Fix several breakages with migration operation

osu.Game/Database/DetachedBeatmapStore.cs

@@ -44,7 +44,7 @@ private void beatmapSetsChanged(IRealmCollection<BeatmapSetInfo> sender, ChangeS
         {
             if (changes == null)
             {
-                if (detachedBeatmapSets.Count > 0 && sender.Count == 0)
+                if (sender is RealmResetEmptySet<BeatmapSetInfo>)
                 {
                     // Usually we'd reset stuff here, but doing so triggers a silly flow which ends up deadlocking realm.
                     // Additionally, user should not be at song select when realm is blocking all operations in the first place.

osu.Game/Database/RealmAccess.cs

@@ -568,7 +568,7 @@ public IDisposable RegisterForNotifications<T>(Func<Realm, IQueryable<T>> query,
             lock (notificationsResetMap)
             {
                 // Store an action which is used when blocking to ensure consumers don't use results of a stale changeset firing.
-                notificationsResetMap.Add(action, () => callback(new EmptyRealmSet<T>(), null));
+                notificationsResetMap.Add(action, () => callback(new RealmResetEmptySet<T>(), null));
             }
 
             return RegisterCustomSubscription(action);

osu.Game/Database/EmptyRealmSet.cs → osu.Game/Database/RealmResetEmptySet.cs

@@ -12,7 +12,13 @@
 
 namespace osu.Game.Database
 {
-    public class EmptyRealmSet<T> : IRealmCollection<T>
+    /// <summary>
+    /// This can arrive in <see cref="RealmAccess.RegisterForNotifications{T}"/> callbacks to imply that realm access has been reset.
+    /// </summary>
+    /// <remarks>
+    /// Usually implies that the original database may return soon and the callback can usually be silently ignored.
+    ///</remarks>
+    public class RealmResetEmptySet<T> : IRealmCollection<T>
     {
         private IList<T> emptySet => Array.Empty<T>();
 

osu.Game/OsuGame.cs

@@ -1137,7 +1137,6 @@ protected override void LoadComplete()
             loadComponentSingleFile(new MedalOverlay(), topMostOverlayContent.Add);
 
             loadComponentSingleFile(new BackgroundDataStoreProcessor(), Add);
-            loadComponentSingleFile(new DetachedBeatmapStore(), Add, true);
 
             Add(difficultyRecommender);
             Add(externalLinkOpener = new ExternalLinkOpener());

osu.Game/OsuGameBase.cs

@@ -377,6 +377,10 @@ private void load(ReadableKeyCombinationProvider keyCombinationProvider, Framewo
             dependencies.Cache(previewTrackManager = new PreviewTrackManager(BeatmapManager.BeatmapTrackStore));
             base.Content.Add(previewTrackManager);
 
+            var detachedBeatmapStore = new DetachedBeatmapStore();
+            base.Content.Add(detachedBeatmapStore);
+            dependencies.CacheAs(detachedBeatmapStore);
+
             base.Content.Add(MusicController = new MusicController());
             dependencies.CacheAs(MusicController);
 
@@ -541,7 +545,10 @@ public bool Migrate(string path)
                         realmBlocker = realm.BlockAllOperations("migration");
                         success = true;
                     }
-                    catch { }
+                    catch (Exception ex)
+                    {
+                        Logger.Log($"Attempting to block all operations failed: {ex}", LoggingTarget.Database);
+                    }
 
                     readyToRun.Set();
                 }, false);

osu.Game/Overlays/MusicController.cs

@@ -5,6 +5,7 @@
 using System.Collections.Generic;
 using System.Diagnostics;
 using System.Linq;
+using System.Threading;
 using osu.Framework.Allocation;
 using osu.Framework.Audio;
 using osu.Framework.Audio.Track;
@@ -62,8 +63,7 @@ public partial class MusicController : CompositeDrawable
 
         public DrawableTrack CurrentTrack { get; private set; } = new DrawableTrack(new TrackVirtual(1000));
 
-        [Resolved]
-        private RealmAccess realm { get; set; } = null!;
+        private IBindableList<BeatmapSetInfo> detachedBeatmaps = null!;
 
         private BindableNumber<double> sampleVolume = null!;
 
@@ -76,13 +76,15 @@ public partial class MusicController : CompositeDrawable
         private int randomHistoryDirection;
 
         [BackgroundDependencyLoader]
-        private void load(AudioManager audio, OsuConfigManager configManager)
+        private void load(AudioManager audio, OsuConfigManager configManager, DetachedBeatmapStore detachedBeatmapStore, CancellationToken? cancellationToken)
         {
             AddInternal(audioDuckFilter = new AudioFilter(audio.TrackMixer));
             audio.Tracks.AddAdjustment(AdjustableProperty.Volume, audioDuckVolume);
             sampleVolume = audio.VolumeSample.GetBoundCopy();
 
             configManager.BindWith(OsuSetting.RandomSelectAlgorithm, randomSelectAlgorithm);
+
+            detachedBeatmaps = detachedBeatmapStore.GetDetachedBeatmaps(cancellationToken);
         }
 
         protected override void LoadComplete()
@@ -255,8 +257,8 @@ private PreviousTrackResult prev(bool allowProtectedTracks)
                 playableSet = getNextRandom(-1, allowProtectedTracks);
             else
             {
-                playableSet = getBeatmapSets().AsEnumerable().TakeWhile(i => !i.Equals(current?.BeatmapSetInfo)).LastOrDefault(s => !s.Protected || allowProtectedTracks)
-                              ?? getBeatmapSets().AsEnumerable().LastOrDefault(s => !s.Protected || allowProtectedTracks);
+                playableSet = getBeatmapSets().TakeWhile(i => !i.Equals(current?.BeatmapSetInfo)).LastOrDefault(s => !s.Protected || allowProtectedTracks)
+                              ?? getBeatmapSets().LastOrDefault(s => !s.Protected || allowProtectedTracks);
             }
 
             if (playableSet != null)
@@ -351,10 +353,10 @@ private bool next(bool allowProtectedTracks)
                 playableSet = getNextRandom(1, allowProtectedTracks);
             else
             {
-                playableSet = getBeatmapSets().AsEnumerable().SkipWhile(i => !i.Equals(current?.BeatmapSetInfo))
+                playableSet = getBeatmapSets().SkipWhile(i => !i.Equals(current?.BeatmapSetInfo))
                                               .Where(i => !i.Protected || allowProtectedTracks)
                                               .ElementAtOrDefault(1)
-                              ?? getBeatmapSets().AsEnumerable().FirstOrDefault(i => !i.Protected || allowProtectedTracks);
+                              ?? getBeatmapSets().FirstOrDefault(i => !i.Protected || allowProtectedTracks);
             }
 
             var playableBeatmap = playableSet?.Beatmaps.FirstOrDefault();
@@ -373,7 +375,7 @@ private bool next(bool allowProtectedTracks)
         {
             BeatmapSetInfo result;
 
-            var possibleSets = getBeatmapSets().AsEnumerable().Where(s => !s.Protected || allowProtectedTracks).ToArray();
+            var possibleSets = getBeatmapSets().Where(s => !s.Protected || allowProtectedTracks).ToArray();
 
             if (possibleSets.Length == 0)
                 return null;
@@ -432,7 +434,7 @@ private void restartTrack()
 
         private TrackChangeDirection? queuedDirection;
 
-        private IQueryable<BeatmapSetInfo> getBeatmapSets() => realm.Realm.All<BeatmapSetInfo>().Where(s => !s.DeletePending);
+        private IEnumerable<BeatmapSetInfo> getBeatmapSets() => detachedBeatmaps.Where(s => !s.DeletePending);
 
         private void changeBeatmap(WorkingBeatmap newWorking)
         {
@@ -459,8 +461,8 @@ private void changeBeatmap(WorkingBeatmap newWorking)
                 else
                 {
                     // figure out the best direction based on order in playlist.
-                    int last = getBeatmapSets().AsEnumerable().TakeWhile(b => !b.Equals(current.BeatmapSetInfo)).Count();
-                    int next = getBeatmapSets().AsEnumerable().TakeWhile(b => !b.Equals(newWorking.BeatmapSetInfo)).Count();
+                    int last = getBeatmapSets().TakeWhile(b => !b.Equals(current.BeatmapSetInfo)).Count();
+                    int next = getBeatmapSets().TakeWhile(b => !b.Equals(newWorking.BeatmapSetInfo)).Count();
 
                     direction = last > next ? TrackChangeDirection.Prev : TrackChangeDirection.Next;
                 }