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 io.netty.util.internal.ConcurrentSet;
  14 import java.util.Set;
  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 = new ConcurrentSet<>();
  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         this.registration.close();
  55         this.registration = null;
  56         unregister();
  57     }
  58
  59     /**
  60      * Creates event of type {@link EventType#REGISTER}, set {@link Channel}
  61      * subscriber to the event and post event into event bus.
  62      *
  63      * @param subscriber
  64      *            Channel
  65      */
  66     public void addSubscriber(final Channel subscriber) {
  67         if (!subscriber.isActive()) {
  68             LOG.debug("Channel is not active between websocket server and subscriber {}", subscriber.remoteAddress());
  69         }
  70         final Event event = new Event(EventType.REGISTER);
  71         event.setSubscriber(subscriber);
  72         this.eventBus.post(event);
  73     }
  74
  75     /**
  76      * Creates event of type {@link EventType#DEREGISTER}, sets {@link Channel}
  77      * subscriber to the event and posts event into event bus.
  78      *
  79      * @param subscriber subscriber channel
  80      */
  81     public void removeSubscriber(final Channel subscriber) {
  82         LOG.debug("Subscriber {} is removed.", subscriber.remoteAddress());
  83         final Event event = new Event(EventType.DEREGISTER);
  84         event.setSubscriber(subscriber);
  85         this.eventBus.post(event);
  86     }
  87
  88     /**
  89      * Sets {@link ListenerRegistration} registration.
  90      *
  91      * @param registration
  92      *            DOMDataChangeListener registration
  93      */
  94     @SuppressWarnings("rawtypes")
  95     public void setRegistration(final ListenerRegistration registration) {
  96         this.registration = registration;
  97     }
  98
  99     /**
 100      * Checks if {@link ListenerRegistration} registration exist.
 101      *
 102      * @return True if exist, false otherwise.
 103      */
 104     public boolean isListening() {
 105         return this.registration != null;
 106     }
 107
 108     /**
 109      * Creating and registering {@link EventBusChangeRecorder} of specific
 110      * listener on {@link EventBus}.
 111      *
 112      * @param listener
 113      *            specific listener of notifications
 114      */
 115     @SuppressWarnings({ "unchecked", "rawtypes" })
 116     protected <T extends BaseListenerInterface> void register(final T listener) {
 117         this.eventBusChangeRecorder = new EventBusChangeRecorder(listener);
 118         this.eventBus.register(this.eventBusChangeRecorder);
 119     }
 120
 121     /**
 122      * Post event to event bus.
 123      *
 124      * @param event
 125      *            data of incoming notifications
 126      */
 127     protected void post(final Event event) {
 128         this.eventBus.post(event);
 129     }
 130
 131     /**
 132      * Removes all subscribers and unregisters event bus change recorder form
 133      * event bus.
 134      */
 135     protected void unregister() {
 136         this.subscribers.clear();
 137         this.eventBus.unregister(this.eventBusChangeRecorder);
 138     }
 139 }