opendaylight/md-sal/sal-akka-raft-example/src/main/java/org/opendaylight/controller/cluster/example/ExampleRoleChangeListener.java

   1 /*
   2  * Copyright (c) 2014, 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
   9 package org.opendaylight.controller.cluster.example;
  10
  11 import akka.actor.ActorRef;
  12 import akka.actor.Cancellable;
  13 import akka.actor.Props;
  14 import java.util.HashMap;
  15 import java.util.Map;
  16 import java.util.concurrent.TimeUnit;
  17 import org.opendaylight.controller.cluster.common.actor.AbstractUntypedActor;
  18 import org.opendaylight.controller.cluster.example.messages.RegisterListener;
  19 import org.opendaylight.controller.cluster.notifications.RegisterRoleChangeListener;
  20 import org.opendaylight.controller.cluster.notifications.RegisterRoleChangeListenerReply;
  21 import org.opendaylight.controller.cluster.notifications.RoleChangeNotification;
  22 import scala.concurrent.Await;
  23 import scala.concurrent.duration.FiniteDuration;
  24
  25 /**
  26  * This is a sample implementation of a Role Change Listener which is an actor, which registers itself
  27  * to the ClusterRoleChangeNotifier.
  28  *
  29  * <p>
  30  * The Role Change listener receives a SetNotifiers message with the notifiers to register itself with.
  31  *
  32  * <p>
  33  * It kicks of a scheduler which sends registration messages to the notifiers, till it gets a
  34  *  RegisterRoleChangeListenerReply.
  35  *
  36  * <p>
  37  * If all the notifiers have been regsitered with, then it cancels the scheduler.
  38  * It starts the scheduler again when it receives a new registration
  39  */
  40 public class ExampleRoleChangeListener extends AbstractUntypedActor implements AutoCloseable {
  41     // the akka url should be set to the notifiers actor-system and domain.
  42     private static final String NOTIFIER_AKKA_URL = "akka://raft-test@127.0.0.1:2550/user/";
  43
  44     private final Map<String, Boolean> notifierRegistrationStatus = new HashMap<>();
  45     private Cancellable registrationSchedule = null;
  46     private static final FiniteDuration DURATION = new FiniteDuration(100, TimeUnit.MILLISECONDS);
  47     private static final FiniteDuration SCHEDULER_DURATION = new FiniteDuration(1, TimeUnit.SECONDS);
  48     private static final String[] SHARDS_TO_MONITOR = new String[] {"example"};
  49
  50     public ExampleRoleChangeListener(String memberName) {
  51         scheduleRegistrationListener(SCHEDULER_DURATION);
  52         populateRegistry(memberName);
  53     }
  54
  55     public static Props getProps(final String memberName) {
  56         return Props.create(ExampleRoleChangeListener.class, memberName);
  57     }
  58
  59     @Override
  60     protected void handleReceive(Object message) throws Exception {
  61         if (message instanceof RegisterListener) {
  62             // called by the scheduler at intervals to register any unregistered notifiers
  63             sendRegistrationRequests();
  64
  65         } else if (message instanceof RegisterRoleChangeListenerReply) {
  66             // called by the Notifier
  67             handleRegisterRoleChangeListenerReply(getSender().path().toString());
  68
  69         } else if (message instanceof RoleChangeNotification) {
  70             // called by the Notifier
  71             RoleChangeNotification notification = (RoleChangeNotification) message;
  72
  73             LOG.info("Role Change Notification received for member:{}, old role:{}, new role:{}",
  74                 notification.getMemberId(), notification.getOldRole(), notification.getNewRole());
  75
  76             // the apps dependent on such notifications can be called here
  77             //TODO: add implementation here
  78
  79         }
  80     }
  81
  82     private void scheduleRegistrationListener(FiniteDuration interval) {
  83         LOG.debug("--->scheduleRegistrationListener called.");
  84         registrationSchedule = getContext().system().scheduler().schedule(
  85             interval, interval, getSelf(), new RegisterListener(),
  86             getContext().system().dispatcher(), getSelf());
  87
  88     }
  89
  90     private void populateRegistry(String memberName) {
  91         for (String shard: SHARDS_TO_MONITOR) {
  92             String notifier = new StringBuilder().append(NOTIFIER_AKKA_URL).append(memberName)
  93                 .append("/").append(memberName).append("-notifier").toString();
  94
  95             if (!notifierRegistrationStatus.containsKey(notifier)) {
  96                 notifierRegistrationStatus.put(notifier, false);
  97             }
  98         }
  99
 100         if (!registrationSchedule.isCancelled()) {
 101             scheduleRegistrationListener(SCHEDULER_DURATION);
 102         }
 103     }
 104
 105     @SuppressWarnings("checkstyle:IllegalCatch")
 106     private void sendRegistrationRequests() {
 107         for (Map.Entry<String, Boolean> entry : notifierRegistrationStatus.entrySet()) {
 108             if (!entry.getValue()) {
 109                 try {
 110                     LOG.debug("{} registering with {}", getSelf().path().toString(), entry.getKey());
 111                     ActorRef notifier = Await.result(
 112                         getContext().actorSelection(entry.getKey()).resolveOne(DURATION), DURATION);
 113
 114                     notifier.tell(new RegisterRoleChangeListener(), getSelf());
 115
 116                 } catch (Exception e) {
 117                     LOG.error("ERROR!! Unable to send registration request to notifier {}", entry.getKey());
 118                 }
 119             }
 120         }
 121     }
 122
 123     private void handleRegisterRoleChangeListenerReply(String senderId) {
 124         if (notifierRegistrationStatus.containsKey(senderId)) {
 125             notifierRegistrationStatus.put(senderId, true);
 126
 127             //cancel the schedule when listener is registered with all notifiers
 128             if (!registrationSchedule.isCancelled()) {
 129                 boolean cancelScheduler = true;
 130                 for (Boolean value : notifierRegistrationStatus.values()) {
 131                     cancelScheduler = cancelScheduler & value;
 132                 }
 133                 if (cancelScheduler) {
 134                     registrationSchedule.cancel();
 135                 }
 136             }
 137         } else {
 138             LOG.info(
 139                 "Unexpected, RegisterRoleChangeListenerReply received from notifier which is not known to Listener:{}",
 140                 senderId);
 141         }
 142     }
 143
 144
 145     @Override
 146     public void close() throws Exception {
 147         registrationSchedule.cancel();
 148     }
 149 }