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.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.mdsal.dom.api.DOMNotification;
  32 import org.opendaylight.mdsal.dom.api.DOMNotificationListener;
  33 import org.opendaylight.mdsal.dom.api.DOMNotificationPublishService;
  34 import org.opendaylight.mdsal.dom.api.DOMNotificationService;
  35 import org.opendaylight.mdsal.dom.spi.DOMNotificationSubscriptionListener;
  36 import org.opendaylight.mdsal.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)}
  57  * and non-blocking {@link #offerNotification(DOMNotification)}
  58  * are realized using the Disruptor's native operations. The bounded-blocking {@link
  59  * #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.withLock(
  68             1L, 30L, TimeUnit.MILLISECONDS);
  69     private static final EventHandler<DOMNotificationRouterEvent> DISPATCH_NOTIFICATIONS =
  70             new EventHandler<DOMNotificationRouterEvent>() {
  71         @Override
  72         public void onEvent(final DOMNotificationRouterEvent event, final long sequence,
  73                 final boolean endOfBatch) throws Exception {
  74             event.deliverNotification();
  75
  76         }
  77     };
  78     private static final EventHandler<DOMNotificationRouterEvent> NOTIFY_FUTURE =
  79             new EventHandler<DOMNotificationRouterEvent>() {
  80         @Override
  81         public void onEvent(final DOMNotificationRouterEvent event, final long sequence, final boolean endOfBatch) {
  82             event.setFuture();
  83         }
  84     };
  85
  86     private final Disruptor<DOMNotificationRouterEvent> disruptor;
  87     private final ExecutorService executor;
  88     private volatile Multimap<SchemaPath, ListenerRegistration<? extends
  89             DOMNotificationListener>> listeners = ImmutableMultimap.of();
  90     private final ListenerRegistry<DOMNotificationSubscriptionListener> subscriptionListeners =
  91             ListenerRegistry.create();
  92
  93     @SuppressWarnings("unchecked")
  94     private DOMNotificationRouter(final ExecutorService executor, final int queueDepth, final WaitStrategy strategy) {
  95         this.executor = Preconditions.checkNotNull(executor);
  96
  97         disruptor = new Disruptor<>(DOMNotificationRouterEvent.FACTORY,
  98                 queueDepth, executor, ProducerType.MULTI, strategy);
  99         disruptor.handleEventsWith(DISPATCH_NOTIFICATIONS);
 100         disruptor.after(DISPATCH_NOTIFICATIONS).handleEventsWith(NOTIFY_FUTURE);
 101         disruptor.start();
 102     }
 103
 104     public static DOMNotificationRouter create(final int queueDepth) {
 105         final ExecutorService executor = Executors.newCachedThreadPool();
 106
 107         return new DOMNotificationRouter(executor, queueDepth, DEFAULT_STRATEGY);
 108     }
 109
 110     public static DOMNotificationRouter create(final int queueDepth, final long spinTime,
 111             final long parkTime, final TimeUnit unit) {
 112         final ExecutorService executor = Executors.newCachedThreadPool();
 113         final WaitStrategy strategy = PhasedBackoffWaitStrategy.withLock(spinTime, parkTime, unit);
 114
 115         return new DOMNotificationRouter(executor, queueDepth, strategy);
 116     }
 117
 118     @Override
 119     public synchronized <T extends DOMNotificationListener> ListenerRegistration<T> registerNotificationListener(
 120             final T listener, final Collection<SchemaPath> types) {
 121         final ListenerRegistration<T> reg = new AbstractListenerRegistration<T>(listener) {
 122             @Override
 123             protected void removeRegistration() {
 124                 synchronized (DOMNotificationRouter.this) {
 125                     replaceListeners(ImmutableMultimap.copyOf(Multimaps.filterValues(listeners,
 126                         input -> input != this)));
 127                 }
 128             }
 129         };
 130
 131         if (!types.isEmpty()) {
 132             final Builder<SchemaPath, ListenerRegistration<? extends DOMNotificationListener>> b =
 133                     ImmutableMultimap.builder();
 134             b.putAll(listeners);
 135
 136             for (final SchemaPath t : types) {
 137                 b.put(t, reg);
 138             }
 139
 140             replaceListeners(b.build());
 141         }
 142
 143         return reg;
 144     }
 145
 146     @Override
 147     public <T extends DOMNotificationListener> ListenerRegistration<T> registerNotificationListener(
 148             final T listener, final SchemaPath... types) {
 149         return registerNotificationListener(listener, Arrays.asList(types));
 150     }
 151
 152     /**
 153      * Swaps registered listeners and triggers notification update.
 154      *
 155      * @param newListeners is used to notify listenerTypes changed
 156      */
 157     private void replaceListeners(
 158             final Multimap<SchemaPath, ListenerRegistration<? extends DOMNotificationListener>> newListeners) {
 159         listeners = newListeners;
 160         notifyListenerTypesChanged(newListeners.keySet());
 161     }
 162
 163     @SuppressWarnings("checkstyle:IllegalCatch")
 164     private void notifyListenerTypesChanged(final Set<SchemaPath> typesAfter) {
 165         final List<ListenerRegistration<DOMNotificationSubscriptionListener>> listenersAfter =
 166                 ImmutableList.copyOf(subscriptionListeners.getListeners());
 167         executor.submit(() -> {
 168             for (final ListenerRegistration<DOMNotificationSubscriptionListener> subListener : listenersAfter) {
 169                 try {
 170                     subListener.getInstance().onSubscriptionChanged(typesAfter);
 171                 } catch (final Exception e) {
 172                     LOG.warn("Uncaught exception during invoking listener {}", subListener.getInstance(), e);
 173                 }
 174             }
 175         });
 176     }
 177
 178     @Override
 179     public <L extends DOMNotificationSubscriptionListener> ListenerRegistration<L> registerSubscriptionListener(
 180             final L listener) {
 181         final Set<SchemaPath> initialTypes = listeners.keySet();
 182         executor.submit(() -> listener.onSubscriptionChanged(initialTypes));
 183         return subscriptionListeners.registerWithType(listener);
 184     }
 185
 186     private ListenableFuture<Void> publish(final long seq, final DOMNotification notification,
 187             final Collection<ListenerRegistration<? extends DOMNotificationListener>> subscribers) {
 188         final DOMNotificationRouterEvent event = disruptor.get(seq);
 189         final ListenableFuture<Void> future = event.initialize(notification, subscribers);
 190         disruptor.getRingBuffer().publish(seq);
 191         return future;
 192     }
 193
 194     @Override
 195     public ListenableFuture<? extends Object> putNotification(final DOMNotification notification)
 196             throws InterruptedException {
 197         final Collection<ListenerRegistration<? extends DOMNotificationListener>> subscribers =
 198                 listeners.get(notification.getType());
 199         if (subscribers.isEmpty()) {
 200             return NO_LISTENERS;
 201         }
 202
 203         final long seq = disruptor.getRingBuffer().next();
 204         return publish(seq, notification, subscribers);
 205     }
 206
 207     @SuppressWarnings("checkstyle:IllegalCatch")
 208     private ListenableFuture<? extends Object> tryPublish(final DOMNotification notification,
 209             final Collection<ListenerRegistration<? extends DOMNotificationListener>> subscribers) {
 210         final long seq;
 211         try {
 212             seq = disruptor.getRingBuffer().tryNext();
 213         } catch (final InsufficientCapacityException e) {
 214             return DOMNotificationPublishService.REJECTED;
 215         }
 216
 217         return publish(seq, notification, subscribers);
 218     }
 219
 220     @Override
 221     public ListenableFuture<? extends Object> offerNotification(final DOMNotification notification) {
 222         final Collection<ListenerRegistration<? extends DOMNotificationListener>> subscribers =
 223                 listeners.get(notification.getType());
 224         if (subscribers.isEmpty()) {
 225             return NO_LISTENERS;
 226         }
 227
 228         return tryPublish(notification, subscribers);
 229     }
 230
 231     @Override
 232     public ListenableFuture<? extends Object> offerNotification(final DOMNotification notification, final long timeout,
 233             final TimeUnit unit) throws InterruptedException {
 234         final Collection<ListenerRegistration<? extends DOMNotificationListener>> subscribers =
 235                 listeners.get(notification.getType());
 236         if (subscribers.isEmpty()) {
 237             return NO_LISTENERS;
 238         }
 239
 240         // Attempt to perform a non-blocking publish first
 241         final ListenableFuture<? extends Object> noBlock = tryPublish(notification, subscribers);
 242         if (!DOMNotificationPublishService.REJECTED.equals(noBlock)) {
 243             return noBlock;
 244         }
 245
 246         /*
 247          * FIXME: we need a background thread, which will watch out for blocking too long. Here
 248          *        we will arm a tasklet for it and synchronize delivery of interrupt properly.
 249          */
 250         throw new UnsupportedOperationException("Not implemented yet");
 251     }
 252
 253     @Override
 254     public void close() {
 255         disruptor.shutdown();
 256         executor.shutdown();
 257     }
 258 }