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     private DOMNotificationRouter(final ExecutorService executor, final Disruptor<DOMNotificationRouterEvent> disruptor) {
  85         this.executor = Preconditions.checkNotNull(executor);
  86         this.disruptor = Preconditions.checkNotNull(disruptor);
  87     }
  88
  89     @SuppressWarnings("unchecked")
  90     public static DOMNotificationRouter create(final int queueDepth) {
  91         final ExecutorService executor = Executors.newCachedThreadPool();
  92         final Disruptor<DOMNotificationRouterEvent> disruptor = new Disruptor<>(DOMNotificationRouterEvent.FACTORY, queueDepth, executor, ProducerType.MULTI, DEFAULT_STRATEGY);
  93
  94         disruptor.handleEventsWith(DISPATCH_NOTIFICATIONS);
  95         disruptor.after(DISPATCH_NOTIFICATIONS).handleEventsWith(NOTIFY_FUTURE);
  96         disruptor.start();
  97
  98         return new DOMNotificationRouter(executor, disruptor);
  99     }
 100
 101     @Override
 102     public synchronized <T extends DOMNotificationListener> ListenerRegistration<T> registerNotificationListener(final T listener, final Collection<SchemaPath> types) {
 103         final ListenerRegistration<T> reg = new AbstractListenerRegistration<T>(listener) {
 104             @Override
 105             protected void removeRegistration() {
 106                 final ListenerRegistration<T> me = this;
 107
 108                 synchronized (DOMNotificationRouter.this) {
 109                     replaceListeners(ImmutableMultimap.copyOf(Multimaps.filterValues(listeners, new Predicate<ListenerRegistration<? extends DOMNotificationListener>>() {
 110                         @Override
 111                         public boolean apply(final ListenerRegistration<? extends DOMNotificationListener> input) {
 112                             return input != me;
 113                         }
 114                     })));
 115                 }
 116             }
 117         };
 118
 119         if (!types.isEmpty()) {
 120             final Builder<SchemaPath, ListenerRegistration<? extends DOMNotificationListener>> b = ImmutableMultimap.builder();
 121             b.putAll(listeners);
 122
 123             for (final SchemaPath t : types) {
 124                 b.put(t, reg);
 125             }
 126
 127             replaceListeners(b.build());
 128         }
 129
 130         return reg;
 131     }
 132
 133     @Override
 134     public <T extends DOMNotificationListener> ListenerRegistration<T> registerNotificationListener(final T listener, final SchemaPath... types) {
 135         return registerNotificationListener(listener, Arrays.asList(types));
 136     }
 137
 138     /**
 139      * Swaps registered listeners and triggers notification update
 140      *
 141      * @param newListeners
 142      */
 143     private void replaceListeners(
 144             final Multimap<SchemaPath, ListenerRegistration<? extends DOMNotificationListener>> newListeners) {
 145         listeners = newListeners;
 146         notifyListenerTypesChanged(newListeners.keySet());
 147     }
 148
 149     private void notifyListenerTypesChanged(final Set<SchemaPath> typesAfter) {
 150         final List<ListenerRegistration<DOMNotificationSubscriptionListener>> listenersAfter =ImmutableList.copyOf(subscriptionListeners.getListeners());
 151         executor.submit(new Runnable() {
 152
 153             @Override
 154             public void run() {
 155                 for (final ListenerRegistration<DOMNotificationSubscriptionListener> subListener : listenersAfter) {
 156                     try {
 157                         subListener.getInstance().onSubscriptionChanged(typesAfter);
 158                     } catch (final Exception e) {
 159                         LOG.warn("Uncaught exception during invoking listener {}", subListener.getInstance(), e);
 160                     }
 161                 }
 162             }
 163         });
 164     }
 165
 166     @Override
 167     public <L extends DOMNotificationSubscriptionListener> ListenerRegistration<L> registerSubscriptionListener(
 168             final L listener) {
 169         final Set<SchemaPath> initialTypes = listeners.keySet();
 170         executor.submit(new Runnable() {
 171
 172             @Override
 173             public void run() {
 174                 listener.onSubscriptionChanged(initialTypes);
 175             }
 176         });
 177         return subscriptionListeners.registerWithType(listener);
 178     }
 179
 180     private ListenableFuture<Void> publish(final long seq, final DOMNotification notification, final Collection<ListenerRegistration<? extends DOMNotificationListener>> subscribers) {
 181         final DOMNotificationRouterEvent event = disruptor.get(seq);
 182         final ListenableFuture<Void> future = event.initialize(notification, subscribers);
 183         disruptor.getRingBuffer().publish(seq);
 184         return future;
 185     }
 186
 187     @Override
 188     public ListenableFuture<? extends Object> putNotification(final DOMNotification notification) throws InterruptedException {
 189         final Collection<ListenerRegistration<? extends DOMNotificationListener>> subscribers = listeners.get(notification.getType());
 190         if (subscribers.isEmpty()) {
 191             return NO_LISTENERS;
 192         }
 193
 194         final long seq = disruptor.getRingBuffer().next();
 195         return publish(seq, notification, subscribers);
 196     }
 197
 198     private ListenableFuture<? extends Object> tryPublish(final DOMNotification notification, final Collection<ListenerRegistration<? extends DOMNotificationListener>> subscribers) {
 199         final long seq;
 200         try {
 201              seq = disruptor.getRingBuffer().tryNext();
 202         } catch (final InsufficientCapacityException e) {
 203             return DOMNotificationPublishService.REJECTED;
 204         }
 205
 206         return publish(seq, notification, subscribers);
 207     }
 208
 209     @Override
 210     public ListenableFuture<? extends Object> offerNotification(final DOMNotification notification) {
 211         final Collection<ListenerRegistration<? extends DOMNotificationListener>> subscribers = listeners.get(notification.getType());
 212         if (subscribers.isEmpty()) {
 213             return NO_LISTENERS;
 214         }
 215
 216         return tryPublish(notification, subscribers);
 217     }
 218
 219     @Override
 220     public ListenableFuture<? extends Object> offerNotification(final DOMNotification notification, final long timeout,
 221             final TimeUnit unit) throws InterruptedException {
 222         final Collection<ListenerRegistration<? extends DOMNotificationListener>> subscribers = listeners.get(notification.getType());
 223         if (subscribers.isEmpty()) {
 224             return NO_LISTENERS;
 225         }
 226
 227         // Attempt to perform a non-blocking publish first
 228         final ListenableFuture<? extends Object> noBlock = tryPublish(notification, subscribers);
 229         if (!DOMNotificationPublishService.REJECTED.equals(noBlock)) {
 230             return noBlock;
 231         }
 232
 233         /*
 234          * FIXME: we need a background thread, which will watch out for blocking too long. Here
 235          *        we will arm a tasklet for it and synchronize delivery of interrupt properly.
 236          */
 237         throw new UnsupportedOperationException("Not implemented yet");
 238     }
 239
 240     @Override
 241     public void close() {
 242         disruptor.shutdown();
 243         executor.shutdown();
 244     }
 245 }