Add Health Check API

components/device-mgt/org.wso2.carbon.device.mgt.core/src/main/java/org/wso2/carbon/device/mgt/core/dao/DeviceDAO.java

@@ -674,4 +674,6 @@ public interface DeviceDAO {
                                            int tenantId,
                                            String packageName,
                                            String version) throws DeviceManagementDAOException;
+
+    int getFunctioningDevicesInSystem() throws DeviceManagementDAOException;
 }

components/device-mgt/org.wso2.carbon.device.mgt.core/src/main/java/org/wso2/carbon/device/mgt/core/dao/impl/AbstractDeviceDAOImpl.java

@@ -2617,4 +2617,25 @@ public abstract class AbstractDeviceDAOImpl implements DeviceDAO {
 
         return joiner.toString();
     }
+
+    public int getFunctioningDevicesInSystem() throws DeviceManagementDAOException {
+        Connection conn;
+        PreparedStatement stmt = null;
+        int deviceCount = 0;
+        try {
+            conn = this.getConnection();
+            String sql = "SELECT COUNT(e.DEVICE_ID) AS DEVICE_COUNT FROM DM_ENROLMENT e WHERE STATUS != 'REMOVED'";
+            stmt = conn.prepareStatement(sql);
+            ResultSet rs = stmt.executeQuery();
+
+            if (rs.next()) {
+                deviceCount = rs.getInt("DEVICE_COUNT");
+            }
+        } catch (SQLException e) {
+            throw new DeviceManagementDAOException("Error occurred while fetching count of functioning devices", e);
+        } finally {
+            DeviceManagementDAOUtil.cleanupResources(stmt, null);
+        }
+        return deviceCount;
+    }
 }

components/device-mgt/org.wso2.carbon.device.mgt.core/src/main/java/org/wso2/carbon/device/mgt/core/service/DeviceManagementProviderService.java

@@ -882,4 +882,6 @@ public interface DeviceManagementProviderService {
      * @throws ApplicationManagementException if any service level or DAO level error occurs.
      */
     List<String> getAppVersions(String packageName) throws ApplicationManagementException;
+
+    int getFunctioningDevicesInSystem() throws DeviceManagementException;
 }

components/device-mgt/org.wso2.carbon.device.mgt.core/src/main/java/org/wso2/carbon/device/mgt/core/service/DeviceManagementProviderServiceImpl.java

@@ -4120,4 +4120,28 @@ public class DeviceManagementProviderServiceImpl implements DeviceManagementProv
         deviceConfiguration.setDeviceOwner(deviceOwner);
         return deviceConfiguration;
     }
+
+    public int getFunctioningDevicesInSystem() throws DeviceManagementException {
+        if (log.isDebugEnabled()) {
+            log.debug("Get functioning devices count");
+        }
+        try {
+            DeviceManagementDAOFactory.openConnection();
+            return deviceDAO.getFunctioningDevicesInSystem();
+        } catch (DeviceManagementDAOException e) {
+            String msg = "Error occurred while retrieving the device count";
+            log.error(msg, e);
+            throw new DeviceManagementException(msg, e);
+        } catch (SQLException e) {
+            String msg = "Error occurred while opening a connection to the data source";
+            log.error(msg, e);
+            throw new DeviceManagementException(msg, e);
+        } catch (Exception e) {
+            String msg = "Error occurred in getDeviceCount";
+            log.error(msg, e);
+            throw new DeviceManagementException(msg, e);
+        } finally {
+            DeviceManagementDAOFactory.closeConnection();
+        }
+    }
 }