Always await instead of directly returning Task

https://github.com/davidfowl/AspNetCoreDiagnosticScenarios/blob/master/AsyncGuidance.md#prefer-asyncawait-over-directly-returning-task

The performance impact is negligible (and it's me saying that!)

Emby.Server.Implementations/HttpServer/WebSocketConnection.cs

@@ -82,17 +82,17 @@ namespace Emby.Server.Implementations.HttpServer
         public WebSocketState State => _socket.State;
 
         /// <inheritdoc />
-        public Task SendAsync(OutboundWebSocketMessage message, CancellationToken cancellationToken)
+        public async Task SendAsync(OutboundWebSocketMessage message, CancellationToken cancellationToken)
         {
             var json = JsonSerializer.SerializeToUtf8Bytes(message, _jsonOptions);
-            return _socket.SendAsync(json, WebSocketMessageType.Text, true, cancellationToken);
+            await _socket.SendAsync(json, WebSocketMessageType.Text, true, cancellationToken).ConfigureAwait(false);
         }
 
         /// <inheritdoc />
-        public Task SendAsync<T>(OutboundWebSocketMessage<T> message, CancellationToken cancellationToken)
+        public async Task SendAsync<T>(OutboundWebSocketMessage<T> message, CancellationToken cancellationToken)
         {
             var json = JsonSerializer.SerializeToUtf8Bytes(message, _jsonOptions);
-            return _socket.SendAsync(json, WebSocketMessageType.Text, true, cancellationToken);
+            await _socket.SendAsync(json, WebSocketMessageType.Text, true, cancellationToken).ConfigureAwait(false);
         }
 
         /// <inheritdoc />
@@ -224,12 +224,12 @@ namespace Emby.Server.Implementations.HttpServer
             return ret;
         }
 
-        private Task SendKeepAliveResponse()
+        private async Task SendKeepAliveResponse()
         {
             LastKeepAliveDate = DateTime.UtcNow;
-            return SendAsync(
+            await SendAsync(
                 new OutboundKeepAliveMessage(),
-                CancellationToken.None);
+                CancellationToken.None).ConfigureAwait(false);
         }
 
         /// <inheritdoc />

Emby.Server.Implementations/HttpServer/WebSocketManager.cs

@@ -84,7 +84,7 @@ namespace Emby.Server.Implementations.HttpServer
         /// Processes the web socket message received.
         /// </summary>
         /// <param name="result">The result.</param>
-        private Task ProcessWebSocketMessageReceived(WebSocketMessageInfo result)
+        private async Task ProcessWebSocketMessageReceived(WebSocketMessageInfo result)
         {
             var tasks = new Task[_webSocketListeners.Length];
             for (var i = 0; i < _webSocketListeners.Length; ++i)
@@ -92,7 +92,7 @@ namespace Emby.Server.Implementations.HttpServer
                 tasks[i] = _webSocketListeners[i].ProcessMessageAsync(result);
             }
 
-            return Task.WhenAll(tasks);
+            await Task.WhenAll(tasks).ConfigureAwait(false);
         }
     }
 }

Emby.Server.Implementations/Session/SessionWebSocketListener.cs

@@ -276,11 +276,11 @@ namespace Emby.Server.Implementations.Session
         /// </summary>
         /// <param name="webSocket">The WebSocket.</param>
         /// <returns>Task.</returns>
-        private Task SendForceKeepAlive(IWebSocketConnection webSocket)
+        private async Task SendForceKeepAlive(IWebSocketConnection webSocket)
         {
-            return webSocket.SendAsync(
+            await webSocket.SendAsync(
                 new ForceKeepAliveMessage(WebSocketLostTimeout),
-                CancellationToken.None);
+                CancellationToken.None).ConfigureAwait(false);
         }
     }
 }

Jellyfin.Api/Controllers/DynamicHlsController.cs

@@ -2059,16 +2059,16 @@ public class DynamicHlsController : BaseJellyfinApiController
         }
     }
 
-    private Task DeleteLastFile(string playlistPath, string segmentExtension, int retryCount)
+    private async Task DeleteLastFile(string playlistPath, string segmentExtension, int retryCount)
     {
         var file = GetLastTranscodingFile(playlistPath, segmentExtension, _fileSystem);
 
         if (file is null)
         {
-            return Task.CompletedTask;
+            return;
         }
 
-        return DeleteFile(file.FullName, retryCount);
+        await DeleteFile(file.FullName, retryCount).ConfigureAwait(false);
     }
 
     private async Task DeleteFile(string path, int retryCount)

Jellyfin.Api/Formatters/CssOutputFormatter.cs

@@ -1,6 +1,4 @@
-using System.Text;
-using System.Threading.Tasks;
-using Microsoft.AspNetCore.Http;
+using System.Net.Mime;
 using Microsoft.AspNetCore.Mvc.Formatters;
 
 namespace Jellyfin.Api.Formatters;
@@ -8,28 +6,14 @@ namespace Jellyfin.Api.Formatters;
 /// <summary>
 /// Css output formatter.
 /// </summary>
-public class CssOutputFormatter : TextOutputFormatter
+public sealed class CssOutputFormatter : StringOutputFormatter
 {
     /// <summary>
     /// Initializes a new instance of the <see cref="CssOutputFormatter"/> class.
     /// </summary>
     public CssOutputFormatter()
     {
-        SupportedMediaTypes.Add("text/css");
-
-        SupportedEncodings.Add(Encoding.UTF8);
-        SupportedEncodings.Add(Encoding.Unicode);
-    }
-
-    /// <summary>
-    /// Write context object to stream.
-    /// </summary>
-    /// <param name="context">Writer context.</param>
-    /// <param name="selectedEncoding">Unused. Writer encoding.</param>
-    /// <returns>Write stream task.</returns>
-    public override Task WriteResponseBodyAsync(OutputFormatterWriteContext context, Encoding selectedEncoding)
-    {
-        var stringResponse = context.Object?.ToString();
-        return stringResponse is null ? Task.CompletedTask : context.HttpContext.Response.WriteAsync(stringResponse);
+        SupportedMediaTypes.Clear();
+        SupportedMediaTypes.Add(MediaTypeNames.Text.Css);
     }
 }

Jellyfin.Api/Formatters/XmlOutputFormatter.cs

@@ -1,7 +1,4 @@
 using System.Net.Mime;
-using System.Text;
-using System.Threading.Tasks;
-using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.Mvc.Formatters;
 
 namespace Jellyfin.Api.Formatters;
@@ -9,7 +6,7 @@ namespace Jellyfin.Api.Formatters;
 /// <summary>
 /// Xml output formatter.
 /// </summary>
-public class XmlOutputFormatter : TextOutputFormatter
+public sealed class XmlOutputFormatter : StringOutputFormatter
 {
     /// <summary>
     /// Initializes a new instance of the <see cref="XmlOutputFormatter"/> class.
@@ -18,15 +15,5 @@ public class XmlOutputFormatter : TextOutputFormatter
     {
         SupportedMediaTypes.Clear();
         SupportedMediaTypes.Add(MediaTypeNames.Text.Xml);
-
-        SupportedEncodings.Add(Encoding.UTF8);
-        SupportedEncodings.Add(Encoding.Unicode);
-    }
-
-    /// <inheritdoc />
-    public override Task WriteResponseBodyAsync(OutputFormatterWriteContext context, Encoding selectedEncoding)
-    {
-        var stringResponse = context.Object?.ToString();
-        return stringResponse is null ? Task.CompletedTask : context.HttpContext.Response.WriteAsync(stringResponse);
     }
 }

Jellyfin.Server/Infrastructure/SymlinkFollowingPhysicalFileResultExecutor.cs

@@ -67,38 +67,40 @@ namespace Jellyfin.Server.Infrastructure
         }
 
         /// <inheritdoc />
-        protected override Task WriteFileAsync(ActionContext context, PhysicalFileResult result, RangeItemHeaderValue? range, long rangeLength)
+        protected override async Task WriteFileAsync(ActionContext context, PhysicalFileResult result, RangeItemHeaderValue? range, long rangeLength)
         {
             ArgumentNullException.ThrowIfNull(context);
             ArgumentNullException.ThrowIfNull(result);
 
             if (range is not null && rangeLength == 0)
             {
-                return Task.CompletedTask;
+                return;
             }
 
             // It's a bit of wasted IO to perform this check again, but non-symlinks shouldn't use this code
             if (!IsSymLink(result.FileName))
             {
-                return base.WriteFileAsync(context, result, range, rangeLength);
+                await base.WriteFileAsync(context, result, range, rangeLength).ConfigureAwait(false);
+                return;
             }
 
             var response = context.HttpContext.Response;
 
             if (range is not null)
             {
-                return SendFileAsync(
+                await SendFileAsync(
                     result.FileName,
                     response,
                     offset: range.From ?? 0L,
-                    count: rangeLength);
+                    count: rangeLength).ConfigureAwait(false);
+                return;
             }
 
-            return SendFileAsync(
+            await SendFileAsync(
                 result.FileName,
                 response,
                 offset: 0,
-                count: null);
+                count: null).ConfigureAwait(false);
         }
 
         private async Task SendFileAsync(string filePath, HttpResponse response, long offset, long? count)

MediaBrowser.Controller/Entities/Audio/MusicArtist.cs

@@ -110,15 +110,15 @@ namespace MediaBrowser.Controller.Entities.Audio
             return base.IsSaveLocalMetadataEnabled();
         }
 
-        protected override Task ValidateChildrenInternal(IProgress<double> progress, bool recursive, bool refreshChildMetadata, bool allowRemoveRoot, MetadataRefreshOptions refreshOptions, IDirectoryService directoryService, CancellationToken cancellationToken)
+        protected override async Task ValidateChildrenInternal(IProgress<double> progress, bool recursive, bool refreshChildMetadata, bool allowRemoveRoot, MetadataRefreshOptions refreshOptions, IDirectoryService directoryService, CancellationToken cancellationToken)
         {
             if (IsAccessedByName)
             {
                 // Should never get in here anyway
-                return Task.CompletedTask;
+                return;
             }
 
-            return base.ValidateChildrenInternal(progress, recursive, refreshChildMetadata, false, refreshOptions, directoryService, cancellationToken);
+            await base.ValidateChildrenInternal(progress, recursive, refreshChildMetadata, false, refreshOptions, directoryService, cancellationToken).ConfigureAwait(false);
         }
 
         public override List<string> GetUserDataKeys()

MediaBrowser.Controller/Entities/BaseItem.cs

@@ -1977,8 +1977,8 @@ namespace MediaBrowser.Controller.Entities
             ImageInfos = [..ImageInfos, image];
         }
 
-        public virtual Task UpdateToRepositoryAsync(ItemUpdateType updateReason, CancellationToken cancellationToken)
-         => LibraryManager.UpdateItemAsync(this, GetParent(), updateReason, cancellationToken);
+        public virtual async Task UpdateToRepositoryAsync(ItemUpdateType updateReason, CancellationToken cancellationToken)
+         => await LibraryManager.UpdateItemAsync(this, GetParent(), updateReason, cancellationToken).ConfigureAwait(false);
 
         /// <summary>
         /// Validates that images within the item are still on the filesystem.
@@ -2367,7 +2367,7 @@ namespace MediaBrowser.Controller.Entities
             }
         }
 
-        protected Task RefreshMetadataForOwnedItem(BaseItem ownedItem, bool copyTitleMetadata, MetadataRefreshOptions options, CancellationToken cancellationToken)
+        protected async Task RefreshMetadataForOwnedItem(BaseItem ownedItem, bool copyTitleMetadata, MetadataRefreshOptions options, CancellationToken cancellationToken)
         {
             var newOptions = new MetadataRefreshOptions(options)
             {
@@ -2428,10 +2428,10 @@ namespace MediaBrowser.Controller.Entities
                 }
             }
 
-            return ownedItem.RefreshMetadata(newOptions, cancellationToken);
+            await ownedItem.RefreshMetadata(newOptions, cancellationToken).ConfigureAwait(false);
         }
 
-        protected Task RefreshMetadataForOwnedVideo(MetadataRefreshOptions options, bool copyTitleMetadata, string path, CancellationToken cancellationToken)
+        protected async Task RefreshMetadataForOwnedVideo(MetadataRefreshOptions options, bool copyTitleMetadata, string path, CancellationToken cancellationToken)
         {
             var newOptions = new MetadataRefreshOptions(options)
             {
@@ -2441,9 +2441,7 @@ namespace MediaBrowser.Controller.Entities
             var id = LibraryManager.GetNewItemId(path, typeof(Video));
 
             // Try to retrieve it from the db. If we don't find it, use the resolved version
-            var video = LibraryManager.GetItemById(id) as Video;
-
-            if (video is null)
+            if (LibraryManager.GetItemById(id) is not Video video)
             {
                 video = LibraryManager.ResolvePath(FileSystem.GetFileSystemInfo(path)) as Video;
 
@@ -2452,15 +2450,15 @@ namespace MediaBrowser.Controller.Entities
 
             if (video is null)
             {
-                return Task.FromResult(true);
+                return;
             }
 
             if (video.OwnerId.IsEmpty())
             {
-                video.OwnerId = this.Id;
+                video.OwnerId = Id;
             }
 
-            return RefreshMetadataForOwnedItem(video, copyTitleMetadata, newOptions, cancellationToken);
+            await RefreshMetadataForOwnedItem(video, copyTitleMetadata, newOptions, cancellationToken).ConfigureAwait(false);
         }
 
         public string GetEtag(User user)

MediaBrowser.Controller/Entities/Folder.cs

@@ -528,13 +528,13 @@ namespace MediaBrowser.Controller.Entities
             }
         }
 
-        private Task RefreshMetadataRecursive(IList<BaseItem> children, MetadataRefreshOptions refreshOptions, bool recursive, IProgress<double> progress, CancellationToken cancellationToken)
+        private async Task RefreshMetadataRecursive(IList<BaseItem> children, MetadataRefreshOptions refreshOptions, bool recursive, IProgress<double> progress, CancellationToken cancellationToken)
         {
-            return RunTasks(
+            await RunTasks(
                 (baseItem, innerProgress) => RefreshChildMetadata(baseItem, refreshOptions, recursive && baseItem.IsFolder, innerProgress, cancellationToken),
                 children,
                 progress,
-                cancellationToken);
+                cancellationToken).ConfigureAwait(false);
         }
 
         private async Task RefreshAllMetadataForContainer(IMetadataContainer container, MetadataRefreshOptions refreshOptions, IProgress<double> progress, CancellationToken cancellationToken)
@@ -575,13 +575,13 @@ namespace MediaBrowser.Controller.Entities
         /// <param name="progress">The progress.</param>
         /// <param name="cancellationToken">The cancellation token.</param>
         /// <returns>Task.</returns>
-        private Task ValidateSubFolders(IList<Folder> children, IDirectoryService directoryService, IProgress<double> progress, CancellationToken cancellationToken)
+        private async Task ValidateSubFolders(IList<Folder> children, IDirectoryService directoryService, IProgress<double> progress, CancellationToken cancellationToken)
         {
-            return RunTasks(
+            await RunTasks(
                 (folder, innerProgress) => folder.ValidateChildrenInternal(innerProgress, true, false, false, null, directoryService, cancellationToken),
                 children,
                 progress,
-                cancellationToken);
+                cancellationToken).ConfigureAwait(false);
         }
 
         /// <summary>

MediaBrowser.LocalMetadata/Savers/PlaylistXmlSaver.cs

@@ -45,16 +45,16 @@ namespace MediaBrowser.LocalMetadata.Savers
         }
 
         /// <inheritdoc />
-        protected override Task WriteCustomElementsAsync(BaseItem item, XmlWriter writer)
+        protected override async Task WriteCustomElementsAsync(BaseItem item, XmlWriter writer)
         {
             var game = (Playlist)item;
 
             if (game.PlaylistMediaType == MediaType.Unknown)
             {
-                return Task.CompletedTask;
+                return;
             }
 
-            return writer.WriteElementStringAsync(null, "PlaylistMediaType", null, game.PlaylistMediaType.ToString());
+            await writer.WriteElementStringAsync(null, "PlaylistMediaType", null, game.PlaylistMediaType.ToString()).ConfigureAwait(false);
         }
 
         /// <inheritdoc />

MediaBrowser.Providers/Plugins/AudioDb/AudioDbAlbumProvider.cs

@@ -148,21 +148,19 @@ namespace MediaBrowser.Providers.Plugins.AudioDb
             item.Overview = (overview ?? string.Empty).StripHtml();
         }
 
-        internal Task EnsureInfo(string musicBrainzReleaseGroupId, CancellationToken cancellationToken)
+        internal async Task EnsureInfo(string musicBrainzReleaseGroupId, CancellationToken cancellationToken)
         {
             var xmlPath = GetAlbumInfoPath(_config.ApplicationPaths, musicBrainzReleaseGroupId);
 
             var fileInfo = _fileSystem.GetFileSystemInfo(xmlPath);
 
-            if (fileInfo.Exists)
+            if (fileInfo.Exists
+                && (DateTime.UtcNow - _fileSystem.GetLastWriteTimeUtc(fileInfo)).TotalDays <= 2)
             {
-                if ((DateTime.UtcNow - _fileSystem.GetLastWriteTimeUtc(fileInfo)).TotalDays <= 2)
-                {
-                    return Task.CompletedTask;
-                }
+                return;
             }
 
-            return DownloadInfo(musicBrainzReleaseGroupId, cancellationToken);
+            await DownloadInfo(musicBrainzReleaseGroupId, cancellationToken).ConfigureAwait(false);
         }
 
         internal async Task DownloadInfo(string musicBrainzReleaseGroupId, CancellationToken cancellationToken)

MediaBrowser.Providers/Plugins/AudioDb/AudioDbArtistProvider.cs

@@ -131,7 +131,7 @@ namespace MediaBrowser.Providers.Plugins.AudioDb
             item.Overview = (overview ?? string.Empty).StripHtml();
         }
 
-        internal Task EnsureArtistInfo(string musicBrainzId, CancellationToken cancellationToken)
+        internal async Task EnsureArtistInfo(string musicBrainzId, CancellationToken cancellationToken)
         {
             var xmlPath = GetArtistInfoPath(_config.ApplicationPaths, musicBrainzId);
 
@@ -140,10 +140,10 @@ namespace MediaBrowser.Providers.Plugins.AudioDb
             if (fileInfo.Exists
                 && (DateTime.UtcNow - _fileSystem.GetLastWriteTimeUtc(fileInfo)).TotalDays <= 2)
             {
-                return Task.CompletedTask;
+                return;
             }
 
-            return DownloadArtistInfo(musicBrainzId, cancellationToken);
+            await DownloadArtistInfo(musicBrainzId, cancellationToken).ConfigureAwait(false);
         }
 
         internal async Task DownloadArtistInfo(string musicBrainzId, CancellationToken cancellationToken)

MediaBrowser.Providers/Plugins/StudioImages/StudiosImageProvider.cs

@@ -101,11 +101,11 @@ namespace MediaBrowser.Providers.Plugins.StudioImages
             return string.Format(CultureInfo.InvariantCulture, "{0}/images/{1}/{2}.jpg", GetRepositoryUrl(), image, filename);
         }
 
-        private Task EnsureThumbsList(string file, CancellationToken cancellationToken)
+        private async Task EnsureThumbsList(string file, CancellationToken cancellationToken)
         {
             string url = string.Format(CultureInfo.InvariantCulture, "{0}/thumbs.txt", GetRepositoryUrl());
 
-            return EnsureList(url, file, _fileSystem, cancellationToken);
+            await EnsureList(url, file, _fileSystem, cancellationToken).ConfigureAwait(false);
         }
 
         /// <inheritdoc />