restconf/restconf-nb-rfc8040/src/main/java/org/opendaylight/restconf/nb/rfc8040/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.restconf.nb.rfc8040.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     private EventBusChangeRecorder eventBusChangeRecorder;
  31
  32     private volatile ListenerRegistration<?> registration;
  33
  34     /**
  35      * Creating {@link EventBus}.
  36      */
  37     AbstractCommonSubscriber() {
  38         this.eventBus = new AsyncEventBus(Executors.newSingleThreadExecutor());
  39     }
  40
  41     @Override
  42     public final boolean hasSubscribers() {
  43         return !this.subscribers.isEmpty();
  44     }
  45
  46     @Override
  47     public final Set<Channel> getSubscribers() {
  48         return this.subscribers;
  49     }
  50
  51     @Override
  52     public final void close() throws Exception {
  53         if (this.registration != null) {
  54             this.registration.close();
  55             this.registration = null;
  56         }
  57         deleteDataInDS();
  58         unregister();
  59     }
  60
  61     @Override
  62     public void addSubscriber(final Channel subscriber) {
  63         if (!subscriber.isActive()) {
  64             LOG.debug("Channel is not active between websocket server and subscriber {}", subscriber.remoteAddress());
  65         }
  66         final Event event = new Event(EventType.REGISTER);
  67         event.setSubscriber(subscriber);
  68         this.eventBus.post(event);
  69     }
  70
  71     @Override
  72     public void removeSubscriber(final Channel subscriber) {
  73         LOG.debug("Subscriber {} is removed.", subscriber.remoteAddress());
  74         final Event event = new Event(EventType.DEREGISTER);
  75         event.setSubscriber(subscriber);
  76         this.eventBus.post(event);
  77     }
  78
  79     @Override
  80     public void setRegistration(final ListenerRegistration<?> registration) {
  81         this.registration = registration;
  82     }
  83
  84     @Override
  85     public boolean isListening() {
  86         return this.registration != null;
  87     }
  88
  89     /**
  90      * Creating and registering {@link EventBusChangeRecorder} of specific
  91      * listener on {@link EventBus}.
  92      *
  93      * @param listener Specific listener of notifications.
  94      */
  95     @SuppressWarnings({"unchecked", "rawtypes"})
  96     <T extends BaseListenerInterface> void register(final T listener) {
  97         this.eventBusChangeRecorder = new EventBusChangeRecorder(listener);
  98         this.eventBus.register(this.eventBusChangeRecorder);
  99     }
 100
 101     /**
 102      * Post event to event bus.
 103      *
 104      * @param event Data of incoming notifications.
 105      */
 106     protected void post(final Event event) {
 107         this.eventBus.post(event);
 108     }
 109
 110     /**
 111      * Removes all subscribers and unregisters event bus change recorder form event bus.
 112      */
 113     private void unregister() {
 114         this.subscribers.clear();
 115         this.eventBus.unregister(this.eventBusChangeRecorder);
 116     }
 117 }