From 39221a52dacdc4232f071ab03cac9c70aea8ada6 Mon Sep 17 00:00:00 2001
From: Salman Ahmed <frenzibyte@gmail.com>
Date: Thu, 5 Jan 2023 12:49:45 +0300
Subject: [PATCH 1/2] Fix advanced statistics display using decoupled ruleset
 bindable for difficulty calculation

---
 osu.Game/OsuGameBase.cs                       |  5 ++++-
 .../Screens/Select/Details/AdvancedStats.cs   | 20 +++++++++++++------
 2 files changed, 18 insertions(+), 7 deletions(-)

diff --git a/osu.Game/OsuGameBase.cs b/osu.Game/OsuGameBase.cs
index 36e248c1f2..83a32dd557 100644
--- a/osu.Game/OsuGameBase.cs
+++ b/osu.Game/OsuGameBase.cs
@@ -160,9 +160,12 @@ public virtual string Version
 
         protected Bindable<WorkingBeatmap> Beatmap { get; private set; } // cached via load() method
 
+        /// <summary>
+        /// The current ruleset selection for the local user.
+        /// </summary>
         [Cached]
         [Cached(typeof(IBindable<RulesetInfo>))]
-        protected readonly Bindable<RulesetInfo> Ruleset = new Bindable<RulesetInfo>();
+        protected internal readonly Bindable<RulesetInfo> Ruleset = new Bindable<RulesetInfo>();
 
         /// <summary>
         /// The current mod selection for the local user.
diff --git a/osu.Game/Screens/Select/Details/AdvancedStats.cs b/osu.Game/Screens/Select/Details/AdvancedStats.cs
index 5d0588e67b..3d45679604 100644
--- a/osu.Game/Screens/Select/Details/AdvancedStats.cs
+++ b/osu.Game/Screens/Select/Details/AdvancedStats.cs
@@ -30,14 +30,16 @@ namespace osu.Game.Screens.Select.Details
 {
     public partial class AdvancedStats : Container
     {
+        [Resolved]
+        private BeatmapDifficultyCache difficultyCache { get; set; }
+
         [Resolved]
         private IBindable<IReadOnlyList<Mod>> mods { get; set; }
 
         [Resolved]
-        private IBindable<RulesetInfo> ruleset { get; set; }
+        private OsuGameBase game { get; set; }
 
-        [Resolved]
-        private BeatmapDifficultyCache difficultyCache { get; set; }
+        private IBindable<RulesetInfo> gameRuleset;
 
         protected readonly StatisticRow FirstValue, HpDrain, Accuracy, ApproachRate;
         private readonly StatisticRow starDifficulty;
@@ -84,7 +86,13 @@ protected override void LoadComplete()
         {
             base.LoadComplete();
 
-            ruleset.BindValueChanged(_ => updateStatistics());
+            // the cached ruleset bindable might be a decoupled bindable provided by SongSelect,
+            // which we can't rely on in combination with the game-wide selected mods list,
+            // since mods could be updated to the new ruleset instances while the decoupled bindable is held behind,
+            // therefore resulting in performing difficulty calculation with invalid states.
+            gameRuleset = game.Ruleset.GetBoundCopy();
+            gameRuleset.BindValueChanged(_ => updateStatistics());
+
             mods.BindValueChanged(modsChanged, true);
         }
 
@@ -151,8 +159,8 @@ private void updateStarDifficulty()
 
             starDifficultyCancellationSource = new CancellationTokenSource();
 
-            var normalStarDifficultyTask = difficultyCache.GetDifficultyAsync(BeatmapInfo, ruleset.Value, null, starDifficultyCancellationSource.Token);
-            var moddedStarDifficultyTask = difficultyCache.GetDifficultyAsync(BeatmapInfo, ruleset.Value, mods.Value, starDifficultyCancellationSource.Token);
+            var normalStarDifficultyTask = difficultyCache.GetDifficultyAsync(BeatmapInfo, gameRuleset.Value, null, starDifficultyCancellationSource.Token);
+            var moddedStarDifficultyTask = difficultyCache.GetDifficultyAsync(BeatmapInfo, gameRuleset.Value, mods.Value, starDifficultyCancellationSource.Token);
 
             Task.WhenAll(normalStarDifficultyTask, moddedStarDifficultyTask).ContinueWith(_ => Schedule(() =>
             {

From 8f37e69dc4e8c7804098a7415deb838a33f4933e Mon Sep 17 00:00:00 2001
From: Salman Ahmed <frenzibyte@gmail.com>
Date: Thu, 5 Jan 2023 12:50:38 +0300
Subject: [PATCH 2/2] Schedule difficulty calculation to avoid performing with
 incomplete state updates

---
 osu.Game/Screens/Select/Details/AdvancedStats.cs | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/osu.Game/Screens/Select/Details/AdvancedStats.cs b/osu.Game/Screens/Select/Details/AdvancedStats.cs
index 3d45679604..a383298faa 100644
--- a/osu.Game/Screens/Select/Details/AdvancedStats.cs
+++ b/osu.Game/Screens/Select/Details/AdvancedStats.cs
@@ -150,7 +150,14 @@ private void updateStatistics()
 
         private CancellationTokenSource starDifficultyCancellationSource;
 
-        private void updateStarDifficulty()
+        /// <summary>
+        /// Updates the displayed star difficulty statistics with the values provided by the currently-selected beatmap, ruleset, and selected mods.
+        /// </summary>
+        /// <remarks>
+        /// This is scheduled to avoid scenarios wherein a ruleset changes first before selected mods do,
+        /// potentially resulting in failure during difficulty calculation due to incomplete bindable state updates.
+        /// </remarks>
+        private void updateStarDifficulty() => Scheduler.AddOnce(() =>
         {
             starDifficultyCancellationSource?.Cancel();
 
@@ -172,7 +179,7 @@ private void updateStarDifficulty()
 
                 starDifficulty.Value = ((float)normalDifficulty.Value.Stars, (float)moddedDifficulty.Value.Stars);
             }), starDifficultyCancellationSource.Token, TaskContinuationOptions.OnlyOnRanToCompletion, TaskScheduler.Current);
-        }
+        });
 
         protected override void Dispose(bool isDisposing)
         {