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

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