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

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