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.base.Predicate;
  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.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  * 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  * The fully-blocking {@link #publish(long, DOMNotification, Collection)} and non-blocking {@link #offerNotification(DOMNotification)}
  56  * are realized using the Disruptor's native operations. The bounded-blocking {@link #offerNotification(DOMNotification, long, TimeUnit)}
  57  * is realized by arming a background wakeup interrupt.
  58  */
  59 public final class DOMNotificationRouter implements AutoCloseable, DOMNotificationPublishService,
  60         DOMNotificationService, DOMNotificationSubscriptionListenerRegistry {
  61
  62     private static final Logger LOG = LoggerFactory.getLogger(DOMNotificationRouter.class);
  63     private static final ListenableFuture<Void> NO_LISTENERS = Futures.immediateFuture(null);
  64     private static final WaitStrategy DEFAULT_STRATEGY = PhasedBackoffWaitStrategy.withLock(1L, 30L, TimeUnit.MILLISECONDS);
  65     private static final EventHandler<DOMNotificationRouterEvent> DISPATCH_NOTIFICATIONS = new EventHandler<DOMNotificationRouterEvent>() {
  66         @Override
  67         public void onEvent(final DOMNotificationRouterEvent event, final long sequence, final boolean endOfBatch) throws Exception {
  68             event.deliverNotification();
  69
  70         }
  71     };
  72     private static final EventHandler<DOMNotificationRouterEvent> NOTIFY_FUTURE = new EventHandler<DOMNotificationRouterEvent>() {
  73         @Override
  74         public void onEvent(final DOMNotificationRouterEvent event, final long sequence, final boolean endOfBatch) {
  75             event.setFuture();
  76         }
  77     };
  78
  79     private final Disruptor<DOMNotificationRouterEvent> disruptor;
  80     private final ExecutorService executor;
  81     private volatile Multimap<SchemaPath, ListenerRegistration<? extends DOMNotificationListener>> listeners = ImmutableMultimap.of();
  82     private final ListenerRegistry<DOMNotificationSubscriptionListener> subscriptionListeners = ListenerRegistry.create();
  83
  84     @SuppressWarnings("unchecked")
  85     private DOMNotificationRouter(final ExecutorService executor, final int queueDepth, final WaitStrategy strategy) {
  86         this.executor = Preconditions.checkNotNull(executor);
  87
  88         disruptor = new Disruptor<>(DOMNotificationRouterEvent.FACTORY, queueDepth, executor, ProducerType.MULTI, 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, final TimeUnit unit) {
 101         Preconditions.checkArgument(Long.lowestOneBit(queueDepth) == Long.highestOneBit(queueDepth),
 102                 "Queue depth %s is not power-of-two", queueDepth);
 103         final ExecutorService executor = Executors.newCachedThreadPool();
 104         final WaitStrategy strategy = PhasedBackoffWaitStrategy.withLock(spinTime, parkTime, unit);
 105
 106         return new DOMNotificationRouter(executor, queueDepth, strategy);
 107     }
 108
 109     @Override
 110     public synchronized <T extends DOMNotificationListener> ListenerRegistration<T> registerNotificationListener(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, new Predicate<ListenerRegistration<? extends DOMNotificationListener>>() {
 118                         @Override
 119                         public boolean apply(final ListenerRegistration<? extends DOMNotificationListener> input) {
 120                             return input != me;
 121                         }
 122                     })));
 123                 }
 124             }
 125         };
 126
 127         if (!types.isEmpty()) {
 128             final Builder<SchemaPath, ListenerRegistration<? extends DOMNotificationListener>> b = ImmutableMultimap.builder();
 129             b.putAll(listeners);
 130
 131             for (final SchemaPath t : types) {
 132                 b.put(t, reg);
 133             }
 134
 135             replaceListeners(b.build());
 136         }
 137
 138         return reg;
 139     }
 140
 141     @Override
 142     public <T extends DOMNotificationListener> ListenerRegistration<T> registerNotificationListener(final T listener, final SchemaPath... types) {
 143         return registerNotificationListener(listener, Arrays.asList(types));
 144     }
 145
 146     /**
 147      * Swaps registered listeners and triggers notification update
 148      *
 149      * @param newListeners
 150      */
 151     private void replaceListeners(
 152             final Multimap<SchemaPath, ListenerRegistration<? extends DOMNotificationListener>> newListeners) {
 153         listeners = newListeners;
 154         notifyListenerTypesChanged(newListeners.keySet());
 155     }
 156
 157     private void notifyListenerTypesChanged(final Set<SchemaPath> typesAfter) {
 158         final List<ListenerRegistration<DOMNotificationSubscriptionListener>> listenersAfter =ImmutableList.copyOf(subscriptionListeners.getListeners());
 159         executor.submit(new Runnable() {
 160
 161             @Override
 162             public void run() {
 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
 174     @Override
 175     public <L extends DOMNotificationSubscriptionListener> ListenerRegistration<L> registerSubscriptionListener(
 176             final L listener) {
 177         final Set<SchemaPath> initialTypes = listeners.keySet();
 178         executor.submit(new Runnable() {
 179
 180             @Override
 181             public void run() {
 182                 listener.onSubscriptionChanged(initialTypes);
 183             }
 184         });
 185         return subscriptionListeners.registerWithType(listener);
 186     }
 187
 188     private ListenableFuture<Void> publish(final long seq, final DOMNotification notification, final Collection<ListenerRegistration<? extends DOMNotificationListener>> subscribers) {
 189         final DOMNotificationRouterEvent event = disruptor.get(seq);
 190         final ListenableFuture<Void> future = event.initialize(notification, subscribers);
 191         disruptor.getRingBuffer().publish(seq);
 192         return future;
 193     }
 194
 195     @Override
 196     public ListenableFuture<?> putNotification(final DOMNotification notification) throws InterruptedException {
 197         final Collection<ListenerRegistration<? extends DOMNotificationListener>> subscribers = listeners.get(notification.getType());
 198         if (subscribers.isEmpty()) {
 199             return NO_LISTENERS;
 200         }
 201
 202         final long seq = disruptor.getRingBuffer().next();
 203         return publish(seq, notification, subscribers);
 204     }
 205
 206     private ListenableFuture<?> tryPublish(final DOMNotification notification, final Collection<ListenerRegistration<? extends DOMNotificationListener>> subscribers) {
 207         final long seq;
 208         try {
 209              seq = disruptor.getRingBuffer().tryNext();
 210         } catch (final InsufficientCapacityException e) {
 211             return DOMNotificationPublishService.REJECTED;
 212         }
 213
 214         return publish(seq, notification, subscribers);
 215     }
 216
 217     @Override
 218     public ListenableFuture<?> offerNotification(final DOMNotification notification) {
 219         final Collection<ListenerRegistration<? extends DOMNotificationListener>> subscribers = listeners.get(notification.getType());
 220         if (subscribers.isEmpty()) {
 221             return NO_LISTENERS;
 222         }
 223
 224         return tryPublish(notification, subscribers);
 225     }
 226
 227     @Override
 228     public ListenableFuture<?> offerNotification(final DOMNotification notification, final long timeout,
 229             final TimeUnit unit) throws InterruptedException {
 230         final Collection<ListenerRegistration<? extends DOMNotificationListener>> subscribers = listeners.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 }