Improve podcast episode GridEntry creation performance.

Tested on a library with ~5000 podcast episodes on an AMD Ryzen 7700X. Startup time decreases by ~400 ms in Release mode.

Source/LibationUiBase/GridView/GridEntry[TStatus].cs

@@ -1,7 +1,6 @@
 using ApplicationServices;
 using DataLayer;
 using Dinah.Core;
-using Dinah.Core.Threading;
 using FileLiberator;
 using LibationFileManager;
 using System;
@@ -9,7 +8,7 @@ using System.Collections;
 using System.Collections.Generic;
 using System.ComponentModel;
 using System.Linq;
-using System.Runtime.CompilerServices;
+using System.Threading;
 using System.Threading.Tasks;
 
 namespace LibationUiBase.GridView
@@ -311,6 +310,36 @@ namespace LibationUiBase.GridView
 
 		#endregion
 
+
+		/// <summary>
+		/// Creates <see cref="IGridEntry"/> for all non-episode books in an enumeration of <see cref="DataLayer.LibraryBook"/>.
+		/// </summary>
+		/// <remarks>Can be called from any thread, but requires the calling thread's <see cref="SynchronizationContext.Current"/> to be valid.</remarks>
+		public static  async Task<List<TEntry>> GetAllProductsAsync<TEntry>(IEnumerable<LibraryBook> libraryBooks, Func<LibraryBook, bool> includeIf, Func<LibraryBook, TEntry> factory)
+			where TEntry : IGridEntry
+		{
+			var products = libraryBooks.Where(includeIf).ToArray();
+			if (products.Length == 0)
+				return [];
+
+			int parallelism = int.Max(1, Environment.ProcessorCount - 1);
+
+			(int batchSize, int rem) = int.DivRem(products.Length, parallelism);
+			if (rem != 0) batchSize++;
+
+			var syncContext = SynchronizationContext.Current;
+
+			//Asynchronously create a GridEntry for every book in the library
+			var tasks = products.Chunk(batchSize).Select(batch => Task.Run(() =>
+			{
+				SynchronizationContext.SetSynchronizationContext(syncContext);
+				return batch.Select(factory).OfType<TEntry>().ToArray();
+			}));
+
+			return (await Task.WhenAll(tasks)).SelectMany(a => a).ToList();
+		}
+
+
 		~GridEntry()
 		{
 			PictureStorage.PictureCached -= PictureStorage_PictureCached;

Source/LibationUiBase/GridView/LibraryBookEntry[TStatus].cs

@@ -3,8 +3,6 @@ using System;
 using System.Collections.Generic;
 using System.ComponentModel;
 using System.Threading.Tasks;
-using System.Threading;
-using System.Linq;
 
 namespace LibationUiBase.GridView
 {
@@ -36,29 +34,9 @@ namespace LibationUiBase.GridView
 		/// <summary>
 		/// Creates <see cref="LibraryBookEntry{TStatus}"/> for all non-episode books in an enumeration of <see cref="LibraryBook"/>.
 		/// </summary>
-		/// <remarks>Can be called from any thread, but requires the calling thread's <see cref="SynchronizationContext.Current"/> to be valid.</remarks>
+		/// <remarks>Can be called from any thread, but requires the calling thread's <see cref="System.Threading.SynchronizationContext.Current"/> to be valid.</remarks>
 		public static async Task<List<IGridEntry>> GetAllProductsAsync(IEnumerable<LibraryBook> libraryBooks)
-		{
+			=> await GetAllProductsAsync(libraryBooks, lb => lb.Book.IsProduct(), lb => new LibraryBookEntry<TStatus>(lb) as IGridEntry);
-			var products = libraryBooks.Where(lb => lb.Book.IsProduct()).ToArray();
-			if (products.Length == 0)
-				return [];
-
-			int parallelism = int.Max(1, Environment.ProcessorCount - 1);
-
-			(int batchSize, int rem) = int.DivRem(products.Length, parallelism);
-			if (rem != 0) batchSize++;
-
-			var syncContext = SynchronizationContext.Current;
-
-			//Asynchronously create an ILibraryBookEntry for every book in the library
-			var tasks = products.Chunk(batchSize).Select(batch => Task.Run(() =>
-			{
-				SynchronizationContext.SetSynchronizationContext(syncContext);
-				return batch.Select(lb => new LibraryBookEntry<TStatus>(lb) as IGridEntry);
-			}));
-
-			return (await Task.WhenAll(tasks)).SelectMany(a => a).ToList();
-		}
 
 		protected override string GetBookTags() => string.Join("\r\n", Book.UserDefinedItem.TagsEnumerated);
 	}

Source/LibationUiBase/GridView/SeriesEntry[TStatus].cs

@@ -1,4 +1,5 @@
 using DataLayer;
+using Dinah.Core.Collections.Generic;
 using System;
 using System.Collections.Generic;
 using System.Linq;
@@ -62,56 +63,32 @@ namespace LibationUiBase.GridView
 		/// <remarks>Can be called from any thread, but requires the calling thread's <see cref="SynchronizationContext.Current"/> to be valid.</remarks>
 		public static async Task<List<ISeriesEntry>> GetAllSeriesEntriesAsync(IEnumerable<LibraryBook> libraryBooks)
 		{
-			var seriesBooks = libraryBooks.Where(lb => lb.Book.IsEpisodeParent()).ToArray();
+			var seriesEntries = await GetAllProductsAsync(libraryBooks, lb => lb.Book.IsEpisodeParent(), lb => new SeriesEntry<TStatus>(lb, []) as ISeriesEntry);
-			var allEpisodes = libraryBooks.Where(lb => lb.Book.IsEpisodeChild()).ToArray();
+			var seriesDict = seriesEntries.ToDictionarySafe(s => s.AudibleProductId);
+			await GetAllProductsAsync(libraryBooks, lb => lb.Book.IsEpisodeChild(), CreateAndLinkEpisodeEntry);
 
-			var seriesEntries = new ISeriesEntry[seriesBooks.Length];
+			//sort episodes by series order descending and update SeriesEntry
-			var seriesEpisodes = new ILibraryBookEntry[seriesBooks.Length][];
+			foreach (var series in seriesEntries)
-
-			var syncContext = SynchronizationContext.Current;
-			var options = new ParallelOptions { MaxDegreeOfParallelism = int.Max(1, Environment.ProcessorCount - 1) };
-
-			//Asynchronously create an ILibraryBookEntry for every episode in the library
-			await Parallel.ForEachAsync(getAllEpisodes(), options,  createEpisodeEntry);
-
-			//Match all episode entries to their corresponding parents
-			for (int i = seriesEntries.Length - 1; i >= 0; i--)
 			{
-				var series = seriesEntries[i];
+				series.Children.Sort((a, b) => -a.SeriesOrder.CompareTo(b.SeriesOrder));
-
-				//Sort episodes by series order descending, then add them to their parent's entry
-				Array.Sort(seriesEpisodes[i], (a, b) => -a.SeriesOrder.CompareTo(b.SeriesOrder));
-				series.Children.AddRange(seriesEpisodes[i]);
 				series.UpdateLibraryBook(series.LibraryBook);
 			}
 
-			return seriesEntries.Where(s => s.Children.Count != 0).Cast<ISeriesEntry>().ToList();
+			return seriesEntries.Where(s => s.Children.Count != 0).ToList();
 
-			//Create a LibraryBookEntry for a single episode
+			//Create a LibraryBookEntry for an episode and link it to its series parent
-			ValueTask createEpisodeEntry((int seriesIndex, int episodeIndex, LibraryBook episode) data, CancellationToken cancellationToken)
+			LibraryBookEntry<TStatus> CreateAndLinkEpisodeEntry(LibraryBook episode)
 			{
-				SynchronizationContext.SetSynchronizationContext(syncContext);
+				foreach (var s in episode.Book.SeriesLink)
-				var parent = seriesEntries[data.seriesIndex];
+				{
-				seriesEpisodes[data.seriesIndex][data.episodeIndex] = new LibraryBookEntry<TStatus>(data.episode, parent);
+					if (seriesDict.TryGetValue(s.Series.AudibleSeriesId, out var seriesParent))
-				return ValueTask.CompletedTask;
+					{
+						var entry = new LibraryBookEntry<TStatus>(episode, seriesParent);
+						seriesParent.Children.Add(entry);
+						return entry;
 					}
-
-			//Enumeration all series episodes, along with the index to its seriesEntries entry
-			//and an index to its seriesEpisodes entry
-			IEnumerable<(int seriesIndex, int episodeIndex, LibraryBook episode)> getAllEpisodes()
-			{
-				for (int i = 0; i < seriesBooks.Length; i++)
-				{
-					var series = seriesBooks[i];
-					var childEpisodes = allEpisodes.FindChildren(series);
-
-					SynchronizationContext.SetSynchronizationContext(syncContext);
-					seriesEntries[i] = new SeriesEntry<TStatus>(series, []);
-					seriesEpisodes[i] = new ILibraryBookEntry[childEpisodes.Count];
-
-					for (int j = 0; j < childEpisodes.Count; j++)
-						yield return (i, j, childEpisodes[j]);
 				}
+				return null;
 			}
 		}