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 org.opendaylight.mdsal.dom.spi.DOMNotificationSubscriptionListener;
  11 import org.opendaylight.mdsal.dom.spi.DOMNotificationSubscriptionListenerRegistry;
  12
  13 import org.opendaylight.mdsal.dom.api.DOMNotification;
  14 import org.opendaylight.mdsal.dom.api.DOMNotificationListener;
  15 import org.opendaylight.mdsal.dom.api.DOMNotificationPublishService;
  16 import org.opendaylight.mdsal.dom.api.DOMNotificationService;
  17 import com.google.common.base.Preconditions;
  18 import com.google.common.base.Predicate;
  19 import com.google.common.collect.ImmutableList;
  20 import com.google.common.collect.ImmutableMultimap;
  21 import com.google.common.collect.ImmutableMultimap.Builder;
  22 import com.google.common.collect.Multimap;
  23 import com.google.common.collect.Multimaps;
  24 import com.google.common.util.concurrent.Futures;
  25 import com.google.common.util.concurrent.ListenableFuture;
  26 import com.lmax.disruptor.EventHandler;
  27 import com.lmax.disruptor.InsufficientCapacityException;
  28 import com.lmax.disruptor.PhasedBackoffWaitStrategy;
  29 import com.lmax.disruptor.WaitStrategy;
  30 import com.lmax.disruptor.dsl.Disruptor;
  31 import com.lmax.disruptor.dsl.ProducerType;
  32 import java.util.Arrays;
  33 import java.util.Collection;
  34 import java.util.List;
  35 import java.util.Set;
  36 import java.util.concurrent.ExecutorService;
  37 import java.util.concurrent.Executors;
  38 import java.util.concurrent.TimeUnit;
  39 import org.opendaylight.yangtools.concepts.AbstractListenerRegistration;
  40 import org.opendaylight.yangtools.concepts.ListenerRegistration;
  41 import org.opendaylight.yangtools.util.ListenerRegistry;
  42 import org.opendaylight.yangtools.yang.model.api.SchemaPath;
  43 import org.slf4j.Logger;
  44 import org.slf4j.LoggerFactory;
  45
  46 /**
  47  * Joint implementation of {@link DOMNotificationPublishService} and {@link DOMNotificationService}. Provides
  48  * routing of notifications from publishers to subscribers.
  49  *
  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  * The fully-blocking {@link #publish(long, DOMNotification, Collection)} and non-blocking {@link #offerNotification(DOMNotification)}
  57  * are realized using the Disruptor's native operations. The bounded-blocking {@link #offerNotification(DOMNotification, long, TimeUnit)}
  58  * is realized by arming a background wakeup interrupt.
  59  */
  60 public final class DOMNotificationRouter implements AutoCloseable, DOMNotificationPublishService,
  61         DOMNotificationService, DOMNotificationSubscriptionListenerRegistry {
  62
  63     private static final Logger LOG = LoggerFactory.getLogger(DOMNotificationRouter.class);
  64     private static final ListenableFuture<Void> NO_LISTENERS = Futures.immediateFuture(null);
  65     private static final WaitStrategy DEFAULT_STRATEGY = PhasedBackoffWaitStrategy.withLock(1L, 30L, TimeUnit.MILLISECONDS);
  66     private static final EventHandler<DOMNotificationRouterEvent> DISPATCH_NOTIFICATIONS = new EventHandler<DOMNotificationRouterEvent>() {
  67         @Override
  68         public void onEvent(final DOMNotificationRouterEvent event, final long sequence, final boolean endOfBatch) throws Exception {
  69             event.deliverNotification();
  70
  71         }
  72     };
  73     private static final EventHandler<DOMNotificationRouterEvent> NOTIFY_FUTURE = new EventHandler<DOMNotificationRouterEvent>() {
  74         @Override
  75         public void onEvent(final DOMNotificationRouterEvent event, final long sequence, final boolean endOfBatch) {
  76             event.setFuture();
  77         }
  78     };
  79
  80     private final Disruptor<DOMNotificationRouterEvent> disruptor;
  81     private final ExecutorService executor;
  82     private volatile Multimap<SchemaPath, ListenerRegistration<? extends DOMNotificationListener>> listeners = ImmutableMultimap.of();
  83     private final ListenerRegistry<DOMNotificationSubscriptionListener> subscriptionListeners = ListenerRegistry.create();
  84
  85     @SuppressWarnings("unchecked")
  86     private DOMNotificationRouter(final ExecutorService executor, final int queueDepth, final WaitStrategy strategy) {
  87         this.executor = Preconditions.checkNotNull(executor);
  88
  89         disruptor = new Disruptor<>(DOMNotificationRouterEvent.FACTORY, queueDepth, executor, ProducerType.MULTI, strategy);
  90         disruptor.handleEventsWith(DISPATCH_NOTIFICATIONS);
  91         disruptor.after(DISPATCH_NOTIFICATIONS).handleEventsWith(NOTIFY_FUTURE);
  92         disruptor.start();
  93     }
  94
  95     public static DOMNotificationRouter create(final int queueDepth) {
  96         final ExecutorService executor = Executors.newCachedThreadPool();
  97
  98         return new DOMNotificationRouter(executor, queueDepth, DEFAULT_STRATEGY);
  99     }
 100
 101     public static DOMNotificationRouter create(final int queueDepth, final long spinTime, final long parkTime, final TimeUnit unit) {
 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(final T listener, final Collection<SchemaPath> types) {
 110         final ListenerRegistration<T> reg = new AbstractListenerRegistration<T>(listener) {
 111             @Override
 112             protected void removeRegistration() {
 113                 final ListenerRegistration<T> me = this;
 114
 115                 synchronized (DOMNotificationRouter.this) {
 116                     replaceListeners(ImmutableMultimap.copyOf(Multimaps.filterValues(listeners, new Predicate<ListenerRegistration<? extends DOMNotificationListener>>() {
 117                         @Override
 118                         public boolean apply(final ListenerRegistration<? extends DOMNotificationListener> input) {
 119                             return input != me;
 120                         }
 121                     })));
 122                 }
 123             }
 124         };
 125
 126         if (!types.isEmpty()) {
 127             final Builder<SchemaPath, ListenerRegistration<? extends DOMNotificationListener>> b = ImmutableMultimap.builder();
 128             b.putAll(listeners);
 129
 130             for (final SchemaPath t : types) {
 131                 b.put(t, reg);
 132             }
 133
 134             replaceListeners(b.build());
 135         }
 136
 137         return reg;
 138     }
 139
 140     @Override
 141     public <T extends DOMNotificationListener> ListenerRegistration<T> registerNotificationListener(final T listener, final SchemaPath... types) {
 142         return registerNotificationListener(listener, Arrays.asList(types));
 143     }
 144
 145     /**
 146      * Swaps registered listeners and triggers notification update
 147      *
 148      * @param newListeners
 149      */
 150     private void replaceListeners(
 151             final Multimap<SchemaPath, ListenerRegistration<? extends DOMNotificationListener>> newListeners) {
 152         listeners = newListeners;
 153         notifyListenerTypesChanged(newListeners.keySet());
 154     }
 155
 156     private void notifyListenerTypesChanged(final Set<SchemaPath> typesAfter) {
 157         final List<ListenerRegistration<DOMNotificationSubscriptionListener>> listenersAfter =ImmutableList.copyOf(subscriptionListeners.getListeners());
 158         executor.submit(new Runnable() {
 159
 160             @Override
 161             public void run() {
 162                 for (final ListenerRegistration<DOMNotificationSubscriptionListener> subListener : listenersAfter) {
 163                     try {
 164                         subListener.getInstance().onSubscriptionChanged(typesAfter);
 165                     } catch (final Exception e) {
 166                         LOG.warn("Uncaught exception during invoking listener {}", subListener.getInstance(), e);
 167                     }
 168                 }
 169             }
 170         });
 171     }
 172
 173     @Override
 174     public <L extends DOMNotificationSubscriptionListener> ListenerRegistration<L> registerSubscriptionListener(
 175             final L listener) {
 176         final Set<SchemaPath> initialTypes = listeners.keySet();
 177         executor.submit(new Runnable() {
 178
 179             @Override
 180             public void run() {
 181                 listener.onSubscriptionChanged(initialTypes);
 182             }
 183         });
 184         return subscriptionListeners.registerWithType(listener);
 185     }
 186
 187     private ListenableFuture<Void> publish(final long seq, final DOMNotification notification, 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) throws InterruptedException {
 196         final Collection<ListenerRegistration<? extends DOMNotificationListener>> subscribers = listeners.get(notification.getType());
 197         if (subscribers.isEmpty()) {
 198             return NO_LISTENERS;
 199         }
 200
 201         final long seq = disruptor.getRingBuffer().next();
 202         return publish(seq, notification, subscribers);
 203     }
 204
 205     private ListenableFuture<? extends Object> tryPublish(final DOMNotification notification, final Collection<ListenerRegistration<? extends DOMNotificationListener>> subscribers) {
 206         final long seq;
 207         try {
 208              seq = disruptor.getRingBuffer().tryNext();
 209         } catch (final InsufficientCapacityException e) {
 210             return DOMNotificationPublishService.REJECTED;
 211         }
 212
 213         return publish(seq, notification, subscribers);
 214     }
 215
 216     @Override
 217     public ListenableFuture<? extends Object> offerNotification(final DOMNotification notification) {
 218         final Collection<ListenerRegistration<? extends DOMNotificationListener>> subscribers = listeners.get(notification.getType());
 219         if (subscribers.isEmpty()) {
 220             return NO_LISTENERS;
 221         }
 222
 223         return tryPublish(notification, subscribers);
 224     }
 225
 226     @Override
 227     public ListenableFuture<? extends Object> offerNotification(final DOMNotification notification, final long timeout,
 228             final TimeUnit unit) throws InterruptedException {
 229         final Collection<ListenerRegistration<? extends DOMNotificationListener>> subscribers = listeners.get(notification.getType());
 230         if (subscribers.isEmpty()) {
 231             return NO_LISTENERS;
 232         }
 233
 234         // Attempt to perform a non-blocking publish first
 235         final ListenableFuture<? extends Object> noBlock = tryPublish(notification, subscribers);
 236         if (!DOMNotificationPublishService.REJECTED.equals(noBlock)) {
 237             return noBlock;
 238         }
 239
 240         /*
 241          * FIXME: we need a background thread, which will watch out for blocking too long. Here
 242          *        we will arm a tasklet for it and synchronize delivery of interrupt properly.
 243          */
 244         throw new UnsupportedOperationException("Not implemented yet");
 245     }
 246
 247     @Override
 248     public void close() {
 249         disruptor.shutdown();
 250         executor.shutdown();
 251     }
 252 }