imrpoved heart beat to handle cluster formation changed

components/heartbeat-management/io.entgra.device.mgt.core.server.bootup.heartbeat.beacon/pom.xml

@@ -70,6 +70,7 @@
                             !io.entgra.device.mgt.core.server.bootup.heartbeat.beacon.internal,
                             io.entgra.device.mgt.core.server.bootup.heartbeat.beacon.*
                         </Export-Package>
+                        <DynamicImport-Package>*</DynamicImport-Package>
                     </instructions>
                 </configuration>
             </plugin>

components/heartbeat-management/io.entgra.device.mgt.core.server.bootup.heartbeat.beacon/src/main/java/io/entgra/device/mgt/core/server/bootup/heartbeat/beacon/internal/HeartBeatBeaconComponent.java

@@ -28,6 +28,7 @@ import io.entgra.device.mgt.core.server.bootup.heartbeat.beacon.service.HeartBea
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 import org.osgi.service.component.ComponentContext;
+import org.wso2.carbon.core.ServerStartupObserver;
 import org.wso2.carbon.ndatasource.core.DataSourceService;
 
 import java.util.List;
@@ -73,7 +74,9 @@ public class HeartBeatBeaconComponent {
                         clusterFormationChangedNotifierRepository);
 
                 //Setting up executors to notify heart beat status */
-                HeartBeatExecutor.setUpNotifiers(HeartBeatBeaconUtils.getServerDetails());
+                HeartBeatExecutor heartBeatExecutor = new HeartBeatExecutor();
+                componentContext.getBundleContext().registerService(
+                        ServerStartupObserver.class.getName(), heartBeatExecutor, null);
             }
 
 

components/heartbeat-management/io.entgra.device.mgt.core.server.bootup.heartbeat.beacon/src/main/java/io/entgra/device/mgt/core/server/bootup/heartbeat/beacon/internal/HeartBeatExecutor.java

@@ -26,13 +26,16 @@ import io.entgra.device.mgt.core.server.bootup.heartbeat.beacon.dto.ServerContex
 import io.entgra.device.mgt.core.server.bootup.heartbeat.beacon.exception.HeartBeatManagementException;
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
+import org.wso2.carbon.core.ServerStartupObserver;
 
 import java.io.IOException;
+import java.net.SocketException;
+import java.net.UnknownHostException;
 import java.util.concurrent.Executors;
 import java.util.concurrent.ScheduledExecutorService;
 import java.util.concurrent.TimeUnit;
 
-public class HeartBeatExecutor {
+public class HeartBeatExecutor implements ServerStartupObserver {
 
     private static Log log = LogFactory.getLog(HeartBeatExecutor.class);
     private static final int DEFAULT__NOTIFIER_INTERVAL = 5;
@@ -43,6 +46,20 @@ public class HeartBeatExecutor {
         CONFIG = HeartBeatBeaconConfig.getInstance();
     }
 
+    @Override
+    public void completingServerStartup() {
+
+    }
+
+    @Override
+    public void completedServerStartup() {
+        try {
+            setUpNotifiers(HeartBeatBeaconUtils.getServerDetails());
+        } catch (HeartBeatBeaconConfigurationException | UnknownHostException | SocketException e) {
+            throw new RuntimeException(e);
+        }
+    }
+
     static void setUpNotifiers(ServerContext ctx) throws HeartBeatBeaconConfigurationException {
         ScheduledExecutorService executor =
                 Executors.newSingleThreadScheduledExecutor();

components/heartbeat-management/io.entgra.device.mgt.core.server.bootup.heartbeat.beacon/src/main/java/io/entgra/device/mgt/core/server/bootup/heartbeat/beacon/service/ClusterFormationChangedNotifierRepository.java

@@ -15,9 +15,8 @@
  * specific language governing permissions and limitations
  * under the License.
  */
-package io.entgra.device.mgt.core.device.mgt.core.push.notification.mgt;
+package io.entgra.device.mgt.core.server.bootup.heartbeat.beacon.service;
 
-import io.entgra.device.mgt.core.server.bootup.heartbeat.beacon.service.ClusterFormationChangedNotifier;
 import org.apache.commons.lang.StringUtils;
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
@@ -41,7 +40,7 @@ public class ClusterFormationChangedNotifierRepository {
     public void addNotifier(String className) {
         try {
             if (!StringUtils.isEmpty(className)) {
-                Class<?> clz = ClassLoader.getSystemClassLoader()forName(className);
+                Class<?> clz = Class.forName(className);
                 ClusterFormationChangedNotifier notifier = (ClusterFormationChangedNotifier) clz.newInstance();
                 notifiers.put(notifier.getType(), notifier);
             }

components/heartbeat-management/io.entgra.device.mgt.core.server.bootup.heartbeat.beacon/src/main/java/io/entgra/device/mgt/core/server/bootup/heartbeat/beacon/service/HeartBeatManagementServiceImpl.java

@@ -235,6 +235,7 @@ public class HeartBeatManagementServiceImpl implements HeartBeatManagementServic
                         }
                     } else {
                         //first time execution, elect if not present
+                        heartBeatDAO.purgeCandidates();
                         electCandidate(servers);
                     }
                     HeartBeatBeaconDAOFactory.commitTransaction();
@@ -268,6 +269,10 @@ public class HeartBeatManagementServiceImpl implements HeartBeatManagementServic
                     String serverUUID = HeartBeatBeaconDataHolder.getInstance().getLocalServerUUID();
                     ServerContext serverContext = servers.get(serverUUID);
 
+                    if (log.isDebugEnabled()) {
+                        log.debug("HashIndex (previous, current) : " + lastHashIndex + ", " + serverContext.getIndex());
+                        log.debug("ActiveServerCount (previous, current) : " + lastActiveCount + ", " + servers.size());
+                    }
                     // cluster change can be identified, either by changing hash index or changing active server count
                     if ((lastHashIndex != serverContext.getIndex()) || (lastActiveCount != servers.size())) {
                         lastHashIndex = serverContext.getIndex();
@@ -280,6 +285,9 @@ public class HeartBeatManagementServiceImpl implements HeartBeatManagementServic
                             Runnable r = new Runnable() {
                                 @Override
                                 public void run() {
+                                    if (log.isDebugEnabled()) {
+                                        log.debug("notify cluster formation changed : " + notifier.getType());
+                                    }
                                     notifier.notifyClusterFormationChanged(lastHashIndex, lastActiveCount);
                                 }
                             };