2 * Copyright (c) 2013 Cisco Systems, Inc. and others. All rights reserved.
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
8 package org.opendaylight.yangtools.util;
10 import static java.util.Objects.requireNonNull;
12 import com.google.common.base.MoreObjects;
13 import java.util.Collection;
14 import java.util.Collections;
15 import java.util.EventListener;
17 import java.util.concurrent.ConcurrentHashMap;
18 import java.util.stream.Stream;
19 import org.eclipse.jdt.annotation.NonNull;
20 import org.opendaylight.yangtools.concepts.AbstractListenerRegistration;
21 import org.opendaylight.yangtools.concepts.ListenerRegistration;
22 import org.opendaylight.yangtools.concepts.Mutable;
25 * A registry of EventListeners, maintaining a set of registrations. This class is thread-safe.
27 * @param <T> Type of listeners this registry handles
29 public final class ListenerRegistry<T extends EventListener> implements Mutable {
30 private final Set<RegistrationImpl<? extends T>> listeners = ConcurrentHashMap.newKeySet();
31 // This conversion is known to be safe.
32 @SuppressWarnings({ "rawtypes", "unchecked" })
33 private final Set<ListenerRegistration<T>> unmodifiableView = (Set) Collections.unmodifiableSet(listeners);
35 private final String name;
37 private ListenerRegistry(final String name) {
41 public static <T extends EventListener> @NonNull ListenerRegistry<T> create() {
42 return new ListenerRegistry<>(null);
45 public static <T extends EventListener> @NonNull ListenerRegistry<T> create(final @NonNull String name) {
46 return new ListenerRegistry<>(requireNonNull(name));
49 @Deprecated(forRemoval = true)
50 public @NonNull Set<? extends ListenerRegistration<? extends T>> getRegistrations() {
51 return unmodifiableView;
55 listeners.stream().forEach(RegistrationImpl::close);
58 public boolean isEmpty() {
59 return listeners.isEmpty();
62 public Stream<? extends T> streamListeners() {
63 return listeners.stream().filter(RegistrationImpl::notClosed).map(RegistrationImpl::getInstance);
66 public <L extends T> @NonNull ListenerRegistration<L> register(final L listener) {
67 final RegistrationImpl<L> ret = new RegistrationImpl<>(listener, listeners);
73 public String toString() {
74 return MoreObjects.toStringHelper(this).omitNullValues()
76 .add("size", listeners.size())
80 private static final class RegistrationImpl<T extends EventListener> extends AbstractListenerRegistration<T> {
81 private Collection<?> removeFrom;
83 RegistrationImpl(final T instance, final Collection<?> removeFrom) {
85 this.removeFrom = requireNonNull(removeFrom);
89 protected void removeRegistration() {
90 removeFrom.remove(this);
91 // Do not retain reference to that state