fixes concurrency issues on get or add album

PiwigoDirectorySync/PiwigoDirectorySync.csproj

@@ -25,6 +25,7 @@
         <PackageReference Include="Microsoft.Extensions.Configuration.Json" Version="7.0.0"/>
         <PackageReference Include="Microsoft.Extensions.Logging.Configuration" Version="7.0.0" />
         <PackageReference Include="Piwigo.Client" Version="0.1.0.19" />
+        <PackageReference Include="Polly" Version="7.2.4" />
         <PackageReference Include="Serilog" Version="3.0.1" />
         <PackageReference Include="Serilog.Extensions.Logging" Version="7.0.0" />
         <PackageReference Include="Serilog.Sinks.Console" Version="4.1.0" />

PiwigoDirectorySync/Services/FileIndexer.cs

@@ -1,9 +1,11 @@
 using System.Collections.Concurrent;
+using System.Data;
 using System.Threading.Channels;
 using Microsoft.EntityFrameworkCore;
 using Microsoft.Extensions.DependencyInjection;
 using PiwigoDirectorySync.Infrastructure;
 using PiwigoDirectorySync.Persistence;
+using Polly;
 using Serilog;
 
 namespace PiwigoDirectorySync.Services;
@@ -62,7 +64,7 @@ internal class FileIndexer : IFileIndexer
 
             var relativePath = Path.GetRelativePath(piwigoServer.RootDirectory, fullFilePath);
 
-            var album = await GetOrAddAlbumAsync(db, piwigoServer, fileInfo.Directory!, ct);
+            var album = await GetOrAddAlbumAsync(piwigoServerId, fileInfo.Directory!, ct);
 
             var image = await GetOrAddImageAsync(db, album, relativePath, ct);
 
@@ -86,15 +88,14 @@ internal class FileIndexer : IFileIndexer
         }
     }
 
-    private static async Task<ImageEntity> GetOrAddImageAsync(PersistenceContext db, AlbumEntity album, string relativePath, CancellationToken ct)
+    private static async Task<ImageEntity> GetOrAddImageAsync(PersistenceContext db, int albumId, string relativePath, CancellationToken ct)
     {
-        var imageEntity = await db.PiwigoImages.Where(i => i.AlbumId == album.Id && i.FilePath == relativePath).FirstOrDefaultAsync(ct);
+        var imageEntity = await db.PiwigoImages.Where(i => i.AlbumId == albumId && i.FilePath == relativePath).FirstOrDefaultAsync(ct);
         if (imageEntity is null)
         {
             imageEntity = new ImageEntity
             {
-                AlbumId = album.Id,
-                Album = album,
+                AlbumId = albumId,
                 FilePath = relativePath,
                 UploadRequired = true,
                 DeleteRequired = false
@@ -105,38 +106,52 @@ internal class FileIndexer : IFileIndexer
         return imageEntity;
     }
 
-    private static async Task<AlbumEntity> GetOrAddAlbumAsync(PersistenceContext db, ServerEntity server, DirectoryInfo directory, CancellationToken ct)
+    private async Task<int> GetOrAddAlbumAsync(int serverId, DirectoryInfo directory, CancellationToken ct)
     {
-        var albumPath = Path.GetRelativePath(server.RootDirectory, directory.FullName);
-        var album = await db.PiwigoAlbums.FindByServerAndPathAsync(server.Id, albumPath, ct);
+        return await Policy.Handle<DbUpdateException>()
+            .RetryAsync(3, (ex, _) => { _logger.Warning(ex, "Could not create album for directory {AlbumDirectory}, retrying", directory); })
+            .ExecuteAsync(async () =>
+            {
+                await using var scope = _serviceProvider.CreateAsyncScope();
+                await using var db = scope.ServiceProvider.GetRequiredService<PersistenceContext>();
+                await using var tx = await db.Database.BeginTransactionAsync(IsolationLevel.Serializable, ct);
+                var piwigoServer = await db.PiwigoServers.GetByIdAsync(serverId, ct);
+
+                _logger.Information("Get or crate album for directory {AlbumDirectory}", directory);
+
+                var albumId = await GetOrAddAlbumAsync(db, serverId, piwigoServer.RootDirectory, directory, ct);
+
+                await tx.CommitAsync(ct);
+                return albumId;
+            });
+    }
+
+    private static async Task<int> GetOrAddAlbumAsync(PersistenceContext db, int serverId, string rootDirectory, DirectoryInfo directory, CancellationToken ct)
+    {
+        var albumPath = Path.GetRelativePath(rootDirectory, directory.FullName);
+        var album = await db.PiwigoAlbums.FindByServerAndPathAsync(serverId, albumPath, ct);
         if (album != null)
         {
-            return album;
+            return album.Id;
         }
 
-        AlbumEntity? parentAlbum;
-        if (string.Equals(new DirectoryInfo(server.RootDirectory).FullName, directory.Parent!.FullName))
+        int? parentAlbumId = null;
+        if (!string.Equals(new DirectoryInfo(rootDirectory).FullName, directory.Parent!.FullName))
         {
-            parentAlbum = null;
-        }
-        else
-        {
-            parentAlbum = await GetOrAddAlbumAsync(db, server, directory.Parent!, ct);
+            parentAlbumId = await GetOrAddAlbumAsync(db, serverId, rootDirectory, directory.Parent!, ct);
         }
 
         album = new AlbumEntity
         {
-            ServerId = server.Id,
-            Server = server,
+            ServerId = serverId,
             Name = directory.Name,
             Path = albumPath,
-            ParentId = parentAlbum?.Id,
-            Parent = parentAlbum
+            ParentId = parentAlbumId
         };
         db.PiwigoAlbums.Add(album);
 
         await db.SaveChangesAsync(ct);
 
-        return album;
+        return album.Id;
     }
 }