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