making HealthStatEventReceiver singleton and fixing references in com…

…ponents

components/org.apache.stratos.autoscaler/src/main/java/org/apache/stratos/autoscaler/event/receiver/health/AutoscalerHealthStatEventReceiver.java

@@ -45,18 +45,18 @@ public class AutoscalerHealthStatEventReceiver {
  private ExecutorService executorService;
 
  public AutoscalerHealthStatEventReceiver() {
- this.healthStatEventReceiver = new HealthStatEventReceiver();
+ this.healthStatEventReceiver = HealthStatEventReceiver.getInstance();
  addEventListeners();
  }
 
- public void execute() {
- healthStatEventReceiver.setExecutorService(executorService);
- healthStatEventReceiver.execute();
-
- if (log.isInfoEnabled()) {
- log.info("Autoscaler health stat event receiver thread started");
- }
- }
+// public void execute() {
+// healthStatEventReceiver.setExecutorService(executorService);
+// healthStatEventReceiver.execute();
+//
+// if (log.isInfoEnabled()) {
+// log.info("Autoscaler health stat event receiver thread started");
+// }
+// }
 
  private void addEventListeners() {
  // Listen to health stat events that affect clusters

components/org.apache.stratos.autoscaler/src/main/java/org/apache/stratos/autoscaler/internal/AutoscalerServiceComponent.java

@@ -181,8 +181,8 @@ private void executeCoordinatorTasks()
 
  // Start health stat receiver
  autoscalerHealthStatEventReceiver = new AutoscalerHealthStatEventReceiver();
- autoscalerHealthStatEventReceiver.setExecutorService(executorService);
- autoscalerHealthStatEventReceiver.execute();
+// autoscalerHealthStatEventReceiver.setExecutorService(executorService);
+// autoscalerHealthStatEventReceiver.execute();
  if (log.isDebugEnabled()) {
  log.debug("Health statistics receiver thread started");
  }

components/org.apache.stratos.messaging/src/main/java/org/apache/stratos/messaging/message/receiver/health/stat/HealthStatEventReceiver.java

@@ -21,36 +21,52 @@
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
+import org.apache.stratos.common.threading.StratosThreadPool;
 import org.apache.stratos.messaging.broker.subscribe.EventSubscriber;
 import org.apache.stratos.messaging.listener.EventListener;
+import org.apache.stratos.messaging.message.receiver.StratosEventReceiver;
 import org.apache.stratos.messaging.util.MessagingUtil;
 
 import java.util.concurrent.ExecutorService;
 
 /**
  * A thread for receiving health stat information from message broker
  */
-public class HealthStatEventReceiver {
+public class HealthStatEventReceiver extends StratosEventReceiver {
  private static final Log log = LogFactory.getLog(HealthStatEventReceiver.class);
 
  private final HealthStatEventMessageDelegator messageDelegator;
  private final HealthStatEventMessageListener messageListener;
  private EventSubscriber eventSubscriber;
- private boolean terminated;
- private ExecutorService executorService;
+ private static volatile HealthStatEventReceiver instance;
 
- public HealthStatEventReceiver() {
+ private HealthStatEventReceiver() {
+ // TODO: make pool size configurable
+ this.executorService = StratosThreadPool.getExecutorService("healthstat-event-receiver", 100);
  HealthStatEventMessageQueue messageQueue = new HealthStatEventMessageQueue();
  this.messageDelegator = new HealthStatEventMessageDelegator(messageQueue);
  this.messageListener = new HealthStatEventMessageListener(messageQueue);
+ execute();
+ }
+
+ public static HealthStatEventReceiver getInstance () {
+ if (instance == null) {
+ synchronized (HealthStatEventReceiver.class) {
+ if (instance == null) {
+ instance = new HealthStatEventReceiver();
+ }
+ }
+ }
+
+ return instance;
  }
 
  public void addEventListener(EventListener eventListener) {
  messageDelegator.addEventListener(eventListener);
  }
 
 
- public void execute() {
+ private void execute() {
  try {
  // Start topic subscriber thread
  eventSubscriber = new EventSubscriber(MessagingUtil.Topics.HEALTH_STAT_TOPIC.getTopicName(), messageListener);
@@ -69,17 +85,17 @@ public void execute() {
  }
  }
 
- public void terminate() {
- eventSubscriber.terminate();
- messageDelegator.terminate();
- terminated = true;
- }
-
- public ExecutorService getExecutorService() {
- return executorService;
- }
-
- public void setExecutorService(ExecutorService executorService) {
- this.executorService = executorService;
- }
+// public void terminate() {
+// eventSubscriber.terminate();
+// messageDelegator.terminate();
+// terminated = true;
+// }
+//
+// public ExecutorService getExecutorService() {
+// return executorService;
+// }
+//
+// public void setExecutorService(ExecutorService executorService) {
+// this.executorService = executorService;
+// }
 }