Implement review fixes

<UserStory> 1960: Service Refactoring </UserStory>

UserStory #1960

<Changes>
1. Replaced the Controller load/save workflow with initialize() and shutdown() methods.
2. Moved startup checks such as admin verification, low stock alerts, and payment reminders into Controller::initialize().
3. Updated UserInterface to use the new Controller initialization and shutdown flow.
4. Updated DataStore::getUsers() and DataStore::getNotifications() to load data directly from shared memory.
5. Added logic to rebuild user notification mappings when user data is loaded from shared memory.
6. Implemented user and notification persistence through DataStore::saveUsers() and DataStore::saveNotifications().
7. Updated UserManagementService to use TrackedRecord-based shared memory records.
8. Added DataStore locking and unlocking to user management operations for synchronization.
9. Updated createUser(), updateUserDetails(), removeUser(), and deleteNotification() to persist changes through shared memory.
10. Removed legacy loadUsers() and saveUsers() implementations from UserManagementService.
11. Added required header dependencies for shared memory support.
</Changes>

<Test>
N/A
</Test>

<Review>
Sreeja Reghukumar, please review
</Review>

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem.vcxproj

@@ -157,6 +157,7 @@
     <ClInclude Include="core\patterns\Observer.h" />
     <ClInclude Include="core\patterns\Subject.h" />
     <ClInclude Include="datastores\DataStore.h" />
+    <ClInclude Include="datastores\DataStoreLockGuard.h" />
     <ClInclude Include="datastores\sharedmemory\FileHeader.h" />
     <ClInclude Include="datastores\sharedmemory\MappingInfo.h" />
     <ClInclude Include="datastores\sharedmemory\RecordState.h" />

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/controllers/Controller.cpp

@@ -588,63 +588,37 @@ void Controller::configureNotifications(bool paymentNotifications, bool serviceN
 }
 
 /*
-Function: loadSystemData
+Function: initialize
-Description: Loads all system data from persistent storage into memory.
+Description: Initializes the system and run system checks to ensure critical configurations, such as verifying admin existence.
-             Invokes the respective management services to load users, inventory items, services,
-             combo packages, service bookings, job cards, invoices, and observers.
 Parameters:
     - None
 Returns:
-    - void
+    - bool
 */
-void Controller::loadSystemData()
+bool Controller::initialize()
 {
-    m_userManagementService.loadUsers();
+    auto& dataStore = DataStore::getInstance();
-    m_inventoryManagementService.loadInventoryItems();
-    m_serviceManagementService.loadServices();
-    m_serviceManagementService.loadComboPackages();
-    m_serviceManagementService.loadServiceBookings();
-    m_serviceManagementService.loadJobCards();
-    m_paymentManagementService.loadInvoices();
-    m_serviceManagementService.loadObservers();
-    m_paymentManagementService.loadObservers();
-    m_inventoryManagementService.loadObservers();
-}
 
-/*
+    if (!dataStore.initialize())
-Function: saveSystemData
+    {
-Description: Saves all system data from memory back to persistent storage.
+        return false;
-             Invokes the respective management services to save users, inventory items, services,
+    }
-             combo packages, service bookings, job cards, invoices, and observers.
-Parameters:
-    - None
-Returns:
-    - void
-*/
-void Controller::saveSystemData()
-{
-    m_userManagementService.saveUsers();
-    m_inventoryManagementService.saveInventoryItems();
-    m_serviceManagementService.saveServices();
-    m_serviceManagementService.saveComboPackages();
-    m_serviceManagementService.saveServiceBookings();
-    m_serviceManagementService.saveJobCards();
-    m_paymentManagementService.saveInvoices();
-    m_serviceManagementService.saveObservers();
-    m_paymentManagementService.saveObservers();
-    m_inventoryManagementService.saveObservers();
-}
-
-/*
-Function: runSystemChecks
-Description: Runs system checks to ensure critical configurations, such as verifying admin existence.
-Parameter: None
-Return type: void
-*/
-void Controller::runSystemChecks()
-{
     m_userManagementService.ensureAdminExists();
     m_inventoryManagementService.sendLowStockAlerts();
     m_paymentManagementService.sendPaymentReminders();
+    return true;
 }
 
+/*
+Function: shutdown
+Description: Shutdown the system, and do necessary cleanups
+Parameters:
+    - None
+Returns:
+    - void
+*/
+void Controller::shutdown()
+{
+    auto& dataStore = DataStore::getInstance();
+    dataStore.shutdown();
+}

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/controllers/Controller.h

@@ -70,7 +70,6 @@ public:
     util::Vector<const Notification*> getNotifications();
     void deleteNotification(const std::string& notificationID);
     void configureNotifications(bool paymentNotifications, bool serviceNotifications);
-    void loadSystemData();
+    bool initialize();
-    void saveSystemData();
+    void shutdown();
-    void runSystemChecks();
 };

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/datastores/DataStore.cpp

@@ -13,9 +13,42 @@ Date: 19-May-2026
 #include "SerializedRecords.h"
 #include "FileHelper.h"
 
+/*
+Function: DataStore
+Description: Constructs the DataStore singleton and initializes
+             internal handles to their default values.
+Parameters:
+    - None
+Returns:
+    - None
+*/
 DataStore::DataStore() :
     m_globalMutex(NULL) {}
 
+/*
+Function: ~DataStore
+Description: Destroys the DataStore singleton and releases all
+             cached application objects owned by the datastore.
+             This includes users, notifications, services,
+             combo packages, inventory items, service bookings,
+             job cards, and invoices.
+Parameters:
+    - None
+Returns:
+    - None
+*/
+DataStore::~DataStore()
+{
+    clearCache(m_userCache);
+    clearCache(m_notificationCache);
+    clearCache(m_serviceCache);
+    clearCache(m_comboPackageCache);
+    clearCache(m_inventoryItemCache);
+    clearCache(m_serviceBookingCache);
+    clearCache(m_jobCardCache);
+    clearCache(m_invoiceCache);
+}
+
 /*
 Function: initialize
 Description: Initializes the shared-memory datastore.
@@ -193,9 +226,25 @@ Parameters:
 Returns:
     - util::Map<std::string, TrackedRecord<User>>: Collection of user records
 */
-util::Map<std::string, TrackedRecord<User>> DataStore::getUsers()
+util::Map<std::string, TrackedRecord<User>>& DataStore::getUsers()
 {
-    return util::Map<std::string, TrackedRecord<User>>();
+    auto users = loadRecords<User, SerializedUser>(m_users);
+    refreshCache(m_userCache, users);
+    auto& notifications = getNotifications();
+    int numberOfNotifications = m_notificationCache.getSize();
+    for (int index = 0; index < numberOfNotifications; index++)
+    {
+        Notification* notification = notifications.getValueAt(index).data;
+        const std::string& recipientUserId = notification->getRecipientUserId();
+        int userIndex = m_userCache.find(recipientUserId);
+        if (userIndex == -1)
+        {
+            throw std::runtime_error("Invalid recipient user ID");
+        }
+        User* user = m_userCache.getValueAt(userIndex).data;
+        user->addNotification(notification);
+    }
+    return m_userCache;
 }
 
 /*
@@ -206,9 +255,11 @@ Parameters:
 Returns:
     - util::Map<std::string, TrackedRecord<Notification>>: Collection of notification records
 */
-util::Map<std::string, TrackedRecord<Notification>> DataStore::getNotifications()
+util::Map<std::string, TrackedRecord<Notification>>& DataStore::getNotifications()
 {
-    return util::Map<std::string, TrackedRecord<Notification>>();
+    auto notifications = loadRecords<Notification, SerializedNotification>(m_notifications);
+    refreshCache(m_notificationCache, notifications);
+    return m_notificationCache;
 }
 
 /*
@@ -219,9 +270,9 @@ Parameters:
 Returns:
     - util::Map<std::string, TrackedRecord<Service>>: Collection of service records
 */
-util::Map<std::string, TrackedRecord<Service>> DataStore::getServices()
+util::Map<std::string, TrackedRecord<Service>>& DataStore::getServices()
 {
-    return util::Map<std::string, TrackedRecord<Service>>();
+    return m_serviceCache;
 }
 
 /*
@@ -232,9 +283,9 @@ Parameters:
 Returns:
     - util::Map<std::string, TrackedRecord<ComboPackage>>: Collection of combo package records
 */
-util::Map<std::string, TrackedRecord<ComboPackage>> DataStore::getComboPackages()
+util::Map<std::string, TrackedRecord<ComboPackage>>& DataStore::getComboPackages()
 {
-    return util::Map<std::string, TrackedRecord<ComboPackage>>();
+    return m_comboPackageCache;
 }
 
 /*
@@ -245,9 +296,9 @@ Parameters:
 Returns:
     - util::Map<std::string, TrackedRecord<InventoryItem>>: Collection of inventory item records
 */
-util::Map<std::string, TrackedRecord<InventoryItem>> DataStore::getInventoryItems()
+util::Map<std::string, TrackedRecord<InventoryItem>>& DataStore::getInventoryItems()
 {
-    return util::Map<std::string, TrackedRecord<InventoryItem>>();
+    return m_inventoryItemCache;
 }
 
 /*
@@ -258,9 +309,9 @@ Parameters:
 Returns:
     - util::Map<std::string, TrackedRecord<ServiceBooking>>: Collection of service booking records
 */
-util::Map<std::string, TrackedRecord<ServiceBooking>> DataStore::getServiceBookings()
+util::Map<std::string, TrackedRecord<ServiceBooking>>& DataStore::getServiceBookings()
 {
-    return util::Map<std::string, TrackedRecord<ServiceBooking>>();
+    return m_serviceBookingCache;
 }
 
 /*
@@ -271,9 +322,9 @@ Parameters:
 Returns:
     - util::Map<std::string, TrackedRecord<JobCard>>: Collection of job card records
 */
-util::Map<std::string, TrackedRecord<JobCard>> DataStore::getJobCards()
+util::Map<std::string, TrackedRecord<JobCard>>& DataStore::getJobCards()
 {
-    return util::Map<std::string, TrackedRecord<JobCard>>();
+    return m_jobCardCache;
 }
 
 /*
@@ -284,22 +335,9 @@ Parameters:
 Returns:
     - util::Map<std::string, TrackedRecord<Invoice>>: Collection of invoice records
 */
-util::Map<std::string, TrackedRecord<Invoice>> DataStore::getInvoices()
+util::Map<std::string, TrackedRecord<Invoice>>& DataStore::getInvoices()
 {
-    return util::Map<std::string, TrackedRecord<Invoice>>();
+    return m_invoiceCache;
-}
-
-/*
-Function: getPayments
-Description: Retrieves all payment records from the datastore.
-Parameters:
-    - None
-Returns:
-    - util::Map<std::string, TrackedRecord<Payment>>: Collection of payment records
-*/
-util::Map<std::string, TrackedRecord<Payment>> DataStore::getPayments()
-{
-    return util::Map<std::string, TrackedRecord<Payment>>();
 }
 
 /*
@@ -308,11 +346,11 @@ Description: Retrieves all service management observer records from the datastor
 Parameters:
     - None
 Returns:
-    - util::Map<std::string, TrackedRecord<std::string>>: Collection of observer records
+    - util::Map<std::string, User*>: Collection of observer records
 */
-util::Map<std::string, TrackedRecord<std::string>> DataStore::getServiceManagementObservers()
+util::Map<std::string, User*> DataStore::getServiceManagementObservers()
 {
-    return util::Map<std::string, TrackedRecord<std::string>>();
+    return util::Map<std::string, User*>();
 }
 
 /*
@@ -321,11 +359,11 @@ Description: Retrieves all payment management observer records from the datastor
 Parameters:
     - None
 Returns:
-    - util::Map<std::string, TrackedRecord<std::string>>: Collection of observer records
+    - util::Map<std::string, User*>: Collection of observer records
 */
-util::Map<std::string, TrackedRecord<std::string>> DataStore::getPaymentManagementObservers()
+util::Map<std::string, User*> DataStore::getPaymentManagementObservers()
 {
-    return util::Map<std::string, TrackedRecord<std::string>>();
+    return util::Map<std::string, User*>();
 }
 
 /*
@@ -334,46 +372,49 @@ Description: Retrieves all inventory management observer records from the datast
 Parameters:
     - None
 Returns:
-    - util::Map<std::string, TrackedRecord<std::string>>: Collection of observer records
+    - util::Map<std::string, User*>: Collection of observer records
 */
-util::Map<std::string, TrackedRecord<std::string>> DataStore::getInventoryManagementObservers()
+util::Map<std::string, User*> DataStore::getInventoryManagementObservers()
 {
-    return util::Map<std::string, TrackedRecord<std::string>>();
+    return util::Map<std::string, User*>();
 }
 
 /*
 Function: saveUsers
 Description: Persists all user records to the datastore.
 Parameters:
-    - users: util::Map<std::string, TrackedRecord<User>>&, collection of user records
+    - None
 Returns:
     - None
 */
-void DataStore::saveUsers(util::Map<std::string, TrackedRecord<User>>& users)
+void DataStore::saveUsers()
 {
+    saveRecords<User, SerializedUser>(m_users, m_userCache);
+    saveNotifications();
 }
 
 /*
 Function: saveNotifications
 Description: Persists all notification records to the datastore.
 Parameters:
-    - notifications: util::Map<std::string, TrackedRecord<Notification>>&, collection of notification records
+    - None
 Returns:
     - None
 */
-void DataStore::saveNotifications(util::Map<std::string, TrackedRecord<Notification>>& notifications)
+void DataStore::saveNotifications()
 {
+    saveRecords<Notification, SerializedNotification>(m_notifications, m_notificationCache);
 }
 
 /*
 Function: saveServices
 Description: Persists all service records to the datastore.
 Parameters:
-    - services: util::Map<std::string, TrackedRecord<Service>>&, collection of service records
+    - None
 Returns:
     - None
 */
-void DataStore::saveServices(util::Map<std::string, TrackedRecord<Service>>& services)
+void DataStore::saveServices()
 {
 }
 
@@ -381,11 +422,11 @@ void DataStore::saveServices(util::Map<std::string, TrackedRecord<Service>>& ser
 Function: saveComboPackages
 Description: Persists all combo package records to the datastore.
 Parameters:
-    - comboPackages: util::Map<std::string, TrackedRecord<ComboPackage>>&, collection of combo package records
+    - None
 Returns:
     - None
 */
-void DataStore::saveComboPackages(util::Map<std::string, TrackedRecord<ComboPackage>>& comboPackages)
+void DataStore::saveComboPackages()
 {
 }
 
@@ -393,11 +434,11 @@ void DataStore::saveComboPackages(util::Map<std::string, TrackedRecord<ComboPack
 Function: saveInventoryItems
 Description: Persists all inventory item records to the datastore.
 Parameters:
-    - inventoryItems: util::Map<std::string, TrackedRecord<InventoryItem>>&, collection of inventory item records
+    - None
 Returns:
     - None
 */
-void DataStore::saveInventoryItems(util::Map<std::string, TrackedRecord<InventoryItem>>& inventoryItems)
+void DataStore::saveInventoryItems()
 {
 }
 
@@ -405,11 +446,11 @@ void DataStore::saveInventoryItems(util::Map<std::string, TrackedRecord<Inventor
 Function: saveServiceBookings
 Description: Persists all service booking records to the datastore.
 Parameters:
-    - bookings: util::Map<std::string, TrackedRecord<ServiceBooking>>&, collection of service booking records
+    - None
 Returns:
     - None
 */
-void DataStore::saveServiceBookings(util::Map<std::string, TrackedRecord<ServiceBooking>>& bookings)
+void DataStore::saveServiceBookings()
 {
 }
 
@@ -417,11 +458,11 @@ void DataStore::saveServiceBookings(util::Map<std::string, TrackedRecord<Service
 Function: saveJobCards
 Description: Persists all job card records to the datastore.
 Parameters:
-    - jobCards: util::Map<std::string, TrackedRecord<JobCard>>&, collection of job card records
+    - None
 Returns:
     - None
 */
-void DataStore::saveJobCards(util::Map<std::string, TrackedRecord<JobCard>>& jobCards)
+void DataStore::saveJobCards()
 {
 }
 
@@ -429,23 +470,11 @@ void DataStore::saveJobCards(util::Map<std::string, TrackedRecord<JobCard>>& job
 Function: saveInvoices
 Description: Persists all invoice records to the datastore.
 Parameters:
-    - invoices: util::Map<std::string, TrackedRecord<Invoice>>&, collection of invoice records
+    - None
 Returns:
     - None
 */
-void DataStore::saveInvoices(util::Map<std::string, TrackedRecord<Invoice>>& invoices)
+void DataStore::saveInvoices()
-{
-}
-
-/*
-Function: savePayments
-Description: Persists all payment records to the datastore.
-Parameters:
-    - payments: util::Map<std::string, TrackedRecord<Payment>>&, collection of payment records
-Returns:
-    - None
-*/
-void DataStore::savePayments(util::Map<std::string, TrackedRecord<Payment>>& payments)
 {
 }
 
@@ -457,7 +486,7 @@ Parameters:
 Returns:
     - None
 */
-void DataStore::saveServiceManagementObservers(util::Map<std::string, TrackedRecord<std::string>>& observers)
+void DataStore::saveServiceManagementObservers(util::Map<std::string, User*>& observers)
 {
 }
 
@@ -465,11 +494,11 @@ void DataStore::saveServiceManagementObservers(util::Map<std::string, TrackedRec
 Function: savePaymentManagementObservers
 Description: Persists all payment management observer records to the datastore.
 Parameters:
-    - observers: util::Map<std::string, TrackedRecord<std::string>>&, collection of observer records
+    - observers: util::Map<std::string, User*>&, collection of observer records
 Returns:
     - None
 */
-void DataStore::savePaymentManagementObservers(util::Map<std::string, TrackedRecord<std::string>>& observers)
+void DataStore::savePaymentManagementObservers(util::Map<std::string, User*>& observers)
 {
 }
 
@@ -477,11 +506,11 @@ void DataStore::savePaymentManagementObservers(util::Map<std::string, TrackedRec
 Function: saveInventoryManagementObservers
 Description: Persists all inventory management observer records to the datastore.
 Parameters:
-    - observers: util::Map<std::string, TrackedRecord<std::string>>&, collection of observer records
+    - observers: util::Map<std::string, User*>&, collection of observer records
 Returns:
     - None
 */
-void DataStore::saveInventoryManagementObservers(util::Map<std::string, TrackedRecord<std::string>>& observers)
+void DataStore::saveInventoryManagementObservers(util::Map<std::string, User*>& observers)
 {
 }
 
@@ -554,3 +583,4 @@ bool DataStore::unlockDataStore()
     }
     return ReleaseMutex(m_globalMutex) != 0;
 }
+

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/datastores/DataStore.h

@@ -20,12 +20,12 @@ class InventoryItem;
 class ServiceBooking;
 class JobCard;
 class Invoice;
-class Payment;
 
 class DataStore
 {
 private:
     DataStore();
+    ~DataStore();
     DataStore(const DataStore&) = delete;
     DataStore& operator=(const DataStore&) = delete;
     DataStore(DataStore&&) = delete;
@@ -43,34 +43,40 @@ private:
     MappingInfo m_serviceManagementObservers;
     MappingInfo m_paymentManagementObservers;
     MappingInfo m_inventoryManagementObservers;
+    util::Map<std::string, TrackedRecord<User>> m_userCache;
+    util::Map<std::string, TrackedRecord<Notification>> m_notificationCache;
+    util::Map<std::string, TrackedRecord<Service>> m_serviceCache;
+    util::Map<std::string, TrackedRecord<ComboPackage>> m_comboPackageCache;
+    util::Map<std::string, TrackedRecord<InventoryItem>> m_inventoryItemCache;
+    util::Map<std::string, TrackedRecord<ServiceBooking>> m_serviceBookingCache;
+    util::Map<std::string, TrackedRecord<JobCard>> m_jobCardCache;
+    util::Map<std::string, TrackedRecord<Invoice>> m_invoiceCache;
 public:
     static DataStore& getInstance();
     bool initialize();
     void shutdown();
-    util::Map<std::string, TrackedRecord<User>> getUsers();
+    util::Map<std::string, TrackedRecord<User>>& getUsers();
-    util::Map<std::string, TrackedRecord<Notification>> getNotifications();
+    util::Map<std::string, TrackedRecord<Notification>>& getNotifications();
-    util::Map<std::string, TrackedRecord<Service>> getServices();
+    util::Map<std::string, TrackedRecord<Service>>& getServices();
-    util::Map<std::string, TrackedRecord<ComboPackage>> getComboPackages();
+    util::Map<std::string, TrackedRecord<ComboPackage>>& getComboPackages();
-    util::Map<std::string, TrackedRecord<InventoryItem>> getInventoryItems();
+    util::Map<std::string, TrackedRecord<InventoryItem>>& getInventoryItems();
-    util::Map<std::string, TrackedRecord<ServiceBooking>> getServiceBookings();
+    util::Map<std::string, TrackedRecord<ServiceBooking>>& getServiceBookings();
-    util::Map<std::string, TrackedRecord<JobCard>> getJobCards();
+    util::Map<std::string, TrackedRecord<JobCard>>& getJobCards();
-    util::Map<std::string, TrackedRecord<Invoice>> getInvoices();
+    util::Map<std::string, TrackedRecord<Invoice>>& getInvoices();
-    util::Map<std::string, TrackedRecord<Payment>> getPayments();
+    util::Map<std::string, User*> getServiceManagementObservers();
-    util::Map<std::string, TrackedRecord<std::string>> getServiceManagementObservers();
+    util::Map<std::string, User*> getPaymentManagementObservers();
-    util::Map<std::string, TrackedRecord<std::string>> getPaymentManagementObservers();
+    util::Map<std::string, User*> getInventoryManagementObservers();
-    util::Map<std::string, TrackedRecord<std::string>> getInventoryManagementObservers();
+    void saveUsers();
-    void saveUsers(util::Map<std::string, TrackedRecord<User>>& users);
+    void saveNotifications();
-    void saveNotifications(util::Map<std::string, TrackedRecord<Notification>>& notifications);
+    void saveServices();
-    void saveServices(util::Map<std::string, TrackedRecord<Service>>& services);
+    void saveComboPackages();
-    void saveComboPackages(util::Map<std::string, TrackedRecord<ComboPackage>>& comboPackages);
+    void saveInventoryItems();
-    void saveInventoryItems(util::Map<std::string, TrackedRecord<InventoryItem>>& inventoryItems);
+    void saveServiceBookings();
-    void saveServiceBookings(util::Map<std::string, TrackedRecord<ServiceBooking>>& bookings);
+    void saveJobCards();
-    void saveJobCards(util::Map<std::string, TrackedRecord<JobCard>>& jobCards);
+    void saveInvoices();
-    void saveInvoices(util::Map<std::string, TrackedRecord<Invoice>>& invoices);
+    void saveServiceManagementObservers(util::Map<std::string, User*>& observers);
-    void savePayments(util::Map<std::string, TrackedRecord<Payment>>& payments);
+    void savePaymentManagementObservers(util::Map<std::string, User*>& observers);
-    void saveServiceManagementObservers(util::Map<std::string, TrackedRecord<std::string>>& observers);
+    void saveInventoryManagementObservers(util::Map<std::string, User*>& observers);
-    void savePaymentManagementObservers(util::Map<std::string, TrackedRecord<std::string>>& observers);
-    void saveInventoryManagementObservers(util::Map<std::string, TrackedRecord<std::string>>& observers);
     bool lockDataStore();
     bool unlockDataStore();
 private:
@@ -78,6 +84,8 @@ private:
     util::Map<std::string, TrackedRecord<TObject>> loadRecords(MappingInfo& mapping);
     template<typename TObject, typename TSerialized>
     void saveRecords(MappingInfo& mapping, util::Map<std::string, TrackedRecord<TObject>>& records);
+    template<typename TObject> void clearCache(util::Map<std::string, TrackedRecord<TObject>>&cache);
+    template<typename TObject> void refreshCache(util::Map<std::string, TrackedRecord<TObject>>&cache, util::Map<std::string, TrackedRecord<TObject>>&refreshedCache);
 };
 
 /*
@@ -123,9 +131,7 @@ Description: Persists all modified and newly added records
              shared-memory mapping. Modified records overwrite
              their existing slots, while new records are
              appended to the end of the mapping. Records marked
-             as CLEAN are ignored. After persistence, all
+             as CLEAN are ignored.
-             temporary objects owned by the tracked records are
-             destroyed to release memory.
 Parameter:
     - mapping: Reference to the mapping where records are
                stored.
@@ -158,14 +164,74 @@ template<typename TObject, typename TSerialized> void DataStore::saveRecords(Map
                 continue;
             }
             size_t recordCount = SharedMemory::getRecordCount(mapping);
-            TSerialized* destination = static_cast<TSerialized*>(SharedMemory::getRecordAddress(mapping, recordCount));
+            TSerialized* destination = static_cast<TSerialized*>(SharedMemory::getRecordAddress(mapping,recordCount));
             *destination = serialized;
             SharedMemory::setRecordCount(mapping, recordCount + 1);
+            record.slotIndex = recordCount;
+        }
+        record.state = RecordState::CLEAN;
+    }
+}
+
+/*
+Function: clearCache
+Description: Releases all objects owned by the cache and
+             clears the cache contents.
+Parameters:
+    - cache: Cache to be cleared.
+Returns:
+    - None
+*/
+template<typename TObject>
+void DataStore::clearCache(util::Map<std::string, TrackedRecord<TObject>>&cache)
+{
+    for (int index = 0; index < cache.getSize(); ++index)
+    {
+        delete cache.getValueAt(index).data;
+        cache.getValueAt(index).data = nullptr;
+    }
+    cache.clear();
+}
+
+/*
+Function: refreshCache
+Description: Refreshes the cache while preserving object addresses
+             for records that already exist. Existing objects are
+             updated in-place so that pointers held elsewhere remain
+             valid after the refresh.
+Parameters:
+    - cache: Existing cache to refresh.
+    - refreshedCache: Newly loaded cache contents.
+Returns:
+    - None
+*/
+template<typename TObject>
+void DataStore::refreshCache(util::Map<std::string, TrackedRecord<TObject>>& cache, util::Map<std::string, TrackedRecord<TObject>>& refreshedCache)
+{
+    util::Map<std::string, TrackedRecord<TObject>> oldCache = cache;
+    cache.clear();
+    for (int index = 0; index < refreshedCache.getSize(); ++index)
+    {
+        const std::string& id = refreshedCache.getKeyAt(index);
+        TrackedRecord<TObject>& refreshedRecord = refreshedCache.getValueAt(index);
+        int oldIndex = oldCache.find(id);
+        if (oldIndex != -1)
+        {
+            TrackedRecord<TObject>& oldRecord = oldCache.getValueAt(oldIndex);
+            *oldRecord.data = *refreshedRecord.data;
+            oldRecord.slotIndex = refreshedRecord.slotIndex;
+            oldRecord.state = refreshedRecord.state;
+            delete refreshedRecord.data;
+            refreshedRecord.data = oldRecord.data;
+        }
+        cache.insert(id, refreshedRecord);
+    }
+    for (int index = 0; index < oldCache.getSize(); ++index)
+    {
+        const std::string& id = oldCache.getKeyAt(index);
+        if (cache.find(id) == -1)
+        {
+            delete oldCache.getValueAt(index).data;
         }
-    }
-    for (int index = 0; index < records.getSize(); ++index)
-    {
-        delete records.getValueAt(index).data;
-        records.getValueAt(index).data = nullptr;
     }
 }

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/datastores/DataStoreLockGuard.h

@@ -0,0 +1,28 @@
+/*
+File: DataStoreLockGuard.h
+Description: Defines the DataStoreLockGuard class used to manage DataStore
+             locking and unlocking automatically within a scope.
+Author: Trenser
+Date: 12-June-2026
+*/
+
+#pragma once
+#include "DataStore.h"
+
+class DataStoreLockGuard
+{
+public:
+    explicit DataStoreLockGuard(DataStore& dataStore)
+        : m_dataStore(dataStore)
+    {
+        m_dataStore.lockDataStore();
+    }
+    ~DataStoreLockGuard()
+    {
+        m_dataStore.unlockDataStore();
+    }
+    DataStoreLockGuard(const DataStoreLockGuard&) = delete;
+    DataStoreLockGuard& operator=(const DataStoreLockGuard&) = delete;
+private:
+    DataStore& m_dataStore;
+};

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/datastores/sharedmemory/SharedMemory.cpp

@@ -10,6 +10,7 @@ Created: 11-June-2026
 */
 
 #include "SharedMemory.h"
+#include "Windows.h"
 #include "Config.h"
 
 /*

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/services/UserManagementService.cpp

@@ -20,6 +20,9 @@ Date:19-May-2026
 #include "UserManagementService.h"
 #include "Vector.h"
 #include "Validator.h"
+#include "Utility.h"
+#include "TrackedRecord.h"
+#include "DataStoreLockGuard.h"
 
 /*
 Function: ensureAdminExists
@@ -31,12 +34,13 @@ Return type: void
 */
 void UserManagementService::ensureAdminExists()
 {
+	DataStoreLockGuard lock(m_dataStore);
 	auto& usersMap = m_dataStore.getUsers();
 	int usersMapSize = usersMap.getSize();
 	bool isAdminFound = false;
 	for (int index = 0; index < usersMapSize; index++)
 	{
-		User* user = usersMap.getValueAt(index);
+		User* user = usersMap.getValueAt(index).data;
 		if (user && user->getUserType() == util::UserType::ADMIN)
 		{
 			isAdminFound = true;
@@ -73,7 +77,9 @@ void UserManagementService::createUser(const std::string& username, const std::s
 	InventoryManagementService inventoryManagementService;
 	PaymentManagementService paymentManagementService;
 	ServiceManagementService serviceManagementService;
-	auto& usersMap = m_dataStore.getUsers();
+	DataStoreLockGuard lock(m_dataStore);
+	auto& trackedUsersMap = m_dataStore.getUsers();
+	auto usersMap = util::getObjects(trackedUsersMap);
 	if (util::isUsernameDuplicate(username, usersMap))
 	{
 		throw std::runtime_error("Username already exists");
@@ -87,13 +93,14 @@ void UserManagementService::createUser(const std::string& username, const std::s
 		throw std::runtime_error("Phone already exists");
 	}
 	User* newUser = Factory::getObject<User>(username, password, name, phone, email, type);
-	usersMap.insert(newUser->getId(), newUser);
+	trackedUsersMap.insert(newUser->getId(), util::createNewRecord(newUser));
 	paymentManagementService.attach(newUser);
 	serviceManagementService.attach(newUser);
 	if (newUser->getUserType() == util::UserType::ADMIN)
 	{
 		inventoryManagementService.attach(newUser);
 	}
+	m_dataStore.saveUsers();
 }
 
 /*
@@ -107,19 +114,24 @@ Return type: void
 */
 void UserManagementService::updateUserDetails(const std::string& userID, const std::string& email, const std::string& phone)
 {
-	auto& usersMap = m_dataStore.getUsers();
+	DataStoreLockGuard lock(m_dataStore);
-	int index = usersMap.find(userID);
+	auto& trackedUsersMap = m_dataStore.getUsers();
+	auto usersMap = util::getObjects(trackedUsersMap);
+	int index = trackedUsersMap.find(userID);
 	if (index == -1)
 	{
 		throw std::runtime_error("User does not exist!\n");
 	}
-	User* user = usersMap.getValueAt(index);
+	User* user = trackedUsersMap.getValueAt(index).data;
+	bool isModified = false;
 	if (email != user->getEmail())
 	{
 		if (util::isEmailDuplicate(email, usersMap))
 		{
 			throw std::runtime_error("Email already exists!\n");
 		}
+		user->setEmail(email);
+		isModified = true;
 	}
 	if (phone != user->getPhone())
 	{
@@ -127,9 +139,14 @@ void UserManagementService::updateUserDetails(const std::string& userID, const s
 		{
 			throw std::runtime_error("Phone number already exists!\n");
 		}
-	}
-	user->setEmail(email);
 		user->setPhone(phone);
+		isModified = true;
+	}
+	if (isModified)
+	{
+		trackedUsersMap.getValueAt(index).state = RecordState::MODIFIED;
+		m_dataStore.saveUsers();
+	}
 }
 
 /*
@@ -144,12 +161,13 @@ Throws:
 */
 util::Vector<Notification*> UserManagementService::getUserNotifications(const std::string& userID)
 {
-	auto& usersMap = m_dataStore.getUsers();
+	DataStoreLockGuard lock(m_dataStore);
-	if (usersMap.find(userID) == -1)
+	auto& trackedUsersMap = m_dataStore.getUsers(); 
+	if (trackedUsersMap.find(userID) == -1)
 	{
 		throw std::runtime_error("No user found with given UserID");
 	}
-	User* user = usersMap[userID];
+	User* user = trackedUsersMap[userID].data;
 	if (user)
 	{
 		auto& notifications = user->getNotifications();
@@ -169,97 +187,41 @@ util::Vector<Notification*> UserManagementService::getUserNotifications(const st
 
 /*
 Function: deleteNotification
-Description: Deletes a specific notification associated with a given user ID.
+Description: Marks a specific notification associated with a given user
+			 as inactive.
 Parameters:
 	- notificationID: The unique ID of the notification to be deleted.
 	- userID: The unique ID of the user whose notification is to be deleted.
 Returns:
 	- void
 Throws:
-	- std::runtime_error if no user is found with the given UserID or if no notification is found with the given NotificationID.
+	- std::runtime_error if no user is found with the given UserID or
+	  if no notification is found with the given NotificationID.
 */
 void UserManagementService::deleteNotification(const std::string& notificationID, const std::string& userID)
 {
-	auto& usersMap = m_dataStore.getUsers();
+	DataStoreLockGuard lock(m_dataStore);
-	if (usersMap.find(userID) == -1)
+	auto& trackedUsersMap = m_dataStore.getUsers();
+	auto& trackedNotificationsMap = m_dataStore.getNotifications();
+	int userIndex = trackedUsersMap.find(userID);
+	if (userIndex == -1)
 	{
 		throw std::runtime_error("No user found with given UserID");
 	}
-	User* user = usersMap[userID];
+	User* user = trackedUsersMap.getValueAt(userIndex).data;
 	auto& notifications = user->getNotifications();
 	if (notifications.find(notificationID) == -1)
 	{
 		throw std::runtime_error("No notification found with given NotificationID");
 	}
-	notifications.remove(notificationID);
+	int notificationIndex = trackedNotificationsMap.find(notificationID);
-}
+	if (notificationIndex == -1)
-
-/*
-Function: loadUsers
-Description: Loads users and notifications from persistent storage into the datastore.
-             Validates that each notification’s recipient exists and attaches the
-             notification to the corresponding user.
-Parameters:
-    - None
-Returns:
-    - void
-Throws:
-    - std::runtime_error if a notification recipient user ID is invalid
-*/
-void UserManagementService::loadUsers()
-{
-    util::FileManager<User> userFileManager(config::file::USER_FILE);
-    util::FileManager<Notification> notificationFileManager(config::file::NOTIFICATION_FILE);
-    auto& users = m_dataStore.getUsers();
-    auto usersMap = userFileManager.load();
-    auto notificationsMap = notificationFileManager.load();
-    int numberOfUsers = usersMap.getSize();
-    int numberOfNotifications = notificationsMap.getSize();
-    for (int index = 0; index < numberOfUsers; index++)
 	{
-        users[usersMap.getKeyAt(index)] = usersMap.getValueAt(index);
+		throw std::runtime_error("No notification found with given NotificationID");
 	}
-    for (int index = 0; index < numberOfNotifications; index++)
+	notifications[notificationID]->setState(util::State::INACTIVE);
-    {
+	trackedNotificationsMap.getValueAt(notificationIndex).state = RecordState::MODIFIED;
-        Notification* notification = notificationsMap.getValueAt(index);
+	m_dataStore.saveNotifications();
-        const std::string& recipientUserId = notification->getRecipientUserId();
-        int userIndex = users.find(recipientUserId);
-        if (userIndex == -1)
-        {
-            throw std::runtime_error("Invalid recipient user ID");
-        }
-        User* user = users.getValueAt(userIndex);
-        user->addNotification(notification);
-    }
-}
-
-/*
-Function: saveUsers
-Description: Saves users and their notifications from the datastore to persistent storage.
-             Collects notifications from all users into a single map before saving.
-Parameters:
-    - None
-Returns:
-    - void
-*/
-void UserManagementService::saveUsers()
-{
-    util::FileManager<User> userFileManager(config::file::USER_FILE);
-    util::FileManager<Notification> notificationFileManager(config::file::NOTIFICATION_FILE);
-    auto& users = m_dataStore.getUsers();
-    util::Map<std::string, Notification*> notifications;
-    for (int userIndex = 0; userIndex < users.getSize(); userIndex++)
-    {
-        User* user = users.getValueAt(userIndex);
-        auto& userNotifications = user->getNotifications();
-        for (int notificationIndex = 0; notificationIndex < userNotifications.getSize(); notificationIndex++)
-        {
-            notifications[userNotifications.getKeyAt(notificationIndex)] =
-                userNotifications.getValueAt(notificationIndex);
-        }
-    }
-    userFileManager.save(users);
-    notificationFileManager.save(notifications);
 }
 
 /*
@@ -270,7 +232,9 @@ Return type: util::Map<std::string, User*>
 */
 util::Map<std::string, User*> UserManagementService::getUsers()
 {
-	return m_dataStore.getUsers();
+	DataStoreLockGuard lock(m_dataStore);
+	auto users = util::getObjects(m_dataStore.getUsers());
+	return users;
 }
 
 /*
@@ -281,10 +245,12 @@ Return type: User*
 */
 User* UserManagementService::getUser(const std::string& userID)
 {
-	int index = m_dataStore.getUsers().find(userID);
+	DataStoreLockGuard lock(m_dataStore);
+	auto& trackedUsersMap = m_dataStore.getUsers();
+	int index = trackedUsersMap.find(userID);
 	if (index != -1)
 	{
-		return m_dataStore.getUsers().getValueAt(index);
+		return trackedUsersMap.getValueAt(index).data;
 	}
 	return nullptr;
 }
@@ -300,10 +266,12 @@ void UserManagementService::removeUser(const std::string& userID)
 	InventoryManagementService inventoryManagementService;
 	PaymentManagementService paymentManagementService;
 	ServiceManagementService serviceManagementService;
-	int index = m_dataStore.getUsers().find(userID);
+	DataStoreLockGuard lock(m_dataStore);
+	auto& trackedUsersMap = m_dataStore.getUsers();
+	int index = trackedUsersMap.find(userID);
 	if (index != -1)
 	{
-		User* user = m_dataStore.getUsers().getValueAt(index);
+		User* user = trackedUsersMap.getValueAt(index).data;
 		if (user != nullptr)
 		{
 			if (user->getUserType() == util::UserType::CUSTOMER)
@@ -314,21 +282,37 @@ void UserManagementService::removeUser(const std::string& userID)
 			{
 				serviceManagementService.cancelTechnicianJobs(userID);
 			}
-			user->setState(util::State::INACTIVE);
 			inventoryManagementService.detach(user);
 			paymentManagementService.detach(user);
 			serviceManagementService.detach(user);
+			user->setState(util::State::INACTIVE);
+			trackedUsersMap.getValueAt(index).state = RecordState::MODIFIED;
+			m_dataStore.saveUsers();
 		}
 	}
 }
 
+/*
+Function: getUsers
+Description: Retrieves all active users of the specified type from
+			 the DataStore.
+Parameters:
+	- type: The user type to filter by
+			(ADMIN, CUSTOMER, or TECHNICIAN).
+Returns:
+	- util::Map<std::string, User*>:
+	  Collection of active users matching the specified type,
+	  keyed by user ID.
+*/
 util::Map<std::string, User*> UserManagementService::getUsers(util::UserType type) 
 {
-	util::Map<std::string, User*>& currentUsers = m_dataStore.getUsers();
+	DataStoreLockGuard lock(m_dataStore);
+	auto& trackedUsersMap = m_dataStore.getUsers();
+	util::Map<std::string, User*> currentUsers = util::getObjects(trackedUsersMap);
 	util::Map<std::string, User*> filteredUsersMap;
-	for (int iterator = 0; iterator < currentUsers.getSize(); iterator++)
+	for (int index = 0; index < currentUsers.getSize(); index++)
 	{
-		User* currentUser = currentUsers.getValueAt(iterator);
+		User* currentUser = currentUsers.getValueAt(index);
 		if (currentUser && currentUser->getState() == util::State::ACTIVE && currentUser->getUserType() == type)
 		{
 			filteredUsersMap.insert(currentUser->getId(), currentUser);

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/services/UserManagementService.h

@@ -31,6 +31,4 @@ public:
     util::Vector<Notification*> getUserNotifications(const std::string& userID);
     void deleteNotification(const std::string& notificationID, const std::string& userID);
     void ensureAdminExists();
-    void loadUsers();
-    void saveUsers();
 };

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/utilities/Utility.h

@@ -99,4 +99,80 @@ namespace util
         auto observerIDs = service->getObserverIDs();
         util::saveRecords(filePath, observerIDs);
     }
+
+    template<typename TObject>
+    Map<std::string, TObject*> getObjects(const Map<std::string, TrackedRecord<TObject>>& trackedRecords);
+
+    template<typename TObject>
+    Map<std::string, const TObject*> getConstObjects(const Map<std::string, TrackedRecord<TObject>>& trackedRecords);
+
+    template<typename TObject>
+    TrackedRecord<TObject> createNewRecord(TObject* object);
+}
+
+/*
+Function: getObjects
+Description: Extracts the object pointers from a tracked-record
+             collection and returns them as a map keyed by the
+             same identifiers.
+Parameters:
+    - trackedRecords: Collection of tracked records.
+Returns:
+    - Map<std::string, TObject*>: Collection of object pointers.
+*/
+template<typename TObject>
+util::Map<std::string, TObject*> util::getObjects(const util::Map<std::string, TrackedRecord<TObject>>& trackedRecords)
+{
+    util::Map<std::string, TObject*> objects;
+    for (int index = 0; index < trackedRecords.getSize(); ++index)
+    {
+        const std::string& key = trackedRecords.getKeyAt(index);
+        TObject* object = trackedRecords.getValueAt(index).data;
+        objects.insert(key, object);
+    }
+    return objects;
+}
+
+/*
+Function: getConstObjects
+Description: Extracts the object pointers from a tracked-record
+             collection and returns them as a read-only map
+             keyed by the same identifiers.
+Parameters:
+    - trackedRecords: Collection of tracked records.
+Returns:
+    - Map<std::string, const TObject*>:
+      Collection of read-only object pointers.
+*/
+template<typename TObject>
+util::Map<std::string, const TObject*> util::getConstObjects(
+    const util::Map<std::string, TrackedRecord<TObject>>& trackedRecords)
+{
+    util::Map<std::string, const TObject*> objects;
+    for (int index = 0; index < trackedRecords.getSize(); ++index)
+    {
+        const std::string& key = trackedRecords.getKeyAt(index);
+        const TObject* object = trackedRecords.getValueAt(index).data;
+        objects.insert(key, object);
+    }
+    return objects;
+}
+
+/*
+Function: createNewRecord
+Description: Creates a tracked record for a newly created
+             object. The record is initialized with
+             NEW_RECORD state.
+Parameters:
+    - object: Pointer to the newly created object.
+Returns:
+    - TrackedRecord<TObject>: Initialized tracked record.
+*/
+template<typename TObject>
+TrackedRecord<TObject> util::createNewRecord(TObject* object)
+{
+    TrackedRecord<TObject> record;
+    record.data = object;
+    record.state = RecordState::NEW_RECORD;
+    return record;
 }

Trenser.VehicleServiceSystem/Trenser.VehicleServiceSystem/views/UserInterface.cpp

@@ -27,8 +27,11 @@ void UserInterface::run()
 {
 	try
 	{
-		m_controller.loadSystemData();
+		if (!m_controller.initialize())
-		m_controller.runSystemChecks();
+		{
+			std::cout << "Error: Failed to initialize the system!";
+			return;
+		}
 		bool isMenuActive = true;
 		while (isMenuActive)
 		{
@@ -49,7 +52,7 @@ void UserInterface::run()
 				util::pressEnter();
 			}
 		}
-		m_controller.saveSystemData();
+		m_controller.shutdown();
 	}
 	catch (const std::invalid_argument& exception)
 	{