Optimize Guid comparisons

* Use Guid.Equals(Guid) instead of the == override
* Ban the usage of Guid.Equals(Object) to prevent accidental boxing
* Compare to default(Guid) instead of Guid.Empty

Emby.Server.Implementations/Channels/ChannelManager.cs

@@ -162,7 +162,7 @@ namespace Emby.Server.Implementations.Channels
         /// <inheritdoc />
         public QueryResult<Channel> GetChannelsInternal(ChannelQuery query)
         {
-            var user = query.UserId.Equals(Guid.Empty)
+            var user = query.UserId.Equals(default)
                 ? null
                 : _userManager.GetUserById(query.UserId);
 
@@ -274,7 +274,7 @@ namespace Emby.Server.Implementations.Channels
         /// <inheritdoc />
         public QueryResult<BaseItemDto> GetChannels(ChannelQuery query)
         {
-            var user = query.UserId.Equals(Guid.Empty)
+            var user = query.UserId.Equals(default)
                 ? null
                 : _userManager.GetUserById(query.UserId);
 
@@ -474,7 +474,7 @@ namespace Emby.Server.Implementations.Channels
 
             item.ChannelId = id;
 
-            if (item.ParentId != parentFolderId)
+            if (!item.ParentId.Equals(parentFolderId))
             {
                 forceUpdate = true;
             }
@@ -715,7 +715,9 @@ namespace Emby.Server.Implementations.Channels
             // Find the corresponding channel provider plugin
             var channelProvider = GetChannelProvider(channel);
 
-            var parentItem = query.ParentId == Guid.Empty ? channel : _libraryManager.GetItemById(query.ParentId);
+            var parentItem = query.ParentId.Equals(default)
+                ? channel
+                : _libraryManager.GetItemById(query.ParentId);
 
             var itemsResult = await GetChannelItems(
                 channelProvider,
@@ -726,7 +728,7 @@ namespace Emby.Server.Implementations.Channels
                 cancellationToken)
                 .ConfigureAwait(false);
 
-            if (query.ParentId == Guid.Empty)
+            if (query.ParentId.Equals(default))
             {
                 query.Parent = channel;
             }

Emby.Server.Implementations/Collections/CollectionManager.cs

@@ -265,7 +265,7 @@ namespace Emby.Server.Implementations.Collections
             {
                 var childItem = _libraryManager.GetItemById(guidId);
 
-                var child = collection.LinkedChildren.FirstOrDefault(i => (i.ItemId.HasValue && i.ItemId.Value == guidId) || (childItem != null && string.Equals(childItem.Path, i.Path, StringComparison.OrdinalIgnoreCase)));
+                var child = collection.LinkedChildren.FirstOrDefault(i => (i.ItemId.HasValue && i.ItemId.Value.Equals(guidId)) || (childItem != null && string.Equals(childItem.Path, i.Path, StringComparison.OrdinalIgnoreCase)));
 
                 if (child == null)
                 {

Emby.Server.Implementations/Dto/DtoService.cs

@@ -1308,7 +1308,7 @@ namespace Emby.Server.Implementations.Dto
 
                 var allImages = parent.ImageInfos;
 
-                if (logoLimit > 0 && !(imageTags != null && imageTags.ContainsKey(ImageType.Logo)) && dto.ParentLogoItemId == null)
+                if (logoLimit > 0 && !(imageTags != null && imageTags.ContainsKey(ImageType.Logo)) && dto.ParentLogoItemId is null)
                 {
                     var image = allImages.FirstOrDefault(i => i.Type == ImageType.Logo);
 
@@ -1319,7 +1319,7 @@ namespace Emby.Server.Implementations.Dto
                     }
                 }
 
-                if (artLimit > 0 && !(imageTags != null && imageTags.ContainsKey(ImageType.Art)) && dto.ParentArtItemId == null)
+                if (artLimit > 0 && !(imageTags != null && imageTags.ContainsKey(ImageType.Art)) && dto.ParentArtItemId is null)
                 {
                     var image = allImages.FirstOrDefault(i => i.Type == ImageType.Art);
 
@@ -1330,7 +1330,7 @@ namespace Emby.Server.Implementations.Dto
                     }
                 }
 
-                if (thumbLimit > 0 && !(imageTags != null && imageTags.ContainsKey(ImageType.Thumb)) && (dto.ParentThumbItemId == null || parent is Series) && parent is not ICollectionFolder && parent is not UserView)
+                if (thumbLimit > 0 && !(imageTags != null && imageTags.ContainsKey(ImageType.Thumb)) && (dto.ParentThumbItemId is null || parent is Series) && parent is not ICollectionFolder && parent is not UserView)
                 {
                     var image = allImages.FirstOrDefault(i => i.Type == ImageType.Thumb);
 

Emby.Server.Implementations/EntryPoints/LibraryChangedNotifier.cs

@@ -326,7 +326,7 @@ namespace Emby.Server.Implementations.EntryPoints
         {
             var userIds = _sessionManager.Sessions
                 .Select(i => i.UserId)
-                .Where(i => !i.Equals(Guid.Empty))
+                .Where(i => !i.Equals(default))
                 .Distinct()
                 .ToArray();
 

Emby.Server.Implementations/HttpServer/Security/SessionContext.cs

@@ -47,7 +47,9 @@ namespace Emby.Server.Implementations.HttpServer.Security
         {
             var session = await GetSession(requestContext).ConfigureAwait(false);
 
-            return session.UserId.Equals(Guid.Empty) ? null : _userManager.GetUserById(session.UserId);
+            return session.UserId.Equals(default)
+                ? null
+                : _userManager.GetUserById(session.UserId);
         }
 
         public Task<User?> GetUser(object requestContext)

Emby.Server.Implementations/Library/LibraryManager.cs

@@ -755,7 +755,7 @@ namespace Emby.Server.Implementations.Library
                 Path = path
             };
 
-            if (folder.Id.Equals(Guid.Empty))
+            if (folder.Id.Equals(default))
             {
                 if (string.IsNullOrEmpty(folder.Path))
                 {
@@ -774,7 +774,7 @@ namespace Emby.Server.Implementations.Library
                 folder = dbItem;
             }
 
-            if (folder.ParentId != rootFolder.Id)
+            if (!folder.ParentId.Equals(rootFolder.Id))
             {
                 folder.ParentId = rootFolder.Id;
                 folder.UpdateToRepositoryAsync(ItemUpdateType.MetadataImport, CancellationToken.None).GetAwaiter().GetResult();
@@ -1252,7 +1252,7 @@ namespace Emby.Server.Implementations.Library
         /// <exception cref="ArgumentNullException"><paramref name="id"/> is <c>null</c>.</exception>
         public BaseItem GetItemById(Guid id)
         {
-            if (id == Guid.Empty)
+            if (id.Equals(default))
             {
                 throw new ArgumentException("Guid can't be empty", nameof(id));
             }
@@ -1274,7 +1274,7 @@ namespace Emby.Server.Implementations.Library
 
         public List<BaseItem> GetItemList(InternalItemsQuery query, bool allowExternalContent)
         {
-            if (query.Recursive && query.ParentId != Guid.Empty)
+            if (query.Recursive && !query.ParentId.Equals(default))
             {
                 var parent = GetItemById(query.ParentId);
                 if (parent != null)
@@ -1298,7 +1298,7 @@ namespace Emby.Server.Implementations.Library
 
         public int GetCount(InternalItemsQuery query)
         {
-            if (query.Recursive && !query.ParentId.Equals(Guid.Empty))
+            if (query.Recursive && !query.ParentId.Equals(default))
             {
                 var parent = GetItemById(query.ParentId);
                 if (parent != null)
@@ -1456,7 +1456,7 @@ namespace Emby.Server.Implementations.Library
 
         public QueryResult<BaseItem> GetItemsResult(InternalItemsQuery query)
         {
-            if (query.Recursive && !query.ParentId.Equals(Guid.Empty))
+            if (query.Recursive && !query.ParentId.Equals(default))
             {
                 var parent = GetItemById(query.ParentId);
                 if (parent != null)
@@ -1512,7 +1512,7 @@ namespace Emby.Server.Implementations.Library
         private void AddUserToQuery(InternalItemsQuery query, User user, bool allowExternalContent = true)
         {
             if (query.AncestorIds.Length == 0 &&
-                query.ParentId.Equals(Guid.Empty) &&
+                query.ParentId.Equals(default) &&
                 query.ChannelIds.Count == 0 &&
                 query.TopParentIds.Length == 0 &&
                 string.IsNullOrEmpty(query.AncestorWithPresentationUniqueKey) &&
@@ -1540,7 +1540,7 @@ namespace Emby.Server.Implementations.Library
                 }
 
                 // Translate view into folders
-                if (!view.DisplayParentId.Equals(Guid.Empty))
+                if (!view.DisplayParentId.Equals(default))
                 {
                     var displayParent = GetItemById(view.DisplayParentId);
                     if (displayParent != null)
@@ -1551,7 +1551,7 @@ namespace Emby.Server.Implementations.Library
                     return Array.Empty<Guid>();
                 }
 
-                if (!view.ParentId.Equals(Guid.Empty))
+                if (!view.ParentId.Equals(default))
                 {
                     var displayParent = GetItemById(view.ParentId);
                     if (displayParent != null)
@@ -2153,7 +2153,7 @@ namespace Emby.Server.Implementations.Library
                 return null;
             }
 
-            while (!item.ParentId.Equals(Guid.Empty))
+            while (!item.ParentId.Equals(default))
             {
                 var parent = item.GetParent();
                 if (parent == null || parent is AggregateFolder)
@@ -2231,7 +2231,9 @@ namespace Emby.Server.Implementations.Library
             string viewType,
             string sortName)
         {
-            var parentIdString = parentId.Equals(Guid.Empty) ? null : parentId.ToString("N", CultureInfo.InvariantCulture);
+            var parentIdString = parentId.Equals(default)
+                ? null
+                : parentId.ToString("N", CultureInfo.InvariantCulture);
             var idValues = "38_namedview_" + name + user.Id.ToString("N", CultureInfo.InvariantCulture) + (parentIdString ?? string.Empty) + (viewType ?? string.Empty);
 
             var id = GetNewItemId(idValues, typeof(UserView));
@@ -2265,7 +2267,7 @@ namespace Emby.Server.Implementations.Library
 
             var refresh = isNew || DateTime.UtcNow - item.DateLastRefreshed >= _viewRefreshInterval;
 
-            if (!refresh && !item.DisplayParentId.Equals(Guid.Empty))
+            if (!refresh && !item.DisplayParentId.Equals(default))
             {
                 var displayParent = GetItemById(item.DisplayParentId);
                 refresh = displayParent != null && displayParent.DateLastSaved > item.DateLastRefreshed;
@@ -2332,7 +2334,7 @@ namespace Emby.Server.Implementations.Library
 
             var refresh = isNew || DateTime.UtcNow - item.DateLastRefreshed >= _viewRefreshInterval;
 
-            if (!refresh && !item.DisplayParentId.Equals(Guid.Empty))
+            if (!refresh && !item.DisplayParentId.Equals(default))
             {
                 var displayParent = GetItemById(item.DisplayParentId);
                 refresh = displayParent != null && displayParent.DateLastSaved > item.DateLastRefreshed;
@@ -2365,7 +2367,9 @@ namespace Emby.Server.Implementations.Library
                 throw new ArgumentNullException(nameof(name));
             }
 
-            var parentIdString = parentId.Equals(Guid.Empty) ? null : parentId.ToString("N", CultureInfo.InvariantCulture);
+            var parentIdString = parentId.Equals(default)
+                ? null
+                : parentId.ToString("N", CultureInfo.InvariantCulture);
             var idValues = "37_namedview_" + name + (parentIdString ?? string.Empty) + (viewType ?? string.Empty);
             if (!string.IsNullOrEmpty(uniqueId))
             {
@@ -2409,7 +2413,7 @@ namespace Emby.Server.Implementations.Library
 
             var refresh = isNew || DateTime.UtcNow - item.DateLastRefreshed >= _viewRefreshInterval;
 
-            if (!refresh && !item.DisplayParentId.Equals(Guid.Empty))
+            if (!refresh && !item.DisplayParentId.Equals(default))
             {
                 var displayParent = GetItemById(item.DisplayParentId);
                 refresh = displayParent != null && displayParent.DateLastSaved > item.DateLastRefreshed;

Emby.Server.Implementations/Library/MediaSourceManager.cs

@@ -514,10 +514,10 @@ namespace Emby.Server.Implementations.Library
             _logger.LogInformation("Live stream opened: {@MediaSource}", mediaSource);
             var clone = JsonSerializer.Deserialize<MediaSourceInfo>(json, _jsonOptions);
 
-            if (!request.UserId.Equals(Guid.Empty))
+            if (!request.UserId.Equals(default))
             {
                 var user = _userManager.GetUserById(request.UserId);
-                var item = request.ItemId.Equals(Guid.Empty)
+                var item = request.ItemId.Equals(default)
                     ? null
                     : _libraryManager.GetItemById(request.ItemId);
                 SetDefaultAudioAndSubtitleStreamIndexes(item, clone, user);

Emby.Server.Implementations/Library/MusicManager.cs

@@ -80,7 +80,7 @@ namespace Emby.Server.Implementations.Library
                 {
                     return Guid.Empty;
                 }
-            }).Where(i => !i.Equals(Guid.Empty)).ToArray();
+            }).Where(i => !i.Equals(default)).ToArray();
 
             return GetInstantMixFromGenreIds(genreIds, user, dtoOptions);
         }

Emby.Server.Implementations/Library/SearchEngine.cs

@@ -30,7 +30,7 @@ namespace Emby.Server.Implementations.Library
         public QueryResult<SearchHintInfo> GetSearchHints(SearchQuery query)
         {
             User user = null;
-            if (query.UserId != Guid.Empty)
+            if (!query.UserId.Equals(default))
             {
                 user = _userManager.GetUserById(query.UserId);
             }
@@ -168,10 +168,10 @@ namespace Emby.Server.Implementations.Library
                 {
                     Fields = new ItemFields[]
                     {
-                         ItemFields.AirTime,
-                         ItemFields.DateCreated,
-                         ItemFields.ChannelInfo,
-                         ItemFields.ParentId
+                        ItemFields.AirTime,
+                        ItemFields.DateCreated,
+                        ItemFields.ChannelInfo,
+                        ItemFields.ParentId
                     }
                 }
             };
@@ -180,12 +180,12 @@ namespace Emby.Server.Implementations.Library
 
             if (searchQuery.IncludeItemTypes.Length == 1 && searchQuery.IncludeItemTypes[0] == BaseItemKind.MusicArtist)
             {
-                if (!searchQuery.ParentId.Equals(Guid.Empty))
+                if (!searchQuery.ParentId.Equals(default))
                 {
                     searchQuery.AncestorIds = new[] { searchQuery.ParentId };
+                    searchQuery.ParentId = Guid.Empty;
                 }
 
-                searchQuery.ParentId = Guid.Empty;
                 searchQuery.IncludeItemsByName = true;
                 searchQuery.IncludeItemTypes = Array.Empty<BaseItemKind>();
                 mediaItems = _libraryManager.GetAllArtists(searchQuery).Items.Select(i => i.Item).ToList();

Emby.Server.Implementations/Library/UserViewManager.cs

@@ -142,7 +142,7 @@ namespace Emby.Server.Implementations.Library
 
                     if (index == -1
                         && i is UserView view
-                        && view.DisplayParentId != Guid.Empty)
+                        && !view.DisplayParentId.Equals(default))
                     {
                         index = Array.IndexOf(orders, view.DisplayParentId);
                     }
@@ -214,7 +214,7 @@ namespace Emby.Server.Implementations.Library
                 }
                 else
                 {
-                    var current = list.FirstOrDefault(i => i.Item1 != null && i.Item1.Id == container.Id);
+                    var current = list.FirstOrDefault(i => i.Item1 != null && i.Item1.Id.Equals(container.Id));
 
                     if (current != null)
                     {
@@ -244,7 +244,7 @@ namespace Emby.Server.Implementations.Library
 
             var parents = new List<BaseItem>();
 
-            if (!parentId.Equals(Guid.Empty))
+            if (!parentId.Equals(default))
             {
                 var parentItem = _libraryManager.GetItemById(parentId);
                 if (parentItem is Channel)

Emby.Server.Implementations/LiveTv/EmbyTV/EmbyTV.cs

@@ -2024,7 +2024,7 @@ namespace Emby.Server.Implementations.LiveTv.EmbyTV
                         await writer.WriteElementStringAsync(null, "genre", null, genre).ConfigureAwait(false);
                     }
 
-                    var people = item.Id.Equals(Guid.Empty) ? new List<PersonInfo>() : _libraryManager.GetPeople(item);
+                    var people = item.Id.Equals(default) ? new List<PersonInfo>() : _libraryManager.GetPeople(item);
 
                     var directors = people
                         .Where(i => IsPersonType(i, PersonType.Director))
@@ -2382,7 +2382,7 @@ namespace Emby.Server.Implementations.LiveTv.EmbyTV
         {
             string channelId = seriesTimer.RecordAnyChannel ? null : seriesTimer.ChannelId;
 
-            if (string.IsNullOrWhiteSpace(channelId) && !parent.ChannelId.Equals(Guid.Empty))
+            if (string.IsNullOrWhiteSpace(channelId) && !parent.ChannelId.Equals(default))
             {
                 if (!tempChannelCache.TryGetValue(parent.ChannelId, out LiveTvChannel channel))
                 {
@@ -2441,7 +2441,7 @@ namespace Emby.Server.Implementations.LiveTv.EmbyTV
         {
             string channelId = null;
 
-            if (!programInfo.ChannelId.Equals(Guid.Empty))
+            if (!programInfo.ChannelId.Equals(default))
             {
                 if (!tempChannelCache.TryGetValue(programInfo.ChannelId, out LiveTvChannel channel))
                 {

Emby.Server.Implementations/LiveTv/LiveTvDtoService.cs

@@ -456,7 +456,7 @@ namespace Emby.Server.Implementations.LiveTv
                 info.Id = timer.ExternalId;
             }
 
-            if (!dto.ChannelId.Equals(Guid.Empty) && string.IsNullOrEmpty(info.ChannelId))
+            if (!dto.ChannelId.Equals(default) && string.IsNullOrEmpty(info.ChannelId))
             {
                 var channel = _libraryManager.GetItemById(dto.ChannelId);
 
@@ -522,7 +522,7 @@ namespace Emby.Server.Implementations.LiveTv
                 info.Id = timer.ExternalId;
             }
 
-            if (!dto.ChannelId.Equals(Guid.Empty) && string.IsNullOrEmpty(info.ChannelId))
+            if (!dto.ChannelId.Equals(default) && string.IsNullOrEmpty(info.ChannelId))
             {
                 var channel = _libraryManager.GetItemById(dto.ChannelId);
 

Emby.Server.Implementations/LiveTv/LiveTvManager.cs

@@ -176,7 +176,9 @@ namespace Emby.Server.Implementations.LiveTv
 
         public QueryResult<BaseItem> GetInternalChannels(LiveTvChannelQuery query, DtoOptions dtoOptions, CancellationToken cancellationToken)
         {
-            var user = query.UserId == Guid.Empty ? null : _userManager.GetUserById(query.UserId);
+            var user = query.UserId.Equals(default)
+                ? null
+                : _userManager.GetUserById(query.UserId);
 
             var topFolder = GetInternalLiveTvFolder(cancellationToken);
 
@@ -1268,7 +1270,7 @@ namespace Emby.Server.Implementations.LiveTv
             {
                 cancellationToken.ThrowIfCancellationRequested();
 
-                if (itemId.Equals(Guid.Empty))
+                if (itemId.Equals(default))
                 {
                     // Somehow some invalid data got into the db. It probably predates the boundary checking
                     continue;
@@ -1528,7 +1530,9 @@ namespace Emby.Server.Implementations.LiveTv
 
         public QueryResult<BaseItemDto> GetRecordings(RecordingQuery query, DtoOptions options)
         {
-            var user = query.UserId.Equals(Guid.Empty) ? null : _userManager.GetUserById(query.UserId);
+            var user = query.UserId.Equals(default)
+                ? null
+                : _userManager.GetUserById(query.UserId);
 
             RemoveFields(options);
 
@@ -1587,7 +1591,7 @@ namespace Emby.Server.Implementations.LiveTv
             if (!string.IsNullOrEmpty(query.ChannelId))
             {
                 var guid = new Guid(query.ChannelId);
-                timers = timers.Where(i => guid == _tvDtoService.GetInternalChannelId(i.Item2.Name, i.Item1.ChannelId));
+                timers = timers.Where(i => _tvDtoService.GetInternalChannelId(i.Item2.Name, i.Item1.ChannelId).Equals(guid));
             }
 
             if (!string.IsNullOrEmpty(query.SeriesTimerId))
@@ -1595,7 +1599,7 @@ namespace Emby.Server.Implementations.LiveTv
                 var guid = new Guid(query.SeriesTimerId);
 
                 timers = timers
-                    .Where(i => _tvDtoService.GetInternalSeriesTimerId(i.Item1.SeriesTimerId) == guid);
+                    .Where(i => _tvDtoService.GetInternalSeriesTimerId(i.Item1.SeriesTimerId).Equals(guid));
             }
 
             if (!string.IsNullOrEmpty(query.Id))
@@ -1657,7 +1661,7 @@ namespace Emby.Server.Implementations.LiveTv
             if (!string.IsNullOrEmpty(query.ChannelId))
             {
                 var guid = new Guid(query.ChannelId);
-                timers = timers.Where(i => guid == _tvDtoService.GetInternalChannelId(i.Item2.Name, i.Item1.ChannelId));
+                timers = timers.Where(i => _tvDtoService.GetInternalChannelId(i.Item2.Name, i.Item1.ChannelId).Equals(guid));
             }
 
             if (!string.IsNullOrEmpty(query.SeriesTimerId))
@@ -1665,7 +1669,7 @@ namespace Emby.Server.Implementations.LiveTv
                 var guid = new Guid(query.SeriesTimerId);
 
                 timers = timers
-                    .Where(i => _tvDtoService.GetInternalSeriesTimerId(i.Item1.SeriesTimerId) == guid);
+                    .Where(i => _tvDtoService.GetInternalSeriesTimerId(i.Item1.SeriesTimerId).Equals(guid));
             }
 
             if (!string.IsNullOrEmpty(query.Id))

Emby.Server.Implementations/Playlists/PlaylistManager.cs

@@ -139,7 +139,9 @@ namespace Emby.Server.Implementations.Playlists
                     {
                         new Share
                         {
-                            UserId = options.UserId.Equals(Guid.Empty) ? null : options.UserId.ToString("N", CultureInfo.InvariantCulture),
+                            UserId = options.UserId.Equals(default)
+                                ? null
+                                : options.UserId.ToString("N", CultureInfo.InvariantCulture),
                             CanEdit = true
                         }
                     }
@@ -188,7 +190,7 @@ namespace Emby.Server.Implementations.Playlists
 
         public Task AddToPlaylistAsync(Guid playlistId, IReadOnlyCollection<Guid> itemIds, Guid userId)
         {
-            var user = userId.Equals(Guid.Empty) ? null : _userManager.GetUserById(userId);
+            var user = userId.Equals(default) ? null : _userManager.GetUserById(userId);
 
             return AddToPlaylistInternal(playlistId, itemIds, user, new DtoOptions(false)
             {

Emby.Server.Implementations/Plugins/PluginManager.cs

@@ -483,7 +483,7 @@ namespace Emby.Server.Implementations.Plugins
                     var pluginStr = instance.Version.ToString();
                     bool changed = false;
                     if (string.Equals(manifest.Version, pluginStr, StringComparison.Ordinal)
-                        || manifest.Id != instance.Id)
+                        || !manifest.Id.Equals(instance.Id))
                     {
                         // If a plugin without a manifest failed to load due to an external issue (eg config),
                         // this updates the manifest to the actual plugin values.

Emby.Server.Implementations/Session/SessionManager.cs

@@ -373,7 +373,7 @@ namespace Emby.Server.Implementations.Session
                 info.MediaSourceId = info.ItemId.ToString("N", CultureInfo.InvariantCulture);
             }
 
-            if (!info.ItemId.Equals(Guid.Empty) && info.Item == null && libraryItem != null)
+            if (!info.ItemId.Equals(default) && info.Item == null && libraryItem != null)
             {
                 var current = session.NowPlayingItem;
 
@@ -553,22 +553,24 @@ namespace Emby.Server.Implementations.Session
         {
             var users = new List<User>();
 
-            if (session.UserId != Guid.Empty)
+            if (session.UserId.Equals(default))
             {
-                var user = _userManager.GetUserById(session.UserId);
-
-                if (user == null)
-                {
-                    throw new InvalidOperationException("User not found");
-                }
-
-                users.Add(user);
-
-                users.AddRange(session.AdditionalUsers
-                    .Select(i => _userManager.GetUserById(i.UserId))
-                    .Where(i => i != null));
+                return users;
             }
 
+            var user = _userManager.GetUserById(session.UserId);
+
+            if (user == null)
+            {
+                throw new InvalidOperationException("User not found");
+            }
+
+            users.Add(user);
+
+            users.AddRange(session.AdditionalUsers
+                .Select(i => _userManager.GetUserById(i.UserId))
+                .Where(i => i != null));
+
             return users;
         }
 
@@ -660,7 +662,7 @@ namespace Emby.Server.Implementations.Session
 
             var session = GetSession(info.SessionId);
 
-            var libraryItem = info.ItemId == Guid.Empty
+            var libraryItem = info.ItemId.Equals(default)
                 ? null
                 : GetNowPlayingItem(session, info.ItemId);
 
@@ -755,7 +757,7 @@ namespace Emby.Server.Implementations.Session
 
             var session = GetSession(info.SessionId);
 
-            var libraryItem = info.ItemId.Equals(Guid.Empty)
+            var libraryItem = info.ItemId.Equals(default)
                 ? null
                 : GetNowPlayingItem(session, info.ItemId);
 
@@ -892,7 +894,7 @@ namespace Emby.Server.Implementations.Session
 
             session.StopAutomaticProgress();
 
-            var libraryItem = info.ItemId.Equals(Guid.Empty)
+            var libraryItem = info.ItemId.Equals(default)
                 ? null
                 : GetNowPlayingItem(session, info.ItemId);
 
@@ -902,7 +904,7 @@ namespace Emby.Server.Implementations.Session
                 info.MediaSourceId = info.ItemId.ToString("N", CultureInfo.InvariantCulture);
             }
 
-            if (!info.ItemId.Equals(Guid.Empty) && info.Item == null && libraryItem != null)
+            if (!info.ItemId.Equals(default) && info.Item == null && libraryItem != null)
             {
                 var current = session.NowPlayingItem;
 
@@ -1122,7 +1124,7 @@ namespace Emby.Server.Implementations.Session
 
             var session = GetSessionToRemoteControl(sessionId);
 
-            var user = session.UserId == Guid.Empty ? null : _userManager.GetUserById(session.UserId);
+            var user = session.UserId.Equals(default) ? null : _userManager.GetUserById(session.UserId);
 
             List<BaseItem> items;
 
@@ -1177,7 +1179,7 @@ namespace Emby.Server.Implementations.Session
                                 EnableImages = false
                             })
                         .Where(i => !i.IsVirtualItem)
-                        .SkipWhile(i => i.Id != episode.Id)
+                        .SkipWhile(i => !i.Id.Equals(episode.Id))
                         .ToList();
 
                     if (episodes.Count > 0)
@@ -1191,7 +1193,7 @@ namespace Emby.Server.Implementations.Session
             {
                 var controllingSession = GetSession(controllingSessionId);
                 AssertCanControl(session, controllingSession);
-                if (!controllingSession.UserId.Equals(Guid.Empty))
+                if (!controllingSession.UserId.Equals(default))
                 {
                     command.ControllingUserId = controllingSession.UserId;
                 }
@@ -1310,7 +1312,7 @@ namespace Emby.Server.Implementations.Session
             {
                 var controllingSession = GetSession(controllingSessionId);
                 AssertCanControl(session, controllingSession);
-                if (!controllingSession.UserId.Equals(Guid.Empty))
+                if (!controllingSession.UserId.Equals(default))
                 {
                     command.ControllingUserId = controllingSession.UserId.ToString("N", CultureInfo.InvariantCulture);
                 }
@@ -1383,12 +1385,12 @@ namespace Emby.Server.Implementations.Session
 
             var session = GetSession(sessionId);
 
-            if (session.UserId == userId)
+            if (session.UserId.Equals(userId))
             {
                 throw new ArgumentException("The requested user is already the primary user of the session.");
             }
 
-            if (session.AdditionalUsers.All(i => i.UserId != userId))
+            if (session.AdditionalUsers.All(i => !i.UserId.Equals(userId)))
             {
                 var user = _userManager.GetUserById(userId);
 
@@ -1458,7 +1460,7 @@ namespace Emby.Server.Implementations.Session
             CheckDisposed();
 
             User user = null;
-            if (request.UserId != Guid.Empty)
+            if (!request.UserId.Equals(default))
             {
                 user = _userManager.GetUserById(request.UserId);
             }
@@ -1787,7 +1789,7 @@ namespace Emby.Server.Implementations.Session
                 throw new ArgumentNullException(nameof(info));
             }
 
-            var user = info.UserId == Guid.Empty
+            var user = info.UserId.Equals(default)
                 ? null
                 : _userManager.GetUserById(info.UserId);
 

Emby.Server.Implementations/SyncPlay/Group.cs

@@ -553,7 +553,7 @@ namespace Emby.Server.Implementations.SyncPlay
             if (playingItemRemoved)
             {
                 var itemId = PlayQueue.GetPlayingItemId();
-                if (!itemId.Equals(Guid.Empty))
+                if (!itemId.Equals(default))
                 {
                     var item = _libraryManager.GetItemById(itemId);
                     RunTimeTicks = item.RunTimeTicks ?? 0;

Emby.Server.Implementations/TV/TVSeriesManager.cs

@@ -271,7 +271,7 @@ namespace Emby.Server.Implementations.TV
                         .Cast<Episode>();
                     if (lastWatchedEpisode != null)
                     {
-                        sortedConsideredEpisodes = sortedConsideredEpisodes.SkipWhile(episode => episode.Id != lastWatchedEpisode.Id).Skip(1);
+                        sortedConsideredEpisodes = sortedConsideredEpisodes.SkipWhile(episode => !episode.Id.Equals(lastWatchedEpisode.Id)).Skip(1);
                     }
 
                     nextEpisode = sortedConsideredEpisodes.FirstOrDefault();

Emby.Server.Implementations/Updates/InstallationManager.cs

@@ -227,9 +227,9 @@ namespace Emby.Server.Implementations.Updates
                 availablePackages = availablePackages.Where(x => x.Name.Equals(name, StringComparison.OrdinalIgnoreCase));
             }
 
-            if (id != default)
+            if (!id.Equals(default))
             {
-                availablePackages = availablePackages.Where(x => x.Id == id);
+                availablePackages = availablePackages.Where(x => x.Id.Equals(id));
             }
 
             if (specificVersion != null)
@@ -399,7 +399,7 @@ namespace Emby.Server.Implementations.Updates
         {
             lock (_currentInstallationsLock)
             {
-                var install = _currentInstallations.Find(x => x.Info.Id == id);
+                var install = _currentInstallations.Find(x => x.Info.Id.Equals(id));
                 if (install == default((InstallationInfo, CancellationTokenSource)))
                 {
                     return false;
@@ -498,7 +498,7 @@ namespace Emby.Server.Implementations.Updates
                 var compatibleVersions = GetCompatibleVersions(pluginCatalog, plugin.Name, plugin.Id, minVersion: plugin.Version);
                 var version = compatibleVersions.FirstOrDefault(y => y.Version > plugin.Version);
 
-                if (version != null && CompletedInstallations.All(x => x.Id != version.Id))
+                if (version != null && CompletedInstallations.All(x => !x.Id.Equals(version.Id)))
                 {
                     yield return version;
                 }