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.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.mdsal.dom.api.DOMNotification;
  33 import org.opendaylight.mdsal.dom.api.DOMNotificationListener;
  34 import org.opendaylight.mdsal.dom.api.DOMNotificationPublishService;
  35 import org.opendaylight.mdsal.dom.api.DOMNotificationService;
  36 import org.opendaylight.mdsal.dom.spi.DOMNotificationSubscriptionListener;
  37 import org.opendaylight.mdsal.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)}
  58  * and non-blocking {@link #offerNotification(DOMNotification)}
  59  * are realized using the Disruptor's native operations. The bounded-blocking {@link
  60  * #offerNotification(DOMNotification, long, TimeUnit)}
  61  * is realized by arming a background wakeup interrupt.
  62  */
  63 public final class DOMNotificationRouter implements AutoCloseable, DOMNotificationPublishService,
  64         DOMNotificationService, DOMNotificationSubscriptionListenerRegistry {
  65
  66     private static final Logger LOG = LoggerFactory.getLogger(DOMNotificationRouter.class);
  67     private static final ListenableFuture<Void> NO_LISTENERS = Futures.immediateFuture(null);
  68     private static final WaitStrategy DEFAULT_STRATEGY = PhasedBackoffWaitStrategy.withLock(
  69             1L, 30L, TimeUnit.MILLISECONDS);
  70     private static final EventHandler<DOMNotificationRouterEvent> DISPATCH_NOTIFICATIONS =
  71             new EventHandler<DOMNotificationRouterEvent>() {
  72         @Override
  73         public void onEvent(final DOMNotificationRouterEvent event, final long sequence,
  74                 final boolean endOfBatch) throws Exception {
  75             event.deliverNotification();
  76
  77         }
  78     };
  79     private static final EventHandler<DOMNotificationRouterEvent> NOTIFY_FUTURE =
  80             new EventHandler<DOMNotificationRouterEvent>() {
  81         @Override
  82         public void onEvent(final DOMNotificationRouterEvent event, final long sequence, final boolean endOfBatch) {
  83             event.setFuture();
  84         }
  85     };
  86
  87     private final Disruptor<DOMNotificationRouterEvent> disruptor;
  88     private final ExecutorService executor;
  89     private volatile Multimap<SchemaPath, ListenerRegistration<? extends
  90             DOMNotificationListener>> listeners = ImmutableMultimap.of();
  91     private final ListenerRegistry<DOMNotificationSubscriptionListener> subscriptionListeners =
  92             ListenerRegistry.create();
  93
  94     @SuppressWarnings("unchecked")
  95     private DOMNotificationRouter(final ExecutorService executor, final int queueDepth, final WaitStrategy strategy) {
  96         this.executor = Preconditions.checkNotNull(executor);
  97
  98         disruptor = new Disruptor<>(DOMNotificationRouterEvent.FACTORY,
  99                 queueDepth, executor, ProducerType.MULTI, strategy);
 100         disruptor.handleEventsWith(DISPATCH_NOTIFICATIONS);
 101         disruptor.after(DISPATCH_NOTIFICATIONS).handleEventsWith(NOTIFY_FUTURE);
 102         disruptor.start();
 103     }
 104
 105     public static DOMNotificationRouter create(final int queueDepth) {
 106         final ExecutorService executor = Executors.newCachedThreadPool();
 107
 108         return new DOMNotificationRouter(executor, queueDepth, DEFAULT_STRATEGY);
 109     }
 110
 111     public static DOMNotificationRouter create(final int queueDepth, final long spinTime,
 112             final long parkTime, final TimeUnit unit) {
 113         final ExecutorService executor = Executors.newCachedThreadPool();
 114         final WaitStrategy strategy = PhasedBackoffWaitStrategy.withLock(spinTime, parkTime, unit);
 115
 116         return new DOMNotificationRouter(executor, queueDepth, strategy);
 117     }
 118
 119     @Override
 120     public synchronized <T extends DOMNotificationListener> ListenerRegistration<T> registerNotificationListener(
 121             final T listener, final Collection<SchemaPath> types) {
 122         final ListenerRegistration<T> reg = new AbstractListenerRegistration<T>(listener) {
 123             @Override
 124             protected void removeRegistration() {
 125                 final ListenerRegistration<T> me = this;
 126
 127                 synchronized (DOMNotificationRouter.this) {
 128                     replaceListeners(ImmutableMultimap.copyOf(Multimaps.filterValues(listeners,
 129                             new Predicate<ListenerRegistration<? extends DOMNotificationListener>>() {
 130                             @Override
 131                             public boolean apply(final ListenerRegistration<? extends DOMNotificationListener> input) {
 132                                 return input != me;
 133                             }
 134                         })));
 135                 }
 136             }
 137         };
 138
 139         if (!types.isEmpty()) {
 140             final Builder<SchemaPath, ListenerRegistration<? extends DOMNotificationListener>> b =
 141                     ImmutableMultimap.builder();
 142             b.putAll(listeners);
 143
 144             for (final SchemaPath t : types) {
 145                 b.put(t, reg);
 146             }
 147
 148             replaceListeners(b.build());
 149         }
 150
 151         return reg;
 152     }
 153
 154     @Override
 155     public <T extends DOMNotificationListener> ListenerRegistration<T> registerNotificationListener(
 156             final T listener, final SchemaPath... types) {
 157         return registerNotificationListener(listener, Arrays.asList(types));
 158     }
 159
 160     /**
 161      * Swaps registered listeners and triggers notification update.
 162      *
 163      * @param newListeners is used to notify listenerTypes changed
 164      */
 165     private void replaceListeners(
 166             final Multimap<SchemaPath, ListenerRegistration<? extends DOMNotificationListener>> newListeners) {
 167         listeners = newListeners;
 168         notifyListenerTypesChanged(newListeners.keySet());
 169     }
 170
 171     @SuppressWarnings("checkstyle:IllegalCatch")
 172     private void notifyListenerTypesChanged(final Set<SchemaPath> typesAfter) {
 173         final List<ListenerRegistration<DOMNotificationSubscriptionListener>> listenersAfter =
 174                 ImmutableList.copyOf(subscriptionListeners.getListeners());
 175         executor.submit(new Runnable() {
 176
 177             @Override
 178             public void run() {
 179                 for (final ListenerRegistration<DOMNotificationSubscriptionListener> subListener : listenersAfter) {
 180                     try {
 181                         subListener.getInstance().onSubscriptionChanged(typesAfter);
 182                     } catch (final Exception e) {
 183                         LOG.warn("Uncaught exception during invoking listener {}", subListener.getInstance(), e);
 184                     }
 185                 }
 186             }
 187         });
 188     }
 189
 190     @Override
 191     public <L extends DOMNotificationSubscriptionListener> ListenerRegistration<L> registerSubscriptionListener(
 192             final L listener) {
 193         final Set<SchemaPath> initialTypes = listeners.keySet();
 194         executor.submit(new Runnable() {
 195
 196             @Override
 197             public void run() {
 198                 listener.onSubscriptionChanged(initialTypes);
 199             }
 200         });
 201         return subscriptionListeners.registerWithType(listener);
 202     }
 203
 204     private ListenableFuture<Void> publish(final long seq, final DOMNotification notification,
 205             final Collection<ListenerRegistration<? extends DOMNotificationListener>> subscribers) {
 206         final DOMNotificationRouterEvent event = disruptor.get(seq);
 207         final ListenableFuture<Void> future = event.initialize(notification, subscribers);
 208         disruptor.getRingBuffer().publish(seq);
 209         return future;
 210     }
 211
 212     @Override
 213     public ListenableFuture<? extends Object> putNotification(final DOMNotification notification)
 214             throws InterruptedException {
 215         final Collection<ListenerRegistration<? extends DOMNotificationListener>> subscribers =
 216                 listeners.get(notification.getType());
 217         if (subscribers.isEmpty()) {
 218             return NO_LISTENERS;
 219         }
 220
 221         final long seq = disruptor.getRingBuffer().next();
 222         return publish(seq, notification, subscribers);
 223     }
 224
 225     @SuppressWarnings("checkstyle:IllegalCatch")
 226     private ListenableFuture<? extends Object> tryPublish(final DOMNotification notification,
 227             final Collection<ListenerRegistration<? extends DOMNotificationListener>> subscribers) {
 228         final long seq;
 229         try {
 230             seq = disruptor.getRingBuffer().tryNext();
 231         } catch (final InsufficientCapacityException e) {
 232             return DOMNotificationPublishService.REJECTED;
 233         }
 234
 235         return publish(seq, notification, subscribers);
 236     }
 237
 238     @Override
 239     public ListenableFuture<? extends Object> offerNotification(final DOMNotification notification) {
 240         final Collection<ListenerRegistration<? extends DOMNotificationListener>> subscribers =
 241                 listeners.get(notification.getType());
 242         if (subscribers.isEmpty()) {
 243             return NO_LISTENERS;
 244         }
 245
 246         return tryPublish(notification, subscribers);
 247     }
 248
 249     @Override
 250     public ListenableFuture<? extends Object> offerNotification(final DOMNotification notification, final long timeout,
 251             final TimeUnit unit) throws InterruptedException {
 252         final Collection<ListenerRegistration<? extends DOMNotificationListener>> subscribers =
 253                 listeners.get(notification.getType());
 254         if (subscribers.isEmpty()) {
 255             return NO_LISTENERS;
 256         }
 257
 258         // Attempt to perform a non-blocking publish first
 259         final ListenableFuture<? extends Object> noBlock = tryPublish(notification, subscribers);
 260         if (!DOMNotificationPublishService.REJECTED.equals(noBlock)) {
 261             return noBlock;
 262         }
 263
 264         /*
 265          * FIXME: we need a background thread, which will watch out for blocking too long. Here
 266          *        we will arm a tasklet for it and synchronize delivery of interrupt properly.
 267          */
 268         throw new UnsupportedOperationException("Not implemented yet");
 269     }
 270
 271     @Override
 272     public void close() {
 273         disruptor.shutdown();
 274         executor.shutdown();
 275     }
 276 }