Use a global ruleset config cache

osu.Game/Rulesets/RulesetConfigCache.cs

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+// Copyright (c) 2007-2018 ppy Pty Ltd <contact@ppy.sh>.
+// Licensed under the MIT Licence - https://raw.githubusercontent.com/ppy/osu/master/LICENCE
+
+using System;
+using System.Collections.Generic;
+using osu.Framework.Graphics;
+using osu.Game.Configuration;
+using osu.Game.Rulesets.Configuration;
+
+namespace osu.Game.Rulesets
+{
+    /// <summary>
+    /// A cache that provides a single <see cref="IRulesetConfigManager"/> per-ruleset
+    /// This is done to support referring to and updating ruleset configs from multiple locations in the absence of inter-config bindings.
+    /// </summary>
+    public class RulesetConfigCache : Component
+    {
+        private readonly Dictionary<int, IRulesetConfigManager> configCache = new Dictionary<int, IRulesetConfigManager>();
+        private readonly SettingsStore settingsStore;
+
+        public RulesetConfigCache(SettingsStore settingsStore)
+        {
+            this.settingsStore = settingsStore;
+        }
+
+        /// <summary>
+        /// Retrieves the <see cref="IRulesetConfigManager"/> for a <see cref="Ruleset"/>.
+        /// </summary>
+        /// <param name="ruleset">The <see cref="Ruleset"/> to retrieve the <see cref="IRulesetConfigManager"/> for.</param>
+        /// <returns>The <see cref="IRulesetConfigManager"/> defined by <paramref name="ruleset"/>, null if <paramref name="ruleset"/> doesn't define one.</returns>
+        /// <exception cref="InvalidOperationException">If <paramref name="ruleset"/> doesn't have a valid <see cref="RulesetInfo.ID"/>.</exception>
+        public IRulesetConfigManager GetConfigFor(Ruleset ruleset)
+        {
+            if (ruleset.RulesetInfo.ID == null)
+                throw new InvalidOperationException("The provided ruleset doesn't have a valid id.");
+
+            if (configCache.TryGetValue(ruleset.RulesetInfo.ID.Value, out var existing))
+                return existing;
+
+            return configCache[ruleset.RulesetInfo.ID.Value] = ruleset.CreateConfig(settingsStore);
+        }
+    }
+}