Allocate less Lists

Emby.Dlna/ConnectionManager/ConnectionManagerXmlBuilder.cs

@@ -27,7 +27,7 @@ namespace Emby.Dlna.ConnectionManager
         /// <returns>The <see cref="IEnumerable{StateVariable}"/>.</returns>
         private static IEnumerable<StateVariable> GetStateVariables()
         {
-            var list = new List<StateVariable>
+            return new StateVariable[]
             {
                 new StateVariable
                 {
@@ -114,8 +114,6 @@ namespace Emby.Dlna.ConnectionManager
                     SendsEvents = false
                 }
             };
-
-            return list;
         }
     }
 }

Emby.Dlna/ContentDirectory/ContentDirectoryXmlBuilder.cs

@@ -27,7 +27,7 @@ namespace Emby.Dlna.ContentDirectory
         /// <returns>The <see cref="IEnumerable{StateVariable}"/>.</returns>
         private static IEnumerable<StateVariable> GetStateVariables()
         {
-            var list = new List<StateVariable>
+            return new StateVariable[]
             {
                 new StateVariable
                 {
@@ -154,8 +154,6 @@ namespace Emby.Dlna.ContentDirectory
                     SendsEvents = false
                 }
             };
-
-            return list;
         }
     }
 }

Emby.Naming/AudioBook/AudioBookListResolver.cs

@@ -79,25 +79,25 @@ namespace Emby.Naming.AudioBook
                 {
                     if (group.Count() > 1 || haveChaptersOrPages)
                     {
-                        var ex = new List<AudioBookFileInfo>();
-                        var alt = new List<AudioBookFileInfo>();
+                        List<AudioBookFileInfo>? ex = null;
+                        List<AudioBookFileInfo>? alt = null;
 
                         foreach (var audioFile in group)
                         {
-                            var name = Path.GetFileNameWithoutExtension(audioFile.Path);
-                            if (name.Equals("audiobook", StringComparison.OrdinalIgnoreCase) ||
-                                name.Contains(nameParserResult.Name, StringComparison.OrdinalIgnoreCase) ||
-                                name.Contains(nameWithReplacedDots, StringComparison.OrdinalIgnoreCase))
+                            var name = Path.GetFileNameWithoutExtension(audioFile.Path.AsSpan());
+                            if (name.Equals("audiobook", StringComparison.OrdinalIgnoreCase)
+                                || name.Contains(nameParserResult.Name, StringComparison.OrdinalIgnoreCase)
+                                || name.Contains(nameWithReplacedDots, StringComparison.OrdinalIgnoreCase))
                             {
-                                alt.Add(audioFile);
+                                (alt ??= new()).Add(audioFile);
                             }
                             else
                             {
-                                ex.Add(audioFile);
+                                (ex ??= new()).Add(audioFile);
                             }
                         }
 
-                        if (ex.Count > 0)
+                        if (ex is not null)
                         {
                             var extra = ex
                                 .OrderBy(x => x.Container)
@@ -108,7 +108,7 @@ namespace Emby.Naming.AudioBook
                             extras.AddRange(extra);
                         }
 
-                        if (alt.Count > 0)
+                        if (alt is not null)
                         {
                             var alternatives = alt
                                 .OrderBy(x => x.Container)

Emby.Server.Implementations/Channels/ChannelManager.cs

@@ -401,7 +401,7 @@ namespace Emby.Server.Implementations.Channels
             }
             else
             {
-                results = new List<MediaSourceInfo>();
+                results = Enumerable.Empty<MediaSourceInfo>();
             }
 
             return results

Emby.Server.Implementations/Collections/CollectionManager.cs

@@ -206,8 +206,7 @@ namespace Emby.Server.Implementations.Collections
                 throw new ArgumentException("No collection exists with the supplied Id");
             }
 
-            var list = new List<LinkedChild>();
-            var itemList = new List<BaseItem>();
+            List<BaseItem>? itemList = null;
 
             var linkedChildrenList = collection.GetLinkedChildren();
             var currentLinkedChildrenIds = linkedChildrenList.Select(i => i.Id).ToList();
@@ -223,18 +222,23 @@ namespace Emby.Server.Implementations.Collections
 
                 if (!currentLinkedChildrenIds.Contains(id))
                 {
-                    itemList.Add(item);
+                    (itemList ??= new()).Add(item);
 
-                    list.Add(LinkedChild.Create(item));
                     linkedChildrenList.Add(item);
                 }
             }
 
-            if (list.Count > 0)
+            if (itemList is not null)
             {
-                LinkedChild[] newChildren = new LinkedChild[collection.LinkedChildren.Length + list.Count];
+                var originalLen = collection.LinkedChildren.Length;
+                var newItemCount = itemList.Count;
+                LinkedChild[] newChildren = new LinkedChild[originalLen + newItemCount];
                 collection.LinkedChildren.CopyTo(newChildren, 0);
-                list.CopyTo(newChildren, collection.LinkedChildren.Length);
+                for (int i = 0; i < newItemCount; i++)
+                {
+                    newChildren[originalLen + i] = LinkedChild.Create(itemList[i]);
+                }
+
                 collection.LinkedChildren = newChildren;
                 collection.UpdateRatingToItems(linkedChildrenList);
 

Emby.Server.Implementations/Data/SqliteItemRepository.cs

@@ -586,7 +586,7 @@ namespace Emby.Server.Implementations.Data
         /// <exception cref="ArgumentNullException">
         /// <paramref name="items"/> or <paramref name="cancellationToken"/> is <c>null</c>.
         /// </exception>
-        public void SaveItems(IEnumerable<BaseItem> items, CancellationToken cancellationToken)
+        public void SaveItems(IReadOnlyList<BaseItem> items, CancellationToken cancellationToken)
         {
             ArgumentNullException.ThrowIfNull(items);
 
@@ -594,9 +594,11 @@ namespace Emby.Server.Implementations.Data
 
             CheckDisposed();
 
-            var tuples = new List<(BaseItem, List<Guid>, BaseItem, string, List<string>)>();
-            foreach (var item in items)
+            var itemsLen = items.Count;
+            var tuples = new ValueTuple<BaseItem, List<Guid>, BaseItem, string, List<string>>[itemsLen];
+            for (int i = 0; i < itemsLen; i++)
             {
+                var item = items[i];
                 var ancestorIds = item.SupportsAncestors ?
                     item.GetAncestorIds().Distinct().ToList() :
                     null;
@@ -606,7 +608,7 @@ namespace Emby.Server.Implementations.Data
                 var userdataKey = item.GetUserDataKeys().FirstOrDefault();
                 var inheritedTags = item.GetInheritedTags();
 
-                tuples.Add((item, ancestorIds, topParent, userdataKey, inheritedTags));
+                tuples[i] = (item, ancestorIds, topParent, userdataKey, inheritedTags);
             }
 
             using (var connection = GetConnection())

Emby.Server.Implementations/Dto/DtoService.cs

@@ -85,8 +85,8 @@ namespace Emby.Server.Implementations.Dto
         {
             var accessibleItems = user is null ? items : items.Where(x => x.IsVisible(user)).ToList();
             var returnItems = new BaseItemDto[accessibleItems.Count];
-            var programTuples = new List<(BaseItem, BaseItemDto)>();
-            var channelTuples = new List<(BaseItemDto, LiveTvChannel)>();
+            List<(BaseItem, BaseItemDto)> programTuples = null;
+            List<(BaseItemDto, LiveTvChannel)> channelTuples = null;
 
             for (int index = 0; index < accessibleItems.Count; index++)
             {
@@ -95,11 +95,11 @@ namespace Emby.Server.Implementations.Dto
 
                 if (item is LiveTvChannel tvChannel)
                 {
-                    channelTuples.Add((dto, tvChannel));
+                    (channelTuples ??= new()).Add((dto, tvChannel));
                 }
                 else if (item is LiveTvProgram)
                 {
-                    programTuples.Add((item, dto));
+                    (programTuples ??= new()).Add((item, dto));
                 }
 
                 if (item is IItemByName byName)
@@ -122,12 +122,12 @@ namespace Emby.Server.Implementations.Dto
                 returnItems[index] = dto;
             }
 
-            if (programTuples.Count > 0)
+            if (programTuples is not null)
             {
                 LivetvManager.AddInfoToProgramDto(programTuples, options.Fields, user).GetAwaiter().GetResult();
             }
 
-            if (channelTuples.Count > 0)
+            if (channelTuples is not null)
             {
                 LivetvManager.AddChannelInfo(channelTuples, options, user);
             }

Emby.Server.Implementations/Library/LibraryManager.cs

@@ -356,8 +356,8 @@ namespace Emby.Server.Implementations.Library
             }
 
             var children = item.IsFolder
-                ? ((Folder)item).GetRecursiveChildren(false).ToList()
-                : new List<BaseItem>();
+                ? ((Folder)item).GetRecursiveChildren(false)
+                : Enumerable.Empty<BaseItem>();
 
             foreach (var metadataPath in GetMetadataPaths(item, children))
             {
@@ -1253,7 +1253,7 @@ namespace Emby.Server.Implementations.Library
                 var parent = GetItemById(query.ParentId);
                 if (parent is not null)
                 {
-                    SetTopParentIdsOrAncestors(query, new List<BaseItem> { parent });
+                    SetTopParentIdsOrAncestors(query, new[] { parent });
                 }
             }
 
@@ -1277,7 +1277,7 @@ namespace Emby.Server.Implementations.Library
                 var parent = GetItemById(query.ParentId);
                 if (parent is not null)
                 {
-                    SetTopParentIdsOrAncestors(query, new List<BaseItem> { parent });
+                    SetTopParentIdsOrAncestors(query, new[] { parent });
                 }
             }
 
@@ -1435,7 +1435,7 @@ namespace Emby.Server.Implementations.Library
                 var parent = GetItemById(query.ParentId);
                 if (parent is not null)
                 {
-                    SetTopParentIdsOrAncestors(query, new List<BaseItem> { parent });
+                    SetTopParentIdsOrAncestors(query, new[] { parent });
                 }
             }
 
@@ -1455,7 +1455,7 @@ namespace Emby.Server.Implementations.Library
                 _itemRepository.GetItemList(query));
         }
 
-        private void SetTopParentIdsOrAncestors(InternalItemsQuery query, List<BaseItem> parents)
+        private void SetTopParentIdsOrAncestors(InternalItemsQuery query, IReadOnlyCollection<BaseItem> parents)
         {
             if (parents.All(i => i is ICollectionFolder || i is UserView))
             {
@@ -1602,7 +1602,7 @@ namespace Emby.Server.Implementations.Library
             {
                 _logger.LogError(ex, "Error getting intros");
 
-                return new List<IntroInfo>();
+                return Enumerable.Empty<IntroInfo>();
             }
         }
 
@@ -2876,7 +2876,7 @@ namespace Emby.Server.Implementations.Library
 
         private async Task SavePeopleMetadataAsync(IEnumerable<PersonInfo> people, CancellationToken cancellationToken)
         {
-            var personsToSave = new List<BaseItem>();
+            List<BaseItem> personsToSave = null;
 
             foreach (var person in people)
             {
@@ -2918,12 +2918,12 @@ namespace Emby.Server.Implementations.Library
 
                 if (saveEntity)
                 {
-                    personsToSave.Add(personEntity);
+                    (personsToSave ??= new()).Add(personEntity);
                     await RunMetadataSavers(personEntity, itemUpdateType).ConfigureAwait(false);
                 }
             }
 
-            if (personsToSave.Count > 0)
+            if (personsToSave is not null)
             {
                 CreateItems(personsToSave, null, CancellationToken.None);
             }
@@ -3085,22 +3085,19 @@ namespace Emby.Server.Implementations.Library
                 throw new ArgumentNullException(nameof(path));
             }
 
-            var removeList = new List<NameValuePair>();
+            List<NameValuePair> removeList = null;
 
             foreach (var contentType in _configurationManager.Configuration.ContentTypes)
             {
-                if (string.IsNullOrWhiteSpace(contentType.Name))
-                {
-                    removeList.Add(contentType);
-                }
-                else if (_fileSystem.AreEqual(path, contentType.Name)
+                if (string.IsNullOrWhiteSpace(contentType.Name)
+                    || _fileSystem.AreEqual(path, contentType.Name)
                     || _fileSystem.ContainsSubPath(path, contentType.Name))
                 {
-                    removeList.Add(contentType);
+                    (removeList ??= new()).Add(contentType);
                 }
             }
 
-            if (removeList.Count > 0)
+            if (removeList is not null)
             {
                 _configurationManager.Configuration.ContentTypes = _configurationManager.Configuration.ContentTypes
                     .Except(removeList)

Emby.Server.Implementations/Library/Resolvers/Audio/AudioResolver.cs

@@ -158,7 +158,6 @@ namespace Emby.Server.Implementations.Library.Resolvers.Audio
         private MultiItemResolverResult ResolveMultipleAudio(Folder parent, IEnumerable<FileSystemMetadata> fileSystemEntries, bool parseName)
         {
             var files = new List<FileSystemMetadata>();
-            var items = new List<BaseItem>();
             var leftOver = new List<FileSystemMetadata>();
 
             // Loop through each child file/folder and see if we find a video
@@ -180,7 +179,7 @@ namespace Emby.Server.Implementations.Library.Resolvers.Audio
             var result = new MultiItemResolverResult
             {
                 ExtraFiles = leftOver,
-                Items = items
+                Items = new List<BaseItem>()
             };
 
             var isInMixedFolder = resolverResult.Count > 1 || (parent is not null && parent.IsTopParent);

Emby.Server.Implementations/Library/UserViewManager.cs

@@ -286,7 +286,7 @@ namespace Emby.Server.Implementations.Library
 
             if (parents.Count == 0)
             {
-                return new List<BaseItem>();
+                return Array.Empty<BaseItem>();
             }
 
             if (includeItemTypes.Length == 0)

MediaBrowser.Controller/Persistence/IItemRepository.cs

@@ -28,7 +28,7 @@ namespace MediaBrowser.Controller.Persistence
         /// </summary>
         /// <param name="items">The items.</param>
         /// <param name="cancellationToken">The cancellation token.</param>
-        void SaveItems(IEnumerable<BaseItem> items, CancellationToken cancellationToken);
+        void SaveItems(IReadOnlyList<BaseItem> items, CancellationToken cancellationToken);
 
         void SaveImages(BaseItem item);
 

MediaBrowser.Providers/Manager/ProviderManager.cs

@@ -284,12 +284,12 @@ namespace MediaBrowser.Providers.Manager
             }
             catch (OperationCanceledException)
             {
-                return new List<RemoteImageInfo>();
+                return Enumerable.Empty<RemoteImageInfo>();
             }
             catch (Exception ex)
             {
                 _logger.LogError(ex, "{ProviderName} failed in GetImageInfos for type {ItemType} at {ItemPath}", provider.GetType().Name, item.GetType().Name, item.Path);
-                return new List<RemoteImageInfo>();
+                return Enumerable.Empty<RemoteImageInfo>();
             }
         }
 

MediaBrowser.Providers/Playlists/PlaylistItemsProvider.cs

@@ -87,7 +87,7 @@ namespace MediaBrowser.Providers.Playlists
                 return GetPlsItems(stream);
             }
 
-            return new List<LinkedChild>();
+            return Enumerable.Empty<LinkedChild>();
         }
 
         private IEnumerable<LinkedChild> GetPlsItems(Stream stream)

MediaBrowser.Providers/Plugins/AudioDb/AudioDbArtistImageProvider.cs

@@ -4,6 +4,7 @@
 
 using System.Collections.Generic;
 using System.IO;
+using System.Linq;
 using System.Net.Http;
 using System.Text.Json;
 using System.Threading;
@@ -42,7 +43,7 @@ namespace MediaBrowser.Providers.Plugins.AudioDb
         /// <inheritdoc />
         public IEnumerable<ImageType> GetSupportedImages(BaseItem item)
         {
-            return new List<ImageType>
+            return new ImageType[]
             {
                 ImageType.Primary,
                 ImageType.Logo,
@@ -74,7 +75,7 @@ namespace MediaBrowser.Providers.Plugins.AudioDb
                 }
             }
 
-            return new List<RemoteImageInfo>();
+            return Enumerable.Empty<RemoteImageInfo>();
         }
 
         private IEnumerable<RemoteImageInfo> GetImages(AudioDbArtistProvider.Artist item)

MediaBrowser.Providers/Plugins/MusicBrainz/MusicBrainzAlbumProvider.cs

@@ -157,10 +157,10 @@ public class MusicBrainzAlbumProvider : IRemoteMetadataProvider<MusicAlbum, Albu
         var artists = releaseSearchResult.ArtistCredit;
         if (artists is not null && artists.Count > 0)
         {
-            var artistResults = new List<RemoteSearchResult>();
-
-            foreach (var artist in artists)
+            var artistResults = new RemoteSearchResult[artists.Count];
+            for (int i = 0; i < artists.Count; i++)
             {
+                var artist = artists[i];
                 var artistResult = new RemoteSearchResult
                 {
                     Name = artist.Name
@@ -171,11 +171,11 @@ public class MusicBrainzAlbumProvider : IRemoteMetadataProvider<MusicAlbum, Albu
                     artistResult.SetProviderId(MetadataProvider.MusicBrainzArtist, artist.Artist!.Id.ToString());
                 }
 
-                artistResults.Add(artistResult);
+                artistResults[i] = artistResult;
             }
 
             searchResult.AlbumArtist = artistResults[0];
-            searchResult.Artists = artistResults.ToArray();
+            searchResult.Artists = artistResults;
         }
 
         searchResult.SetProviderId(MetadataProvider.MusicBrainzAlbum, releaseSearchResult.Id.ToString());

MediaBrowser.Providers/Plugins/Omdb/OmdbImageProvider.cs

@@ -38,10 +38,7 @@ namespace MediaBrowser.Providers.Plugins.Omdb
 
         public IEnumerable<ImageType> GetSupportedImages(BaseItem item)
         {
-            return new List<ImageType>
-            {
-                ImageType.Primary
-            };
+            yield return ImageType.Primary;
         }
 
         public async Task<IEnumerable<RemoteImageInfo>> GetImages(BaseItem item, CancellationToken cancellationToken)

MediaBrowser.Providers/Plugins/Tmdb/BoxSets/TmdbBoxSetImageProvider.cs

@@ -48,7 +48,7 @@ namespace MediaBrowser.Providers.Plugins.Tmdb.BoxSets
         /// <inheritdoc />
         public IEnumerable<ImageType> GetSupportedImages(BaseItem item)
         {
-            return new List<ImageType>
+            return new ImageType[]
             {
                 ImageType.Primary,
                 ImageType.Backdrop

MediaBrowser.Providers/Plugins/Tmdb/BoxSets/TmdbBoxSetProvider.cs

@@ -72,7 +72,7 @@ namespace MediaBrowser.Providers.Plugins.Tmdb.BoxSets
 
             var collectionSearchResults = await _tmdbClientManager.SearchCollectionAsync(searchInfo.Name, language, cancellationToken).ConfigureAwait(false);
 
-            var collections = new List<RemoteSearchResult>();
+            var collections = new RemoteSearchResult[collectionSearchResults.Count];
             for (var i = 0; i < collectionSearchResults.Count; i++)
             {
                 var collection = new RemoteSearchResult
@@ -82,7 +82,7 @@ namespace MediaBrowser.Providers.Plugins.Tmdb.BoxSets
                 };
                 collection.SetProviderId(MetadataProvider.Tmdb, collectionSearchResults[i].Id.ToString(CultureInfo.InvariantCulture));
 
-                collections.Add(collection);
+                collections[i] = collection;
             }
 
             return collections;

MediaBrowser.Providers/Plugins/Tmdb/Movies/TmdbMovieImageProvider.cs

@@ -49,7 +49,7 @@ namespace MediaBrowser.Providers.Plugins.Tmdb.Movies
         /// <inheritdoc />
         public IEnumerable<ImageType> GetSupportedImages(BaseItem item)
         {
-            return new List<ImageType>
+            return new ImageType[]
             {
                 ImageType.Primary,
                 ImageType.Backdrop,

MediaBrowser.Providers/Plugins/Tmdb/People/TmdbPersonImageProvider.cs

@@ -46,10 +46,7 @@ namespace MediaBrowser.Providers.Plugins.Tmdb.People
         /// <inheritdoc />
         public IEnumerable<ImageType> GetSupportedImages(BaseItem item)
         {
-            return new List<ImageType>
-            {
-                ImageType.Primary
-            };
+            yield return ImageType.Primary;
         }
 
         /// <inheritdoc />

MediaBrowser.Providers/Plugins/Tmdb/People/TmdbPersonProvider.cs

@@ -67,7 +67,7 @@ namespace MediaBrowser.Providers.Plugins.Tmdb.People
 
             var personSearchResult = await _tmdbClientManager.SearchPersonAsync(searchInfo.Name, cancellationToken).ConfigureAwait(false);
 
-            var remoteSearchResults = new List<RemoteSearchResult>();
+            var remoteSearchResults = new RemoteSearchResult[personSearchResult.Count];
             for (var i = 0; i < personSearchResult.Count; i++)
             {
                 var person = personSearchResult[i];
@@ -79,7 +79,7 @@ namespace MediaBrowser.Providers.Plugins.Tmdb.People
                 };
 
                 remoteSearchResult.SetProviderId(MetadataProvider.Tmdb, person.Id.ToString(CultureInfo.InvariantCulture));
-                remoteSearchResults.Add(remoteSearchResult);
+                remoteSearchResults[i] = remoteSearchResult;
             }
 
             return remoteSearchResults;

MediaBrowser.Providers/Plugins/Tmdb/TV/TmdbEpisodeImageProvider.cs

@@ -47,10 +47,7 @@ namespace MediaBrowser.Providers.Plugins.Tmdb.TV
         /// <inheritdoc />
         public IEnumerable<ImageType> GetSupportedImages(BaseItem item)
         {
-            return new List<ImageType>
-            {
-                ImageType.Primary
-            };
+            yield return ImageType.Primary;
         }
 
         /// <inheritdoc />

MediaBrowser.Providers/Plugins/Tmdb/TV/TmdbSeasonImageProvider.cs

@@ -48,10 +48,7 @@ namespace MediaBrowser.Providers.Plugins.Tmdb.TV
         /// <inheritdoc />
         public IEnumerable<ImageType> GetSupportedImages(BaseItem item)
         {
-            return new List<ImageType>
-            {
-                ImageType.Primary
-            };
+            yield return ImageType.Primary;
         }
 
         /// <inheritdoc />

MediaBrowser.Providers/Plugins/Tmdb/TV/TmdbSeriesImageProvider.cs

@@ -48,7 +48,7 @@ namespace MediaBrowser.Providers.Plugins.Tmdb.TV
         /// <inheritdoc />
         public IEnumerable<ImageType> GetSupportedImages(BaseItem item)
         {
-            return new List<ImageType>
+            return new ImageType[]
             {
                 ImageType.Primary,
                 ImageType.Backdrop,