Speed up interface proxy w/o target type generation significantly

CHANGELOG.md

@@ -5,6 +5,7 @@
 Enhancements:
 - .NET Standard 2.0 and 2.1 support (@lg2de, #485)
 - Non-intercepted methods on a class proxy with target are now forwarded to the target (@stakx, #571)
+- Significant performance improvements with proxy type generation for interface proxies without target. (Up until now, DynamicProxy generated a separate `IInvocation` implementation type for every single proxied method – it is now able to reuse a single predefined type in many cases, thereby reducing the total amount of dynamic type generation.) (@stakx, #573)
 
 Bugfixes:
 - Proxying certain `[Serializable]` classes produces proxy types that fail PEVerify test (@stakx, #367)

ref/Castle.Core-net45.cs

@@ -2787,6 +2787,15 @@ public abstract class InheritanceInvocation : Castle.DynamicProxy.AbstractInvoca
         public override System.Type TargetType { get; }
         protected abstract override void InvokeMethodOnTarget() { }
     }
+    [System.Serializable]
+    public sealed class InterfaceMethodWithoutTargetInvocation : Castle.DynamicProxy.AbstractInvocation
+    {
+        public InterfaceMethodWithoutTargetInvocation(object target, object proxy, Castle.DynamicProxy.IInterceptor[] interceptors, System.Reflection.MethodInfo proxiedMethod, object[] arguments) { }
+        public override object InvocationTarget { get; }
+        public override System.Reflection.MethodInfo MethodInvocationTarget { get; }
+        public override System.Type TargetType { get; }
+        protected override void InvokeMethodOnTarget() { }
+    }
     public static class TypeUtil
     {
         public static System.Type[] GetAllInterfaces(this System.Type type) { }

ref/Castle.Core-netstandard2.0.cs

@@ -2740,6 +2740,14 @@ public abstract class InheritanceInvocation : Castle.DynamicProxy.AbstractInvoca
         public override System.Type TargetType { get; }
         protected abstract override void InvokeMethodOnTarget() { }
     }
+    public sealed class InterfaceMethodWithoutTargetInvocation : Castle.DynamicProxy.AbstractInvocation
+    {
+        public InterfaceMethodWithoutTargetInvocation(object target, object proxy, Castle.DynamicProxy.IInterceptor[] interceptors, System.Reflection.MethodInfo proxiedMethod, object[] arguments) { }
+        public override object InvocationTarget { get; }
+        public override System.Reflection.MethodInfo MethodInvocationTarget { get; }
+        public override System.Type TargetType { get; }
+        protected override void InvokeMethodOnTarget() { }
+    }
     public static class TypeUtil
     {
         public static System.Type[] GetAllInterfaces(this System.Type type) { }

ref/Castle.Core-netstandard2.1.cs

@@ -2740,6 +2740,14 @@ public abstract class InheritanceInvocation : Castle.DynamicProxy.AbstractInvoca
         public override System.Type TargetType { get; }
         protected abstract override void InvokeMethodOnTarget() { }
     }
+    public sealed class InterfaceMethodWithoutTargetInvocation : Castle.DynamicProxy.AbstractInvocation
+    {
+        public InterfaceMethodWithoutTargetInvocation(object target, object proxy, Castle.DynamicProxy.IInterceptor[] interceptors, System.Reflection.MethodInfo proxiedMethod, object[] arguments) { }
+        public override object InvocationTarget { get; }
+        public override System.Reflection.MethodInfo MethodInvocationTarget { get; }
+        public override System.Type TargetType { get; }
+        protected override void InvokeMethodOnTarget() { }
+    }
     public static class TypeUtil
     {
         public static System.Type[] GetAllInterfaces(this System.Type type) { }

src/Castle.Core.Tests/DynamicProxy.Tests/InvocationTypeReuseTestCase.cs

@@ -0,0 +1,75 @@
+// Copyright 2004-2021 Castle Project - http://www.castleproject.org/
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+namespace Castle.DynamicProxy.Tests
+{
+	using System;
+
+	using Castle.DynamicProxy.Internal;
+
+	using NUnit.Framework;
+
+	/// <summary>
+	///   This fixture checks which <see cref="IInvocation"/> types get used for proxied methods.
+	///   Usually, DynamicProxy generates a separate implementation type per proxied method, but
+	///   in some cases, it can reuse predefined implementation types. Because this is beneficial
+	///   for runtime performance (as it reduces the amount of dynamic type generation performed),
+	///   we want to ensure that those predefined types do in fact get picked when they should be.
+	/// </summary>
+	[TestFixture]
+	public class InvocationTypeReuseTestCase : BasePEVerifyTestCase
+	{
+		[Test]
+		public void Non_generic_method_of_interface_proxy_without_target__uses__InterfaceMethodWithoutTargetInvocation()
+		{
+			var recorder = new InvocationTypeRecorder();
+
+			var proxy = generator.CreateInterfaceProxyWithoutTarget<IWithNonGenericMethod>(recorder);
+			proxy.Method();
+
+			Assert.AreEqual(typeof(InterfaceMethodWithoutTargetInvocation), recorder.InvocationType);
+		}
+
+		[Test]
+		public void Generic_method_of_interface_proxy_without_target__uses__InterfaceMethodWithoutTargetInvocation()
+		{
+			var recorder = new InvocationTypeRecorder();
+
+			var proxy = generator.CreateInterfaceProxyWithoutTarget<IWithGenericMethod>(recorder);
+			proxy.Method(42);
+
+			Assert.AreEqual(typeof(InterfaceMethodWithoutTargetInvocation), recorder.InvocationType);
+		}
+
+		public interface IWithNonGenericMethod
+		{
+			void Method();
+		}
+
+		public interface IWithGenericMethod
+		{
+			void Method<T>(T arg);
+		}
+
+		private sealed class InvocationTypeRecorder : IInterceptor
+		{
+			public Type InvocationType { get; private set; }
+
+			public void Intercept(IInvocation invocation)
+			{
+				InvocationType = invocation.GetType();
+			}
+		}
+	}
+}

src/Castle.Core/DynamicProxy/Contributors/InterfaceProxyWithoutTargetContributor.cs

@@ -20,6 +20,7 @@ namespace Castle.DynamicProxy.Contributors
 
 	using Castle.DynamicProxy.Generators;
 	using Castle.DynamicProxy.Generators.Emitters;
+	using Castle.DynamicProxy.Internal;
 
 	internal class InterfaceProxyWithoutTargetContributor : CompositeTypeContributor
 	{
@@ -60,6 +61,15 @@ protected override IEnumerable<MembersCollector> GetCollectors()
 
 		private Type GetInvocationType(MetaMethod method, ClassEmitter emitter)
 		{
+			var methodInfo = method.Method;
+
+			if (canChangeTarget == false && methodInfo.IsAbstract)
+			{
+				// We do not need to generate a custom invocation type because no custom implementation
+				// for `InvokeMethodOnTarget` will be needed (proceeding to target isn't possible here):
+				return typeof(InterfaceMethodWithoutTargetInvocation);
+			}
+
 			var scope = emitter.ModuleScope;
 			Type[] invocationInterfaces;
 			if (canChangeTarget)
@@ -70,14 +80,14 @@ private Type GetInvocationType(MetaMethod method, ClassEmitter emitter)
 			{
 				invocationInterfaces = new[] { typeof(IInvocation) };
 			}
-			var key = new CacheKey(method.Method, CompositionInvocationTypeGenerator.BaseType, invocationInterfaces, null);
+			var key = new CacheKey(methodInfo, CompositionInvocationTypeGenerator.BaseType, invocationInterfaces, null);
 
 			// no locking required as we're already within a lock
 
 			return scope.TypeCache.GetOrAddWithoutTakingLock(key, _ =>
-				new CompositionInvocationTypeGenerator(method.Method.DeclaringType,
+				new CompositionInvocationTypeGenerator(methodInfo.DeclaringType,
 				                                       method,
-				                                       method.Method,
+				                                       methodInfo,
 				                                       canChangeTarget,
 				                                       null)
 				.Generate(emitter, namingScope)

src/Castle.Core/DynamicProxy/Generators/MethodWithInvocationGenerator.cs

@@ -73,21 +73,23 @@ protected override MethodEmitter BuildProxiedMethodBody(MethodEmitter emitter, C
 		{
 			var invocationType = invocation;
 
-			Trace.Assert(MethodToOverride.IsGenericMethod == invocationType.IsGenericTypeDefinition);
 			var genericArguments = Type.EmptyTypes;
 
 			var constructor = invocation.GetConstructors()[0];
 
 			IExpression proxiedMethodTokenExpression;
 			if (MethodToOverride.IsGenericMethod)
 			{
-				// bind generic method arguments to invocation's type arguments
-				genericArguments = emitter.MethodBuilder.GetGenericArguments();
-				invocationType = invocationType.MakeGenericType(genericArguments);
-				constructor = TypeBuilder.GetConstructor(invocationType, constructor);
-
 				// Not in the cache: generic method
+				genericArguments = emitter.MethodBuilder.GetGenericArguments();
 				proxiedMethodTokenExpression = new MethodTokenExpression(MethodToOverride.MakeGenericMethod(genericArguments));
+
+				if (invocationType.IsGenericTypeDefinition)
+				{
+					// bind generic method arguments to invocation's type arguments
+					invocationType = invocationType.MakeGenericType(genericArguments);
+					constructor = TypeBuilder.GetConstructor(invocationType, constructor);
+				}
 			}
 			else
 			{

src/Castle.Core/DynamicProxy/Internal/InterfaceMethodWithoutTargetInvocation.cs

@@ -0,0 +1,61 @@
+// Copyright 2004-2021 Castle Project - http://www.castleproject.org/
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+namespace Castle.DynamicProxy.Internal
+{
+	using System;
+	using System.ComponentModel;
+	using System.Diagnostics;
+	using System.Reflection;
+
+#if FEATURE_SERIALIZATION
+	[Serializable]
+#endif
+	[EditorBrowsable(EditorBrowsableState.Never)]
+	public sealed class InterfaceMethodWithoutTargetInvocation : AbstractInvocation
+	{
+		public InterfaceMethodWithoutTargetInvocation(object target, object proxy, IInterceptor[] interceptors, MethodInfo proxiedMethod, object[] arguments)
+			: base(proxy, interceptors, proxiedMethod, arguments)
+		{
+			// This invocation type is suitable for interface method invocations that cannot proceed
+			// to a target, i.e. where `InvokeMethodOnTarget` will always throw:
+
+			Debug.Assert(target == null, $"{nameof(InterfaceMethodWithoutTargetInvocation)} does not support targets.");
+			Debug.Assert(proxiedMethod.IsAbstract, $"{nameof(InterfaceMethodWithoutTargetInvocation)} does not support non-abstract methods.");
+
+			// Why this restriction? Because it greatly benefits proxy type generation performance.
+			//
+			// For invocations that can proceed to a target, `InvokeMethodOnTarget`'s implementation
+			// depends on the target method's signature. Because of this, DynamicProxy needs to
+			// dynamically generate a separate invocation type per such method. Type generation is
+			// always expensive... that is, slow.
+			//
+			// However, if it is known that `InvokeMethodOnTarget` won't forward, but throw,
+			// no custom (dynamically generated) invocation type is needed at all, and we can use
+			// this unspecific invocation type instead.
+		}
+
+		// The next three properties mimick the behavior seen with an interface proxy without target.
+		// (This is why this type's name starts with `Interface`.) A similar type could be written
+		// for class proxies without target, but the values returned here would be different.
+
+		public override object InvocationTarget => null;
+
+		public override MethodInfo MethodInvocationTarget => null;
+
+		public override Type TargetType => null;
+
+		protected override void InvokeMethodOnTarget() => ThrowOnNoTarget();
+	}
+}