Mechanical code cleanup (sal-dom-broker)
[controller.git] / 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 }

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