Fix: Reliability of receiving media files.

CHANGELOG.md

@@ -3,6 +3,7 @@
 ## 0.2.12
 
 - Improved: Memories viewer redesigned with smoother animations and new quick-action controls.
+- Fix: Reliability of receiving media files.
 
 ## 0.2.11
 

lib/src/database/daos/receipts.dao.dart

@@ -191,6 +191,23 @@ class ReceiptsDao extends DatabaseAccessor<TwonlyDB> with _$ReceiptsDaoMixin {
     )..where((c) => c.receiptId.equals(receiptId))).write(updates);
   }
 
+  Future<Receipt?> rotateReceiptId(String oldReceiptId) async {
+    final newReceiptId = uuid.v4();
+    await updateReceipt(
+      oldReceiptId,
+      ReceiptsCompanion(
+        receiptId: Value(newReceiptId),
+      ),
+    );
+    final updatedReceipt = await getReceiptById(newReceiptId);
+    if (updatedReceipt == null) {
+      Log.error(
+        'Tried to change the receipt ID, but could not get the updated receipt...',
+      );
+    }
+    return updatedReceipt;
+  }
+
   Future<void> updateReceiptByContactAndMessageId(
     int contactId,
     String messageId,

lib/src/services/api/client2client/media.c2c.dart

@@ -121,6 +121,7 @@ Future<void> handleMedia(
   MediaFile? mediaFile;
   Message? message;
 
+  Log.info('Starting transaction for media message ${media.senderMessageId}');
   await twonlyDB.transaction(() async {
     mediaFile = await twonlyDB.mediaFilesDao.insertOrUpdateMedia(
       MediaFilesCompanion(
@@ -163,6 +164,9 @@ Future<void> handleMedia(
       ),
     );
   });
+  Log.info(
+    'Finished transaction for media message ${media.senderMessageId}. Success: ${message != null}',
+  );
 
   if (message != null && mediaFile != null) {
     await twonlyDB.groupsDao.increaseLastMessageExchange(

lib/src/services/api/mediafiles/upload.api.dart

@@ -27,6 +27,16 @@ import 'package:twonly/src/utils/misc.dart';
 import 'package:workmanager/workmanager.dart' hide TaskStatus;
 
 final lockRetransmission = Mutex();
+final Map<String, Mutex> _uploadMutexes = {};
+
+Future<void> _protectMediaUpload(
+  String mediaId,
+  Future<void> Function() action,
+) async {
+  final mutex = _uploadMutexes.putIfAbsent(mediaId, Mutex.new);
+  await mutex.protect(action);
+  _uploadMutexes.remove(mediaId);
+}
 
 Future<void> reuploadMediaFiles() async {
   return exclusiveAccess(
@@ -42,18 +52,33 @@ Future<void> reuploadMediaFiles() async {
 
       final contacts = <int, Contact>{};
 
-      for (final receipt in receipts) {
+      for (var receipt in receipts) {
         if (receipt.retryCount > 1 && receipt.lastRetry != null) {
           final twentyFourHoursAgo = DateTime.now().subtract(
-            const Duration(hours: 24),
+            const Duration(hours: 6),
           );
           if (receipt.lastRetry!.isAfter(twentyFourHoursAgo)) {
             Log.info(
-              'Ignoring ${receipt.receiptId} as it was retried in the last 24h',
+              'Ignoring ${receipt.receiptId} as it was retried in the last 6h',
             );
             continue;
           }
         }
+
+        if (receipt.retryCount >= 2) {
+          // After two retries, change the receiptId. This addresses a bug where the receiver received the message and marked it as received, but the app was closed before the message was fully processed. Because the receipt was already stored, subsequent retries were detected as duplicates and rejected.
+          final oldReceiptId = receipt.receiptId;
+          final updatedReceipt = await twonlyDB.receiptsDao.rotateReceiptId(
+            oldReceiptId,
+          );
+          if (updatedReceipt == null) continue;
+
+          Log.info(
+            'Changed receiptId $oldReceiptId to ${updatedReceipt.receiptId} as retryCount is ${receipt.retryCount}',
+          );
+          receipt = updatedReceipt;
+        }
+
         var messageId = receipt.messageId;
         if (receipt.messageId == null) {
           Log.info('Message not in receipt. Loading it from the content.');
@@ -146,7 +171,7 @@ Future<void> reuploadMediaFiles() async {
           Log.info('Reuploading media file $messageId');
           // the media file should be still on the server, so it should be enough
           // to just resend the message containing the download token.
-          await tryToSendCompleteMessage(receipt: receipt);
+          await tryToSendCompleteMessage(receiptId: receipt.receiptId);
         }
       }
     },
@@ -158,6 +183,7 @@ Future<void> reuploadMediaFile(
   MediaFile mediaFile,
   String messageId,
 ) async {
+  return _protectMediaUpload(mediaFile.mediaId, () async {
     Log.info('Reuploading media file: ${mediaFile.mediaId}');
 
     await twonlyDB.receiptsDao.updateReceiptByContactAndMessageId(
@@ -169,8 +195,14 @@ Future<void> reuploadMediaFile(
       ),
     );
 
-  final reuploadRequestedBy = (mediaFile.reuploadRequestedBy ?? [])
+    // Refresh media file to get latest reuploadRequestedBy
+    final currentMedia = await twonlyDB.mediaFilesDao.getMediaFileById(
+      mediaFile.mediaId,
+    );
+
+    final reuploadRequestedBy = (currentMedia?.reuploadRequestedBy ?? [])
       ..add(contactId);
+
     await twonlyDB.mediaFilesDao.updateMedia(
       mediaFile.mediaId,
       MediaFilesCompanion(
@@ -185,8 +217,9 @@ Future<void> reuploadMediaFile(
       if (mediaFileUpdated.uploadRequestPath.existsSync()) {
         mediaFileUpdated.uploadRequestPath.deleteSync();
       }
-    unawaited(startBackgroundMediaUpload(mediaFileUpdated));
+      await _startBackgroundMediaUploadInternal(mediaFileUpdated);
     }
+  });
 }
 
 final Mutex _lockPreprocessing = Mutex();
@@ -398,6 +431,18 @@ Future<void> insertMediaFileInMessagesTable(
 }
 
 Future<void> startBackgroundMediaUpload(MediaFileService mediaService) async {
+  return _protectMediaUpload(
+    mediaService.mediaFile.mediaId,
+    () => _startBackgroundMediaUploadInternal(mediaService),
+  );
+}
+
+Future<void> _startBackgroundMediaUploadInternal(
+  MediaFileService mediaService,
+) async {
+  // Refresh the media file state inside the mutex
+  await mediaService.updateFromDB();
+
   if (mediaService.mediaFile.uploadState == UploadState.initialized ||
       mediaService.mediaFile.uploadState == UploadState.preprocessing) {
     await mediaService.setUploadState(UploadState.preprocessing);
@@ -603,10 +648,7 @@ Future<void> _createUploadRequest(MediaFileService media) async {
   await media.uploadRequestPath.writeAsBytes(uploadRequestBytes);
 }
 
-Mutex protectUpload = Mutex();
-
 Future<void> _uploadUploadRequest(MediaFileService media) async {
-  await protectUpload.protect(() async {
   final currentMedia = await twonlyDB.mediaFilesDao.getMediaFileById(
     media.mediaFile.mediaId,
   );
@@ -614,7 +656,7 @@ Future<void> _uploadUploadRequest(MediaFileService media) async {
   if (currentMedia == null ||
       currentMedia.uploadState == UploadState.backgroundUploadTaskStarted) {
     Log.info('Download for ${media.mediaFile.mediaId} already started.');
-      return null;
+    return;
   }
 
   final apiUrl =
@@ -650,7 +692,6 @@ Future<void> _uploadUploadRequest(MediaFileService media) async {
   } else {
     unawaited(uploadFileFastOrEnqueue(task, media));
   }
-  });
 }
 
 Future<void> uploadFileFastOrEnqueue(

lib/src/services/api/messages.api.dart

@@ -80,15 +80,29 @@ Future<(Uint8List, Uint8List?)?> tryToSendCompleteMessage({
         return null;
       }
     }
-    // ignore: parameter_assignments
+
-    receiptId = receipt.receiptId;
+    if (receipt.retryCount >= 2) {
+      // After two retries, change the receiptId. This addresses a bug where the receiver received the message and marked it as received,
+      // but the app was closed before the message was fully processed. Because the receipt was already stored, subsequent retries were
+      // detected as duplicates and rejected.
+      final oldReceiptId = receipt.receiptId;
+      final updatedReceipt = await twonlyDB.receiptsDao.rotateReceiptId(
+        oldReceiptId,
+      );
+      if (updatedReceipt != null) {
+        Log.info(
+          'Changed receiptId $oldReceiptId to ${updatedReceipt.receiptId} as retryCount is ${receipt.retryCount}',
+        );
+        receipt = updatedReceipt;
+      }
+    }
 
     final contact = await twonlyDB.contactsDao.getContactById(
       receipt.contactId,
     );
     if (contact == null || contact.accountDeleted) {
       Log.warn('Will not send message again as user does not exist anymore.');
-      await twonlyDB.receiptsDao.deleteReceipt(receiptId);
+      await twonlyDB.receiptsDao.deleteReceipt(receipt.receiptId);
       return null;
     }
 
@@ -100,13 +114,13 @@ Future<(Uint8List, Uint8List?)?> tryToSendCompleteMessage({
     }
 
     final message = pb.Message.fromBuffer(receipt.message)
-      ..receiptId = receiptId;
+      ..receiptId = receipt.receiptId;
 
     final encryptedContent = pb.EncryptedContent.fromBuffer(
       message.encryptedContent,
     );
 
-    Log.info('Uploading $receiptId.');
+    Log.info('Uploading ${receipt.receiptId}.');
 
     Uint8List? pushData;
     if (receipt.retryCount == 0) {
@@ -164,7 +178,7 @@ Future<(Uint8List, Uint8List?)?> tryToSendCompleteMessage({
     if (resp.isError) {
       Log.warn('Could not transmit message got ${resp.error}.');
       if (resp.error == ErrorCode.UserIdNotFound) {
-        await twonlyDB.receiptsDao.deleteReceipt(receiptId);
+        await twonlyDB.receiptsDao.deleteReceipt(receipt.receiptId);
         await twonlyDB.contactsDao.updateContact(
           receipt.contactId,
           const ContactsCompanion(accountDeleted: Value(true)),
@@ -182,10 +196,10 @@ Future<(Uint8List, Uint8List?)?> tryToSendCompleteMessage({
         );
       }
       if (!receipt.contactWillSendsReceipt) {
-        await twonlyDB.receiptsDao.deleteReceipt(receiptId);
+        await twonlyDB.receiptsDao.deleteReceipt(receipt.receiptId);
       } else {
         await twonlyDB.receiptsDao.updateReceipt(
-          receiptId,
+          receipt.receiptId,
           ReceiptsCompanion(
             ackByServerAt: Value(clock.now()),
             retryCount: Value(receipt.retryCount + 1),
@@ -197,8 +211,8 @@ Future<(Uint8List, Uint8List?)?> tryToSendCompleteMessage({
     }
   } catch (e) {
     Log.error('Unknown Error when sending message: $e');
-    if (receiptId != null) {
+    if (receipt != null) {
-      await twonlyDB.receiptsDao.deleteReceipt(receiptId);
+      await twonlyDB.receiptsDao.deleteReceipt(receipt.receiptId);
     }
   }
   return null;

lib/src/services/api/server_messages.api.dart

@@ -4,6 +4,7 @@ import 'dart:io';
 import 'package:clock/clock.dart';
 import 'package:drift/drift.dart';
 import 'package:hashlib/random.dart';
+import 'package:mutex/mutex.dart';
 import 'package:twonly/globals.dart';
 import 'package:twonly/locator.dart';
 import 'package:twonly/src/database/daos/contacts.dao.dart';
@@ -77,24 +78,32 @@ Future<void> handleServerMessage(server.ServerToClient msg) async {
 
 DateTime lastPushKeyRequest = clock.now().subtract(const Duration(hours: 1));
 
+final Map<String, Mutex> _messageLocks = {};
+
 Future<void> handleClient2ClientMessage(NewMessage newMessage) async {
   final body = Uint8List.fromList(newMessage.body);
-  final fromUserId = newMessage.fromUserId.toInt();
-
   final message = Message.fromBuffer(body);
   final receiptId = message.receiptId;
 
+  final mutex = _messageLocks.putIfAbsent(receiptId, Mutex.new);
+  await mutex.protect(() async {
+    await _handleClient2ClientMessage(newMessage, message);
+  });
+  _messageLocks.remove(receiptId);
+}
+
+Future<void> _handleClient2ClientMessage(
+  NewMessage newMessage,
+  Message message,
+) async {
+  final fromUserId = newMessage.fromUserId.toInt();
+  final receiptId = message.receiptId;
+
   if (await twonlyDB.receiptsDao.isDuplicated(receiptId)) {
     return;
   }
 
-  try {
+  Log.info('Started processing message with receiptId $receiptId');
-    await twonlyDB.receiptsDao.gotReceipt(receiptId);
-    Log.info('Got a message with receiptId $receiptId');
-  } catch (e) {
-    Log.error(e);
-    return;
-  }
 
   switch (message.type) {
     case Message_Type.SENDER_DELIVERY_RECEIPT:
@@ -209,7 +218,14 @@ Future<void> handleClient2ClientMessage(NewMessage newMessage) async {
         await tryToSendCompleteMessage(receiptId: receiptId);
       }
     case Message_Type.TEST_NOTIFICATION:
-      return;
+      break;
+  }
+
+  try {
+    await twonlyDB.receiptsDao.gotReceipt(receiptId);
+    Log.info('Got a message with receiptId $receiptId');
+  } catch (e) {
+    Log.error('Error marking message as received $receiptId: $e');
   }
 }
 
@@ -238,6 +254,8 @@ Future<(EncryptedContent?, PlaintextContent?)> handleEncryptedMessageRaw(
     );
   }
 
+  Log.info('Calling handleEncryptedMessage for $receiptId');
+
   final (a, b) = await handleEncryptedMessage(
     fromUserId,
     encryptedContent,
@@ -245,6 +263,8 @@ Future<(EncryptedContent?, PlaintextContent?)> handleEncryptedMessageRaw(
     receiptId,
   );
 
+  Log.info('Finished handleEncryptedMessage for $receiptId');
+
   if (Platform.isAndroid && a == null && b == null) {
     // Message was handled without any error -> Show push notification to the user.
     await showPushNotificationFromServerMessages(fromUserId, encryptedContent);

lib/src/services/signal/encryption.signal.dart

@@ -41,8 +41,10 @@ signalDecryptMessage(
   int type,
 ) async {
   // Hold the lock only for the cryptographic operation, not for network I/O
+  Log.info('Acquiring lockingSignalProtocol for $fromUserId');
   final (decryptedContent, errorType, needsResync) = await lockingSignalProtocol
       .protect(() async {
+        Log.info('Lock acquired for $fromUserId');
         try {
           final session = SessionCipher.fromStore(
             (await getSignalStore())!,
@@ -97,6 +99,8 @@ signalDecryptMessage(
         }
       });
 
+  Log.info('Released lockingSignalProtocol for $fromUserId');
+
   // Handle session resync OUTSIDE the lock to avoid holding it during
   // network round-trips (which can block for up to 60 seconds)
   if (needsResync && !resyncedUsers.contains(fromUserId)) {