/*
* Copyright (C) 2008 Yohan Liyanage.
*
* 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.nebulaframework.grid.cluster.manager.services.heartbeat;
import java.util.UUID;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.nebulaframework.grid.cluster.manager.ClusterManager;
import org.nebulaframework.grid.service.message.ServiceMessage;
import org.nebulaframework.grid.service.message.ServiceMessageType;
/**
* HeartBeatTracker keeps track of HeartBeats from a specific
* {@code GridNode}, and if more than {@link ClusterHeartBeatService#MAX_MISS}
* heartbeats are missed, it dispatches a {@link ServiceMessage}
* notifying that a {@link ServiceMessageType#HEARTBEAT_FAILED} has
* occurred for the given {@code GridNode}.
*
* @author Yohan Liyanage
* @version 1.0
*/
class HeartBeatTracker implements Runnable {
private static Log log = LogFactory.getLog(HeartBeatTracker.class);
private UUID nodeId;
private long lastBeat = System.currentTimeMillis();
private int missed = 0;
private boolean stopped = false;
/**
* Constructs a {@code HeartBeatTracker} which is to
* track the heartbeats from a {@code GridNode} with
* given nodeId
*
* @param nodeId {@code GridNode} id
*/
public HeartBeatTracker(UUID nodeId) {
super();
this.nodeId = nodeId;
}
/**
* Checks for HeartBeats and notifies if heartbeats
* have missed for more than {@link ClusterHeartBeatService#MAX_MISS}.
* <p>
* Executed on a separate thread.
*/
public void run() {
while (!stopped) {
// Remember time before sleeping
long sleepTime = System.currentTimeMillis();
try {
// Sleep for BEAT_PERIOD
Thread.sleep(ClusterHeartBeatService.BEAT_PERIOD);
} catch (InterruptedException e) {
log.warn("Heartbeat Sleep Interrupted", e);
continue;
}
// Check if stopped during sleep
if (stopped)
break;
// If no new beat during sleep time
if (lastBeat - sleepTime < 0) {
missed++;
// If missed more than MAX_MISS, notify
if (missed > ClusterHeartBeatService.MAX_MISS) {
ServiceMessage message = new ServiceMessage(nodeId
.toString(), ServiceMessageType.HEARTBEAT_FAILED);
ClusterManager.getInstance().getServiceMessageSender()
.sendServiceMessage(message);
log.warn("[Heartbeat] Heartbeat Failed on " + nodeId.toString());
stop();
}
}
}
}
/**
* Invoked to notify that a new heartbeat has received
* from the {@code GridNode} of this {@code HeartBeatTracker}.
*/
public void notifyBeat() {
lastBeat = System.currentTimeMillis();
missed = 0;
}
/**
* Starts the {@code HeartBeatTracker}.
*/
public void start() {
Thread beatThread = new Thread(this, "HeartBeatTracker-"
+ nodeId.toString());
beatThread.setDaemon(true);
beatThread.setPriority(Thread.MAX_PRIORITY);
beatThread.start();
log.debug("[HeartBeat] Started Tracking : " + nodeId);
}
/**
* Stops the {@code HeartBeatTracker}.
*/
public void stop() {
log.debug("[HeartBeat] Stopped Tracking : " + nodeId);
this.stopped = true;
}
}