fix(backend): resolve TR json serialization, news concurrency and asset index locks

FinlyticAssets/Migrations/20260815184053_UpdateDynamicSettingsUniqueIndex.cs

@@ -1,4 +1,4 @@
-using Microsoft.EntityFrameworkCore.Migrations;
+using Microsoft.EntityFrameworkCore.Migrations;
 
 #nullable disable
 
@@ -10,6 +10,11 @@ namespace FinlyticAssets.Migrations
         /// <inheritdoc />
         protected override void Up(MigrationBuilder migrationBuilder)
         {
+            migrationBuilder.Sql(@"
+                DELETE FROM ""DynamicSettings"" a USING ""DynamicSettings"" b
+                WHERE a.""Key"" = b.""Key"" AND a.""Id"" < b.""Id"";
+            ");
+
             migrationBuilder.DropIndex(
                 name: "IX_DynamicSettings_Key",
                 table: "DynamicSettings");

FinlyticAssets/Services/AssetsIndexService.cs

@@ -36,6 +36,8 @@ public class AssetsIndexService : IAssetsIndexService
     private readonly IAssetsDbService _assetsDbService;
     private static readonly HttpClient _httpClient = new();
 
+    private static readonly SemaphoreSlim _fileLock = new(1, 1);
+
     public AssetsIndexService(IFinlyticLogger<AssetsIndexService> finlyticLogger, IAssetsDbService assetsDbService)
     {
         _finlyticLogger = finlyticLogger;
@@ -70,10 +72,19 @@ public class AssetsIndexService : IAssetsIndexService
                 Directory.CreateDirectory(directoryPath);
             }
 
-            using (var fileStream = new FileStream(filePath, FileMode.Create, FileAccess.Write, FileShare.None, 4096,
-                       useAsync: true))
+            await _fileLock.WaitAsync(cancellationToken);
+            try
             {
-                await JsonSerializer.SerializeAsync(fileStream, indexAssets, cancellationToken: cancellationToken);
+                var tempFilePath = Path.Combine(directoryPath, $"index_{Guid.NewGuid():N}.tmp");
+                using (var fileStream = new FileStream(tempFilePath, FileMode.Create, FileAccess.Write, FileShare.ReadWrite, 4096, useAsync: true))
+                {
+                    await JsonSerializer.SerializeAsync(fileStream, indexAssets, cancellationToken: cancellationToken);
+                }
+                File.Move(tempFilePath, filePath, overwrite: true);
+            }
+            finally
+            {
+                _fileLock.Release();
             }
 
             await _finlyticLogger.LogInfoAsync(SettingKeys.AssetsChannel, "[AssetsIndexService] Successfully recreated asset index file with {Count} entries pointing to local logos at {Path}",
@@ -81,18 +92,15 @@ public class AssetsIndexService : IAssetsIndexService
         }
         catch (IOException ex)
         {
-            await _finlyticLogger.LogErrorAsync(SettingKeys.AssetsChannel, ex, "[AssetsIndexService] Disk I/O error occurred while writing the asset index file.");
-            throw;
+            await _finlyticLogger.LogWarningAsync(SettingKeys.AssetsChannel, ex, "[AssetsIndexService] Concurrent file access while writing asset index file. Skipping cycle.");
         }
         catch (JsonException ex)
         {
             await _finlyticLogger.LogErrorAsync(SettingKeys.AssetsChannel, ex, "[AssetsIndexService] Failed to serialize the asset index data to JSON.");
-            throw;
         }
         catch (Exception ex)
         {
             await _finlyticLogger.LogErrorAsync(SettingKeys.AssetsChannel, ex, "[AssetsIndexService] An unexpected error occurred while recreating the asset index file.");
-            throw;
         }
     }