Add cancellation token support for beatmap difficulty calculation.

osu.Game/Beatmaps/BeatmapDifficultyCache.cs

@@ -147,13 +147,13 @@ namespace osu.Game.Beatmaps
                 if (CheckExists(lookup, out var existing))
                     return existing;
 
-                return computeDifficulty(lookup);
+                return computeDifficulty(lookup, token);
             }, token, TaskCreationOptions.HideScheduler | TaskCreationOptions.RunContinuationsAsynchronously, updateScheduler);
         }
 
         public Task<List<TimedDifficultyAttributes>> GetTimedDifficultyAttributesAsync(WorkingBeatmap beatmap, Ruleset ruleset, Mod[] mods, CancellationToken token = default)
         {
-            return Task.Factory.StartNew(() => ruleset.CreateDifficultyCalculator(beatmap).CalculateTimed(mods),
+            return Task.Factory.StartNew(() => ruleset.CreateDifficultyCalculator(beatmap).CalculateTimed(mods, token),
                 token,
                 TaskCreationOptions.HideScheduler | TaskCreationOptions.RunContinuationsAsynchronously,
                 updateScheduler);
@@ -270,8 +270,9 @@ namespace osu.Game.Beatmaps
         /// Computes the difficulty defined by a <see cref="DifficultyCacheLookup"/> key, and stores it to the timed cache.
         /// </summary>
         /// <param name="key">The <see cref="DifficultyCacheLookup"/> that defines the computation parameters.</param>
+        /// <param name="cancellationToken">The cancellation token.</param>
         /// <returns>The <see cref="StarDifficulty"/>.</returns>
-        private StarDifficulty computeDifficulty(in DifficultyCacheLookup key)
+        private StarDifficulty computeDifficulty(in DifficultyCacheLookup key, CancellationToken cancellationToken = default)
         {
             // In the case that the user hasn't given us a ruleset, use the beatmap's default ruleset.
             var beatmapInfo = key.BeatmapInfo;
@@ -283,7 +284,7 @@ namespace osu.Game.Beatmaps
                 Debug.Assert(ruleset != null);
 
                 var calculator = ruleset.CreateDifficultyCalculator(beatmapManager.GetWorkingBeatmap(key.BeatmapInfo));
-                var attributes = calculator.Calculate(key.OrderedMods);
+                var attributes = calculator.Calculate(key.OrderedMods, cancellationToken);
 
                 return new StarDifficulty(attributes);
             }

osu.Game/Beatmaps/BeatmapModelManager.cs

@@ -408,7 +408,7 @@ namespace osu.Game.Beatmaps
                     beatmap.BeatmapInfo.Ruleset = ruleset;
 
                     // TODO: this should be done in a better place once we actually need to dynamically update it.
-                    beatmap.BeatmapInfo.StarDifficulty = ruleset?.CreateInstance().CreateDifficultyCalculator(new DummyConversionBeatmap(beatmap)).Calculate().StarRating ?? 0;
+                    beatmap.BeatmapInfo.StarDifficulty = ruleset?.CreateInstance().CreateDifficultyCalculator(new DummyConversionBeatmap(beatmap)).Calculate(null).StarRating ?? 0;
                     beatmap.BeatmapInfo.Length = calculateLength(beatmap);
                     beatmap.BeatmapInfo.BPM = 60000 / beatmap.GetMostCommonBeatLength();
 

osu.Game/Rulesets/Difficulty/DifficultyCalculator.cs

@@ -4,6 +4,7 @@
 using System;
 using System.Collections.Generic;
 using System.Linq;
+using System.Threading;
 using osu.Framework.Audio.Track;
 using osu.Framework.Extensions.IEnumerableExtensions;
 using osu.Game.Beatmaps;
@@ -39,10 +40,11 @@ namespace osu.Game.Rulesets.Difficulty
         /// Calculates the difficulty of the beatmap using a specific mod combination.
         /// </summary>
         /// <param name="mods">The mods that should be applied to the beatmap.</param>
+        /// <param name="cancellationToken">The cancellation token.</param>
         /// <returns>A structure describing the difficulty of the beatmap.</returns>
-        public DifficultyAttributes Calculate(params Mod[] mods)
+        public DifficultyAttributes Calculate(IEnumerable<Mod> mods, CancellationToken cancellationToken = default)
         {
-            preProcess(mods);
+            preProcess(mods, cancellationToken);
 
             var skills = CreateSkills(Beatmap, playableMods, clockRate);
 
@@ -62,10 +64,11 @@ namespace osu.Game.Rulesets.Difficulty
         /// Calculates the difficulty of the beatmap and returns a set of <see cref="TimedDifficultyAttributes"/> representing the difficulty at every relevant time value in the beatmap.
         /// </summary>
         /// <param name="mods">The mods that should be applied to the beatmap.</param>
+        /// <param name="cancellationToken">The cancellation token.</param>
         /// <returns>The set of <see cref="TimedDifficultyAttributes"/>.</returns>
-        public List<TimedDifficultyAttributes> CalculateTimed(params Mod[] mods)
+        public List<TimedDifficultyAttributes> CalculateTimed(IEnumerable<Mod> mods, CancellationToken cancellationToken = default)
         {
-            preProcess(mods);
+            preProcess(mods, cancellationToken);
 
             var attribs = new List<TimedDifficultyAttributes>();
 
@@ -99,7 +102,7 @@ namespace osu.Game.Rulesets.Difficulty
                 if (combination is MultiMod multi)
                     yield return Calculate(multi.Mods);
                 else
-                    yield return Calculate(combination);
+                    yield return Calculate(new[] { combination });
             }
         }
 
@@ -112,11 +115,12 @@ namespace osu.Game.Rulesets.Difficulty
         /// Performs required tasks before every calculation.
         /// </summary>
         /// <param name="mods">The original list of <see cref="Mod"/>s.</param>
-        private void preProcess(Mod[] mods)
+        /// <param name="cancellationToken">The cancellation cancellationToken.</param>
+        private void preProcess(IEnumerable<Mod> mods, CancellationToken cancellationToken = default)
         {
             playableMods = mods.Select(m => m.DeepClone()).ToArray();
 
-            Beatmap = beatmap.GetPlayableBeatmap(ruleset.RulesetInfo, playableMods);
+            Beatmap = beatmap.GetPlayableBeatmap(ruleset.RulesetInfo, playableMods, cancellationToken: cancellationToken);
 
             var track = new TrackVirtual(10000);
             playableMods.OfType<IApplicableToTrack>().ForEach(m => m.ApplyToTrack(track));

osu.Game/Stores/BeatmapImporter.cs

@@ -284,7 +284,7 @@ namespace osu.Game.Stores
             decoded.BeatmapInfo.Ruleset = rulesetInstance.RulesetInfo;
 
             // TODO: this should be done in a better place once we actually need to dynamically update it.
-            beatmap.StarRating = rulesetInstance.CreateDifficultyCalculator(new DummyConversionBeatmap(decoded)).Calculate().StarRating;
+            beatmap.StarRating = rulesetInstance.CreateDifficultyCalculator(new DummyConversionBeatmap(decoded)).Calculate(null).StarRating;
             beatmap.Length = calculateLength(decoded);
             beatmap.BPM = 60000 / decoded.GetMostCommonBeatLength();
         }