add proxy instance caching

3 files changed, 17 insertions, 9 deletions

diff --git a/src/SMAPI/Framework/Reflection/InterfaceProxyBuilder.cs b/src/SMAPI/Framework/Reflection/InterfaceProxyBuilder.cs
index 49cc6bca..63a594fa 100644
--- a/src/SMAPI/Framework/Reflection/InterfaceProxyBuilder.cs
+++ b/src/SMAPI/Framework/Reflection/InterfaceProxyBuilder.cs
@@ -3,6 +3,7 @@ using System.Collections.Generic;
 using System.Linq;
 using System.Reflection;
 using System.Reflection.Emit;
+using System.Runtime.CompilerServices;
 
 namespace StardewModdingAPI.Framework.Reflection
 {
@@ -14,7 +15,7 @@ namespace StardewModdingAPI.Framework.Reflection
         *********/
         private static readonly string TargetFieldName = "__Target";
         private static readonly string GlueFieldName = "__Glue";
-        private static readonly MethodInfo CreateInstanceForProxyTypeNameMethod = typeof(InterfaceProxyGlue).GetMethod(nameof(InterfaceProxyGlue.CreateInstanceForProxyTypeName), new Type[] { typeof(string), typeof(object) });
+        private static readonly MethodInfo ObtainInstanceForProxyTypeNameMethod = typeof(InterfaceProxyGlue).GetMethod(nameof(InterfaceProxyGlue.ObtainInstanceForProxyTypeName), new Type[] { typeof(string), typeof(object) });
 
         /*********
         ** Fields
@@ -28,6 +29,8 @@ namespace StardewModdingAPI.Framework.Reflection
         /// <summary>The generated proxy type.</summary>
         private Type ProxyType;
 
+        /// <summary>A cache of all proxies generated by this builder.</summary>
+        private readonly ConditionalWeakTable<object, object> ProxyCache = new();
 
         /*********
         ** Public methods
@@ -168,15 +171,20 @@ namespace StardewModdingAPI.Framework.Reflection
             this.ProxyType = proxyBuilder.CreateType();
         }
 
-        /// <summary>Create an instance of the proxy for a target instance.</summary>
+        /// <summary>Get an existing or create a new instance of the proxy for a target instance.</summary>
         /// <param name="targetInstance">The target instance.</param>
         /// <param name="factory">The <see cref="InterfaceProxyFactory"/> that requested to build a proxy.</param>
-        public object CreateInstance(object targetInstance, InterfaceProxyFactory factory)
+        public object ObtainInstance(object targetInstance, InterfaceProxyFactory factory)
         {
+            if (this.ProxyCache.TryGetValue(targetInstance, out object proxyInstance))
+                return proxyInstance;
+
             ConstructorInfo constructor = this.ProxyType.GetConstructor(new[] { this.TargetType, typeof(InterfaceProxyGlue) });
             if (constructor == null)
                 throw new InvalidOperationException($"Couldn't find the constructor for generated proxy type '{this.ProxyType.Name}'."); // should never happen
-            return constructor.Invoke(new[] { targetInstance, new InterfaceProxyGlue(factory) });
+            proxyInstance = constructor.Invoke(new[] { targetInstance, new InterfaceProxyGlue(factory) });
+            this.ProxyCache.Add(targetInstance, proxyInstance);
+            return proxyInstance;
         }
 
 
@@ -297,7 +305,7 @@ namespace StardewModdingAPI.Framework.Reflection
                     il.Emit(OpCodes.Ldfld, glueField);
                     il.Emit(OpCodes.Ldstr, proxyTypeName);
                     il.Emit(OpCodes.Ldloc, inputLocal);
-                    il.Emit(OpCodes.Call, CreateInstanceForProxyTypeNameMethod);
+                    il.Emit(OpCodes.Call, ObtainInstanceForProxyTypeNameMethod);
                     il.Emit(OpCodes.Castclass, outputLocal.LocalType);
                     il.Emit(OpCodes.Stloc, outputLocal);
 
diff --git a/src/SMAPI/Framework/Reflection/InterfaceProxyFactory.cs b/src/SMAPI/Framework/Reflection/InterfaceProxyFactory.cs
index 72b4254c..daeac2ad 100644
--- a/src/SMAPI/Framework/Reflection/InterfaceProxyFactory.cs
+++ b/src/SMAPI/Framework/Reflection/InterfaceProxyFactory.cs
@@ -42,7 +42,7 @@ namespace StardewModdingAPI.Framework.Reflection
 
             // create instance
             InterfaceProxyBuilder builder = this.ObtainBuilder(instance.GetType(), typeof(TInterface), sourceModID, targetModID);
-            return (TInterface)builder.CreateInstance(instance, this);
+            return (TInterface)builder.ObtainInstance(instance, this);
         }
 
         internal InterfaceProxyBuilder ObtainBuilder(Type targetType, Type interfaceType, string sourceModID, string targetModID)
diff --git a/src/SMAPI/Framework/Reflection/InterfaceProxyGlue.cs b/src/SMAPI/Framework/Reflection/InterfaceProxyGlue.cs
index 8d0d74a7..f98b54a2 100644
--- a/src/SMAPI/Framework/Reflection/InterfaceProxyGlue.cs
+++ b/src/SMAPI/Framework/Reflection/InterfaceProxyGlue.cs
@@ -10,13 +10,13 @@ namespace StardewModdingAPI.Framework.Reflection
             this.Factory = factory;
         }
 
-        /// <summary>Creates a new proxied instance by its type name.</summary>
+        /// <summary>Get an existing or create a new proxied instance by its type name.</summary>
         /// <param name="proxyTypeName">The full name of the proxy type.</param>
         /// <param name="toProxy">The target instance to proxy.</param>
-        public object CreateInstanceForProxyTypeName(string proxyTypeName, object toProxy)
+        public object ObtainInstanceForProxyTypeName(string proxyTypeName, object toProxy)
         {
             var builder = this.Factory.GetBuilderByProxyTypeName(proxyTypeName);
-            return builder.CreateInstance(toProxy, this.Factory);
+            return builder.ObtainInstance(toProxy, this.Factory);
         }
     }
 }