implemented the clear in the server

src/main/java/entgra/mailsender/Service/MailQueueService.java

@@ -7,6 +7,9 @@ import java.util.List;
 public interface MailQueueService {
 
     void enqueMails(List<MailModel> mailModelList);
+
     MailModel getHighPriorityMail();
 
+    void clearOnServerShutdown();
+
 }

src/main/java/entgra/mailsender/Service/MailQueueServiceImpl.java

@@ -21,9 +21,8 @@ public class MailQueueServiceImpl implements MailQueueService{
     @Autowired
     MailDAO mailDAO;
 
-//    private volatile Thread
-//            processingThread;
-//    private volatile boolean isProcessingMails;
+    private volatile Thread processingThread;
+    private volatile boolean isProcessingMails;
 //    private final MailDAO mailDAO;
 
     @Override
@@ -58,22 +57,22 @@ public class MailQueueServiceImpl implements MailQueueService{
         return null;
     }
 
-//    public void clearOnServerShutdown(){
-//        BlockingQueue<MailModel> priorityQueue = PriorityQueueHolder.getInstance().getPriorityQueue();
-//        if (processingThread != null){
-//            while (isProcessingMails){
-//                try {
-//                    Thread.sleep(1000);
-//                }catch (InterruptedException e){
-//                    Thread.currentThread().interrupt();
-//                    logger.info("Error waiting for the processing cycle to complete" + e.getMessage());
-//                }
-//                isProcessingMails = priorityQueue.peek() != null;
-//            }
-//            processingThread.interrupt();
-//        }
-//        logger.info("Server shutdown");
-//    }
+    public void clearOnServerShutdown(){
+        BlockingQueue<MailModel> priorityQueue = PriorityQueueHolder.getInstance().getPriorityQueue();
+        if (processingThread != null){
+            while (isProcessingMails){
+                try {
+                    Thread.sleep(1000);
+                }catch (InterruptedException e){
+                    Thread.currentThread().interrupt();
+                    logger.info("Error waiting for the processing cycle to complete" + e.getMessage());
+                }
+                isProcessingMails = priorityQueue.peek() != null;
+            }
+            processingThread.interrupt();
+        }
+        logger.info("Server shutdown");
+    }
 
 
 }

src/main/java/entgra/mailsender/Service/MailServiceImpl.java

@@ -3,27 +3,39 @@ package entgra.mailsender.Service;
 import entgra.mailsender.DAO.MailDAO;
 import entgra.mailsender.DTO.MailModel;
 import entgra.mailsender.util.PriorityQueueHolder;
+import jakarta.annotation.PreDestroy;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.mail.javamail.JavaMailSender;
 import org.springframework.mail.javamail.MimeMessageHelper;
 import org.springframework.stereotype.Service;
 
-import java.util.*;
-import java.util.function.Supplier;
+import java.util.List;
 import java.util.logging.Logger;
 
 
 @Service
 public class MailServiceImpl implements MailService {
     Logger logger = Logger.getLogger(String.valueOf(MailServiceImpl.class));
+    private volatile boolean shutdownRequested = false;
+
+    @Autowired
+    private MailQueueService mailQueueService;
+
+//    private final mailQueueService mailQueueService;
+
+
+    @PreDestroy
+    public void shutdown() {
+        shutdownRequested = true;
+        mailQueueService.clearOnServerShutdown();
+    }
 
     @Autowired
     private JavaMailSender javaMailSender;
 
     @Autowired
     private MailDAO mailDAO;
-    @Autowired
-    private MailQueueService mailQueueService;
+
 
 
     public void sendEmail(MailModel emailModel){
@@ -34,6 +46,7 @@ public class MailServiceImpl implements MailService {
         }
 
         mailDAO.addMail(emailModel); // save the mail details in the database
+        syncMailWithDB();
 
 
     //here we need to check the unsent mail details