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Java example source code file (ClusterListener.java)

This example Java source code file (ClusterListener.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

arraylist, cancellable, clusterlistener, list, loggingadapter, member, memberevent, memberremoved, memberup, override, string, subscribed, topics, unreachablemember, util

The ClusterListener.java Java example source code

/*
 *
 *  * Copyright 2015 Skymind,Inc.
 *  *
 *  *    Licensed under the Apache License, Version 2.0 (the "License");
 *  *    you may not use this file except in compliance with the License.
 *  *    You may obtain a copy of the License at
 *  *
 *  *        http://www.apache.org/licenses/LICENSE-2.0
 *  *
 *  *    Unless required by applicable law or agreed to in writing, software
 *  *    distributed under the License is distributed on an "AS IS" BASIS,
 *  *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  *    See the License for the specific language governing permissions and
 *  *    limitations under the License.
 *
 */

package org.deeplearning4j.scaleout.actor.core;

import java.util.ArrayList;
import java.util.List;

import akka.actor.ActorRef;
import akka.actor.Cancellable;
import akka.actor.UntypedActor;
import akka.cluster.Cluster;
import akka.cluster.ClusterEvent.MemberEvent;
import akka.cluster.ClusterEvent.MemberRemoved;
import akka.cluster.ClusterEvent.MemberUp;
import akka.cluster.ClusterEvent.UnreachableMember;
import akka.contrib.pattern.DistributedPubSubExtension;
import akka.contrib.pattern.DistributedPubSubMediator;
import akka.event.Logging;
import akka.event.LoggingAdapter;

public class ClusterListener extends UntypedActor {
	LoggingAdapter log = Logging.getLogger(getContext().system(), this);
	Cluster cluster = Cluster.get(getContext().system());
	protected ActorRef mediator = DistributedPubSubExtension.get(getContext().system()).mediator();
	public final static String TOPICS = "topics";
	private List<String> topics = new ArrayList();
	private Cancellable topicTask;
	//subscribe to cluster changes
	@Override
	public void preStart() {
		//#subscribe
		cluster.subscribe(getSelf(), MemberEvent.class);
		//replicate the network
		mediator.tell(new DistributedPubSubMediator.Subscribe(TOPICS,getSelf()), getSelf());
		log.info("Subscribed to cluster events");
		/*topicTask = context().system().scheduler().schedule(Duration.createComplex(10,TimeUnit.SECONDS), Duration.createComplex(10,TimeUnit.SECONDS), new Runnable() {

			@Override
			public void run() {
				log.info("Current topics " + topics);
				//reply
				mediator.tell(new DistributedPubSubMediator.Publish(ClusterListener.TOPICS,
						topics), getSelf());
			}

		}, context().dispatcher());
		 */


		//#subscribe
	}

	//re-subscribe when restart
	@Override
	public void postStop() {
		cluster.unsubscribe(getSelf());
		log.info("UnSubscribed to cluster events");
		if(topicTask != null)
			topicTask.cancel();


	}

	@Override
	public void onReceive(Object message) {
		if (message instanceof MemberUp) {
			MemberUp mUp = (MemberUp) message;
			log.info("Member is Up: {}", mUp.member());

		} else if (message instanceof UnreachableMember) {
			UnreachableMember mUnreachable = (UnreachableMember) message;
			log.info("Member detected as unreachable: {}", mUnreachable.member());

		} else if (message instanceof MemberRemoved) {
			MemberRemoved mRemoved = (MemberRemoved) message;
			log.info("Member is Removed: {}", mRemoved.member());

		} else if (message instanceof MemberEvent) {
			// ignore

		} 

		else if(message instanceof DistributedPubSubMediator.SubscribeAck) {
			DistributedPubSubMediator.SubscribeAck ack = (DistributedPubSubMediator.SubscribeAck) message;
			topics.add(ack.subscribe().topic());
		}

		else if(message instanceof DistributedPubSubMediator.UnsubscribeAck) {
			DistributedPubSubMediator.UnsubscribeAck unsub = (DistributedPubSubMediator.UnsubscribeAck) message;
			topics.remove(unsub.unsubscribe().topic());
		}

		else if(message instanceof List) {
			log.info("Topics sent " + message);
		}


		else {
			unhandled(message);
		}

	}
}

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