opendaylight/md-sal/sal-distributed-datastore/src/main/java/org/opendaylight/controller/cluster/datastore/DataChangeListenerSupport.java

   1 /*
   2  * Copyright (c) 2015 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.controller.cluster.datastore;
   9
  10 import com.google.common.base.Preconditions;
  11 import java.util.ArrayList;
  12 import java.util.List;
  13 import akka.actor.ActorRef;
  14 import akka.actor.ActorSelection;
  15 import org.opendaylight.controller.cluster.datastore.messages.EnableNotification;
  16 import org.opendaylight.controller.cluster.datastore.messages.RegisterChangeListener;
  17 import org.opendaylight.controller.cluster.datastore.messages.RegisterChangeListenerReply;
  18 import org.opendaylight.controller.md.sal.common.api.data.AsyncDataChangeListener;
  19 import org.opendaylight.yangtools.concepts.ListenerRegistration;
  20 import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier;
  21 import org.opendaylight.yangtools.yang.data.api.schema.NormalizedNode;
  22 import org.slf4j.Logger;
  23 import org.slf4j.LoggerFactory;
  24
  25 final class DataChangeListenerSupport extends LeaderLocalDelegateFactory<RegisterChangeListener, ListenerRegistration<AsyncDataChangeListener<YangInstanceIdentifier, NormalizedNode<?, ?>>>> {
  26     private static final Logger LOG = LoggerFactory.getLogger(DataChangeListenerSupport.class);
  27     private final List<DelayedListenerRegistration> delayedListenerRegistrations = new ArrayList<>();
  28     private final List<ActorSelection> dataChangeListeners =  new ArrayList<>();
  29     private final Shard shard;
  30
  31     DataChangeListenerSupport(final Shard shard) {
  32         this.shard = Preconditions.checkNotNull(shard);
  33     }
  34
  35     @Override
  36     void onLeadershipChange(final boolean isLeader) {
  37         for (ActorSelection dataChangeListener : dataChangeListeners) {
  38             dataChangeListener.tell(new EnableNotification(isLeader), shard.getSelf());
  39         }
  40
  41         if (isLeader) {
  42             for (DelayedListenerRegistration reg: delayedListenerRegistrations) {
  43                 if(!reg.isClosed()) {
  44                     reg.setDelegate(createDelegate(reg.getRegisterChangeListener()));
  45                 }
  46             }
  47
  48             delayedListenerRegistrations.clear();
  49         }
  50     }
  51
  52     @Override
  53     void onMessage(final RegisterChangeListener message, final boolean isLeader) {
  54
  55         LOG.debug("{}: registerDataChangeListener for {}, leader: {}", shard.persistenceId(), message.getPath(), isLeader);
  56
  57         ListenerRegistration<AsyncDataChangeListener<YangInstanceIdentifier,
  58                                                      NormalizedNode<?, ?>>> registration;
  59         if (isLeader) {
  60             registration = createDelegate(message);
  61         } else {
  62             LOG.debug("{}: Shard is not the leader - delaying registration", shard.persistenceId());
  63
  64             DelayedListenerRegistration delayedReg = new DelayedListenerRegistration(message);
  65             delayedListenerRegistrations.add(delayedReg);
  66             registration = delayedReg;
  67         }
  68
  69         ActorRef listenerRegistration = shard.getContext().actorOf(
  70                 DataChangeListenerRegistration.props(registration));
  71
  72         LOG.debug("{}: registerDataChangeListener sending reply, listenerRegistrationPath = {} ",
  73                 shard.persistenceId(), listenerRegistration.path());
  74
  75         shard.getSender().tell(new RegisterChangeListenerReply(listenerRegistration), shard.getSelf());
  76     }
  77
  78     @Override
  79     ListenerRegistration<AsyncDataChangeListener<YangInstanceIdentifier, NormalizedNode<?, ?>>> createDelegate(
  80             final RegisterChangeListener message) {
  81         ActorSelection dataChangeListenerPath = shard.getContext().system().actorSelection(
  82                 message.getDataChangeListenerPath());
  83
  84         // Notify the listener if notifications should be enabled or not
  85         // If this shard is the leader then it will enable notifications else
  86         // it will not
  87         dataChangeListenerPath.tell(new EnableNotification(true), shard.getSelf());
  88
  89         // Now store a reference to the data change listener so it can be notified
  90         // at a later point if notifications should be enabled or disabled
  91         dataChangeListeners.add(dataChangeListenerPath);
  92
  93         AsyncDataChangeListener<YangInstanceIdentifier, NormalizedNode<?, ?>> listener =
  94                 new DataChangeListenerProxy(dataChangeListenerPath);
  95
  96         LOG.debug("{}: Registering for path {}", shard.persistenceId(), message.getPath());
  97
  98         return shard.getDataStore().registerChangeListener(message.getPath(), listener,
  99                 message.getScope());
 100     }
 101 }