
  92     }
  93
  94     public static DOMNotificationRouter create(final int queueDepth) {
  95         final ExecutorService executor = Executors.newCachedThreadPool();
  96
  97         return new DOMNotificationRouter(executor, queueDepth, DEFAULT_STRATEGY);
  98     }
  99
 100     public static DOMNotificationRouter create(final int queueDepth, final long spinTime, final long parkTime,
 101                                                final TimeUnit unit) {
 102         Preconditions.checkArgument(Long.lowestOneBit(queueDepth) == Long.highestOneBit(queueDepth),
 103                                     "Queue depth %s is not power-of-two", queueDepth);
 104         final ExecutorService executor = Executors.newCachedThreadPool();
 105         final WaitStrategy strategy = PhasedBackoffWaitStrategy.withLock(spinTime, parkTime, unit);
 106
 107         return new DOMNotificationRouter(executor, queueDepth, strategy);
 108     }
 109
 110     @Override
 111     public synchronized <T extends DOMNotificationListener> ListenerRegistration<T> registerNotificationListener(
 112             final T listener, final Collection<SchemaPath> types) {
 113         final ListenerRegistration<T> reg = new AbstractListenerRegistration<T>(listener) {
 114             @Override
 115             protected void removeRegistration() {
 116                 final ListenerRegistration<T> me = this;
 117
 118                 synchronized (DOMNotificationRouter.this) {
 119                     replaceListeners(ImmutableMultimap.copyOf(Multimaps.filterValues(listeners, input -> input != me)));
 120                 }
 121             }
 122         };
 123
 124         if (!types.isEmpty()) {
 125             final Builder<SchemaPath, ListenerRegistration<? extends DOMNotificationListener>> b = ImmutableMultimap
 126                     .builder();
 127             b.putAll(listeners);
 128
 129             for (final SchemaPath t : types) {
 130                 b.put(t, reg);
 131             }
 132
 133             replaceListeners(b.build());
 134         }
 135
 136         return reg;
 137     }
 138
 139     @Override
 140     public <T extends DOMNotificationListener> ListenerRegistration<T> registerNotificationListener(final T listener,
 141                                                                                                     final
 142                                                                                                     SchemaPath...
 143                                                                                                             types) {
 144         return registerNotificationListener(listener, Arrays.asList(types));
 145     }
 146
 147     /**
 148      * Swaps registered listeners and triggers notification update.
 149      *
 150      * @param newListeners listeners
 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<ListenerRegistration<DOMNotificationSubscriptionListener>> listenersAfter = ImmutableList
 161                 .copyOf(subscriptionListeners.getListeners());
 162         executor.execute(() -> {
 163             for (final ListenerRegistration<DOMNotificationSubscriptionListener> subListener : listenersAfter) {
 164                 try {
 165                     subListener.getInstance().onSubscriptionChanged(typesAfter);
 166                 } catch (final Exception e) {
 167                     LOG.warn("Uncaught exception during invoking listener {}", subListener.getInstance(), e);
 168                 }
 169             }
 170         });
 171     }
 172
 173     @Override
 174     public <L extends DOMNotificationSubscriptionListener> ListenerRegistration<L> registerSubscriptionListener(
 175             final L listener) {
 176         final Set<SchemaPath> initialTypes = listeners.keySet();
 177         executor.execute(() -> listener.onSubscriptionChanged(initialTypes));
 178         return subscriptionListeners.registerWithType(listener);
 179     }
 180
 181     private ListenableFuture<Void> publish(final long seq, final DOMNotification notification,
 182                                            final Collection<ListenerRegistration<? extends DOMNotificationListener>>
 183                                                    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<?> putNotification(final DOMNotification notification) throws InterruptedException {
 192         final Collection<ListenerRegistration<? extends DOMNotificationListener>> subscribers = listeners
 193                 .get(notification.getType());
 194         if (subscribers.isEmpty()) {
 195             return NO_LISTENERS;
 196         }
 197
 198         final long seq = disruptor.getRingBuffer().next();
 199         return publish(seq, notification, subscribers);
 200     }
 201
 202     private ListenableFuture<?> tryPublish(final DOMNotification notification,
 203                                            final Collection<ListenerRegistration<? extends DOMNotificationListener>>
 204                                                    subscribers) {
 205         final long seq;
 206         try {
 207             seq = disruptor.getRingBuffer().tryNext();
 208         } catch (final InsufficientCapacityException e) {
 209             return DOMNotificationPublishService.REJECTED;
 210         }
 211
 212         return publish(seq, notification, subscribers);
 213     }
 214
 215     @Override
 216     public ListenableFuture<?> offerNotification(final DOMNotification notification) {
 217         final Collection<ListenerRegistration<? extends DOMNotificationListener>> subscribers = listeners
 218                 .get(notification.getType());
 219         if (subscribers.isEmpty()) {
 220             return NO_LISTENERS;
 221         }
 222
 223         return tryPublish(notification, subscribers);
 224     }
 225
 226     @Override
 227     public ListenableFuture<?> offerNotification(final DOMNotification notification, final long timeout,
 228                                                  final TimeUnit unit) throws InterruptedException {
 229         final Collection<ListenerRegistration<? extends DOMNotificationListener>> subscribers = listeners
 230                 .get(notification.getType());
 231         if (subscribers.isEmpty()) {
 232             return NO_LISTENERS;
 233         }
 234
 235         // Attempt to perform a non-blocking publish first
 236         final ListenableFuture<?> noBlock = tryPublish(notification, subscribers);
 237         if (!DOMNotificationPublishService.REJECTED.equals(noBlock)) {
 238             return noBlock;
 239         }
 240
 241         /*
 242          * FIXME: we need a background thread, which will watch out for blocking too long. Here
 243          *        we will arm a tasklet for it and synchronize delivery of interrupt properly.
 244          */
 245         throw new UnsupportedOperationException("Not implemented yet");
 246     }
 247
 248     @Override
 249     public void close() {
 250         disruptor.shutdown();
 251         executor.shutdown();
 252     }
 253 }