Implement Singleton Pattern for DeviceTaskConfigurationServiceImpl

components/device-mgt/io.entgra.device.mgt.core.device.mgt.core/src/main/java/io/entgra/device/mgt/core/device/mgt/core/metadata/mgt/DeviceTaskConfigurationServiceImpl.java

@@ -49,13 +49,21 @@ public class DeviceTaskConfigurationServiceImpl implements DeviceTaskConfigurati
 
     private final MetadataManagementService metadataManagementService;
 
-    private final Cache<String, DeviceFrequencyMap> cache;
+    private static DeviceTaskConfigurationServiceImpl instance;
 
-    public DeviceTaskConfigurationServiceImpl() {
-        this.metadataManagementService = new MetadataManagementServiceImpl();
-        this.cache = CacheBuilder.newBuilder()
+    private static final Cache<String, DeviceFrequencyMap> cache = CacheBuilder.newBuilder()
             .expireAfterWrite(1, TimeUnit.HOURS)
             .build();
+
+    private DeviceTaskConfigurationServiceImpl() {
+        this.metadataManagementService = new MetadataManagementServiceImpl();
+    }
+
+    public static synchronized DeviceTaskConfigurationServiceImpl getInstance() {
+        if (instance == null) {
+            instance = new DeviceTaskConfigurationServiceImpl();
+        }
+        return instance;
     }
 
     private Metadata constructTaskFrequencyMetadata(Map<String, Integer> deviceFrequencies) {

components/device-mgt/io.entgra.device.mgt.core.device.mgt.core/src/main/java/io/entgra/device/mgt/core/device/mgt/core/metadata/mgt/TaskConfigurationStartupHandler.java

@@ -43,7 +43,7 @@ public class TaskConfigurationStartupHandler implements ServerStartupObserver {
         Thread t = new Thread(new Runnable() {
             @Override
             public void run() {
-                DeviceTaskConfigurationService deviceTaskConfigurationService = new DeviceTaskConfigurationServiceImpl();
+                DeviceTaskConfigurationService deviceTaskConfigurationService = DeviceTaskConfigurationServiceImpl.getInstance();
                 RealmService realmService = DeviceManagementDataHolder.getInstance().getRealmService();
                     if (log.isDebugEnabled()) {
                         log.debug("Server has just started, hence started adding default task frequencies");

components/device-mgt/io.entgra.device.mgt.core.device.mgt.core/src/main/java/io/entgra/device/mgt/core/device/mgt/core/task/Utils.java

@@ -71,7 +71,7 @@ public class Utils {
     }
 
     public static int getTenantedTaskFrequency(int tenantId, String deviceType) throws MetadataManagementException {
-        DeviceTaskConfigurationService deviceTaskConfigurationService = new DeviceTaskConfigurationServiceImpl();
+        DeviceTaskConfigurationService deviceTaskConfigurationService = DeviceTaskConfigurationServiceImpl.getInstance();
         return deviceTaskConfigurationService.getTaskFrequency(deviceType, tenantId);
     }
 

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

@@ -156,7 +156,7 @@ public class DeviceTaskManagerTest extends BaseDeviceManagementTest {
     @Test(groups = "Device Task Manager Test Group", description = "Testing device detail retriever task execution")
     public void testDeviceDetailRetrieverTaskExecute() throws OperationManagementException, MetadataManagementException {
         DeviceDetailsRetrieverTask deviceDetailsRetrieverTask = new DeviceDetailsRetrieverTask();
-        DeviceTaskConfigurationService deviceTaskConfigurationService = new DeviceTaskConfigurationServiceImpl();
+        DeviceTaskConfigurationService deviceTaskConfigurationService = DeviceTaskConfigurationServiceImpl.getInstance();
         deviceTaskConfigurationService.addTaskFrequency(MultitenantConstants.SUPER_TENANT_ID, FREQUENCY,TestDataHolder.TEST_DEVICE_TYPE);
         Map<String, String> map = new HashMap<>();
         map.put("DEVICE_TYPE", TestDataHolder.TEST_DEVICE_TYPE);

components/tenant-mgt/io.entgra.device.mgt.core.tenant.mgt.core/src/main/java/io/entgra/device/mgt/core/tenant/mgt/core/internal/TenantMgtServiceComponent.java

@@ -72,7 +72,7 @@ public class TenantMgtServiceComponent {
             componentContext.getBundleContext().registerService(DeviceStatusManagementService.class.getName(),
                     deviceStatusManagementService, null);
             TenantMgtDataHolder.getInstance().setDeviceStatusManagementService(deviceStatusManagementService);
-            DeviceTaskConfigurationService deviceTaskConfigurationService = new DeviceTaskConfigurationServiceImpl();
+            DeviceTaskConfigurationService deviceTaskConfigurationService = DeviceTaskConfigurationServiceImpl.getInstance();
             TenantMgtDataHolder.getInstance().setDeviceTaskConfigurationService(deviceTaskConfigurationService);
             DeviceMgtTenantListener deviceMgtTenantListener = new DeviceMgtTenantListener();
             if(log.isDebugEnabled()) {