Merge pull request #17576 from obiwantoby/perf/batch-mediasourcecount-dto

Bugfix: #17547 | Batching MediaSourceCount into one call

2 files changed, 45 insertions, 12 deletions

diff --git a/Emby.Server.Implementations/Dto/DtoService.cs b/Emby.Server.Implementations/Dto/DtoService.cs
index da0c52df5b..6fa057702c 100644
--- a/Emby.Server.Implementations/Dto/DtoService.cs
+++ b/Emby.Server.Implementations/Dto/DtoService.cs
@@ -253,6 +253,18 @@ namespace Emby.Server.Implementations.Dto
                 }
             }
 
+            // Batch-detect which videos own alternate versions to avoid the per-item alternate-version
+            // queries in MediaSourceCount. Videos absent from this set have a single media source.
+            IReadOnlySet<Guid>? alternateVersionItemIds = null;
+            if (options.ContainsField(ItemFields.MediaSourceCount))
+            {
+                var versionItemIds = accessibleItems.OfType<Video>().Select(i => i.Id).ToList();
+                if (versionItemIds.Count > 0)
+                {
+                    alternateVersionItemIds = _libraryManager.GetItemIdsWithAlternateVersions(versionItemIds);
+                }
+            }
+
             for (int index = 0; index < accessibleItems.Count; index++)
             {
                 var item = accessibleItems[index];
@@ -267,7 +279,8 @@ namespace Emby.Server.Implementations.Dto
                     playedCountBatch,
                     artistsBatch,
                     resumeDataBatch?.GetValueOrDefault(item.Id),
-                    peopleBatch);
+                    peopleBatch,
+                    alternateVersionItemIds);
 
                 if (item is LiveTvChannel tvChannel)
                 {
@@ -330,7 +343,8 @@ namespace Emby.Server.Implementations.Dto
             Dictionary<Guid, (int Played, int Total)>? playedCountBatch = null,
             IReadOnlyDictionary<string, MusicArtist[]>? artistsBatch = null,
             VersionResumeData? resumeData = null,
-            IReadOnlyDictionary<Guid, IReadOnlyList<PersonInfo>>? peopleBatch = null)
+            IReadOnlyDictionary<Guid, IReadOnlyList<PersonInfo>>? peopleBatch = null,
+            IReadOnlySet<Guid>? alternateVersionItemIds = null)
         {
             var dto = new BaseItemDto
             {
@@ -399,7 +413,7 @@ namespace Emby.Server.Implementations.Dto
                 AttachStudios(dto, item);
             }
 
-            AttachBasicFields(dto, item, owner, options, artistsBatch, user);
+            AttachBasicFields(dto, item, owner, options, artistsBatch, user, alternateVersionItemIds);
 
             if (options.ContainsField(ItemFields.CanDelete))
             {
@@ -984,7 +998,8 @@ namespace Emby.Server.Implementations.Dto
         /// <param name="options">The options.</param>
         /// <param name="artistsBatch">Optional pre-fetched artist lookup shared across a batch of items.</param>
         /// <param name="user">The user, for per-user values such as the accessible media source count.</param>
-        private void AttachBasicFields(BaseItemDto dto, BaseItem item, BaseItem? owner, DtoOptions options, IReadOnlyDictionary<string, MusicArtist[]>? artistsBatch = null, User? user = null)
+        /// <param name="alternateVersionItemIds">Optional pre-fetched set of item IDs that own alternate versions, shared across a batch of items.</param>
+        private void AttachBasicFields(BaseItemDto dto, BaseItem item, BaseItem? owner, DtoOptions options, IReadOnlyDictionary<string, MusicArtist[]>? artistsBatch = null, User? user = null, IReadOnlySet<Guid>? alternateVersionItemIds = null)
         {
             if (options.ContainsField(ItemFields.DateCreated))
             {
@@ -1298,15 +1313,27 @@ namespace Emby.Server.Implementations.Dto
 
                 if (options.ContainsField(ItemFields.MediaSourceCount))
                 {
-                    // Match the per-user filtering of the media sources: versions the user cannot
-                    // access are not selectable, so they must not count towards the badge either.
-                    var mediaSourceCount = user is null
-                        || (!video.PrimaryVersionId.HasValue && video.LinkedAlternateVersions.Length == 0 && !video.HasLocalAlternateVersions)
-                            ? video.MediaSourceCount
-                            : video.GetAllVersions().Count(v => v.Id.Equals(video.Id) || v.IsVisibleStandalone(user));
-                    if (mediaSourceCount != 1)
+                    // A video with no primary version and no alternate versions always has a single
+                    // media source. Only compute the count for videos that might have more: a primary
+                    // version, or membership in the batch's set of items that own alternate versions.
+                    // Without the batch we can't rule it out, so fall back to computing (the single-item
+                    // path). Everything else is the common case and keeps the default count of one.
+                    var mayHaveAlternateVersions = alternateVersionItemIds is null
+                        || video.PrimaryVersionId.HasValue
+                        || alternateVersionItemIds.Contains(video.Id);
+
+                    if (mayHaveAlternateVersions)
                     {
-                        dto.MediaSourceCount = mediaSourceCount;
+                        // Match the per-user filtering of the media sources: versions the user cannot
+                        // access are not selectable, so they must not count towards the badge either.
+                        var mediaSourceCount = user is null
+                            || (!video.PrimaryVersionId.HasValue && video.LinkedAlternateVersions.Length == 0 && !video.HasLocalAlternateVersions)
+                                ? video.MediaSourceCount
+                                : video.GetAllVersions().Count(v => v.Id.Equals(video.Id) || v.IsVisibleStandalone(user));
+                        if (mediaSourceCount != 1)
+                        {
+                            dto.MediaSourceCount = mediaSourceCount;
+                        }
                     }
                 }
 
diff --git a/Emby.Server.Implementations/Library/LibraryManager.cs b/Emby.Server.Implementations/Library/LibraryManager.cs
index 19371f68d7..0c7c411d0c 100644
--- a/Emby.Server.Implementations/Library/LibraryManager.cs
+++ b/Emby.Server.Implementations/Library/LibraryManager.cs
@@ -2235,6 +2235,12 @@ namespace Emby.Server.Implementations.Library
         }
 
         /// <inheritdoc />
+        public IReadOnlySet<Guid> GetItemIdsWithAlternateVersions(IReadOnlyList<Guid> itemIds)
+        {
+            return _linkedChildrenService.GetItemIdsWithAlternateVersions(itemIds);
+        }
+
+        /// <inheritdoc />
         public void UpsertLinkedChild(Guid parentId, Guid childId, MediaBrowser.Controller.Entities.LinkedChildType childType)
         {
             _linkedChildrenService.UpsertLinkedChild(parentId, childId, childType);