fix Data\Movies error regression when patching dictionary (#711)

src/SMAPI/Framework/TemporaryHacks/MiniMonoModHotfix.cs

@@ -8,12 +8,12 @@
 // Special thanks to 0x0ade for submitting this worokaround! Copy/pasted and adapted from MonoMod.
 
 using System;
+using System.Reflection;
 using System.Collections.Generic;
 using System.Diagnostics.CodeAnalysis;
-using System.Reflection;
-using System.Reflection.Emit;
 using System.Runtime.CompilerServices;
 using HarmonyLib;
+using System.Reflection.Emit;
 
 // ReSharper disable once CheckNamespace -- Temporary hotfix submitted by the MonoMod author.
 namespace MonoMod.Utils
@@ -24,38 +24,38 @@ namespace MonoMod.Utils
     {
         // .NET Framework can break member ordering if using Module.Resolve* on certain members.
 
-        private static readonly object[] _NoArgs = new object[0];
-        private static readonly object[] _CacheGetterArgs = { /* MemberListType.All */ 0, /* name apparently always null? */ null };
+        private static object[] _NoArgs = new object[0];
+        private static object[] _CacheGetterArgs = { /* MemberListType.All */ 0, /* name apparently always null? */ null };
 
-        private static readonly Type t_RuntimeModule =
+        private static Type t_RuntimeModule =
             typeof(Module).Assembly
             .GetType("System.Reflection.RuntimeModule");
 
-        private static readonly PropertyInfo p_RuntimeModule_RuntimeType =
+        private static PropertyInfo p_RuntimeModule_RuntimeType =
             typeof(Module).Assembly
             .GetType("System.Reflection.RuntimeModule")
             ?.GetProperty("RuntimeType", BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance);
 
-        private static readonly Type t_RuntimeType =
+        private static Type t_RuntimeType =
             typeof(Type).Assembly
             .GetType("System.RuntimeType");
 
-        private static readonly PropertyInfo p_RuntimeType_Cache =
+        private static PropertyInfo p_RuntimeType_Cache =
             typeof(Type).Assembly
             .GetType("System.RuntimeType")
             ?.GetProperty("Cache", BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance);
 
-        private static readonly MethodInfo m_RuntimeTypeCache_GetFieldList =
+        private static MethodInfo m_RuntimeTypeCache_GetFieldList =
             typeof(Type).Assembly
             .GetType("System.RuntimeType+RuntimeTypeCache")
             ?.GetMethod("GetFieldList", BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance);
 
-        private static readonly MethodInfo m_RuntimeTypeCache_GetPropertyList =
+        private static MethodInfo m_RuntimeTypeCache_GetPropertyList =
             typeof(Type).Assembly
             .GetType("System.RuntimeType+RuntimeTypeCache")
             ?.GetMethod("GetPropertyList", BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance);
 
-        private static readonly ConditionalWeakTable<Type, object> _CacheFixed = new ConditionalWeakTable<Type, object>();
+        private static readonly ConditionalWeakTable<Type, CacheFixEntry> _CacheFixed = new ConditionalWeakTable<Type, CacheFixEntry>();
 
         public static void Apply()
         {
@@ -143,24 +143,80 @@ namespace MonoMod.Utils
                 if (!t_RuntimeType.IsInstanceOfType(type))
                     continue;
 
-                _CacheFixed.GetValue(type, rt =>
-                {
+                CacheFixEntry entry = _CacheFixed.GetValue(type, rt => {
+                    CacheFixEntry entryNew = new CacheFixEntry();
+                    object cache;
+                    Array properties, fields;
 
-                    object cache = p_RuntimeType_Cache.GetValue(rt, _NoArgs);
-                    _FixReflectionCacheOrder<PropertyInfo>(cache, m_RuntimeTypeCache_GetPropertyList);
-                    _FixReflectionCacheOrder<FieldInfo>(cache, m_RuntimeTypeCache_GetFieldList);
+                    // All RuntimeTypes MUST have a cache, the getter is non-virtual, it creates on demand and asserts non-null.
+                    entryNew.Cache = cache = p_RuntimeType_Cache.GetValue(rt, _NoArgs);
+                    entryNew.Properties = properties = _GetArray(cache, m_RuntimeTypeCache_GetPropertyList);
+                    entryNew.Fields = fields = _GetArray(cache, m_RuntimeTypeCache_GetFieldList);
 
-                    return new object();
+                    _FixReflectionCacheOrder<PropertyInfo>(properties);
+                    _FixReflectionCacheOrder<FieldInfo>(fields);
+
+                    entryNew.NeedsVerify = false;
+                    return entryNew;
                 });
+
+                if (entry.NeedsVerify && !_Verify(entry, type))
+                {
+                    lock (entry)
+                    {
+                        _FixReflectionCacheOrder<PropertyInfo>(entry.Properties);
+                        _FixReflectionCacheOrder<FieldInfo>(entry.Fields);
+                    }
+                }
+
+                entry.NeedsVerify = true;
             }
         }
 
-        private static void _FixReflectionCacheOrder<T>(object cache, MethodInfo getter) where T : MemberInfo
+        private static bool _Verify(CacheFixEntry entry, Type type)
+        {
+            object cache;
+            Array properties, fields;
+
+            // The cache can sometimes be invalidated.
+            // TODO: Figure out if only the arrays get replaced or if the entire cache object gets replaced!
+            if (entry.Cache != (cache = p_RuntimeType_Cache.GetValue(type, _NoArgs)))
+            {
+                entry.Cache = cache;
+                entry.Properties = _GetArray(cache, m_RuntimeTypeCache_GetPropertyList);
+                entry.Fields = _GetArray(cache, m_RuntimeTypeCache_GetFieldList);
+                return false;
+
+            }
+            else if (entry.Properties != (properties = _GetArray(cache, m_RuntimeTypeCache_GetPropertyList)))
+            {
+                entry.Properties = properties;
+                entry.Fields = _GetArray(cache, m_RuntimeTypeCache_GetFieldList);
+                return false;
+
+            }
+            else if (entry.Fields != (fields = _GetArray(cache, m_RuntimeTypeCache_GetFieldList)))
+            {
+                entry.Fields = fields;
+                return false;
+
+            }
+            else
+            {
+                // Cache should still be the same, no re-fix necessary.
+                return true;
+            }
+        }
+
+        private static Array _GetArray(object cache, MethodInfo getter)
         {
             // Get and discard once, otherwise we might not be getting the actual backing array.
             getter.Invoke(cache, _CacheGetterArgs);
-            Array orig = (Array)getter.Invoke(cache, _CacheGetterArgs);
+            return (Array)getter.Invoke(cache, _CacheGetterArgs);
+        }
 
+        private static void _FixReflectionCacheOrder<T>(Array orig) where T : MemberInfo
+        {
             // Sort using a short-lived list.
             List<T> list = new List<T>(orig.Length);
             for (int i = 0; i < orig.Length; i++)
@@ -172,5 +228,12 @@ namespace MonoMod.Utils
                 orig.SetValue(list[i], i);
         }
 
+        private class CacheFixEntry
+        {
+            public object Cache;
+            public Array Properties;
+            public Array Fields;
+            public bool NeedsVerify;
+        }
     }
 }