From 9c7878e997666a1009c16b0ff722f14233c57c1d Mon Sep 17 00:00:00 2001
From: Dennis Daume <daume.dennis@gmail.com>
Date: Sat, 8 Nov 2014 20:03:45 +0100
Subject: [PATCH] Share the subscription to the artwork key changes so we don't
 create a billion subscriptions and consume more and more memory with each
 search

---
 Espera.View/ViewModels/ArtistViewModel.cs | 22 +++++++++++++---------
 Espera.View/ViewModels/LocalViewModel.cs  |  8 ++------
 2 files changed, 15 insertions(+), 15 deletions(-)

diff --git a/Espera.View/ViewModels/ArtistViewModel.cs b/Espera.View/ViewModels/ArtistViewModel.cs
index e5200e21..7771bc2f 100644
--- a/Espera.View/ViewModels/ArtistViewModel.cs
+++ b/Espera.View/ViewModels/ArtistViewModel.cs
@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.Linq;
 using System.Reactive.Linq;
 using System.Reactive.Subjects;
 using System.Threading.Tasks;
@@ -12,7 +13,7 @@ namespace Espera.View.ViewModels
 {
     public sealed class ArtistViewModel : ReactiveObject, IComparable<ArtistViewModel>, IEquatable<ArtistViewModel>, IDisposable
     {
-        private readonly Subject<IObservable<string>> artworkKeys;
+        private readonly ReactiveList<LocalSong> songs; 
         private readonly ObservableAsPropertyHelper<BitmapSource> cover;
         private readonly int orderHint;
 
@@ -20,19 +21,19 @@ public sealed class ArtistViewModel : ReactiveObject, IComparable<ArtistViewMode
         /// The constructor.
         /// </summary>
         /// <param name="artistName"></param>
-        /// <param name="artworkKeys"></param>
+        /// <param name="songs"></param>
         /// <param name="orderHint">
         /// A hint that tells this instance which position it has in the artist list. This helps for
         /// priorizing the album cover loading. The higher the number, the earlier it is in the list
         /// (Think of a reversed sorted list).
         /// </param>
-        public ArtistViewModel(string artistName, IEnumerable<IObservable<string>> artworkKeys, int orderHint = 1)
+        public ArtistViewModel(string artistName, IEnumerable<LocalSong> songs, int orderHint = 1)
         {
-            this.artworkKeys = new Subject<IObservable<string>>();
+            this.songs = new ReactiveList<LocalSong>();
 
             this.orderHint = orderHint;
 
-            this.cover = this.artworkKeys
+            this.cover = this.songs.ItemsAdded.Select(x => x.WhenAnyValue(y => y.ArtworkKey))
                 .Merge()
                 .Where(x => x != null)
                 .Distinct() // Ignore duplicate artworks
@@ -42,7 +43,7 @@ public ArtistViewModel(string artistName, IEnumerable<IObservable<string>> artwo
                 .ToProperty(this, x => x.Cover);
             var connect = this.Cover; // Connect the property to the source observable immediately
 
-            this.UpdateArtwork(artworkKeys);
+            this.UpdateSongs(songs);
 
             this.Name = artistName;
             this.IsAllArtists = false;
@@ -93,11 +94,14 @@ public bool Equals(ArtistViewModel other)
             return this.Name == other.Name;
         }
 
-        public void UpdateArtwork(IEnumerable<IObservable<string>> keys)
+        public void UpdateSongs(IEnumerable<LocalSong> songs)
         {
-            foreach (IObservable<string> key in keys)
+            var songsToAdd = songs.Where(x => !this.songs.Contains(x)).ToList();
+
+            // Can't use AddRange here, ReactiveList resets the list on big changes and we don't get the add notification
+            foreach (LocalSong song in songsToAdd)
             {
-                this.artworkKeys.OnNext(key);
+                this.songs.Add(song);
             }
         }
 
diff --git a/Espera.View/ViewModels/LocalViewModel.cs b/Espera.View/ViewModels/LocalViewModel.cs
index bc184209..c8c5174b 100644
--- a/Espera.View/ViewModels/LocalViewModel.cs
+++ b/Espera.View/ViewModels/LocalViewModel.cs
@@ -166,19 +166,15 @@ private void UpdateArtists()
             {
                 ArtistViewModel model = this.allArtists.FirstOrDefault(x => x.Name.Equals(songs.Key, StringComparison.InvariantCultureIgnoreCase));
 
-                List<IObservable<string>> artworkKeys = songs
-                    .Select(x => x.WhenAnyValue(y => y.ArtworkKey))
-                    .ToList();
-
                 if (model == null)
                 {
                     int priority = orderedArtists.IndexOf(songs.Key) + 1;
-                    this.allArtists.Add(new ArtistViewModel(songs.Key, artworkKeys, priority));
+                    this.allArtists.Add(new ArtistViewModel(songs.Key, songs, priority));
                 }
 
                 else
                 {
-                    model.UpdateArtwork(artworkKeys);
+                    model.UpdateSongs(songs);
                 }
             }
         }