Merge branch 'master' into fix-spinner-tests

osu.Game.Tests/Database/GeneralUsageTests.cs

@@ -1,3 +1,6 @@
+// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
+// See the LICENCE file in the repository root for full licence text.
+
 using System;
 using System.Threading;
 using System.Threading.Tasks;

osu.Game.Tests/Database/RealmLiveTests.cs

@@ -0,0 +1,213 @@
+// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
+// See the LICENCE file in the repository root for full licence text.
+
+using System;
+using System.Diagnostics;
+using System.Linq;
+using System.Threading.Tasks;
+using NUnit.Framework;
+using osu.Game.Beatmaps;
+using osu.Game.Database;
+using osu.Game.Models;
+using Realms;
+
+#nullable enable
+
+namespace osu.Game.Tests.Database
+{
+    public class RealmLiveTests : RealmTest
+    {
+        [Test]
+        public void TestLiveCastability()
+        {
+            RunTestWithRealm((realmFactory, _) =>
+            {
+                RealmLive<RealmBeatmap> beatmap = realmFactory.CreateContext().Write(r => r.Add(new RealmBeatmap(CreateRuleset(), new RealmBeatmapDifficulty(), new RealmBeatmapMetadata()))).ToLive();
+
+                ILive<IBeatmapInfo> iBeatmap = beatmap;
+
+                Assert.AreEqual(0, iBeatmap.Value.Length);
+            });
+        }
+
+        [Test]
+        public void TestValueAccessWithOpenContext()
+        {
+            RunTestWithRealm((realmFactory, _) =>
+            {
+                RealmLive<RealmBeatmap>? liveBeatmap = null;
+                Task.Factory.StartNew(() =>
+                {
+                    using (var threadContext = realmFactory.CreateContext())
+                    {
+                        var beatmap = threadContext.Write(r => r.Add(new RealmBeatmap(CreateRuleset(), new RealmBeatmapDifficulty(), new RealmBeatmapMetadata())));
+
+                        liveBeatmap = beatmap.ToLive();
+                    }
+                }, TaskCreationOptions.LongRunning | TaskCreationOptions.HideScheduler).Wait();
+
+                Debug.Assert(liveBeatmap != null);
+
+                Task.Factory.StartNew(() =>
+                {
+                    Assert.DoesNotThrow(() =>
+                    {
+                        using (realmFactory.CreateContext())
+                        {
+                            var resolved = liveBeatmap.Value;
+
+                            Assert.IsTrue(resolved.Realm.IsClosed);
+                            Assert.IsTrue(resolved.IsValid);
+
+                            // can access properties without a crash.
+                            Assert.IsFalse(resolved.Hidden);
+                        }
+                    });
+                }, TaskCreationOptions.LongRunning | TaskCreationOptions.HideScheduler).Wait();
+            });
+        }
+
+        [Test]
+        public void TestScopedReadWithoutContext()
+        {
+            RunTestWithRealm((realmFactory, _) =>
+            {
+                RealmLive<RealmBeatmap>? liveBeatmap = null;
+                Task.Factory.StartNew(() =>
+                {
+                    using (var threadContext = realmFactory.CreateContext())
+                    {
+                        var beatmap = threadContext.Write(r => r.Add(new RealmBeatmap(CreateRuleset(), new RealmBeatmapDifficulty(), new RealmBeatmapMetadata())));
+
+                        liveBeatmap = beatmap.ToLive();
+                    }
+                }, TaskCreationOptions.LongRunning | TaskCreationOptions.HideScheduler).Wait();
+
+                Debug.Assert(liveBeatmap != null);
+
+                Task.Factory.StartNew(() =>
+                {
+                    liveBeatmap.PerformRead(beatmap =>
+                    {
+                        Assert.IsTrue(beatmap.IsValid);
+                        Assert.IsFalse(beatmap.Hidden);
+                    });
+                }, TaskCreationOptions.LongRunning | TaskCreationOptions.HideScheduler).Wait();
+            });
+        }
+
+        [Test]
+        public void TestScopedWriteWithoutContext()
+        {
+            RunTestWithRealm((realmFactory, _) =>
+            {
+                RealmLive<RealmBeatmap>? liveBeatmap = null;
+                Task.Factory.StartNew(() =>
+                {
+                    using (var threadContext = realmFactory.CreateContext())
+                    {
+                        var beatmap = threadContext.Write(r => r.Add(new RealmBeatmap(CreateRuleset(), new RealmBeatmapDifficulty(), new RealmBeatmapMetadata())));
+
+                        liveBeatmap = beatmap.ToLive();
+                    }
+                }, TaskCreationOptions.LongRunning | TaskCreationOptions.HideScheduler).Wait();
+
+                Debug.Assert(liveBeatmap != null);
+
+                Task.Factory.StartNew(() =>
+                {
+                    liveBeatmap.PerformWrite(beatmap => { beatmap.Hidden = true; });
+                    liveBeatmap.PerformRead(beatmap => { Assert.IsTrue(beatmap.Hidden); });
+                }, TaskCreationOptions.LongRunning | TaskCreationOptions.HideScheduler).Wait();
+            });
+        }
+
+        [Test]
+        public void TestValueAccessWithoutOpenContextFails()
+        {
+            RunTestWithRealm((realmFactory, _) =>
+            {
+                RealmLive<RealmBeatmap>? liveBeatmap = null;
+                Task.Factory.StartNew(() =>
+                {
+                    using (var threadContext = realmFactory.CreateContext())
+                    {
+                        var beatmap = threadContext.Write(r => r.Add(new RealmBeatmap(CreateRuleset(), new RealmBeatmapDifficulty(), new RealmBeatmapMetadata())));
+
+                        liveBeatmap = beatmap.ToLive();
+                    }
+                }, TaskCreationOptions.LongRunning | TaskCreationOptions.HideScheduler).Wait();
+
+                Debug.Assert(liveBeatmap != null);
+
+                Task.Factory.StartNew(() =>
+                {
+                    Assert.Throws<InvalidOperationException>(() =>
+                    {
+                        var unused = liveBeatmap.Value;
+                    });
+                }, TaskCreationOptions.LongRunning | TaskCreationOptions.HideScheduler).Wait();
+            });
+        }
+
+        [Test]
+        public void TestLiveAssumptions()
+        {
+            RunTestWithRealm((realmFactory, _) =>
+            {
+                int changesTriggered = 0;
+
+                using (var updateThreadContext = realmFactory.CreateContext())
+                {
+                    updateThreadContext.All<RealmBeatmap>().SubscribeForNotifications(gotChange);
+                    RealmLive<RealmBeatmap>? liveBeatmap = null;
+
+                    Task.Factory.StartNew(() =>
+                    {
+                        using (var threadContext = realmFactory.CreateContext())
+                        {
+                            var ruleset = CreateRuleset();
+                            var beatmap = threadContext.Write(r => r.Add(new RealmBeatmap(ruleset, new RealmBeatmapDifficulty(), new RealmBeatmapMetadata())));
+
+                            // add a second beatmap to ensure that a full refresh occurs below.
+                            // not just a refresh from the resolved Live.
+                            threadContext.Write(r => r.Add(new RealmBeatmap(ruleset, new RealmBeatmapDifficulty(), new RealmBeatmapMetadata())));
+
+                            liveBeatmap = beatmap.ToLive();
+                        }
+                    }, TaskCreationOptions.LongRunning | TaskCreationOptions.HideScheduler).Wait();
+
+                    Debug.Assert(liveBeatmap != null);
+
+                    // not yet seen by main context
+                    Assert.AreEqual(0, updateThreadContext.All<RealmBeatmap>().Count());
+                    Assert.AreEqual(0, changesTriggered);
+
+                    var resolved = liveBeatmap.Value;
+
+                    // retrieval causes an implicit refresh. even changes that aren't related to the retrieval are fired at this point.
+                    Assert.AreEqual(2, updateThreadContext.All<RealmBeatmap>().Count());
+                    Assert.AreEqual(1, changesTriggered);
+
+                    // even though the realm that this instance was resolved for was closed, it's still valid.
+                    Assert.IsTrue(resolved.Realm.IsClosed);
+                    Assert.IsTrue(resolved.IsValid);
+
+                    // can access properties without a crash.
+                    Assert.IsFalse(resolved.Hidden);
+
+                    updateThreadContext.Write(r =>
+                    {
+                        // can use with the main context.
+                        r.Remove(resolved);
+                    });
+                }
+
+                void gotChange(IRealmCollection<RealmBeatmap> sender, ChangeSet changes, Exception error)
+                {
+                    changesTriggered++;
+                }
+            });
+        }
+    }
+}

osu.Game.Tests/Visual/Audio/TestSceneAudioFilter.cs

@@ -6,6 +6,7 @@ using NUnit.Framework;
 using osu.Framework.Allocation;
 using osu.Framework.Audio;
 using osu.Framework.Audio.Track;
+using osu.Framework.Bindables;
 using osu.Framework.Graphics;
 using osu.Framework.Graphics.Containers;
 using osu.Framework.Graphics.Sprites;
@@ -18,16 +19,19 @@ namespace osu.Game.Tests.Visual.Audio
 {
     public class TestSceneAudioFilter : OsuTestScene
     {
-        private OsuSpriteText lowpassText;
+        private OsuSpriteText lowPassText;
-        private AudioFilter lowpassFilter;
+        private AudioFilter lowPassFilter;
 
-        private OsuSpriteText highpassText;
+        private OsuSpriteText highPassText;
-        private AudioFilter highpassFilter;
+        private AudioFilter highPassFilter;
 
         private Track track;
 
         private WaveformTestBeatmap beatmap;
 
+        private OsuSliderBar<int> lowPassSlider;
+        private OsuSliderBar<int> highPassSlider;
+
         [BackgroundDependencyLoader]
         private void load(AudioManager audio)
         {
@@ -38,53 +42,89 @@ namespace osu.Game.Tests.Visual.Audio
             {
                 Children = new Drawable[]
                 {
-                    lowpassFilter = new AudioFilter(audio.TrackMixer),
+                    lowPassFilter = new AudioFilter(audio.TrackMixer),
-                    highpassFilter = new AudioFilter(audio.TrackMixer, BQFType.HighPass),
+                    highPassFilter = new AudioFilter(audio.TrackMixer, BQFType.HighPass),
-                    lowpassText = new OsuSpriteText
+                    lowPassText = new OsuSpriteText
                     {
                         Padding = new MarginPadding(20),
-                        Text = $"Low Pass: {lowpassFilter.Cutoff.Value}hz",
+                        Text = $"Low Pass: {lowPassFilter.Cutoff}hz",
                         Font = new FontUsage(size: 40)
                     },
-                    new OsuSliderBar<int>
+                    lowPassSlider = new OsuSliderBar<int>
                     {
                         Width = 500,
                         Height = 50,
                         Padding = new MarginPadding(20),
-                        Current = { BindTarget = lowpassFilter.Cutoff }
+                        Current = new BindableInt
+                        {
+                            MinValue = 0,
+                            MaxValue = AudioFilter.MAX_LOWPASS_CUTOFF,
+                        }
                     },
-                    highpassText = new OsuSpriteText
+                    highPassText = new OsuSpriteText
                     {
                         Padding = new MarginPadding(20),
-                        Text = $"High Pass: {highpassFilter.Cutoff.Value}hz",
+                        Text = $"High Pass: {highPassFilter.Cutoff}hz",
                         Font = new FontUsage(size: 40)
                     },
-                    new OsuSliderBar<int>
+                    highPassSlider = new OsuSliderBar<int>
                     {
                         Width = 500,
                         Height = 50,
                         Padding = new MarginPadding(20),
-                        Current = { BindTarget = highpassFilter.Cutoff }
+                        Current = new BindableInt
+                        {
+                            MinValue = 0,
+                            MaxValue = AudioFilter.MAX_LOWPASS_CUTOFF,
+                        }
                     }
                 }
             });
-            lowpassFilter.Cutoff.ValueChanged += e => lowpassText.Text = $"Low Pass: {e.NewValue}hz";
+
-            highpassFilter.Cutoff.ValueChanged += e => highpassText.Text = $"High Pass: {e.NewValue}hz";
+            lowPassSlider.Current.ValueChanged += e =>
+            {
+                lowPassText.Text = $"Low Pass: {e.NewValue}hz";
+                lowPassFilter.Cutoff = e.NewValue;
+            };
+
+            highPassSlider.Current.ValueChanged += e =>
+            {
+                highPassText.Text = $"High Pass: {e.NewValue}hz";
+                highPassFilter.Cutoff = e.NewValue;
+            };
         }
 
+        #region Overrides of Drawable
+
+        protected override void Update()
+        {
+            base.Update();
+            highPassSlider.Current.Value = highPassFilter.Cutoff;
+            lowPassSlider.Current.Value = lowPassFilter.Cutoff;
+        }
+
+        #endregion
+
         [SetUpSteps]
         public void SetUpSteps()
         {
             AddStep("Play Track", () => track.Start());
+
+            AddStep("Reset filters", () =>
+            {
+                lowPassFilter.Cutoff = AudioFilter.MAX_LOWPASS_CUTOFF;
+                highPassFilter.Cutoff = 0;
+            });
+
             waitTrackPlay();
         }
 
         [Test]
-        public void TestLowPass()
+        public void TestLowPassSweep()
         {
             AddStep("Filter Sweep", () =>
             {
-                lowpassFilter.CutoffTo(AudioFilter.MAX_LOWPASS_CUTOFF).Then()
+                lowPassFilter.CutoffTo(AudioFilter.MAX_LOWPASS_CUTOFF).Then()
                              .CutoffTo(0, 2000, Easing.OutCubic);
             });
 
@@ -92,7 +132,7 @@ namespace osu.Game.Tests.Visual.Audio
 
             AddStep("Filter Sweep (reverse)", () =>
             {
-                lowpassFilter.CutoffTo(0).Then()
+                lowPassFilter.CutoffTo(0).Then()
                              .CutoffTo(AudioFilter.MAX_LOWPASS_CUTOFF, 2000, Easing.InCubic);
             });
 
@@ -101,11 +141,11 @@ namespace osu.Game.Tests.Visual.Audio
         }
 
         [Test]
-        public void TestHighPass()
+        public void TestHighPassSweep()
         {
             AddStep("Filter Sweep", () =>
             {
-                highpassFilter.CutoffTo(0).Then()
+                highPassFilter.CutoffTo(0).Then()
                               .CutoffTo(AudioFilter.MAX_LOWPASS_CUTOFF, 2000, Easing.InCubic);
             });
 
@@ -113,7 +153,7 @@ namespace osu.Game.Tests.Visual.Audio
 
             AddStep("Filter Sweep (reverse)", () =>
             {
-                highpassFilter.CutoffTo(AudioFilter.MAX_LOWPASS_CUTOFF).Then()
+                highPassFilter.CutoffTo(AudioFilter.MAX_LOWPASS_CUTOFF).Then()
                               .CutoffTo(0, 2000, Easing.OutCubic);
             });
 

osu.Game/Audio/Effects/AudioFilter.cs

@@ -4,7 +4,6 @@
 using System.Diagnostics;
 using ManagedBass.Fx;
 using osu.Framework.Audio.Mixing;
-using osu.Framework.Bindables;
 using osu.Framework.Graphics;
 
 namespace osu.Game.Audio.Effects
@@ -21,10 +20,25 @@ namespace osu.Game.Audio.Effects
         private readonly BQFParameters filter;
         private readonly BQFType type;
 
+        private bool isAttached;
+
+        private int cutoff;
+
         /// <summary>
-        /// The current cutoff of this filter.
+        /// The cutoff frequency of this filter.
         /// </summary>
-        public BindableNumber<int> Cutoff { get; }
+        public int Cutoff
+        {
+            get => cutoff;
+            set
+            {
+                if (value == cutoff)
+                    return;
+
+                cutoff = value;
+                updateFilter(cutoff);
+            }
+        }
 
         /// <summary>
         /// A Component that implements a BASS FX BiQuad Filter Effect.
@@ -36,102 +50,96 @@ namespace osu.Game.Audio.Effects
             this.mixer = mixer;
             this.type = type;
 
-            int initialCutoff;
-
-            switch (type)
-            {
-                case BQFType.HighPass:
-                    initialCutoff = 1;
-                    break;
-
-                case BQFType.LowPass:
-                    initialCutoff = MAX_LOWPASS_CUTOFF;
-                    break;
-
-                default:
-                    initialCutoff = 500; // A default that should ensure audio remains audible for other filters.
-                    break;
-            }
-
-            Cutoff = new BindableNumber<int>(initialCutoff)
-            {
-                MinValue = 1,
-                MaxValue = MAX_LOWPASS_CUTOFF
-            };
-
             filter = new BQFParameters
             {
                 lFilter = type,
-                fCenter = initialCutoff,
                 fBandwidth = 0,
-                fQ = 0.7f // This allows fCenter to go up to 22049hz (nyquist - 1hz) without overflowing and causing weird filter behaviour (see: https://www.un4seen.com/forum/?topic=19542.0)
+                // This allows fCenter to go up to 22049hz (nyquist - 1hz) without overflowing and causing weird filter behaviour (see: https://www.un4seen.com/forum/?topic=19542.0)
+                fQ = 0.7f
             };
 
-            // Don't start attached if this is low-pass or high-pass filter (as they have special auto-attach/detach logic)
+            Cutoff = getInitialCutoff(type);
-            if (type != BQFType.LowPass && type != BQFType.HighPass)
-                attachFilter();
-
-            Cutoff.ValueChanged += updateFilter;
         }
 
-        private void attachFilter()
+        private int getInitialCutoff(BQFType type)
         {
-            Debug.Assert(!mixer.Effects.Contains(filter));
+            switch (type)
-            mixer.Effects.Add(filter);
-        }
-
-        private void detachFilter()
-        {
-            Debug.Assert(mixer.Effects.Contains(filter));
-            mixer.Effects.Remove(filter);
-        }
-
-        private void updateFilter(ValueChangedEvent<int> cutoff)
-        {
-            // Workaround for weird behaviour when rapidly setting fCenter of a low-pass filter to nyquist - 1hz.
-            if (type == BQFType.LowPass)
             {
-                if (cutoff.NewValue >= MAX_LOWPASS_CUTOFF)
+                case BQFType.HighPass:
-                {
+                    return 1;
-                    detachFilter();
-                    return;
-                }
 
-                if (cutoff.OldValue >= MAX_LOWPASS_CUTOFF && cutoff.NewValue < MAX_LOWPASS_CUTOFF)
+                case BQFType.LowPass:
-                    attachFilter();
+                    return MAX_LOWPASS_CUTOFF;
+
+                default:
+                    return 500; // A default that should ensure audio remains audible for other filters.
+            }
+        }
+
+        private void updateFilter(int newValue)
+        {
+            switch (type)
+            {
+                case BQFType.LowPass:
+                    // Workaround for weird behaviour when rapidly setting fCenter of a low-pass filter to nyquist - 1hz.
+                    if (newValue >= MAX_LOWPASS_CUTOFF)
+                    {
+                        ensureDetached();
+                        return;
+                    }
+
+                    break;
+
+                // Workaround for weird behaviour when rapidly setting fCenter of a high-pass filter to 1hz.
+                case BQFType.HighPass:
+                    if (newValue <= 1)
+                    {
+                        ensureDetached();
+                        return;
+                    }
+
+                    break;
             }
 
-            // Workaround for weird behaviour when rapidly setting fCenter of a high-pass filter to 1hz.
+            ensureAttached();
-            if (type == BQFType.HighPass)
-            {
-                if (cutoff.NewValue <= 1)
-                {
-                    detachFilter();
-                    return;
-                }
-
-                if (cutoff.OldValue <= 1 && cutoff.NewValue > 1)
-                    attachFilter();
-            }
 
             var filterIndex = mixer.Effects.IndexOf(filter);
+
             if (filterIndex < 0) return;
 
             if (mixer.Effects[filterIndex] is BQFParameters existingFilter)
             {
-                existingFilter.fCenter = cutoff.NewValue;
+                existingFilter.fCenter = newValue;
 
                 // required to update effect with new parameters.
                 mixer.Effects[filterIndex] = existingFilter;
             }
         }
 
+        private void ensureAttached()
+        {
+            if (isAttached)
+                return;
+
+            Debug.Assert(!mixer.Effects.Contains(filter));
+            mixer.Effects.Add(filter);
+            isAttached = true;
+        }
+
+        private void ensureDetached()
+        {
+            if (!isAttached)
+                return;
+
+            Debug.Assert(mixer.Effects.Contains(filter));
+            mixer.Effects.Remove(filter);
+            isAttached = false;
+        }
+
         protected override void Dispose(bool isDisposing)
         {
             base.Dispose(isDisposing);
-
+            ensureDetached();
-            if (mixer.Effects.Contains(filter))
-                detachFilter();
         }
     }
 }

osu.Game/Audio/Effects/ITransformableFilter.cs

@@ -1,7 +1,6 @@
 // Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
 // See the LICENCE file in the repository root for full licence text.
 
-using osu.Framework.Bindables;
 using osu.Framework.Graphics;
 using osu.Framework.Graphics.Transforms;
 
@@ -12,7 +11,7 @@ namespace osu.Game.Audio.Effects
         /// <summary>
         /// The filter cutoff.
         /// </summary>
-        BindableNumber<int> Cutoff { get; }
+        int Cutoff { get; set; }
     }
 
     public static class FilterableAudioComponentExtensions
@@ -40,7 +39,7 @@ namespace osu.Game.Audio.Effects
         public static TransformSequence<T> CutoffTo<T, TEasing>(this T component, int newCutoff, double duration, TEasing easing)
             where T : class, ITransformableFilter, IDrawable
             where TEasing : IEasingFunction
-            => component.TransformBindableTo(component.Cutoff, newCutoff, duration, easing);
+            => component.TransformTo(nameof(component.Cutoff), newCutoff, duration, easing);
 
         /// <summary>
         /// Smoothly adjusts filter cutoff over time.
@@ -49,6 +48,6 @@ namespace osu.Game.Audio.Effects
         public static TransformSequence<T> CutoffTo<T, TEasing>(this TransformSequence<T> sequence, int newCutoff, double duration, TEasing easing)
             where T : class, ITransformableFilter, IDrawable
             where TEasing : IEasingFunction
-            => sequence.Append(o => o.TransformBindableTo(o.Cutoff, newCutoff, duration, easing));
+            => sequence.Append(o => o.TransformTo(nameof(o.Cutoff), newCutoff, duration, easing));
     }
 }

osu.Game/Database/RealmLive.cs

@@ -0,0 +1,111 @@
+// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
+// See the LICENCE file in the repository root for full licence text.
+
+using System;
+using System.Threading;
+using Realms;
+
+#nullable enable
+
+namespace osu.Game.Database
+{
+    /// <summary>
+    /// Provides a method of working with realm objects over longer application lifetimes.
+    /// </summary>
+    /// <typeparam name="T">The underlying object type.</typeparam>
+    public class RealmLive<T> : ILive<T> where T : RealmObject, IHasGuidPrimaryKey
+    {
+        public Guid ID { get; }
+
+        private readonly SynchronizationContext? fetchedContext;
+        private readonly int fetchedThreadId;
+
+        /// <summary>
+        /// The original live data used to create this instance.
+        /// </summary>
+        private readonly T data;
+
+        /// <summary>
+        /// Construct a new instance of live realm data.
+        /// </summary>
+        /// <param name="data">The realm data.</param>
+        public RealmLive(T data)
+        {
+            this.data = data;
+
+            fetchedContext = SynchronizationContext.Current;
+            fetchedThreadId = Thread.CurrentThread.ManagedThreadId;
+
+            ID = data.ID;
+        }
+
+        /// <summary>
+        /// Perform a read operation on this live object.
+        /// </summary>
+        /// <param name="perform">The action to perform.</param>
+        public void PerformRead(Action<T> perform)
+        {
+            if (originalDataValid)
+            {
+                perform(data);
+                return;
+            }
+
+            using (var realm = Realm.GetInstance(data.Realm.Config))
+                perform(realm.Find<T>(ID));
+        }
+
+        /// <summary>
+        /// Perform a read operation on this live object.
+        /// </summary>
+        /// <param name="perform">The action to perform.</param>
+        public TReturn PerformRead<TReturn>(Func<T, TReturn> perform)
+        {
+            if (typeof(RealmObjectBase).IsAssignableFrom(typeof(TReturn)))
+                throw new InvalidOperationException($"Realm live objects should not exit the scope of {nameof(PerformRead)}.");
+
+            if (originalDataValid)
+                return perform(data);
+
+            using (var realm = Realm.GetInstance(data.Realm.Config))
+                return perform(realm.Find<T>(ID));
+        }
+
+        /// <summary>
+        /// Perform a write operation on this live object.
+        /// </summary>
+        /// <param name="perform">The action to perform.</param>
+        public void PerformWrite(Action<T> perform) =>
+            PerformRead(t =>
+            {
+                var transaction = t.Realm.BeginWrite();
+                perform(t);
+                transaction.Commit();
+            });
+
+        public T Value
+        {
+            get
+            {
+                if (originalDataValid)
+                    return data;
+
+                T retrieved;
+
+                using (var realm = Realm.GetInstance(data.Realm.Config))
+                    retrieved = realm.Find<T>(ID);
+
+                if (!retrieved.IsValid)
+                    throw new InvalidOperationException("Attempted to access value without an open context");
+
+                return retrieved;
+            }
+        }
+
+        private bool originalDataValid => isCorrectThread && data.IsValid;
+
+        // this matches realm's internal thread validation (see https://github.com/realm/realm-dotnet/blob/903b4d0b304f887e37e2d905384fb572a6496e70/Realm/Realm/Native/SynchronizationContextScheduler.cs#L72)
+        private bool isCorrectThread
+            => (fetchedContext != null && SynchronizationContext.Current == fetchedContext) || fetchedThreadId == Thread.CurrentThread.ManagedThreadId;
+    }
+}

osu.Game/Database/RealmObjectExtensions.cs

@@ -2,6 +2,7 @@
 // See the LICENCE file in the repository root for full licence text.
 
 using System.Collections.Generic;
+using System.Linq;
 using AutoMapper;
 using osu.Game.Input.Bindings;
 using Realms;
@@ -47,5 +48,17 @@ namespace osu.Game.Database
 
             return mapper.Map<T>(item);
         }
+
+        public static List<RealmLive<T>> ToLive<T>(this IEnumerable<T> realmList)
+            where T : RealmObject, IHasGuidPrimaryKey
+        {
+            return realmList.Select(l => new RealmLive<T>(l)).ToList();
+        }
+
+        public static RealmLive<T> ToLive<T>(this T realmObject)
+            where T : RealmObject, IHasGuidPrimaryKey
+        {
+            return new RealmLive<T>(realmObject);
+        }
     }
 }

osu.Game/Screens/Play/PlayerLoader.cs

@@ -35,6 +35,8 @@ namespace osu.Game.Screens.Play
     {
         protected const float BACKGROUND_BLUR = 15;
 
+        private const double content_out_duration = 300;
+
         public override bool HideOverlaysOnEnter => hideOverlays;
 
         public override bool DisallowExternalBeatmapRulesetChanges => true;
@@ -135,36 +137,39 @@ namespace osu.Game.Screens.Play
             muteWarningShownOnce = sessionStatics.GetBindable<bool>(Static.MutedAudioNotificationShownOnce);
             batteryWarningShownOnce = sessionStatics.GetBindable<bool>(Static.LowBatteryNotificationShownOnce);
 
-            InternalChild = (content = new LogoTrackingContainer
+            InternalChildren = new Drawable[]
             {
-                Anchor = Anchor.Centre,
+                (content = new LogoTrackingContainer
-                Origin = Anchor.Centre,
-                RelativeSizeAxes = Axes.Both,
-            }).WithChildren(new Drawable[]
-            {
-                MetadataInfo = new BeatmapMetadataDisplay(Beatmap.Value, Mods, content.LogoFacade)
                 {
-                    Alpha = 0,
                     Anchor = Anchor.Centre,
                     Origin = Anchor.Centre,
-                },
+                    RelativeSizeAxes = Axes.Both,
-                PlayerSettings = new FillFlowContainer<PlayerSettingsGroup>
+                }).WithChildren(new Drawable[]
                 {
-                    Anchor = Anchor.TopRight,
+                    MetadataInfo = new BeatmapMetadataDisplay(Beatmap.Value, Mods, content.LogoFacade)
-                    Origin = Anchor.TopRight,
-                    AutoSizeAxes = Axes.Both,
-                    Direction = FillDirection.Vertical,
-                    Spacing = new Vector2(0, 20),
-                    Margin = new MarginPadding(25),
-                    Children = new PlayerSettingsGroup[]
                     {
-                        VisualSettings = new VisualSettings(),
+                        Alpha = 0,
-                        new InputSettings()
+                        Anchor = Anchor.Centre,
-                    }
+                        Origin = Anchor.Centre,
-                },
+                    },
-                idleTracker = new IdleTracker(750),
+                    PlayerSettings = new FillFlowContainer<PlayerSettingsGroup>
+                    {
+                        Anchor = Anchor.TopRight,
+                        Origin = Anchor.TopRight,
+                        AutoSizeAxes = Axes.Both,
+                        Direction = FillDirection.Vertical,
+                        Spacing = new Vector2(0, 20),
+                        Margin = new MarginPadding(25),
+                        Children = new PlayerSettingsGroup[]
+                        {
+                            VisualSettings = new VisualSettings(),
+                            new InputSettings()
+                        }
+                    },
+                    idleTracker = new IdleTracker(750),
+                }),
                 lowPassFilter = new AudioFilter(audio.TrackMixer)
-            });
+            };
 
             if (Beatmap.Value.BeatmapInfo.EpilepsyWarning)
             {
@@ -195,7 +200,6 @@ namespace osu.Game.Screens.Play
                     epilepsyWarning.DimmableBackground = b;
             });
 
-            lowPassFilter.CutoffTo(500, 100, Easing.OutCubic);
             Beatmap.Value.Track.AddAdjustment(AdjustableProperty.Volume, volumeAdjustment);
 
             content.ScaleTo(0.7f);
@@ -240,15 +244,15 @@ namespace osu.Game.Screens.Play
         public override bool OnExiting(IScreen next)
         {
             cancelLoad();
+            contentOut();
 
-            content.ScaleTo(0.7f, 150, Easing.InQuint);
+            // Ensure the screen doesn't expire until all the outwards fade operations have completed.
-            this.FadeOut(150);
+            this.Delay(content_out_duration).FadeOut();
 
             ApplyToBackground(b => b.IgnoreUserSettings.Value = true);
 
             BackgroundBrightnessReduction = false;
             Beatmap.Value.Track.RemoveAdjustment(AdjustableProperty.Volume, volumeAdjustment);
-            lowPassFilter.CutoffTo(AudioFilter.MAX_LOWPASS_CUTOFF, 100, Easing.InCubic);
 
             return base.OnExiting(next);
         }
@@ -344,6 +348,7 @@ namespace osu.Game.Screens.Play
 
             content.FadeInFromZero(400);
             content.ScaleTo(1, 650, Easing.OutQuint).Then().Schedule(prepareNewPlayer);
+            lowPassFilter.CutoffTo(1000, 650, Easing.OutQuint);
 
             ApplyToBackground(b => b?.FadeColour(Color4.White, 800, Easing.OutQuint));
         }
@@ -353,8 +358,9 @@ namespace osu.Game.Screens.Play
             // Ensure the logo is no longer tracking before we scale the content
             content.StopTracking();
 
-            content.ScaleTo(0.7f, 300, Easing.InQuint);
+            content.ScaleTo(0.7f, content_out_duration * 2, Easing.OutQuint);
-            content.FadeOut(250);
+            content.FadeOut(content_out_duration, Easing.OutQuint);
+            lowPassFilter.CutoffTo(AudioFilter.MAX_LOWPASS_CUTOFF, content_out_duration);
         }
 
         private void pushWhenLoaded()
@@ -381,7 +387,7 @@ namespace osu.Game.Screens.Play
 
                 contentOut();
 
-                TransformSequence<PlayerLoader> pushSequence = this.Delay(250);
+                TransformSequence<PlayerLoader> pushSequence = this.Delay(content_out_duration);
 
                 // only show if the warning was created (i.e. the beatmap needs it)
                 // and this is not a restart of the map (the warning expires after first load).
@@ -400,6 +406,11 @@ namespace osu.Game.Screens.Play
                         })
                         .Delay(EpilepsyWarning.FADE_DURATION);
                 }
+                else
+                {
+                    // This goes hand-in-hand with the restoration of low pass filter in contentOut().
+                    this.TransformBindableTo(volumeAdjustment, 0, content_out_duration, Easing.OutCubic);
+                }
 
                 pushSequence.Schedule(() =>
                 {