restconf/restconf-nb-bierman02/src/main/java/org/opendaylight/netconf/sal/streams/listeners/AbstractCommonSubscriber.java

   1 /*
   2  * Copyright (c) 2016 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.netconf.sal.streams.listeners;
   9
  10 import com.google.common.eventbus.AsyncEventBus;
  11 import com.google.common.eventbus.EventBus;
  12 import io.netty.channel.Channel;
  13 import java.util.Set;
  14 import java.util.concurrent.ConcurrentHashMap;
  15 import java.util.concurrent.Executors;
  16 import org.opendaylight.yangtools.concepts.ListenerRegistration;
  17 import org.slf4j.Logger;
  18 import org.slf4j.LoggerFactory;
  19
  20 /**
  21  * Features of subscribing part of both notifications.
  22  */
  23 abstract class AbstractCommonSubscriber extends AbstractQueryParams implements BaseListenerInterface {
  24
  25     private static final Logger LOG = LoggerFactory.getLogger(AbstractCommonSubscriber.class);
  26
  27     private final Set<Channel> subscribers = ConcurrentHashMap.newKeySet();
  28     private final EventBus eventBus;
  29
  30     @SuppressWarnings("rawtypes")
  31     private EventBusChangeRecorder eventBusChangeRecorder;
  32     @SuppressWarnings("rawtypes")
  33     private ListenerRegistration registration;
  34
  35     /**
  36      * Creating {@link EventBus}.
  37      */
  38     protected AbstractCommonSubscriber() {
  39         this.eventBus = new AsyncEventBus(Executors.newSingleThreadExecutor());
  40     }
  41
  42     @Override
  43     public final boolean hasSubscribers() {
  44         return !this.subscribers.isEmpty();
  45     }
  46
  47     @Override
  48     public final Set<Channel> getSubscribers() {
  49         return this.subscribers;
  50     }
  51
  52     @Override
  53     public final void close() {
  54         if (registration != null) {
  55             this.registration.close();
  56             this.registration = null;
  57         }
  58
  59         unregister();
  60     }
  61
  62     /**
  63      * Creates event of type {@link EventType#REGISTER}, set {@link Channel}
  64      * subscriber to the event and post event into event bus.
  65      *
  66      * @param subscriber
  67      *            Channel
  68      */
  69     public void addSubscriber(final Channel subscriber) {
  70         if (!subscriber.isActive()) {
  71             LOG.debug("Channel is not active between websocket server and subscriber {}", subscriber.remoteAddress());
  72         }
  73         final Event event = new Event(EventType.REGISTER);
  74         event.setSubscriber(subscriber);
  75         this.eventBus.post(event);
  76     }
  77
  78     /**
  79      * Creates event of type {@link EventType#DEREGISTER}, sets {@link Channel}
  80      * subscriber to the event and posts event into event bus.
  81      *
  82      * @param subscriber subscriber channel
  83      */
  84     public void removeSubscriber(final Channel subscriber) {
  85         LOG.debug("Subscriber {} is removed.", subscriber.remoteAddress());
  86         final Event event = new Event(EventType.DEREGISTER);
  87         event.setSubscriber(subscriber);
  88         this.eventBus.post(event);
  89     }
  90
  91     /**
  92      * Sets {@link ListenerRegistration} registration.
  93      *
  94      * @param registration
  95      *            DOMDataChangeListener registration
  96      */
  97     @SuppressWarnings("rawtypes")
  98     public void setRegistration(final ListenerRegistration registration) {
  99         this.registration = registration;
 100     }
 101
 102     /**
 103      * Checks if {@link ListenerRegistration} registration exist.
 104      *
 105      * @return True if exist, false otherwise.
 106      */
 107     public boolean isListening() {
 108         return this.registration != null;
 109     }
 110
 111     /**
 112      * Creating and registering {@link EventBusChangeRecorder} of specific
 113      * listener on {@link EventBus}.
 114      *
 115      * @param listener
 116      *            specific listener of notifications
 117      */
 118     @SuppressWarnings({ "unchecked", "rawtypes" })
 119     protected <T extends BaseListenerInterface> void register(final T listener) {
 120         this.eventBusChangeRecorder = new EventBusChangeRecorder(listener);
 121         this.eventBus.register(this.eventBusChangeRecorder);
 122     }
 123
 124     /**
 125      * Post event to event bus.
 126      *
 127      * @param event
 128      *            data of incoming notifications
 129      */
 130     protected void post(final Event event) {
 131         this.eventBus.post(event);
 132     }
 133
 134     /**
 135      * Removes all subscribers and unregisters event bus change recorder form
 136      * event bus.
 137      */
 138     protected void unregister() {
 139         this.subscribers.clear();
 140         this.eventBus.unregister(this.eventBusChangeRecorder);
 141     }
 142 }