Refactor KPS

- Remove '#nullable disable' in KeysPerSecondCalculator and
  KeysPerSecondCounter
- Remove KeysPerSecondCalculator IDisposable implementation
- Make KeysPerSecondCalculator static instance initialized once by
  KeysPerSecondCounters
- Auto transfer dependencies from KeysPerSecondCounter to
  KeysPerSecondCalculator using Resolved properties
- Add internal reset logic to KeysPerSecondCalculator and make it
  independent from Player
- Use GameplayClock.TrueGameplayRate to get real-time rate. If 0 then it
  defaults to the last non 0 rate if no such mod is enabled

osu.Game/Screens/Play/HUD/KPSCounter/KeysPerSecondCalculator.cs

@@ -1,8 +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.
 
-#nullable disable
-
 using System;
 using System.Collections.Generic;
 using System.Linq;
@@ -12,59 +10,93 @@ using osu.Game.Rulesets.UI;
 
 namespace osu.Game.Screens.Play.HUD.KPSCounter
 {
-    public class KeysPerSecondCalculator : IDisposable
+    public class KeysPerSecondCalculator
     {
-        private static KeysPerSecondCalculator instance;
-
         public static void AddInput()
         {
-            instance?.onNewInput?.Invoke();
-        }
-
-        public static KeysPerSecondCalculator GetInstance(GameplayClock gameplayClock = null, DrawableRuleset drawableRuleset = null)
-        {
-            if (instance != null) return instance;
-
-            try
-            {
-                return new KeysPerSecondCalculator(gameplayClock, drawableRuleset);
-            }
-            catch (ArgumentNullException)
-            {
-                return null;
-            }
+            onNewInput?.Invoke();
         }
 
         private readonly List<double> timestamps;
-        private readonly GameplayClock gameplayClock;
-        private readonly DrawableRuleset drawableRuleset;
+        private GameplayClock? gameplayClock;
+        private DrawableRuleset? drawableRuleset;
 
-        private event Action onNewInput;
+        public GameplayClock? GameplayClock
+        {
+            get => gameplayClock;
+            set
+            {
+                onResetRequested?.Invoke();
 
-        private IClock workingClock => (IClock)drawableRuleset?.FrameStableClock ?? gameplayClock;
+                if (value != null)
+                {
+                    gameplayClock = value;
+                }
+            }
+        }
 
-        // Having the rate from mods is preferred to using GameplayClock.TrueGameplayRate()
-        // as it returns 0 when paused in replays, not useful for players who want to "analyze" a replay.
-        private double rate => (drawableRuleset.Mods.FirstOrDefault(m => m is ModRateAdjust) as ModRateAdjust)?.SpeedChange.Value
+        public DrawableRuleset? DrawableRuleset
+        {
+            get => drawableRuleset;
+            set
+            {
+                onResetRequested?.Invoke();
+
+                if (value != null)
+                {
+                    drawableRuleset = value;
+                    baseRate = (drawableRuleset.Mods.FirstOrDefault(m => m is ModRateAdjust) as ModRateAdjust)?.SpeedChange.Value
                                ?? 1;
+                }
+            }
+        }
+
+        private static event Action? onNewInput;
+        private static event Action? onResetRequested;
+
+        private IClock? workingClock => drawableRuleset?.FrameStableClock;
+
+        private double baseRate;
+
+        private double rate
+        {
+            get
+            {
+                if (gameplayClock != null)
+                {
+                    if (gameplayClock.TrueGameplayRate > 0)
+                    {
+                        baseRate = gameplayClock.TrueGameplayRate;
+                    }
+                }
+
+                return baseRate;
+            }
+        }
 
         private double maxTime = double.NegativeInfinity;
 
         public bool Ready => workingClock != null && gameplayClock != null;
         public int Value => timestamps.Count(isTimestampWithinSpan);
 
-        private KeysPerSecondCalculator(GameplayClock gameplayClock, DrawableRuleset drawableRuleset)
+        public KeysPerSecondCalculator()
         {
-            instance = this;
             timestamps = new List<double>();
-            this.gameplayClock = gameplayClock ?? throw new ArgumentNullException(nameof(gameplayClock));
-            this.drawableRuleset = drawableRuleset;
             onNewInput += addTimestamp;
+            onResetRequested += cleanUp;
+        }
+
+        private void cleanUp()
+        {
+            timestamps.Clear();
+            maxTime = double.NegativeInfinity;
         }
 
         private void addTimestamp()
         {
-            if (Ready && workingClock.CurrentTime >= maxTime && gameplayClock.TrueGameplayRate > 0)
+            if (workingClock == null) return;
+
+            if (workingClock.CurrentTime >= maxTime)
             {
                 timestamps.Add(workingClock.CurrentTime);
                 maxTime = workingClock.CurrentTime;
@@ -73,19 +105,11 @@ namespace osu.Game.Screens.Play.HUD.KPSCounter
 
         private bool isTimestampWithinSpan(double timestamp)
         {
-            if (!Ready)
-                return false;
+            if (workingClock == null) return false;
 
             double span = 1000 * rate;
             double relativeTime = workingClock.CurrentTime - timestamp;
             return relativeTime >= 0 && relativeTime <= span;
         }
-
-        public void Dispose()
-        {
-            instance = null;
-        }
-
-        ~KeysPerSecondCalculator() => Dispose();
     }
 }

osu.Game/Screens/Play/HUD/KPSCounter/KeysPerSecondCounter.cs

@@ -1,15 +1,12 @@
 // 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.
 
-#nullable disable
-
 using osu.Framework.Allocation;
 using osu.Framework.Bindables;
 using osu.Framework.Graphics;
 using osu.Framework.Graphics.Containers;
 using osu.Framework.Graphics.Sprites;
 using osu.Framework.Localisation;
-using osu.Game.Configuration;
 using osu.Game.Graphics;
 using osu.Game.Graphics.Sprites;
 using osu.Game.Graphics.UserInterface;
@@ -24,21 +21,24 @@ namespace osu.Game.Screens.Play.HUD.KPSCounter
         private const float alpha_when_invalid = 0.3f;
 
         private readonly Bindable<bool> valid = new Bindable<bool>();
-        private GameplayClock gameplayClock;
+
+        private static readonly KeysPerSecondCalculator calculator = new KeysPerSecondCalculator();
+
+        [Resolved]
+        private GameplayClock? gameplayClock
+        {
+            get => calculator.GameplayClock;
+            set => calculator.GameplayClock = value;
+        }
 
         [Resolved(canBeNull: true)]
-        private DrawableRuleset drawableRuleset { get; set; }
-
-        private KeysPerSecondCalculator calculator => KeysPerSecondCalculator.GetInstance(gameplayClock, drawableRuleset);
-
-        [SettingSource("Smoothing time", "How smooth the counter should change\nThe more it is smooth, the less it's accurate.")]
-        public BindableNumber<double> SmoothingTime { get; } = new BindableNumber<double>(350)
+        private DrawableRuleset? drawableRuleset
         {
-            MaxValue = 1000,
-            MinValue = 0
-        };
+            get => calculator.DrawableRuleset;
+            set => calculator.DrawableRuleset = value;
+        }
 
-        protected override double RollingDuration => SmoothingTime.Value;
+        protected override double RollingDuration => 350;
 
         public bool UsesFixedAnchor { get; set; }
 
@@ -48,9 +48,8 @@ namespace osu.Game.Screens.Play.HUD.KPSCounter
         }
 
         [BackgroundDependencyLoader]
-        private void load(OsuColour colours, GameplayClock clock, DrawableRuleset ruleset)
+        private void load(OsuColour colours)
         {
-            gameplayClock = clock;
             Colour = colours.BlueLighter;
             valid.BindValueChanged(e =>
                 DrawableCount.FadeTo(e.NewValue ? 1 : alpha_when_invalid, 1000, Easing.OutQuint));
@@ -61,7 +60,7 @@ namespace osu.Game.Screens.Play.HUD.KPSCounter
             base.Update();
 
             valid.Value = calculator.Ready;
-            Current.Value = calculator.Value;
+            Current.Value = calculator.Ready ? calculator.Value : 0;
         }
 
         protected override IHasText CreateText() => new TextComponent

osu.Game/Screens/Play/Player.cs

@@ -34,7 +34,6 @@ using osu.Game.Rulesets.Scoring;
 using osu.Game.Rulesets.UI;
 using osu.Game.Scoring;
 using osu.Game.Scoring.Legacy;
-using osu.Game.Screens.Play.HUD.KPSCounter;
 using osu.Game.Screens.Ranking;
 using osu.Game.Skinning;
 using osu.Game.Users;
@@ -1046,8 +1045,6 @@ namespace osu.Game.Screens.Play
 
             fadeOut();
 
-            KeysPerSecondCalculator.GetInstance()?.Dispose();
-
             return base.OnExiting(e);
         }