making TenantEventReceiver a singleton and fixing the references in t…

…he components

components/org.apache.stratos.cartridge.agent/src/main/java/org/apache/stratos/cartridge/agent/CartridgeAgentEventListeners.java

@@ -79,8 +79,8 @@ public CartridgeAgentEventListeners() {
 
  this.instanceNotifierEventReceiver = new InstanceNotifierEventReceiver();
 
- this.tenantEventReceiver = new TenantEventReceiver();
- this.tenantEventReceiver.setExecutorService(eventListenerExecutorService);
+ this.tenantEventReceiver = TenantEventReceiver.getInstance();
+// this.tenantEventReceiver.setExecutorService(eventListenerExecutorService);
 
  extensionHandler = new DefaultExtensionHandler();
 

components/org.apache.stratos.load.balancer/src/main/java/org/apache/stratos/load/balancer/internal/LoadBalancerServiceComponent.java

@@ -225,9 +225,9 @@ private void startTopologyEventReceiver(ExecutorService executorService, Topolog
 
  private void startTenantEventReceiver(ExecutorService executorService) {
 
- tenantEventReceiver = new TenantEventReceiver();
- tenantEventReceiver.setExecutorService(executorService);
- tenantEventReceiver.execute();
+ tenantEventReceiver = TenantEventReceiver.getInstance();
+// tenantEventReceiver.setExecutorService(executorService);
+// tenantEventReceiver.execute();
  if (log.isInfoEnabled()) {
  log.info("Tenant event receiver thread started");
  }

components/org.apache.stratos.messaging/src/main/java/org/apache/stratos/messaging/message/receiver/tenant/TenantEventReceiver.java

@@ -21,11 +21,13 @@
 
 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.publish.EventPublisher;
 import org.apache.stratos.messaging.broker.publish.EventPublisherPool;
 import org.apache.stratos.messaging.broker.subscribe.EventSubscriber;
 import org.apache.stratos.messaging.event.initializer.CompleteTenantRequestEvent;
 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;
@@ -34,28 +36,43 @@
  * A thread for receiving tenant information from message broker and
  * build tenant information in tenant manager.
  */
-public class TenantEventReceiver {
+public class TenantEventReceiver extends StratosEventReceiver {
  private static final Log log = LogFactory.getLog(TenantEventReceiver.class);
  private TenantEventMessageDelegator messageDelegator;
  private TenantEventMessageListener messageListener;
  private EventSubscriber eventSubscriber;
- private ExecutorService executorService;
+ private static volatile TenantEventReceiver instance;
 
- public TenantEventReceiver() {
+ private TenantEventReceiver() {
+ // TODO: make pool size configurable
+ this.executorService = StratosThreadPool.getExecutorService("tenant-event-receiver", 100);
  TenantEventMessageQueue messageQueue = new TenantEventMessageQueue();
  this.messageDelegator = new TenantEventMessageDelegator(messageQueue);
  this.messageListener = new TenantEventMessageListener(messageQueue);
+ execute();
+ }
+
+ public static TenantEventReceiver getInstance () {
+ if (instance == null) {
+ synchronized (TenantEventReceiver.class) {
+ if (instance == null) {
+ instance = new TenantEventReceiver();
+ }
+ }
+ }
+
+ return instance;
  }
 
  public void addEventListener(EventListener eventListener) {
  messageDelegator.addEventListener(eventListener);
  }
 
- public void setExecutorService(ExecutorService executorService) {
- this.executorService = executorService;
- }
+// public void setExecutorService(ExecutorService executorService) {
+// this.executorService = executorService;
+// }
 
- public void execute() {
+ private void execute() {
  try {
  // Start topic subscriber thread
  eventSubscriber = new EventSubscriber(MessagingUtil.Topics.TENANT_TOPIC.getTopicName(), messageListener);