--- /dev/null
+/*
+ * Copyright (c) 2014 Cisco Systems, Inc. and others. All rights reserved.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v1.0 which accompanies this distribution,
+ * and is available at http://www.eclipse.org/legal/epl-v10.html
+ */
+package org.opendaylight.controller.md.sal.dom.broker.impl;
+
+import com.google.common.base.Preconditions;
+import com.google.common.base.Predicate;
+import com.google.common.collect.ImmutableMultimap;
+import com.google.common.collect.ImmutableMultimap.Builder;
+import com.google.common.collect.Multimap;
+import com.google.common.collect.Multimaps;
+import com.google.common.util.concurrent.Futures;
+import com.google.common.util.concurrent.ListenableFuture;
+import com.lmax.disruptor.EventHandler;
+import com.lmax.disruptor.InsufficientCapacityException;
+import com.lmax.disruptor.SleepingWaitStrategy;
+import com.lmax.disruptor.WaitStrategy;
+import com.lmax.disruptor.dsl.Disruptor;
+import com.lmax.disruptor.dsl.ProducerType;
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.TimeUnit;
+import org.opendaylight.controller.md.sal.dom.api.DOMNotification;
+import org.opendaylight.controller.md.sal.dom.api.DOMNotificationListener;
+import org.opendaylight.controller.md.sal.dom.api.DOMNotificationPublishService;
+import org.opendaylight.controller.md.sal.dom.api.DOMNotificationService;
+import org.opendaylight.yangtools.concepts.AbstractListenerRegistration;
+import org.opendaylight.yangtools.concepts.ListenerRegistration;
+import org.opendaylight.yangtools.yang.model.api.SchemaPath;
+
+/**
+ * Joint implementation of {@link DOMNotificationPublishService} and {@link DOMNotificationService}. Provides
+ * routing of notifications from publishers to subscribers.
+ *
+ * Internal implementation works by allocating a two-handler Disruptor. The first handler delivers notifications
+ * to subscribed listeners and the second one notifies whoever may be listening on the returned future. Registration
+ * state tracking is performed by a simple immutable multimap -- when a registration or unregistration occurs we
+ * re-generate the entire map from scratch and set it atomically. While registrations/unregistrations synchronize
+ * on this instance, notifications do not take any locks here.
+ *
+ * The fully-blocking {@link #publish(long, DOMNotification, Collection)} and non-blocking {@link #offerNotification(DOMNotification)}
+ * are realized using the Disruptor's native operations. The bounded-blocking {@link #offerNotification(DOMNotification, long, TimeUnit)}
+ * is realized by arming a background wakeup interrupt.
+ */
+public final class DOMNotificationRouter implements AutoCloseable, DOMNotificationPublishService, DOMNotificationService {
+ private static final ListenableFuture<Void> NO_LISTENERS = Futures.immediateFuture(null);
+ private static final WaitStrategy DEFAULT_STRATEGY = new SleepingWaitStrategy();
+ private static final EventHandler<DOMNotificationRouterEvent> DISPATCH_NOTIFICATIONS = new EventHandler<DOMNotificationRouterEvent>() {
+ @Override
+ public void onEvent(final DOMNotificationRouterEvent event, final long sequence, final boolean endOfBatch) throws Exception {
+ event.deliverNotification();
+
+ }
+ };
+ private static final EventHandler<DOMNotificationRouterEvent> NOTIFY_FUTURE = new EventHandler<DOMNotificationRouterEvent>() {
+ @Override
+ public void onEvent(final DOMNotificationRouterEvent event, final long sequence, final boolean endOfBatch) {
+ event.setFuture();
+ }
+ };
+
+ private final Disruptor<DOMNotificationRouterEvent> disruptor;
+ private final ExecutorService executor;
+ private volatile Multimap<SchemaPath, ListenerRegistration<? extends DOMNotificationListener>> listeners = ImmutableMultimap.of();
+
+ private DOMNotificationRouter(final ExecutorService executor, final Disruptor<DOMNotificationRouterEvent> disruptor) {
+ this.executor = Preconditions.checkNotNull(executor);
+ this.disruptor = Preconditions.checkNotNull(disruptor);
+ }
+
+ @SuppressWarnings("unchecked")
+ public static DOMNotificationRouter create(final int queueDepth) {
+ final ExecutorService executor = Executors.newCachedThreadPool();
+ final Disruptor<DOMNotificationRouterEvent> disruptor = new Disruptor<>(DOMNotificationRouterEvent.FACTORY, queueDepth, executor, ProducerType.MULTI, DEFAULT_STRATEGY);
+
+ disruptor.after(DISPATCH_NOTIFICATIONS).handleEventsWith(NOTIFY_FUTURE);
+ disruptor.start();
+
+ return new DOMNotificationRouter(executor, disruptor);
+ }
+
+ @Override
+ public synchronized <T extends DOMNotificationListener> ListenerRegistration<T> registerNotificationListener(final T listener, final Collection<SchemaPath> types) {
+ final ListenerRegistration<T> reg = new AbstractListenerRegistration<T>(listener) {
+ @Override
+ protected void removeRegistration() {
+ final ListenerRegistration<T> me = this;
+
+ synchronized (DOMNotificationRouter.this) {
+ listeners = ImmutableMultimap.copyOf(Multimaps.filterValues(listeners, new Predicate<ListenerRegistration<? extends DOMNotificationListener>>() {
+ @Override
+ public boolean apply(final ListenerRegistration<? extends DOMNotificationListener> input) {
+ return input != me;
+ }
+ }));
+ }
+ }
+ };
+
+ if (!types.isEmpty()) {
+ final Builder<SchemaPath, ListenerRegistration<? extends DOMNotificationListener>> b = ImmutableMultimap.builder();
+ b.putAll(listeners);
+
+ for (SchemaPath t : types) {
+ b.put(t, reg);
+ }
+
+ listeners = b.build();
+ }
+
+ return reg;
+ }
+
+ @Override
+ public <T extends DOMNotificationListener> ListenerRegistration<T> registerNotificationListener(final T listener, final SchemaPath... types) {
+ return registerNotificationListener(listener, Arrays.asList(types));
+ }
+
+ private ListenableFuture<Void> publish(final long seq, final DOMNotification notification, final Collection<ListenerRegistration<? extends DOMNotificationListener>> subscribers) {
+ final DOMNotificationRouterEvent event = disruptor.get(seq);
+ final ListenableFuture<Void> future = event.initialize(notification, subscribers);
+ disruptor.getRingBuffer().publish(seq);
+ return future;
+ }
+
+ @Override
+ public ListenableFuture<? extends Object> putNotification(final DOMNotification notification) throws InterruptedException {
+ final Collection<ListenerRegistration<? extends DOMNotificationListener>> subscribers = listeners.get(notification.getType());
+ if (subscribers.isEmpty()) {
+ return NO_LISTENERS;
+ }
+
+ final long seq = disruptor.getRingBuffer().next();
+ return publish(seq, notification, subscribers);
+ }
+
+ private ListenableFuture<? extends Object> tryPublish(final DOMNotification notification, final Collection<ListenerRegistration<? extends DOMNotificationListener>> subscribers) {
+ final long seq;
+ try {
+ seq = disruptor.getRingBuffer().tryNext();
+ } catch (InsufficientCapacityException e) {
+ return DOMNotificationPublishService.REJECTED;
+ }
+
+ return publish(seq, notification, subscribers);
+ }
+
+ @Override
+ public ListenableFuture<? extends Object> offerNotification(final DOMNotification notification) {
+ final Collection<ListenerRegistration<? extends DOMNotificationListener>> subscribers = listeners.get(notification.getType());
+ if (subscribers.isEmpty()) {
+ return NO_LISTENERS;
+ }
+
+ return tryPublish(notification, subscribers);
+ }
+
+ @Override
+ public ListenableFuture<? extends Object> offerNotification(final DOMNotification notification, final long timeout,
+ final TimeUnit unit) throws InterruptedException {
+ final Collection<ListenerRegistration<? extends DOMNotificationListener>> subscribers = listeners.get(notification.getType());
+ if (subscribers.isEmpty()) {
+ return NO_LISTENERS;
+ }
+
+ // Attempt to perform a non-blocking publish first
+ final ListenableFuture<? extends Object> noBlock = tryPublish(notification, subscribers);
+ if (!DOMNotificationPublishService.REJECTED.equals(noBlock)) {
+ return noBlock;
+ }
+
+ /*
+ * FIXME: we need a background thread, which will watch out for blocking too long. Here
+ * we will arm a tasklet for it and synchronize delivery of interrupt properly.
+ */
+ throw new UnsupportedOperationException("Not implemented yet");
+ }
+
+ @Override
+ public void close() {
+ disruptor.shutdown();
+ executor.shutdown();
+ }
+}
Code Review / controller.git / blobdiff