2 * Copyright (c) 2014 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.controller.md.sal.dom.api;
10 import com.google.common.util.concurrent.Futures;
11 import com.google.common.util.concurrent.ListenableFuture;
12 import java.util.concurrent.TimeUnit;
13 import javax.annotation.Nonnegative;
14 import javax.annotation.Nonnull;
17 * A {@link DOMService} which allows its user to send {@link DOMNotification}s. It
18 * provides two styles of initiating the notification delivery, similar to
19 * {@link java.util.concurrent.BlockingQueue}:
20 * - a put-style method which waits until the implementation can accept the notification
22 * - an offer-style method, which attempts to enqueue the notification, but allows
23 * the caller to specify that it should never wait, or put an upper bound on how
24 * long it is going to wait.
26 public interface DOMNotificationPublishService extends DOMService {
28 * Well-known value indicating that the implementation is currently not
29 * able to accept a notification.
31 ListenableFuture<Object> REJECTED = Futures.immediateFailedFuture(new Throwable("Unacceptable blocking conditions encountered"));
34 * Publish a notification. The result of this method is a {@link ListenableFuture}
35 * which will complete once the notification has been delivered to all immediate
36 * registrants. The type of the object resulting from the future is not defined
37 * and implementations may use it to convey additional information related to the
40 * Abstract subclasses can refine the return type as returning a promise of a
41 * more specific type, e.g.:
43 * public interface DeliveryStatus { int getListenerCount(); }
44 * ListenableFuture<? extends DeliveryStatus> putNotification(DOMNotification notification);
46 * Once the Future succeeds, the resulting object can be queried for traits using
49 * // Can block when (for example) the implemention's ThreadPool queue is full
50 * Object o = service.putNotification(notif).get();
51 * if (o instanceof DeliveryStatus) {
52 * DeliveryStatus ds = (DeliveryStatus)o;
53 * LOG.debug("Notification was received by {} listeners", ds.getListenerCount(););
57 * In case an implementation is running out of resources, it can block the calling
58 * thread until enough resources become available to accept the notification for
59 * processing, or it is interrupted.
61 * Caution: completion here means that the implementation has completed processing
62 * of the notification. This does not mean that all existing registrants
63 * have seen the notification. Most importantly, the delivery process at
64 * other cluster nodes may have not begun yet.
66 * @param notification Notification to be published.
67 * @return A listenable future which will report completion when the service
68 * has finished propagating the notification to its immediate registrants.
69 * @throws InterruptedException if interrupted while waiting
70 * @throws NullPointerException if notification is null.
72 @Nonnull ListenableFuture<? extends Object> putNotification(@Nonnull DOMNotification notification) throws InterruptedException;
75 * Attempt to publish a notification. The result of this method is a {@link ListenableFuture}
76 * which will complete once the notification has been delivered to all immediate
77 * registrants. The type of the object resulting from the future is not defined
78 * and implementations may use it to convey additional information related to the
79 * publishing process. Unlike {@link #putNotification(DOMNotification)}, this method
80 * is guaranteed not to block if the underlying implementation encounters contention.
82 * @param notification Notification to be published.
83 * @return A listenable future which will report completion when the service
84 * has finished propagating the notification to its immediate registrants,
85 * or {@value #REJECTED} if resource constraints prevent
86 * the implementation from accepting the notification for delivery.
87 * @throws NullPointerException if notification is null.
89 @Nonnull ListenableFuture<? extends Object> offerNotification(@Nonnull DOMNotification notification);
92 * Attempt to publish a notification. The result of this method is a {@link ListenableFuture}
93 * which will complete once the notification has been delivered to all immediate
94 * registrants. The type of the object resulting from the future is not defined
95 * and implementations may use it to convey additional information related to the
96 * publishing process. Unlike {@link #putNotification(DOMNotification)}, this method
97 * is guaranteed to block more than the specified timeout.
99 * @param notification Notification to be published.
100 * @param timeout how long to wait before giving up, in units of unit
101 * @param unit a TimeUnit determining how to interpret the timeout parameter
102 * @return A listenable future which will report completion when the service
103 * has finished propagating the notification to its immediate registrants,
104 * or {@value #REJECTED} if resource constraints prevent
105 * the implementation from accepting the notification for delivery.
106 * @throws InterruptedException if interrupted while waiting
107 * @throws NullPointerException if notification or unit is null.
108 * @throws IllegalArgumentException if timeout is negative.
110 @Nonnull ListenableFuture<? extends Object> offerNotification(@Nonnull DOMNotification notification,
111 @Nonnegative long timeout, @Nonnull TimeUnit unit) throws InterruptedException;