import com.lmax.disruptor.WaitStrategy;
import com.lmax.disruptor.dsl.Disruptor;
import com.lmax.disruptor.dsl.ProducerType;
+import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
import java.util.Arrays;
import java.util.Collection;
import java.util.List;
* Joint implementation of {@link DOMNotificationPublishService} and {@link DOMNotificationService}. Provides
* routing of notifications from publishers to subscribers.
*
+ * <p>
* 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)}
+ * <p>
+ * 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.
*/
+@SuppressFBWarnings(value = "NP_NONNULL_PARAM_VIOLATION", justification = "Void is the only allowed value")
public final class DOMNotificationRouter implements AutoCloseable, DOMNotificationPublishService,
DOMNotificationService, DOMNotificationSubscriptionListenerRegistry {
private static final Logger LOG = LoggerFactory.getLogger(DOMNotificationRouter.class);
private static final ListenableFuture<Void> NO_LISTENERS = Futures.immediateFuture(null);
- private static final WaitStrategy DEFAULT_STRATEGY = PhasedBackoffWaitStrategy.withLock(1L, 30L, TimeUnit.MILLISECONDS);
- private static final EventHandler<DOMNotificationRouterEvent> DISPATCH_NOTIFICATIONS =
- (event, sequence, endOfBatch) -> event.deliverNotification();
- private static final EventHandler<DOMNotificationRouterEvent> NOTIFY_FUTURE =
- (event, sequence, endOfBatch) -> event.setFuture();
+ private static final WaitStrategy DEFAULT_STRATEGY = PhasedBackoffWaitStrategy
+ .withLock(1L, 30L, TimeUnit.MILLISECONDS);
+ private static final EventHandler<DOMNotificationRouterEvent> DISPATCH_NOTIFICATIONS
+ = (event, sequence, endOfBatch) -> event.deliverNotification();
+ private static final EventHandler<DOMNotificationRouterEvent> NOTIFY_FUTURE = (event, sequence, endOfBatch) -> event
+ .setFuture();
private final Disruptor<DOMNotificationRouterEvent> disruptor;
private final ExecutorService executor;
- private volatile Multimap<SchemaPath, ListenerRegistration<? extends DOMNotificationListener>> listeners = ImmutableMultimap.of();
- private final ListenerRegistry<DOMNotificationSubscriptionListener> subscriptionListeners = ListenerRegistry.create();
+ private volatile Multimap<SchemaPath, ListenerRegistration<? extends DOMNotificationListener>> listeners
+ = ImmutableMultimap.of();
+ private final ListenerRegistry<DOMNotificationSubscriptionListener> subscriptionListeners = ListenerRegistry
+ .create();
@SuppressWarnings("unchecked")
private DOMNotificationRouter(final ExecutorService executor, final int queueDepth, final WaitStrategy strategy) {
this.executor = Preconditions.checkNotNull(executor);
- disruptor = new Disruptor<>(DOMNotificationRouterEvent.FACTORY, queueDepth, executor, ProducerType.MULTI, strategy);
+ disruptor = new Disruptor<>(DOMNotificationRouterEvent.FACTORY, queueDepth, executor, ProducerType.MULTI,
+ strategy);
disruptor.handleEventsWith(DISPATCH_NOTIFICATIONS);
disruptor.after(DISPATCH_NOTIFICATIONS).handleEventsWith(NOTIFY_FUTURE);
disruptor.start();
return new DOMNotificationRouter(executor, queueDepth, DEFAULT_STRATEGY);
}
- public static DOMNotificationRouter create(final int queueDepth, final long spinTime, final long parkTime, final TimeUnit unit) {
+ public static DOMNotificationRouter create(final int queueDepth, final long spinTime, final long parkTime,
+ final TimeUnit unit) {
Preconditions.checkArgument(Long.lowestOneBit(queueDepth) == Long.highestOneBit(queueDepth),
- "Queue depth %s is not power-of-two", queueDepth);
+ "Queue depth %s is not power-of-two", queueDepth);
final ExecutorService executor = Executors.newCachedThreadPool();
final WaitStrategy strategy = PhasedBackoffWaitStrategy.withLock(spinTime, parkTime, unit);
}
@Override
- public synchronized <T extends DOMNotificationListener> ListenerRegistration<T> registerNotificationListener(final T listener, final Collection<SchemaPath> types) {
+ 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() {
};
if (!types.isEmpty()) {
- final Builder<SchemaPath, ListenerRegistration<? extends DOMNotificationListener>> b = ImmutableMultimap.builder();
+ final Builder<SchemaPath, ListenerRegistration<? extends DOMNotificationListener>> b = ImmutableMultimap
+ .builder();
b.putAll(listeners);
for (final SchemaPath t : types) {
}
@Override
- public <T extends DOMNotificationListener> ListenerRegistration<T> registerNotificationListener(final T listener, final SchemaPath... types) {
+ public <T extends DOMNotificationListener> ListenerRegistration<T> registerNotificationListener(final T listener,
+ final
+ SchemaPath...
+ types) {
return registerNotificationListener(listener, Arrays.asList(types));
}
/**
- * Swaps registered listeners and triggers notification update
+ * Swaps registered listeners and triggers notification update.
*
- * @param newListeners
+ * @param newListeners listeners
*/
private void replaceListeners(
final Multimap<SchemaPath, ListenerRegistration<? extends DOMNotificationListener>> newListeners) {
notifyListenerTypesChanged(newListeners.keySet());
}
+ @SuppressWarnings("checkstyle:IllegalCatch")
private void notifyListenerTypesChanged(final Set<SchemaPath> typesAfter) {
- final List<ListenerRegistration<DOMNotificationSubscriptionListener>> listenersAfter =ImmutableList.copyOf(subscriptionListeners.getListeners());
- executor.submit(() -> {
+ final List<ListenerRegistration<DOMNotificationSubscriptionListener>> listenersAfter = ImmutableList
+ .copyOf(subscriptionListeners.getListeners());
+ executor.execute(() -> {
for (final ListenerRegistration<DOMNotificationSubscriptionListener> subListener : listenersAfter) {
try {
subListener.getInstance().onSubscriptionChanged(typesAfter);
public <L extends DOMNotificationSubscriptionListener> ListenerRegistration<L> registerSubscriptionListener(
final L listener) {
final Set<SchemaPath> initialTypes = listeners.keySet();
- executor.submit(() -> listener.onSubscriptionChanged(initialTypes));
+ executor.execute(() -> listener.onSubscriptionChanged(initialTypes));
return subscriptionListeners.registerWithType(listener);
}
- private ListenableFuture<Void> publish(final long seq, final DOMNotification notification, final Collection<ListenerRegistration<? extends DOMNotificationListener>> subscribers) {
+ 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);
@Override
public ListenableFuture<?> putNotification(final DOMNotification notification) throws InterruptedException {
- final Collection<ListenerRegistration<? extends DOMNotificationListener>> subscribers = listeners.get(notification.getType());
+ final Collection<ListenerRegistration<? extends DOMNotificationListener>> subscribers = listeners
+ .get(notification.getType());
if (subscribers.isEmpty()) {
return NO_LISTENERS;
}
return publish(seq, notification, subscribers);
}
- private ListenableFuture<?> tryPublish(final DOMNotification notification, final Collection<ListenerRegistration<? extends DOMNotificationListener>> subscribers) {
+ private ListenableFuture<?> tryPublish(final DOMNotification notification,
+ final Collection<ListenerRegistration<? extends DOMNotificationListener>>
+ subscribers) {
final long seq;
try {
- seq = disruptor.getRingBuffer().tryNext();
+ seq = disruptor.getRingBuffer().tryNext();
} catch (final InsufficientCapacityException e) {
return DOMNotificationPublishService.REJECTED;
}
@Override
public ListenableFuture<?> offerNotification(final DOMNotification notification) {
- final Collection<ListenerRegistration<? extends DOMNotificationListener>> subscribers = listeners.get(notification.getType());
+ final Collection<ListenerRegistration<? extends DOMNotificationListener>> subscribers = listeners
+ .get(notification.getType());
if (subscribers.isEmpty()) {
return NO_LISTENERS;
}
@Override
public ListenableFuture<?> offerNotification(final DOMNotification notification, final long timeout,
- final TimeUnit unit) throws InterruptedException {
- final Collection<ListenerRegistration<? extends DOMNotificationListener>> subscribers = listeners.get(notification.getType());
+ final TimeUnit unit) throws InterruptedException {
+ final Collection<ListenerRegistration<? extends DOMNotificationListener>> subscribers = listeners
+ .get(notification.getType());
if (subscribers.isEmpty()) {
return NO_LISTENERS;
}