opendaylight/md-sal/sal-binding-broker/src/main/java/org/opendaylight/controller/md/sal/binding/compat/ListenerMapGeneration.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.binding.compat;
   9
  10 import com.google.common.cache.CacheBuilder;
  11 import com.google.common.cache.CacheLoader;
  12 import com.google.common.cache.LoadingCache;
  13 import com.google.common.collect.ImmutableMultimap;
  14 import com.google.common.collect.ImmutableSet;
  15 import com.google.common.collect.Multimap;
  16 import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
  17 import java.util.Arrays;
  18 import java.util.Collection;
  19 import java.util.HashSet;
  20 import java.util.Set;
  21 import java.util.stream.Collectors;
  22 import org.opendaylight.yangtools.yang.binding.Notification;
  23
  24 /**
  25  * An immutable view of the current generation of listeners.
  26  */
  27 @Deprecated
  28 final class ListenerMapGeneration {
  29     private static final int CACHE_MAX_ENTRIES = 1000;
  30
  31     /**
  32      * Constant map of notification type to subscribed listeners.
  33      */
  34     private final Multimap<Class<? extends Notification>, NotificationListenerRegistration<?>> typeToListeners;
  35
  36     /**
  37      * Dynamic cache of notification implementation to matching listeners. This cache loads entries based on
  38      * the contents of the {@link #typeToListeners} map.
  39      */
  40     private final LoadingCache<Class<?>, Iterable<NotificationListenerRegistration<?>>> implementationToListeners =
  41             CacheBuilder.newBuilder()
  42             .weakKeys()
  43             .maximumSize(CACHE_MAX_ENTRIES)
  44             .build(new CacheLoader<Class<?>, Iterable<NotificationListenerRegistration<?>>>() {
  45                 @Override
  46                 public Iterable<NotificationListenerRegistration<?>> load(final Class<?> key) {
  47                     final Set<NotificationListenerRegistration<?>> regs = new HashSet<>();
  48
  49                     for (final Class<?> type : getNotificationTypes(key)) {
  50                         @SuppressWarnings("unchecked")
  51                         final Collection<NotificationListenerRegistration<?>> l =
  52                                 typeToListeners.get((Class<? extends Notification>) type);
  53                         if (l != null) {
  54                             regs.addAll(l);
  55                         }
  56                     }
  57
  58                     return ImmutableSet.copyOf(regs);
  59                 }
  60             });
  61
  62     ListenerMapGeneration() {
  63         typeToListeners = ImmutableMultimap.of();
  64     }
  65
  66     ListenerMapGeneration(final Multimap<Class<? extends Notification>,
  67             NotificationListenerRegistration<?>> listeners) {
  68         this.typeToListeners = ImmutableMultimap.copyOf(listeners);
  69     }
  70
  71     /**
  72      * Current listeners. Exposed for creating the next generation.
  73      *
  74      * @return Current type-to-listener map.
  75      */
  76     Multimap<Class<? extends Notification>, NotificationListenerRegistration<?>> getListeners() {
  77         return typeToListeners;
  78     }
  79
  80     /**
  81      * Look up the listeners which need to see this notification delivered.
  82      *
  83      * @param notification Notification object
  84      * @return Iterable of listeners, guaranteed to be nonnull.
  85      */
  86     public Iterable<NotificationListenerRegistration<?>> listenersFor(final Notification notification) {
  87         // Safe to use, as our loader does not throw checked exceptions
  88         return implementationToListeners.getUnchecked(notification.getClass());
  89     }
  90
  91     public Iterable<Class<? extends Notification>> getKnownTypes() {
  92         return typeToListeners.keySet();
  93     }
  94
  95     @SuppressFBWarnings(value = "UPM_UNCALLED_PRIVATE_METHOD",
  96             justification = "https://github.com/spotbugs/spotbugs/issues/811")
  97     private static Iterable<Class<?>> getNotificationTypes(final Class<?> cls) {
  98         return Arrays.stream(cls.getInterfaces())
  99                 .filter(input -> !Notification.class.equals(input) && Notification.class.isAssignableFrom(input))
 100                 .collect(Collectors.toList());
 101     }
 102 }