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