Notify cluster formation changed implementation

components/device-mgt/io.entgra.device.mgt.core.device.mgt.core/src/test/java/io/entgra/device/mgt/core/device/mgt/core/TestHeartBeatManagementService.java

@@ -66,4 +66,9 @@ public class TestHeartBeatManagementService implements HeartBeatManagementServic
     @Override public Map<Integer, ServerContext> getActiveServers() throws HeartBeatManagementException {
         return null;
     }
+
+    @Override
+    public void notifyClusterFormationChanged(int elapsedTimeInSeconds) throws HeartBeatManagementException {
+
+    }
 }

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

@@ -22,6 +22,7 @@ import io.entgra.device.mgt.core.server.bootup.heartbeat.beacon.HeartBeatBeaconC
 import io.entgra.device.mgt.core.server.bootup.heartbeat.beacon.HeartBeatBeaconUtils;
 import io.entgra.device.mgt.core.server.bootup.heartbeat.beacon.config.datasource.DataSourceConfig;
 import io.entgra.device.mgt.core.server.bootup.heartbeat.beacon.exception.InvalidConfigurationStateException;
+import io.entgra.device.mgt.core.server.bootup.heartbeat.beacon.service.ClusterFormationChangedNotifier;
 import org.w3c.dom.Document;
 import org.wso2.carbon.utils.CarbonUtils;
 
@@ -29,8 +30,10 @@ import javax.xml.bind.JAXBContext;
 import javax.xml.bind.JAXBException;
 import javax.xml.bind.Unmarshaller;
 import javax.xml.bind.annotation.XmlElement;
+import javax.xml.bind.annotation.XmlElementWrapper;
 import javax.xml.bind.annotation.XmlRootElement;
 import java.io.File;
+import java.util.List;
 
 @XmlRootElement(name = "HeartBeatBeaconConfig")
 public class HeartBeatBeaconConfig {
@@ -50,6 +53,7 @@ public class HeartBeatBeaconConfig {
     private static final String SERVER_UUID_FILE_LOCATION =
             CarbonUtils.getCarbonConfigDirPath() + File.separator + "server-credentials.properties";
 
+    private List<String> notifiers;
     private HeartBeatBeaconConfig() {
     }
 
@@ -135,4 +139,13 @@ public class HeartBeatBeaconConfig {
         }
     }
 
+    @XmlElementWrapper(name = "ClusterFormationChangedNotifiers", required = true)
+    @XmlElement(name = "Notifier", required = true)
+    public List<String> getNotifiers() {
+        return notifiers;
+    }
+
+    public void setNotifiers(List<String> notifiers) {
+        this.notifiers = notifiers;
+    }
 }

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

@@ -22,6 +22,7 @@ import io.entgra.device.mgt.core.server.bootup.heartbeat.beacon.HeartBeatBeaconU
 import io.entgra.device.mgt.core.server.bootup.heartbeat.beacon.config.HeartBeatBeaconConfig;
 import io.entgra.device.mgt.core.server.bootup.heartbeat.beacon.config.datasource.DataSourceConfig;
 import io.entgra.device.mgt.core.server.bootup.heartbeat.beacon.dao.HeartBeatBeaconDAOFactory;
+import io.entgra.device.mgt.core.server.bootup.heartbeat.beacon.service.ClusterFormationChangedNotifierRepository;
 import io.entgra.device.mgt.core.server.bootup.heartbeat.beacon.service.HeartBeatManagementService;
 import io.entgra.device.mgt.core.server.bootup.heartbeat.beacon.service.HeartBeatManagementServiceImpl;
 import org.apache.commons.logging.Log;
@@ -29,6 +30,8 @@ import org.apache.commons.logging.LogFactory;
 import org.osgi.service.component.ComponentContext;
 import org.wso2.carbon.ndatasource.core.DataSourceService;
 
+import java.util.List;
+
 /**
  * @scr.component name="io.entgra.device.mgt.core.server.bootup.heartbeat.beacon.heartbeatBeaconComponent"
  * immediate="true"
@@ -58,10 +61,23 @@ public class HeartBeatBeaconComponent {
                 DataSourceConfig dsConfig = HeartBeatBeaconConfig.getInstance().getDataSourceConfig();
                 HeartBeatBeaconDAOFactory.init(dsConfig);
 
+                ClusterFormationChangedNotifierRepository clusterFormationChangedNotifierRepository
+                        = new ClusterFormationChangedNotifierRepository();
+                List<String> notifiers = HeartBeatBeaconConfig.getInstance().getNotifiers();
+                if (notifiers != null && notifiers.size() > 0) {
+                    for (String notifier : notifiers) {
+                        clusterFormationChangedNotifierRepository.addNotifier(notifier);
+                    }
+                }
+                HeartBeatBeaconDataHolder.getInstance().setClusterFormationChangedNotifierRepository(
+                        clusterFormationChangedNotifierRepository);
+
                 //Setting up executors to notify heart beat status */
                 HeartBeatExecutor.setUpNotifiers(HeartBeatBeaconUtils.getServerDetails());
             }
 
+
+
             if (log.isDebugEnabled()) {
                 log.debug("Heart Beat Notifier bundle has been successfully initialized");
             }

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/HeartBeatBeaconDataHolder.java

@@ -18,6 +18,7 @@
 
 package io.entgra.device.mgt.core.server.bootup.heartbeat.beacon.internal;
 
+import io.entgra.device.mgt.core.server.bootup.heartbeat.beacon.service.ClusterFormationChangedNotifierRepository;
 import io.entgra.device.mgt.core.server.bootup.heartbeat.beacon.service.HeartBeatManagementService;
 
 public class HeartBeatBeaconDataHolder {
@@ -27,6 +28,7 @@ public class HeartBeatBeaconDataHolder {
 
     private static HeartBeatBeaconDataHolder thisInstance = new HeartBeatBeaconDataHolder();
 
+    private ClusterFormationChangedNotifierRepository clusterFormationChangedNotifierRepository;
     private HeartBeatBeaconDataHolder() {}
 
     public static HeartBeatBeaconDataHolder getInstance() {
@@ -48,4 +50,12 @@ public class HeartBeatBeaconDataHolder {
     public void setLocalServerUUID(String localServerUUID) {
         this.localServerUUID = localServerUUID;
     }
+
+    public ClusterFormationChangedNotifierRepository getClusterFormationChangedNotifierRepository() {
+        return clusterFormationChangedNotifierRepository;
+    }
+
+    public void setClusterFormationChangedNotifierRepository(ClusterFormationChangedNotifierRepository clusterFormationChangedNotifierRepository) {
+        this.clusterFormationChangedNotifierRepository = clusterFormationChangedNotifierRepository;
+    }
 }

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

@@ -69,6 +69,7 @@ public class HeartBeatExecutor {
                     try {
                         recordHeartBeat(designatedUUID);
                         electDynamicTaskExecutionCandidate(cumilativeTimeOut);
+                        notifyClusterFormationChanged(cumilativeTimeOut);
                     } catch (Exception e) {
                         log.error("Error while executing record heart beat task. This will result in schedule operation malfunction.", e);
                     }
@@ -98,5 +99,8 @@ public class HeartBeatExecutor {
         HeartBeatBeaconDataHolder.getInstance().getHeartBeatManagementService().electCandidate(cumilativeTimeOut);
     }
 
+    static void notifyClusterFormationChanged(int cumilativeTimeOut) throws HeartBeatManagementException {
+        HeartBeatBeaconDataHolder.getInstance().getHeartBeatManagementService().notifyClusterFormationChanged(cumilativeTimeOut);
+    }
 
 }

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/ClusterFormationChangedNotifier.java

@@ -0,0 +1,25 @@
+/*
+ * Copyright (c) 2018 - 2023, Entgra (Pvt) Ltd. (http://www.entgra.io) All Rights Reserved.
+ *
+ * Entgra (Pvt) Ltd. 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 io.entgra.device.mgt.core.server.bootup.heartbeat.beacon.service;
+
+public interface ClusterFormationChangedNotifier {
+
+    String getType();
+
+    void notifyClusterFormationChanged(int hashIndex, int activeServerCount);
+}

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

@@ -0,0 +1,64 @@
+/*
+ * Copyright (c) 2018 - 2023, Entgra (Pvt) Ltd. (http://www.entgra.io) All Rights Reserved.
+ *
+ * Entgra (Pvt) Ltd. 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 io.entgra.device.mgt.core.server.bootup.heartbeat.beacon.service;
+
+import org.apache.commons.lang.StringUtils;
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+
+public class ClusterFormationChangedNotifierRepository {
+
+    private Map<String, ClusterFormationChangedNotifier> notifiers;
+    private static final Log log = LogFactory.getLog(ClusterFormationChangedNotifierRepository.class);
+
+    public ClusterFormationChangedNotifierRepository() {
+        this.notifiers = new ConcurrentHashMap<>();
+    }
+
+    public void addNotifier(ClusterFormationChangedNotifier notifier) {
+        notifiers.put(notifier.getType(), notifier);
+    }
+
+    public void addNotifier(String className) {
+        try {
+            if (!StringUtils.isEmpty(className)) {
+                Class<?> clz = Class.forName(className);
+                ClusterFormationChangedNotifier notifier = (ClusterFormationChangedNotifier) clz.newInstance();
+                notifiers.put(notifier.getType(), notifier);
+            }
+        } catch (ClassNotFoundException e) {
+            log.error("Provided ClusterFormationChangedNotifier implementation '" + className + "' cannot be found", e);
+        } catch (InstantiationException e) {
+            log.error("Error occurred while instantiating ClusterFormationChangedNotifier implementation '" +
+                    className + "'", e);
+        } catch (IllegalAccessException e) {
+            log.error("Error occurred while adding ClusterFormationChangedNotifier implementation '" + className + "'", e);
+        }
+    }
+
+    public ClusterFormationChangedNotifier getNotifier(String type) {
+        return notifiers.get(type);
+    }
+
+    public Map<String, ClusterFormationChangedNotifier> getNotifiers() {
+        return notifiers;
+    }
+}

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/HeartBeatManagementService.java

@@ -36,6 +36,7 @@ public interface HeartBeatManagementService {
     boolean recordHeartBeat(HeartBeatEvent event) throws HeartBeatManagementException;
 
     void electCandidate(int elapsedTimeInSeconds) throws HeartBeatManagementException;
+    void notifyClusterFormationChanged(int elapsedTimeInSeconds) throws HeartBeatManagementException;
 
     boolean updateTaskExecutionAcknowledgement(String newTask) throws HeartBeatManagementException;
 

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

@@ -48,6 +48,9 @@ public class HeartBeatManagementServiceImpl implements HeartBeatManagementServic
 
     private final HeartBeatDAO heartBeatDAO;
 
+    private static int lastActiveCount = -1;
+    private static int lastHashIndex = -1;
+
     public HeartBeatManagementServiceImpl() {
         this.heartBeatDAO = HeartBeatBeaconDAOFactory.getHeartBeatDAO();
     }
@@ -254,6 +257,55 @@ public class HeartBeatManagementServiceImpl implements HeartBeatManagementServic
             throw new HeartBeatManagementException(msg);
         }
     }
+    @Override
+    public void notifyClusterFormationChanged(int elapsedTimeInSeconds) throws HeartBeatManagementException {
+        if (HeartBeatBeaconConfig.getInstance().isEnabled()) {
+            try {
+                HeartBeatBeaconDAOFactory.beginTransaction();
+                Map<String, ServerContext> servers = heartBeatDAO.getActiveServerDetails(elapsedTimeInSeconds);
+                HeartBeatBeaconDAOFactory.commitTransaction();
+                if (servers != null && !servers.isEmpty()) {
+                    String serverUUID = HeartBeatBeaconDataHolder.getInstance().getLocalServerUUID();
+                    ServerContext serverContext = servers.get(serverUUID);
+
+                    // 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();
+                        lastActiveCount = servers.size();
+
+                        ClusterFormationChangedNotifierRepository repository = HeartBeatBeaconDataHolder.getInstance().getClusterFormationChangedNotifierRepository();
+                        Map<String, ClusterFormationChangedNotifier> notifiers = repository.getNotifiers();
+                        for (String type : notifiers.keySet()) {
+                            ClusterFormationChangedNotifier notifier = notifiers.get(type);
+                            Runnable r = new Runnable() {
+                                @Override
+                                public void run() {
+                                    notifier.notifyClusterFormationChanged(lastHashIndex, lastActiveCount);
+                                }
+                            };
+                            new Thread(r).start();
+                        }
+                    }
+                }
+            } catch (HeartBeatDAOException e) {
+                String msg = "Error occurred while notifyClusterFormationChanged.";
+                log.error(msg, e);
+                throw new HeartBeatManagementException(msg, e);
+            } catch (TransactionManagementException e) {
+                HeartBeatBeaconDAOFactory.rollbackTransaction();
+                String msg = "Error occurred while electing candidate for dynamic task execution. Issue in opening a connection to the underlying data source";
+                log.error(msg, e);
+                throw new HeartBeatManagementException(msg, e);
+            } finally {
+                HeartBeatBeaconDAOFactory.closeConnection();
+            }
+        } else {
+            String msg = "Heart Beat Configuration Disabled. Error while notifyClusterFormationChanged.";
+            log.error(msg);
+            throw new HeartBeatManagementException(msg);
+        }
+    }
+
 
     private void electCandidate(Map<String, ServerContext> servers) throws HeartBeatDAOException {
         String electedCandidate = getRandomElement(servers.keySet());

components/policy-mgt/io.entgra.device.mgt.core.policy.mgt.core/src/test/java/io/entgra/device/mgt/core/policy/mgt/core/mock/TestHeartBeatManagementService.java

@@ -66,4 +66,9 @@ public class TestHeartBeatManagementService implements HeartBeatManagementServic
     @Override public Map<Integer, ServerContext> getActiveServers() throws HeartBeatManagementException {
         return null;
     }
+
+    @Override
+    public void notifyClusterFormationChanged(int elapsedTimeInSeconds) throws HeartBeatManagementException {
+
+    }
 }

features/heartbeat-management/io.entgra.device.mgt.core.server.heart.beat.feature/src/main/resources/conf/heart-beat-config.xml

@@ -49,4 +49,7 @@
     <NotifierFrequencyInSeconds>300</NotifierFrequencyInSeconds>
     <TimeSkewInSeconds>5</TimeSkewInSeconds>
     <ServerTimeOutIntervalInSeconds>600</ServerTimeOutIntervalInSeconds>
+    <ClusterFormationChangedNotifiers>
+        <Notifier></Notifier>
+    </ClusterFormationChangedNotifiers>
 </HeartBeatBeaconConfig>

features/heartbeat-management/io.entgra.device.mgt.core.server.heart.beat.feature/src/main/resources/conf_templates/templates/repository/conf/heart-beat-config.xml.j2

@@ -51,11 +51,21 @@
      <NotifierFrequencyInSeconds>{{heart_beat_beacon_conf.notifier_frequency_in_seconds}}</NotifierFrequencyInSeconds>
      <TimeSkewInSeconds>{{heart_beat_beacon_conf.time_skew_in_seconds}}</TimeSkewInSeconds>
      <ServerTimeOutIntervalInSeconds>{{heart_beat_beacon_conf.sever_timeout_interval_in_seconds}}</ServerTimeOutIntervalInSeconds>
+         {% if heart_beat_beacon_conf.cluster_formation_changed_configs.cluster_formation_changed_notifiers is defined %}
+         <ClusterFormationChangedNotifiers>
+             {%- for cluster_formation_changed_notifier in heart_beat_beacon_conf.cluster_formation_changed_configs.cluster_formation_changed_notifiers -%}
+             <Notifier>{{cluster_formation_changed_notifier}}</Notifier>
+             {% endfor %}
+         </ClusterFormationChangedNotifiers>
+         {% endif %}
      {% else %}
      <Enable>false</Enable>
      <NotifierInitialDelayInSeconds>30</NotifierInitialDelayInSeconds>
      <NotifierFrequencyInSeconds>300</NotifierFrequencyInSeconds>
      <TimeSkewInSeconds>5</TimeSkewInSeconds>
      <ServerTimeOutIntervalInSeconds>600</ServerTimeOutIntervalInSeconds>
+     <ClusterFormationChangedNotifiers>
+         <Notifier></Notifier>
+     </ClusterFormationChangedNotifiers>
      {% endif %}
 </HeartBeatBeaconConfig>