/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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.apache.stratos.load.balancer.extension.api;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.stratos.load.balancer.common.statistics.LoadBalancerStatisticsReader;
import org.apache.stratos.load.balancer.common.statistics.notifier.LoadBalancerStatisticsNotifier;
import org.apache.stratos.messaging.event.Event;
import org.apache.stratos.messaging.listener.topology.*;
import org.apache.stratos.messaging.message.receiver.topology.TopologyEventReceiver;
import org.apache.stratos.messaging.message.receiver.topology.TopologyManager;
/**
* Load balancer extension thread for executing load balancer life-cycle according to the topology updates
* received from the message broker.
*/
public class LoadBalancerExtension implements Runnable {
private static final Log log = LogFactory.getLog(LoadBalancerExtension.class);
private LoadBalancer loadBalancer;
private LoadBalancerStatisticsReader statsReader;
private boolean loadBalancerStarted;
private TopologyEventReceiver topologyEventReceiver;
private LoadBalancerStatisticsNotifier statisticsNotifier;
private boolean terminated;
/**
* Load balancer extension constructor.
* @param loadBalancer Load balancer instance: Mandatory.
* @param statsReader Statistics reader: If null statistics notifier thread will not be started.
*/
public LoadBalancerExtension(LoadBalancer loadBalancer, LoadBalancerStatisticsReader statsReader) {
this.loadBalancer = loadBalancer;
this.statsReader = statsReader;
}
@Override
public void run() {
try {
if(log.isInfoEnabled()) {
log.info("Load balancer extension started");
}
// Start topology receiver thread
topologyEventReceiver = new TopologyEventReceiver();
addEventListeners();
Thread topologyReceiverThread = new Thread(topologyEventReceiver);
topologyReceiverThread.start();
if(statsReader != null) {
// Start stats notifier thread
statisticsNotifier = new LoadBalancerStatisticsNotifier(statsReader);
Thread statsNotifierThread = new Thread(statisticsNotifier);
statsNotifierThread.start();
}
else {
if(log.isWarnEnabled()) {
log.warn("Load balancer statistics reader not found");
}
}
// Keep the thread live until terminated
while (!terminated);
} catch (Exception e) {
if (log.isErrorEnabled()) {
log.error("Could not start load balancer extension", e);
}
}
}
private void addEventListeners() {
topologyEventReceiver.addEventListener(new CompleteTopologyEventListener() {
@Override
protected void onEvent(Event event) {
try {
// Configure load balancer
loadBalancer.configure(TopologyManager.getTopology());
// Start load balancer
loadBalancer.start();
loadBalancerStarted = true;
} catch (Exception e) {
if (log.isErrorEnabled()) {
log.error("Could not start load balancer", e);
}
terminate();
}
}
});
topologyEventReceiver.addEventListener(new MemberActivatedEventListener() {
@Override
protected void onEvent(Event event) {
reloadConfiguration();
}
});
topologyEventReceiver.addEventListener(new MemberSuspendedEventListener() {
@Override
protected void onEvent(Event event) {
reloadConfiguration();
}
});
topologyEventReceiver.addEventListener(new MemberTerminatedEventListener() {
@Override
protected void onEvent(Event event) {
reloadConfiguration();
}
});
topologyEventReceiver.addEventListener(new ClusterRemovedEventListener() {
@Override
protected void onEvent(Event event) {
reloadConfiguration();
}
});
topologyEventReceiver.addEventListener(new ServiceRemovedEventListener() {
@Override
protected void onEvent(Event event) {
reloadConfiguration();
}
});
}
private void reloadConfiguration() {
try {
if (loadBalancerStarted) {
loadBalancer.reload(TopologyManager.getTopology());
}
} catch (Exception e) {
if (log.isErrorEnabled()) {
log.error("Could not reload load balancer configuration", e);
}
}
}
public void terminate() {
if(topologyEventReceiver != null) {
topologyEventReceiver.terminate();
}
if(statisticsNotifier != null) {
statisticsNotifier.terminate();
}
terminated = true;
}
}