Make RulestStore initialise at construction time

osu.Game.Tests/Visual/Background/TestSceneUserDimContainer.cs

@@ -285,6 +285,12 @@ namespace osu.Game.Tests.Visual.Background
             });
         }
 
+        protected override void Dispose(bool isDisposing)
+        {
+            base.Dispose(isDisposing);
+            rulesets?.Dispose();
+        }
+
         private class DummySongSelect : PlaySongSelect
         {
             protected override BackgroundScreen CreateBackground()

osu.Game.Tests/Visual/SongSelect/TestScenePlaySongSelect.cs

@@ -349,5 +349,11 @@ namespace osu.Game.Tests.Visual.SongSelect
                 DateAdded = DateTimeOffset.UtcNow,
             };
         }
+
+        protected override void Dispose(bool isDisposing)
+        {
+            base.Dispose(isDisposing);
+            rulesets?.Dispose();
+        }
     }
 }

osu.Game/OsuGameBase.cs

@@ -298,6 +298,12 @@ namespace osu.Game
 
         public string[] HandledExtensions => fileImporters.SelectMany(i => i.HandledExtensions).ToArray();
 
+        protected override void Dispose(bool isDisposing)
+        {
+            base.Dispose(isDisposing);
+            RulesetStore?.Dispose();
+        }
+
         private class OsuUserInputManager : UserInputManager
         {
             protected override MouseButtonEventManager CreateButtonManagerFor(MouseButton button)

osu.Game/Rulesets/RulesetStore.cs

@@ -14,25 +14,22 @@ namespace osu.Game.Rulesets
     /// <summary>
     /// Todo: All of this needs to be moved to a RulesetStore.
     /// </summary>
-    public class RulesetStore : DatabaseBackedStore
+    public class RulesetStore : DatabaseBackedStore, IDisposable
     {
-        private static readonly Dictionary<Assembly, Type> loaded_assemblies = new Dictionary<Assembly, Type>();
+        private const string ruleset_library_prefix = "osu.Game.Rulesets";
 
-        static RulesetStore()
+        private readonly Dictionary<Assembly, Type> loadedAssemblies = new Dictionary<Assembly, Type>();
-        {
-            AppDomain.CurrentDomain.AssemblyResolve += currentDomain_AssemblyResolve;
-
-            // On android in release configuration assemblies are loaded from the apk directly into memory.
-            // We cannot read assemblies from cwd, so should check loaded assemblies instead.
-            loadFromAppDomain();
-
-            loadFromDisk();
-        }
 
         public RulesetStore(IDatabaseContextFactory factory)
             : base(factory)
         {
+            // On android in release configuration assemblies are loaded from the apk directly into memory.
+            // We cannot read assemblies from cwd, so should check loaded assemblies instead.
+            loadFromAppDomain();
+            loadFromDisk();
             addMissingRulesets();
+
+            AppDomain.CurrentDomain.AssemblyResolve += resolveRulesetAssembly;
         }
 
         /// <summary>
@@ -54,9 +51,7 @@ namespace osu.Game.Rulesets
         /// </summary>
         public IEnumerable<RulesetInfo> AvailableRulesets { get; private set; }
 
-        private static Assembly currentDomain_AssemblyResolve(object sender, ResolveEventArgs args) => loaded_assemblies.Keys.FirstOrDefault(a => a.FullName == args.Name);
+        private Assembly resolveRulesetAssembly(object sender, ResolveEventArgs args) => loadedAssemblies.Keys.FirstOrDefault(a => a.FullName == args.Name);
-
-        private const string ruleset_library_prefix = "osu.Game.Rulesets";
 
         private void addMissingRulesets()
         {
@@ -64,7 +59,7 @@ namespace osu.Game.Rulesets
             {
                 var context = usage.Context;
 
-                var instances = loaded_assemblies.Values.Select(r => (Ruleset)Activator.CreateInstance(r, (RulesetInfo)null)).ToList();
+                var instances = loadedAssemblies.Values.Select(r => (Ruleset)Activator.CreateInstance(r, (RulesetInfo)null)).ToList();
 
                 //add all legacy modes in correct order
                 foreach (var r in instances.Where(r => r.LegacyID != null).OrderBy(r => r.LegacyID))
@@ -113,7 +108,7 @@ namespace osu.Game.Rulesets
             }
         }
 
-        private static void loadFromAppDomain()
+        private void loadFromAppDomain()
         {
             foreach (var ruleset in AppDomain.CurrentDomain.GetAssemblies())
             {
@@ -126,7 +121,7 @@ namespace osu.Game.Rulesets
             }
         }
 
-        private static void loadFromDisk()
+        private void loadFromDisk()
         {
             try
             {
@@ -141,11 +136,11 @@ namespace osu.Game.Rulesets
             }
         }
 
-        private static void loadRulesetFromFile(string file)
+        private void loadRulesetFromFile(string file)
         {
             var filename = Path.GetFileNameWithoutExtension(file);
 
-            if (loaded_assemblies.Values.Any(t => t.Namespace == filename))
+            if (loadedAssemblies.Values.Any(t => t.Namespace == filename))
                 return;
 
             try
@@ -158,19 +153,35 @@ namespace osu.Game.Rulesets
             }
         }
 
-        private static void addRuleset(Assembly assembly)
+        private void addRuleset(Assembly assembly)
         {
-            if (loaded_assemblies.ContainsKey(assembly))
+            if (loadedAssemblies.ContainsKey(assembly))
                 return;
 
             try
             {
-                loaded_assemblies[assembly] = assembly.GetTypes().First(t => t.IsPublic && t.IsSubclassOf(typeof(Ruleset)));
+                loadedAssemblies[assembly] = assembly.GetTypes().First(t => t.IsPublic && t.IsSubclassOf(typeof(Ruleset)));
             }
             catch (Exception e)
             {
                 Logger.Error(e, $"Failed to add ruleset {assembly}");
             }
         }
+
+        ~RulesetStore()
+        {
+            Dispose(false);
+        }
+
+        public void Dispose()
+        {
+            Dispose(true);
+            GC.SuppressFinalize(this);
+        }
+
+        protected virtual void Dispose(bool disposing)
+        {
+            AppDomain.CurrentDomain.AssemblyResolve -= resolveRulesetAssembly;
+        }
     }
 }