Improve perf of ActivatorUtilities.CreateInstance()

src/libraries/Microsoft.Extensions.DependencyInjection.Abstractions/src/ActivatorUtilities.cs

@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using System;
+using System.Collections.Concurrent;
 using System.Diagnostics;
 using System.Diagnostics.CodeAnalysis;
 using System.Linq.Expressions;
@@ -10,13 +11,25 @@
 using System.Runtime.ExceptionServices;
 using Microsoft.Extensions.Internal;
 
+#if NETCOREAPP
+[assembly: System.Reflection.Metadata.MetadataUpdateHandler(typeof(Microsoft.Extensions.DependencyInjection.ActivatorUtilities.ActivatorUtilitiesUpdateHandler))]
+#endif
+
 namespace Microsoft.Extensions.DependencyInjection
 {
  /// <summary>
  /// Helper code for the various activator services.
  /// </summary>
  public static class ActivatorUtilities
  {
+#if NETCOREAPP
+ // Support caching of constructor metadata for the common case of types in non-collectible assemblies.
+ private static readonly ConcurrentDictionary<Type, ConstructorInfoEx[]> s_constructorInfos = new();
+
+ // Support caching of constructor metadata for types in collectible assemblies.
+ private static readonly Lazy<ConditionalWeakTable<Type, ConstructorInfoEx[]>> s_collectibleConstructorInfos = new();
+#endif
+
 #if NET8_0_OR_GREATER
  // Maximum number of fixed arguments for ConstructorInvoker.Invoke(arg1, etc).
  private const int FixedArgumentThreshold = 4;
@@ -47,6 +60,17 @@ public static object CreateInstance(
  throw new InvalidOperationException(SR.CannotCreateAbstractClasses);
  }
 
+ ConstructorInfoEx[]? constructors;
+#if NETCOREAPP
+ if (!s_constructorInfos.TryGetValue(instanceType, out constructors))
+ {
+ constructors = GetOrAddConstructors(instanceType);
+ }
+#else
+ constructors = CreateConstructorInfoExs(instanceType);
+#endif
+
+ ConstructorInfoEx? constructor;
  IServiceProviderIsService? serviceProviderIsService = provider.GetService<IServiceProviderIsService>();
  // if container supports using IServiceProviderIsService, we try to find the longest ctor that
  // (a) matches all parameters given to CreateInstance
@@ -61,10 +85,11 @@ public static object CreateInstance(
  ConstructorMatcher bestMatcher = default;
  bool multipleBestLengthFound = false;
 
-foreach (ConstructorInfo? constructor in instanceType.GetConstructors())
+for (int i = 0; i < constructors.Length; i++)
  {
- var matcher = new ConstructorMatcher(constructor);
- bool isPreferred = constructor.IsDefined(typeof(ActivatorUtilitiesConstructorAttribute), false);
+ constructor = constructors[i];
+ ConstructorMatcher matcher = new(constructor);
+ bool isPreferred = constructor.IsPreferred;
  int length = matcher.Match(parameters, serviceProviderIsService);
 
  if (isPreferred)
@@ -105,18 +130,79 @@ public static object CreateInstance(
  }
  }
 
- Type?[] argumentTypes = new Type[parameters.Length];
-for (int i = 0; i < argumentTypes.Length; i++)
+ Type?[] argumentTypes;
+if (parameters.Length == 0)
  {
- argumentTypes[i] = parameters[i]?.GetType();
+ argumentTypes = Type.EmptyTypes;
+ }
+ else
+ {
+ argumentTypes = new Type[parameters.Length];
+ for (int i = 0; i < argumentTypes.Length; i++)
+ {
+ argumentTypes[i] = parameters[i]?.GetType();
+ }
  }
 
  FindApplicableConstructor(instanceType, argumentTypes, out ConstructorInfo constructorInfo, out int?[] parameterMap);
- var constructorMatcher = new ConstructorMatcher(constructorInfo);
+
+ // Find the ConstructorInfoEx from the given constructorInfo.
+ constructor = null;
+ foreach (ConstructorInfoEx ctor in constructors)
+ {
+ if (ReferenceEquals(ctor.Info, constructorInfo))
+ {
+ constructor = ctor;
+ break;
+ }
+ }
+
+ Debug.Assert(constructor != null);
+
+ var constructorMatcher = new ConstructorMatcher(constructor);
  constructorMatcher.MapParameters(parameterMap, parameters);
  return constructorMatcher.CreateInstance(provider);
  }
 
+#if NETCOREAPP
+ private static ConstructorInfoEx[] GetOrAddConstructors(
+ [DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.PublicConstructors)] Type type)
+ {
+ // Not found. Do the slower work of checking for the value in the correct cache.
+ // Null and non-collectible load contexts use the default cache.
+ if (!type.Assembly.IsCollectible)
+ {
+ return s_constructorInfos.GetOrAdd(type, CreateConstructorInfoExs(type));
+ }
+
+ // Collectible load contexts should use the ConditionalWeakTable so they can be unloaded.
+ if (s_collectibleConstructorInfos.Value.TryGetValue(type, out ConstructorInfoEx[]? value))
+ {
+ return value;
+ }
+
+ value = CreateConstructorInfoExs(type);
+
+ // ConditionalWeakTable doesn't support GetOrAdd() so use AddOrUpdate(). This means threads
+ // can have different instances for the same type, but that is OK since they are equivalent.
+ s_collectibleConstructorInfos.Value.AddOrUpdate(type, value);
+ return value;
+ }
+#endif // NETCOREAPP
+
+ private static ConstructorInfoEx[] CreateConstructorInfoExs(
+ [DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.PublicConstructors)] Type type)
+ {
+ ConstructorInfo[] constructors = type.GetConstructors();
+ ConstructorInfoEx[]? value = new ConstructorInfoEx[constructors.Length];
+ for (int i = 0; i < constructors.Length; i++)
+ {
+ value[i] = new ConstructorInfoEx(constructors[i]);
+ }
+
+ return value;
+ }
+
  /// <summary>
  /// Create a delegate that will instantiate a type with constructor arguments provided directly
  /// and/or from an <see cref="IServiceProvider"/>.
@@ -551,58 +637,82 @@ private static bool TryCreateParameterMap(ParameterInfo[] constructorParameters,
  return true;
  }
 
- private static object? GetService(IServiceProvider serviceProvider, ParameterInfo parameterInfo)
+ private sealed class ConstructorInfoEx
  {
- // Handle keyed service
- if (TryGetServiceKey(parameterInfo, out object? key))
+ public readonly ConstructorInfo Info;
+ public readonly ParameterInfo[] Parameters;
+ public readonly bool IsPreferred;
+ private readonly object?[]? _parameterKeys;
+
+ public ConstructorInfoEx(ConstructorInfo constructor)
  {
- if (serviceProvider is IKeyedServiceProvider keyedServiceProvider)
+ Info = constructor;
+ Parameters = constructor.GetParameters();
+ IsPreferred = constructor.IsDefined(typeof(ActivatorUtilitiesConstructorAttribute), inherit: false);
+
+ for (int i = 0; i < Parameters.Length; i++)
  {
- return keyedServiceProvider.GetKeyedService(parameterInfo.ParameterType, key);
+ FromKeyedServicesAttribute? attr = (FromKeyedServicesAttribute?)
+ Attribute.GetCustomAttribute(Parameters[i], typeof(FromKeyedServicesAttribute), inherit: false);
+
+ if (attr is not null)
+ {
+ _parameterKeys ??= new object?[Parameters.Length];
+ _parameterKeys[i] = attr.Key;
+ }
  }
- throw new InvalidOperationException(SR.KeyedServicesNotSupported);
  }
- // Try non keyed service
- return serviceProvider.GetService(parameterInfo.ParameterType);
- }
 
- private static bool IsService(IServiceProviderIsService serviceProviderIsService, ParameterInfo parameterInfo)
- {
- // Handle keyed service
- if (TryGetServiceKey(parameterInfo, out object? key))
+ public bool IsService(IServiceProviderIsService serviceProviderIsService, int parameterIndex)
  {
- if (serviceProviderIsService is IServiceProviderIsKeyedService serviceProviderIsKeyedService)
+ ParameterInfo parameterInfo = Parameters[parameterIndex];
+
+ // Handle keyed service
+ object? key = _parameterKeys?[parameterIndex];
+ if (key is not null)
  {
- return serviceProviderIsKeyedService.IsKeyedService(parameterInfo.ParameterType, key);
+ if (serviceProviderIsService is IServiceProviderIsKeyedService serviceProviderIsKeyedService)
+ {
+ return serviceProviderIsKeyedService.IsKeyedService(parameterInfo.ParameterType, key);
+ }
+
+ throw new InvalidOperationException(SR.KeyedServicesNotSupported);
  }
- throw new InvalidOperationException(SR.KeyedServicesNotSupported);
+
+ // Use non-keyed service
+ return serviceProviderIsService.IsService(parameterInfo.ParameterType);
  }
- // Try non keyed service
- return serviceProviderIsService.IsService(parameterInfo.ParameterType);
- }
 
- private static bool TryGetServiceKey(ParameterInfo parameterInfo, out object? key)
- {
- foreach (var attribute in parameterInfo.GetCustomAttributes<FromKeyedServicesAttribute>(false))
+ public object? GetService(IServiceProvider serviceProvider, int parameterIndex)
  {
- key = attribute.Key;
- return true;
+ ParameterInfo parameterInfo = Parameters[parameterIndex];
+
+ // Handle keyed service
+ object? key = _parameterKeys?[parameterIndex];
+ if (key is not null)
+ {
+ if (serviceProvider is IKeyedServiceProvider keyedServiceProvider)
+ {
+ return keyedServiceProvider.GetKeyedService(parameterInfo.ParameterType, key);
+ }
+
+ throw new InvalidOperationException(SR.KeyedServicesNotSupported);
+ }
+
+ // Use non-keyed service
+ return serviceProvider.GetService(parameterInfo.ParameterType);
  }
- key = null;
- return false;
  }
 
  private readonly struct ConstructorMatcher
  {
- private readonly ConstructorInfo _constructor;
- private readonly ParameterInfo[] _parameters;
+ private readonly ConstructorInfoEx _constructor;
  private readonly object?[] _parameterValues;
 
- public ConstructorMatcher(ConstructorInfo constructor)
+ public ConstructorMatcher(ConstructorInfoEx constructor)
  {
  _constructor = constructor;
- _parameters = _constructor.GetParameters();
- _parameterValues = new object?[_parameters.Length];
+ _parameterValues = new object[constructor.Parameters.Length];
  }
 
  public int Match(object[] givenParameters, IServiceProviderIsService serviceProviderIsService)
@@ -612,10 +722,10 @@ public int Match(object[] givenParameters, IServiceProviderIsService serviceProv
  Type? givenType = givenParameters[givenIndex]?.GetType();
  bool givenMatched = false;
 
- for (int applyIndex = 0; applyIndex < _parameters.Length; applyIndex++)
+ for (int applyIndex = 0; applyIndex < _constructor.Parameters.Length; applyIndex++)
  {
  if (_parameterValues[applyIndex] == null &&
-_parameters[applyIndex].ParameterType.IsAssignableFrom(givenType))
+_constructor.Parameters[applyIndex].ParameterType.IsAssignableFrom(givenType))
  {
  givenMatched = true;
  _parameterValues[applyIndex] = givenParameters[givenIndex];
@@ -630,12 +740,12 @@ public int Match(object[] givenParameters, IServiceProviderIsService serviceProv
  }
 
  // confirms the rest of ctor arguments match either as a parameter with a default value or as a service registered
- for (int i = 0; i < _parameters.Length; i++)
+ for (int i = 0; i < _constructor.Parameters.Length; i++)
  {
  if (_parameterValues[i] == null &&
- !IsService(serviceProviderIsService, _parameters[i]))
+ !_constructor.IsService(serviceProviderIsService, i))
  {
- if (ParameterDefaultValue.TryGetDefaultValue(_parameters[i], out object? defaultValue))
+ if (ParameterDefaultValue.TryGetDefaultValue(_constructor.Parameters[i], out object? defaultValue))
  {
  _parameterValues[i] = defaultValue;
  }
@@ -646,21 +756,21 @@ public int Match(object[] givenParameters, IServiceProviderIsService serviceProv
  }
  }
 
- return _parameters.Length;
+ return _constructor.Parameters.Length;
  }
 
  public object CreateInstance(IServiceProvider provider)
  {
- for (int index = 0; index < _parameters.Length; index++)
+ for (int index = 0; index < _constructor.Parameters.Length; index++)
  {
  if (_parameterValues[index] == null)
  {
- object? value = GetService(provider, _parameters[index]);
+ object? value = _constructor.GetService(provider, index);
  if (value == null)
  {
- if (!ParameterDefaultValue.TryGetDefaultValue(_parameters[index], out object? defaultValue))
+ if (!ParameterDefaultValue.TryGetDefaultValue(_constructor.Parameters[index], out object? defaultValue))
  {
- throw new InvalidOperationException(SR.Format(SR.UnableToResolveService, _parameters[index].ParameterType, _constructor.DeclaringType));
+ throw new InvalidOperationException(SR.Format(SR.UnableToResolveService, _constructor.Parameters[index].ParameterType, _constructor.Info.DeclaringType));
  }
  else
  {
@@ -677,7 +787,7 @@ public object CreateInstance(IServiceProvider provider)
 #if NETFRAMEWORK || NETSTANDARD2_0
  try
  {
- return _constructor.Invoke(_parameterValues);
+ return _constructor.Info.Invoke(_parameterValues);
  }
  catch (TargetInvocationException ex) when (ex.InnerException != null)
  {
@@ -686,13 +796,13 @@ public object CreateInstance(IServiceProvider provider)
  throw;
  }
 #else
- return _constructor.Invoke(BindingFlags.DoNotWrapExceptions, binder: null, parameters: _parameterValues, culture: null);
+ return _constructor.Info.Invoke(BindingFlags.DoNotWrapExceptions, binder: null, parameters: _parameterValues, culture: null);
 #endif
  }
 
  public void MapParameters(int?[] parameterMap, object[] givenParameters)
  {
- for (int i = 0; i < _parameters.Length; i++)
+ for (int i = 0; i < _constructor.Parameters.Length; i++)
  {
  if (parameterMap[i] != null)
  {
@@ -974,5 +1084,20 @@ private static object ReflectionFactoryCanonical(
  return constructor.Invoke(BindingFlags.DoNotWrapExceptions, binder: null, constructorArguments, culture: null);
  }
 #endif // NET8_0_OR_GREATER
+
+#if NETCOREAPP
+ internal static class ActivatorUtilitiesUpdateHandler
+ {
+ public static void ClearCache(Type[]? _)
+ {
+ // Ignore the Type[] argument; just clear the caches.
+ s_constructorInfos.Clear();
+ if (s_collectibleConstructorInfos.IsValueCreated)
+ {
+ s_collectibleConstructorInfos.Value.Clear();
+ }
+ }
+ }
+#endif
  }
 }

src/libraries/Microsoft.Extensions.DependencyInjection/tests/CollectibleAssembly/CollectableClasses.cs

@@ -0,0 +1,25 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using Microsoft.Extensions.DependencyInjection;
+
+namespace CollectibleAssembly
+{
+ public class ClassToCreate
+ {
+ public object ClassAsCtorArgument { get; set; }
+
+ public ClassToCreate(ClassAsCtorArgument obj) { ClassAsCtorArgument = obj; }
+
+ public static object Create(ServiceProvider provider)
+ {
+ // Both the type to create (ClassToCreate) and the ctor's arg type (ClassAsCtorArgument) are
+ // located in this assembly, so both types need to be GC'd for this assembly to be collected.
+ return ActivatorUtilities.CreateInstance<ClassToCreate>(provider, new ClassAsCtorArgument());
+ }
+ }
+
+ public class ClassAsCtorArgument
+ {
+ }
+}

src/libraries/Microsoft.Extensions.DependencyInjection.Abstractions/src/ActivatorUtilities.cs

@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using System;
+using System.Collections.Concurrent;
 using System.Diagnostics;
 using System.Diagnostics.CodeAnalysis;
 using System.Linq.Expressions;
@@ -10,13 +11,25 @@
 using System.Runtime.ExceptionServices;
 using Microsoft.Extensions.Internal;
 
+#if NETCOREAPP
+[assembly: System.Reflection.Metadata.MetadataUpdateHandler(typeof(Microsoft.Extensions.DependencyInjection.ActivatorUtilities.ActivatorUtilitiesUpdateHandler))]
+#endif
+
 namespace Microsoft.Extensions.DependencyInjection
 {
  /// <summary>
  /// Helper code for the various activator services.
  /// </summary>
  public static class ActivatorUtilities
  {
+#if NETCOREAPP
+ // Support caching of constructor metadata for the common case of types in non-collectible assemblies.
+ private static readonly ConcurrentDictionary<Type, ConstructorInfoEx[]> s_constructorInfos = new();
+
+ // Support caching of constructor metadata for types in collectible assemblies.
+ private static readonly Lazy<ConditionalWeakTable<Type, ConstructorInfoEx[]>> s_collectibleConstructorInfos = new();
+#endif
+
 #if NET8_0_OR_GREATER
  // Maximum number of fixed arguments for ConstructorInvoker.Invoke(arg1, etc).
  private const int FixedArgumentThreshold = 4;
@@ -47,6 +60,17 @@ public static object CreateInstance(
  throw new InvalidOperationException(SR.CannotCreateAbstractClasses);
  }
 
+ ConstructorInfoEx[]? constructors;
+#if NETCOREAPP
+ if (!s_constructorInfos.TryGetValue(instanceType, out constructors))
+ {
+ constructors = GetOrAddConstructors(instanceType);
+ }
+#else
+ constructors = CreateConstructorInfoExs(instanceType);
+#endif
+
+ ConstructorInfoEx? constructor;
  IServiceProviderIsService? serviceProviderIsService = provider.GetService<IServiceProviderIsService>();
  // if container supports using IServiceProviderIsService, we try to find the longest ctor that
  // (a) matches all parameters given to CreateInstance
@@ -61,10 +85,11 @@ public static object CreateInstance(
  ConstructorMatcher bestMatcher = default;
  bool multipleBestLengthFound = false;
 
-foreach (ConstructorInfo? constructor in instanceType.GetConstructors())
+for (int i = 0; i < constructors.Length; i++)
  {
- var matcher = new ConstructorMatcher(constructor);
- bool isPreferred = constructor.IsDefined(typeof(ActivatorUtilitiesConstructorAttribute), false);
+ constructor = constructors[i];
+ ConstructorMatcher matcher = new(constructor);
+ bool isPreferred = constructor.IsPreferred;
  int length = matcher.Match(parameters, serviceProviderIsService);
 
  if (isPreferred)
@@ -105,18 +130,79 @@ public static object CreateInstance(
  }
  }
 
- Type?[] argumentTypes = new Type[parameters.Length];
-for (int i = 0; i < argumentTypes.Length; i++)
+ Type?[] argumentTypes;
+if (parameters.Length == 0)
  {
- argumentTypes[i] = parameters[i]?.GetType();
+ argumentTypes = Type.EmptyTypes;
+ }
+ else
+ {
+ argumentTypes = new Type[parameters.Length];
+ for (int i = 0; i < argumentTypes.Length; i++)
+ {
+ argumentTypes[i] = parameters[i]?.GetType();
+ }
  }
 
  FindApplicableConstructor(instanceType, argumentTypes, out ConstructorInfo constructorInfo, out int?[] parameterMap);
- var constructorMatcher = new ConstructorMatcher(constructorInfo);
+
+ // Find the ConstructorInfoEx from the given constructorInfo.
+ constructor = null;
+ foreach (ConstructorInfoEx ctor in constructors)
+ {
+ if (ReferenceEquals(ctor.Info, constructorInfo))
+ {
+ constructor = ctor;
+ break;
+ }
+ }
+
+ Debug.Assert(constructor != null);
+
+ var constructorMatcher = new ConstructorMatcher(constructor);
  constructorMatcher.MapParameters(parameterMap, parameters);
  return constructorMatcher.CreateInstance(provider);
  }
 
+#if NETCOREAPP
+ private static ConstructorInfoEx[] GetOrAddConstructors(
+ [DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.PublicConstructors)] Type type)
+ {
+ // Not found. Do the slower work of checking for the value in the correct cache.
+ // Null and non-collectible load contexts use the default cache.
+ if (!type.Assembly.IsCollectible)
+ {
+ return s_constructorInfos.GetOrAdd(type, CreateConstructorInfoExs(type));
+ }
+
+ // Collectible load contexts should use the ConditionalWeakTable so they can be unloaded.
+ if (s_collectibleConstructorInfos.Value.TryGetValue(type, out ConstructorInfoEx[]? value))
+ {
+ return value;
+ }
+
+ value = CreateConstructorInfoExs(type);
+
+ // ConditionalWeakTable doesn't support GetOrAdd() so use AddOrUpdate(). This means threads
+ // can have different instances for the same type, but that is OK since they are equivalent.
+ s_collectibleConstructorInfos.Value.AddOrUpdate(type, value);
+ return value;
+ }
+#endif // NETCOREAPP
+
+ private static ConstructorInfoEx[] CreateConstructorInfoExs(
+ [DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.PublicConstructors)] Type type)
+ {
+ ConstructorInfo[] constructors = type.GetConstructors();
+ ConstructorInfoEx[]? value = new ConstructorInfoEx[constructors.Length];
+ for (int i = 0; i < constructors.Length; i++)
+ {
+ value[i] = new ConstructorInfoEx(constructors[i]);
+ }
+
+ return value;
+ }
+
  /// <summary>
  /// Create a delegate that will instantiate a type with constructor arguments provided directly
  /// and/or from an <see cref="IServiceProvider"/>.
@@ -551,58 +637,82 @@ private static bool TryCreateParameterMap(ParameterInfo[] constructorParameters,
  return true;
  }
 
- private static object? GetService(IServiceProvider serviceProvider, ParameterInfo parameterInfo)
+ private sealed class ConstructorInfoEx
  {
- // Handle keyed service
- if (TryGetServiceKey(parameterInfo, out object? key))
+ public readonly ConstructorInfo Info;
+ public readonly ParameterInfo[] Parameters;
+ public readonly bool IsPreferred;
+ private readonly object?[]? _parameterKeys;
+
+ public ConstructorInfoEx(ConstructorInfo constructor)
  {
- if (serviceProvider is IKeyedServiceProvider keyedServiceProvider)
+ Info = constructor;
+ Parameters = constructor.GetParameters();
+ IsPreferred = constructor.IsDefined(typeof(ActivatorUtilitiesConstructorAttribute), inherit: false);
+
+ for (int i = 0; i < Parameters.Length; i++)
  {
- return keyedServiceProvider.GetKeyedService(parameterInfo.ParameterType, key);
+ FromKeyedServicesAttribute? attr = (FromKeyedServicesAttribute?)
+ Attribute.GetCustomAttribute(Parameters[i], typeof(FromKeyedServicesAttribute), inherit: false);
+
+ if (attr is not null)
+ {
+ _parameterKeys ??= new object?[Parameters.Length];
+ _parameterKeys[i] = attr.Key;
+ }
  }
- throw new InvalidOperationException(SR.KeyedServicesNotSupported);
  }
- // Try non keyed service
- return serviceProvider.GetService(parameterInfo.ParameterType);
- }
 
- private static bool IsService(IServiceProviderIsService serviceProviderIsService, ParameterInfo parameterInfo)
- {
- // Handle keyed service
- if (TryGetServiceKey(parameterInfo, out object? key))
+ public bool IsService(IServiceProviderIsService serviceProviderIsService, int parameterIndex)
  {
- if (serviceProviderIsService is IServiceProviderIsKeyedService serviceProviderIsKeyedService)
+ ParameterInfo parameterInfo = Parameters[parameterIndex];
+
+ // Handle keyed service
+ object? key = _parameterKeys?[parameterIndex];
+ if (key is not null)
  {
- return serviceProviderIsKeyedService.IsKeyedService(parameterInfo.ParameterType, key);
+ if (serviceProviderIsService is IServiceProviderIsKeyedService serviceProviderIsKeyedService)
+ {
+ return serviceProviderIsKeyedService.IsKeyedService(parameterInfo.ParameterType, key);
+ }
+
+ throw new InvalidOperationException(SR.KeyedServicesNotSupported);
  }
- throw new InvalidOperationException(SR.KeyedServicesNotSupported);
+
+ // Use non-keyed service
+ return serviceProviderIsService.IsService(parameterInfo.ParameterType);
  }
- // Try non keyed service
- return serviceProviderIsService.IsService(parameterInfo.ParameterType);
- }
 
- private static bool TryGetServiceKey(ParameterInfo parameterInfo, out object? key)
- {
- foreach (var attribute in parameterInfo.GetCustomAttributes<FromKeyedServicesAttribute>(false))
+ public object? GetService(IServiceProvider serviceProvider, int parameterIndex)
  {
- key = attribute.Key;
- return true;
+ ParameterInfo parameterInfo = Parameters[parameterIndex];
+
+ // Handle keyed service
+ object? key = _parameterKeys?[parameterIndex];
+ if (key is not null)
+ {
+ if (serviceProvider is IKeyedServiceProvider keyedServiceProvider)
+ {
+ return keyedServiceProvider.GetKeyedService(parameterInfo.ParameterType, key);
+ }
+
+ throw new InvalidOperationException(SR.KeyedServicesNotSupported);
+ }
+
+ // Use non-keyed service
+ return serviceProvider.GetService(parameterInfo.ParameterType);
  }
- key = null;
- return false;
  }
 
  private readonly struct ConstructorMatcher
  {
- private readonly ConstructorInfo _constructor;
- private readonly ParameterInfo[] _parameters;
+ private readonly ConstructorInfoEx _constructor;
  private readonly object?[] _parameterValues;
 
- public ConstructorMatcher(ConstructorInfo constructor)
+ public ConstructorMatcher(ConstructorInfoEx constructor)
  {
  _constructor = constructor;
- _parameters = _constructor.GetParameters();
- _parameterValues = new object?[_parameters.Length];
+ _parameterValues = new object[constructor.Parameters.Length];
  }
 
  public int Match(object[] givenParameters, IServiceProviderIsService serviceProviderIsService)
@@ -612,10 +722,10 @@ public int Match(object[] givenParameters, IServiceProviderIsService serviceProv
  Type? givenType = givenParameters[givenIndex]?.GetType();
  bool givenMatched = false;
 
- for (int applyIndex = 0; applyIndex < _parameters.Length; applyIndex++)
+ for (int applyIndex = 0; applyIndex < _constructor.Parameters.Length; applyIndex++)
  {
  if (_parameterValues[applyIndex] == null &&
-_parameters[applyIndex].ParameterType.IsAssignableFrom(givenType))
+_constructor.Parameters[applyIndex].ParameterType.IsAssignableFrom(givenType))
  {
  givenMatched = true;
  _parameterValues[applyIndex] = givenParameters[givenIndex];
@@ -630,12 +740,12 @@ public int Match(object[] givenParameters, IServiceProviderIsService serviceProv
  }
 
  // confirms the rest of ctor arguments match either as a parameter with a default value or as a service registered
- for (int i = 0; i < _parameters.Length; i++)
+ for (int i = 0; i < _constructor.Parameters.Length; i++)
  {
  if (_parameterValues[i] == null &&
- !IsService(serviceProviderIsService, _parameters[i]))
+ !_constructor.IsService(serviceProviderIsService, i))
  {
- if (ParameterDefaultValue.TryGetDefaultValue(_parameters[i], out object? defaultValue))
+ if (ParameterDefaultValue.TryGetDefaultValue(_constructor.Parameters[i], out object? defaultValue))
  {
  _parameterValues[i] = defaultValue;
  }
@@ -646,21 +756,21 @@ public int Match(object[] givenParameters, IServiceProviderIsService serviceProv
  }
  }
 
- return _parameters.Length;
+ return _constructor.Parameters.Length;
  }
 
  public object CreateInstance(IServiceProvider provider)
  {
- for (int index = 0; index < _parameters.Length; index++)
+ for (int index = 0; index < _constructor.Parameters.Length; index++)
  {
  if (_parameterValues[index] == null)
  {
- object? value = GetService(provider, _parameters[index]);
+ object? value = _constructor.GetService(provider, index);
  if (value == null)
  {
- if (!ParameterDefaultValue.TryGetDefaultValue(_parameters[index], out object? defaultValue))
+ if (!ParameterDefaultValue.TryGetDefaultValue(_constructor.Parameters[index], out object? defaultValue))
  {
- throw new InvalidOperationException(SR.Format(SR.UnableToResolveService, _parameters[index].ParameterType, _constructor.DeclaringType));
+ throw new InvalidOperationException(SR.Format(SR.UnableToResolveService, _constructor.Parameters[index].ParameterType, _constructor.Info.DeclaringType));
  }
  else
  {
@@ -677,7 +787,7 @@ public object CreateInstance(IServiceProvider provider)
 #if NETFRAMEWORK || NETSTANDARD2_0
  try
  {
- return _constructor.Invoke(_parameterValues);
+ return _constructor.Info.Invoke(_parameterValues);
  }
  catch (TargetInvocationException ex) when (ex.InnerException != null)
  {
@@ -686,13 +796,13 @@ public object CreateInstance(IServiceProvider provider)
  throw;
  }
 #else
- return _constructor.Invoke(BindingFlags.DoNotWrapExceptions, binder: null, parameters: _parameterValues, culture: null);
+ return _constructor.Info.Invoke(BindingFlags.DoNotWrapExceptions, binder: null, parameters: _parameterValues, culture: null);
 #endif
  }
 
  public void MapParameters(int?[] parameterMap, object[] givenParameters)
  {
- for (int i = 0; i < _parameters.Length; i++)
+ for (int i = 0; i < _constructor.Parameters.Length; i++)
  {
  if (parameterMap[i] != null)
  {
@@ -974,5 +1084,20 @@ private static object ReflectionFactoryCanonical(
  return constructor.Invoke(BindingFlags.DoNotWrapExceptions, binder: null, constructorArguments, culture: null);
  }
 #endif // NET8_0_OR_GREATER
+
+#if NETCOREAPP
+ internal static class ActivatorUtilitiesUpdateHandler
+ {
+ public static void ClearCache(Type[]? _)
+ {
+ // Ignore the Type[] argument; just clear the caches.
+ s_constructorInfos.Clear();
+ if (s_collectibleConstructorInfos.IsValueCreated)
+ {
+ s_collectibleConstructorInfos.Value.Clear();
+ }
+ }
+ }
+#endif
  }
 }

src/libraries/Microsoft.Extensions.DependencyInjection/tests/CollectibleAssembly/CollectableClasses.cs

@@ -0,0 +1,25 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using Microsoft.Extensions.DependencyInjection;
+
+namespace CollectibleAssembly
+{
+ public class ClassToCreate
+ {
+ public object ClassAsCtorArgument { get; set; }
+
+ public ClassToCreate(ClassAsCtorArgument obj) { ClassAsCtorArgument = obj; }
+
+ public static object Create(ServiceProvider provider)
+ {
+ // Both the type to create (ClassToCreate) and the ctor's arg type (ClassAsCtorArgument) are
+ // located in this assembly, so both types need to be GC'd for this assembly to be collected.
+ return ActivatorUtilities.CreateInstance<ClassToCreate>(provider, new ClassAsCtorArgument());
+ }
+ }
+
+ public class ClassAsCtorArgument
+ {
+ }
+}

src/libraries/Microsoft.Extensions.DependencyInjection.Abstractions/src/ActivatorUtilities.cs

@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using System;
+using System.Collections.Concurrent;
 using System.Diagnostics;
 using System.Diagnostics.CodeAnalysis;
 using System.Linq.Expressions;
@@ -10,13 +11,25 @@
 using System.Runtime.ExceptionServices;
 using Microsoft.Extensions.Internal;
 
+#if NETCOREAPP
+[assembly: System.Reflection.Metadata.MetadataUpdateHandler(typeof(Microsoft.Extensions.DependencyInjection.ActivatorUtilities.ActivatorUtilitiesUpdateHandler))]
+#endif
+
 namespace Microsoft.Extensions.DependencyInjection
 {
  /// <summary>
  /// Helper code for the various activator services.
  /// </summary>
  public static class ActivatorUtilities
  {
+#if NETCOREAPP
+ // Support caching of constructor metadata for the common case of types in non-collectible assemblies.
+ private static readonly ConcurrentDictionary<Type, ConstructorInfoEx[]> s_constructorInfos = new();
+
+ // Support caching of constructor metadata for types in collectible assemblies.
+ private static readonly Lazy<ConditionalWeakTable<Type, ConstructorInfoEx[]>> s_collectibleConstructorInfos = new();
+#endif
+
 #if NET8_0_OR_GREATER
  // Maximum number of fixed arguments for ConstructorInvoker.Invoke(arg1, etc).
  private const int FixedArgumentThreshold = 4;
@@ -47,6 +60,17 @@ public static object CreateInstance(
  throw new InvalidOperationException(SR.CannotCreateAbstractClasses);
  }
 
+ ConstructorInfoEx[]? constructors;
+#if NETCOREAPP
+ if (!s_constructorInfos.TryGetValue(instanceType, out constructors))
+ {
+ constructors = GetOrAddConstructors(instanceType);
+ }
+#else
+ constructors = CreateConstructorInfoExs(instanceType);
+#endif
+
+ ConstructorInfoEx? constructor;
  IServiceProviderIsService? serviceProviderIsService = provider.GetService<IServiceProviderIsService>();
  // if container supports using IServiceProviderIsService, we try to find the longest ctor that
  // (a) matches all parameters given to CreateInstance
@@ -61,10 +85,11 @@ public static object CreateInstance(
  ConstructorMatcher bestMatcher = default;
  bool multipleBestLengthFound = false;
 
-foreach (ConstructorInfo? constructor in instanceType.GetConstructors())
+for (int i = 0; i < constructors.Length; i++)
  {
- var matcher = new ConstructorMatcher(constructor);
- bool isPreferred = constructor.IsDefined(typeof(ActivatorUtilitiesConstructorAttribute), false);
+ constructor = constructors[i];
+ ConstructorMatcher matcher = new(constructor);
+ bool isPreferred = constructor.IsPreferred;
  int length = matcher.Match(parameters, serviceProviderIsService);
 
  if (isPreferred)
@@ -105,18 +130,79 @@ public static object CreateInstance(
  }
  }
 
- Type?[] argumentTypes = new Type[parameters.Length];
-for (int i = 0; i < argumentTypes.Length; i++)
+ Type?[] argumentTypes;
+if (parameters.Length == 0)
  {
- argumentTypes[i] = parameters[i]?.GetType();
+ argumentTypes = Type.EmptyTypes;
+ }
+ else
+ {
+ argumentTypes = new Type[parameters.Length];
+ for (int i = 0; i < argumentTypes.Length; i++)
+ {
+ argumentTypes[i] = parameters[i]?.GetType();
+ }
  }
 
  FindApplicableConstructor(instanceType, argumentTypes, out ConstructorInfo constructorInfo, out int?[] parameterMap);
- var constructorMatcher = new ConstructorMatcher(constructorInfo);
+
+ // Find the ConstructorInfoEx from the given constructorInfo.
+ constructor = null;
+ foreach (ConstructorInfoEx ctor in constructors)
+ {
+ if (ReferenceEquals(ctor.Info, constructorInfo))
+ {
+ constructor = ctor;
+ break;
+ }
+ }
+
+ Debug.Assert(constructor != null);
+
+ var constructorMatcher = new ConstructorMatcher(constructor);
  constructorMatcher.MapParameters(parameterMap, parameters);
  return constructorMatcher.CreateInstance(provider);
  }
 
+#if NETCOREAPP
+ private static ConstructorInfoEx[] GetOrAddConstructors(
+ [DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.PublicConstructors)] Type type)
+ {
+ // Not found. Do the slower work of checking for the value in the correct cache.
+ // Null and non-collectible load contexts use the default cache.
+ if (!type.Assembly.IsCollectible)
+ {
+ return s_constructorInfos.GetOrAdd(type, CreateConstructorInfoExs(type));
+ }
+
+ // Collectible load contexts should use the ConditionalWeakTable so they can be unloaded.
+ if (s_collectibleConstructorInfos.Value.TryGetValue(type, out ConstructorInfoEx[]? value))
+ {
+ return value;
+ }
+
+ value = CreateConstructorInfoExs(type);
+
+ // ConditionalWeakTable doesn't support GetOrAdd() so use AddOrUpdate(). This means threads
+ // can have different instances for the same type, but that is OK since they are equivalent.
+ s_collectibleConstructorInfos.Value.AddOrUpdate(type, value);
+ return value;
+ }
+#endif // NETCOREAPP
+
+ private static ConstructorInfoEx[] CreateConstructorInfoExs(
+ [DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.PublicConstructors)] Type type)
+ {
+ ConstructorInfo[] constructors = type.GetConstructors();
+ ConstructorInfoEx[]? value = new ConstructorInfoEx[constructors.Length];
+ for (int i = 0; i < constructors.Length; i++)
+ {
+ value[i] = new ConstructorInfoEx(constructors[i]);
+ }
+
+ return value;
+ }
+
  /// <summary>
  /// Create a delegate that will instantiate a type with constructor arguments provided directly
  /// and/or from an <see cref="IServiceProvider"/>.
@@ -551,58 +637,82 @@ private static bool TryCreateParameterMap(ParameterInfo[] constructorParameters,
  return true;
  }
 
- private static object? GetService(IServiceProvider serviceProvider, ParameterInfo parameterInfo)
+ private sealed class ConstructorInfoEx
  {
- // Handle keyed service
- if (TryGetServiceKey(parameterInfo, out object? key))
+ public readonly ConstructorInfo Info;
+ public readonly ParameterInfo[] Parameters;
+ public readonly bool IsPreferred;
+ private readonly object?[]? _parameterKeys;
+
+ public ConstructorInfoEx(ConstructorInfo constructor)
  {
- if (serviceProvider is IKeyedServiceProvider keyedServiceProvider)
+ Info = constructor;
+ Parameters = constructor.GetParameters();
+ IsPreferred = constructor.IsDefined(typeof(ActivatorUtilitiesConstructorAttribute), inherit: false);
+
+ for (int i = 0; i < Parameters.Length; i++)
  {
- return keyedServiceProvider.GetKeyedService(parameterInfo.ParameterType, key);
+ FromKeyedServicesAttribute? attr = (FromKeyedServicesAttribute?)
+ Attribute.GetCustomAttribute(Parameters[i], typeof(FromKeyedServicesAttribute), inherit: false);
+
+ if (attr is not null)
+ {
+ _parameterKeys ??= new object?[Parameters.Length];
+ _parameterKeys[i] = attr.Key;
+ }
  }
- throw new InvalidOperationException(SR.KeyedServicesNotSupported);
  }
- // Try non keyed service
- return serviceProvider.GetService(parameterInfo.ParameterType);
- }
 
- private static bool IsService(IServiceProviderIsService serviceProviderIsService, ParameterInfo parameterInfo)
- {
- // Handle keyed service
- if (TryGetServiceKey(parameterInfo, out object? key))
+ public bool IsService(IServiceProviderIsService serviceProviderIsService, int parameterIndex)
  {
- if (serviceProviderIsService is IServiceProviderIsKeyedService serviceProviderIsKeyedService)
+ ParameterInfo parameterInfo = Parameters[parameterIndex];
+
+ // Handle keyed service
+ object? key = _parameterKeys?[parameterIndex];
+ if (key is not null)
  {
- return serviceProviderIsKeyedService.IsKeyedService(parameterInfo.ParameterType, key);
+ if (serviceProviderIsService is IServiceProviderIsKeyedService serviceProviderIsKeyedService)
+ {
+ return serviceProviderIsKeyedService.IsKeyedService(parameterInfo.ParameterType, key);
+ }
+
+ throw new InvalidOperationException(SR.KeyedServicesNotSupported);
  }
- throw new InvalidOperationException(SR.KeyedServicesNotSupported);
+
+ // Use non-keyed service
+ return serviceProviderIsService.IsService(parameterInfo.ParameterType);
  }
- // Try non keyed service
- return serviceProviderIsService.IsService(parameterInfo.ParameterType);
- }
 
- private static bool TryGetServiceKey(ParameterInfo parameterInfo, out object? key)
- {
- foreach (var attribute in parameterInfo.GetCustomAttributes<FromKeyedServicesAttribute>(false))
+ public object? GetService(IServiceProvider serviceProvider, int parameterIndex)
  {
- key = attribute.Key;
- return true;
+ ParameterInfo parameterInfo = Parameters[parameterIndex];
+
+ // Handle keyed service
+ object? key = _parameterKeys?[parameterIndex];
+ if (key is not null)
+ {
+ if (serviceProvider is IKeyedServiceProvider keyedServiceProvider)
+ {
+ return keyedServiceProvider.GetKeyedService(parameterInfo.ParameterType, key);
+ }
+
+ throw new InvalidOperationException(SR.KeyedServicesNotSupported);
+ }
+
+ // Use non-keyed service
+ return serviceProvider.GetService(parameterInfo.ParameterType);
  }
- key = null;
- return false;
  }
 
  private readonly struct ConstructorMatcher
  {
- private readonly ConstructorInfo _constructor;
- private readonly ParameterInfo[] _parameters;
+ private readonly ConstructorInfoEx _constructor;
  private readonly object?[] _parameterValues;
 
- public ConstructorMatcher(ConstructorInfo constructor)
+ public ConstructorMatcher(ConstructorInfoEx constructor)
  {
  _constructor = constructor;
- _parameters = _constructor.GetParameters();
- _parameterValues = new object?[_parameters.Length];
+ _parameterValues = new object[constructor.Parameters.Length];
  }
 
  public int Match(object[] givenParameters, IServiceProviderIsService serviceProviderIsService)
@@ -612,10 +722,10 @@ public int Match(object[] givenParameters, IServiceProviderIsService serviceProv
  Type? givenType = givenParameters[givenIndex]?.GetType();
  bool givenMatched = false;
 
- for (int applyIndex = 0; applyIndex < _parameters.Length; applyIndex++)
+ for (int applyIndex = 0; applyIndex < _constructor.Parameters.Length; applyIndex++)
  {
  if (_parameterValues[applyIndex] == null &&
-_parameters[applyIndex].ParameterType.IsAssignableFrom(givenType))
+_constructor.Parameters[applyIndex].ParameterType.IsAssignableFrom(givenType))
  {
  givenMatched = true;
  _parameterValues[applyIndex] = givenParameters[givenIndex];
@@ -630,12 +740,12 @@ public int Match(object[] givenParameters, IServiceProviderIsService serviceProv
  }
 
  // confirms the rest of ctor arguments match either as a parameter with a default value or as a service registered
- for (int i = 0; i < _parameters.Length; i++)
+ for (int i = 0; i < _constructor.Parameters.Length; i++)
  {
  if (_parameterValues[i] == null &&
- !IsService(serviceProviderIsService, _parameters[i]))
+ !_constructor.IsService(serviceProviderIsService, i))
  {
- if (ParameterDefaultValue.TryGetDefaultValue(_parameters[i], out object? defaultValue))
+ if (ParameterDefaultValue.TryGetDefaultValue(_constructor.Parameters[i], out object? defaultValue))
  {
  _parameterValues[i] = defaultValue;
  }
@@ -646,21 +756,21 @@ public int Match(object[] givenParameters, IServiceProviderIsService serviceProv
  }
  }
 
- return _parameters.Length;
+ return _constructor.Parameters.Length;
  }
 
  public object CreateInstance(IServiceProvider provider)
  {
- for (int index = 0; index < _parameters.Length; index++)
+ for (int index = 0; index < _constructor.Parameters.Length; index++)
  {
  if (_parameterValues[index] == null)
  {
- object? value = GetService(provider, _parameters[index]);
+ object? value = _constructor.GetService(provider, index);
  if (value == null)
  {
- if (!ParameterDefaultValue.TryGetDefaultValue(_parameters[index], out object? defaultValue))
+ if (!ParameterDefaultValue.TryGetDefaultValue(_constructor.Parameters[index], out object? defaultValue))
  {
- throw new InvalidOperationException(SR.Format(SR.UnableToResolveService, _parameters[index].ParameterType, _constructor.DeclaringType));
+ throw new InvalidOperationException(SR.Format(SR.UnableToResolveService, _constructor.Parameters[index].ParameterType, _constructor.Info.DeclaringType));
  }
  else
  {
@@ -677,7 +787,7 @@ public object CreateInstance(IServiceProvider provider)
 #if NETFRAMEWORK || NETSTANDARD2_0
  try
  {
- return _constructor.Invoke(_parameterValues);
+ return _constructor.Info.Invoke(_parameterValues);
  }
  catch (TargetInvocationException ex) when (ex.InnerException != null)
  {
@@ -686,13 +796,13 @@ public object CreateInstance(IServiceProvider provider)
  throw;
  }
 #else
- return _constructor.Invoke(BindingFlags.DoNotWrapExceptions, binder: null, parameters: _parameterValues, culture: null);
+ return _constructor.Info.Invoke(BindingFlags.DoNotWrapExceptions, binder: null, parameters: _parameterValues, culture: null);
 #endif
  }
 
  public void MapParameters(int?[] parameterMap, object[] givenParameters)
  {
- for (int i = 0; i < _parameters.Length; i++)
+ for (int i = 0; i < _constructor.Parameters.Length; i++)
  {
  if (parameterMap[i] != null)
  {
@@ -974,5 +1084,20 @@ private static object ReflectionFactoryCanonical(
  return constructor.Invoke(BindingFlags.DoNotWrapExceptions, binder: null, constructorArguments, culture: null);
  }
 #endif // NET8_0_OR_GREATER
+
+#if NETCOREAPP
+ internal static class ActivatorUtilitiesUpdateHandler
+ {
+ public static void ClearCache(Type[]? _)
+ {
+ // Ignore the Type[] argument; just clear the caches.
+ s_constructorInfos.Clear();
+ if (s_collectibleConstructorInfos.IsValueCreated)
+ {
+ s_collectibleConstructorInfos.Value.Clear();
+ }
+ }
+ }
+#endif
  }
 }

src/libraries/Microsoft.Extensions.DependencyInjection/tests/CollectibleAssembly/CollectableClasses.cs

@@ -0,0 +1,25 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using Microsoft.Extensions.DependencyInjection;
+
+namespace CollectibleAssembly
+{
+ public class ClassToCreate
+ {
+ public object ClassAsCtorArgument { get; set; }
+
+ public ClassToCreate(ClassAsCtorArgument obj) { ClassAsCtorArgument = obj; }
+
+ public static object Create(ServiceProvider provider)
+ {
+ // Both the type to create (ClassToCreate) and the ctor's arg type (ClassAsCtorArgument) are
+ // located in this assembly, so both types need to be GC'd for this assembly to be collected.
+ return ActivatorUtilities.CreateInstance<ClassToCreate>(provider, new ClassAsCtorArgument());
+ }
+ }
+
+ public class ClassAsCtorArgument
+ {
+ }
+}

src/libraries/Microsoft.Extensions.DependencyInjection.Abstractions/src/ActivatorUtilities.cs

@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using System;
+using System.Collections.Concurrent;
 using System.Diagnostics;
 using System.Diagnostics.CodeAnalysis;
 using System.Linq.Expressions;
@@ -10,13 +11,25 @@
 using System.Runtime.ExceptionServices;
 using Microsoft.Extensions.Internal;
 
+#if NETCOREAPP
+[assembly: System.Reflection.Metadata.MetadataUpdateHandler(typeof(Microsoft.Extensions.DependencyInjection.ActivatorUtilities.ActivatorUtilitiesUpdateHandler))]
+#endif
+
 namespace Microsoft.Extensions.DependencyInjection
 {
  /// <summary>
  /// Helper code for the various activator services.
  /// </summary>
  public static class ActivatorUtilities
  {
+#if NETCOREAPP
+ // Support caching of constructor metadata for the common case of types in non-collectible assemblies.
+ private static readonly ConcurrentDictionary<Type, ConstructorInfoEx[]> s_constructorInfos = new();
+
+ // Support caching of constructor metadata for types in collectible assemblies.
+ private static readonly Lazy<ConditionalWeakTable<Type, ConstructorInfoEx[]>> s_collectibleConstructorInfos = new();
+#endif
+
 #if NET8_0_OR_GREATER
  // Maximum number of fixed arguments for ConstructorInvoker.Invoke(arg1, etc).
  private const int FixedArgumentThreshold = 4;
@@ -47,6 +60,17 @@ public static object CreateInstance(
  throw new InvalidOperationException(SR.CannotCreateAbstractClasses);
  }
 
+ ConstructorInfoEx[]? constructors;
+#if NETCOREAPP
+ if (!s_constructorInfos.TryGetValue(instanceType, out constructors))
+ {
+ constructors = GetOrAddConstructors(instanceType);
+ }
+#else
+ constructors = CreateConstructorInfoExs(instanceType);
+#endif
+
+ ConstructorInfoEx? constructor;
  IServiceProviderIsService? serviceProviderIsService = provider.GetService<IServiceProviderIsService>();
  // if container supports using IServiceProviderIsService, we try to find the longest ctor that
  // (a) matches all parameters given to CreateInstance
@@ -61,10 +85,11 @@ public static object CreateInstance(
  ConstructorMatcher bestMatcher = default;
  bool multipleBestLengthFound = false;
 
-foreach (ConstructorInfo? constructor in instanceType.GetConstructors())
+for (int i = 0; i < constructors.Length; i++)
  {
- var matcher = new ConstructorMatcher(constructor);
- bool isPreferred = constructor.IsDefined(typeof(ActivatorUtilitiesConstructorAttribute), false);
+ constructor = constructors[i];
+ ConstructorMatcher matcher = new(constructor);
+ bool isPreferred = constructor.IsPreferred;
  int length = matcher.Match(parameters, serviceProviderIsService);
 
  if (isPreferred)
@@ -105,18 +130,79 @@ public static object CreateInstance(
  }
  }
 
- Type?[] argumentTypes = new Type[parameters.Length];
-for (int i = 0; i < argumentTypes.Length; i++)
+ Type?[] argumentTypes;
+if (parameters.Length == 0)
  {
- argumentTypes[i] = parameters[i]?.GetType();
+ argumentTypes = Type.EmptyTypes;
+ }
+ else
+ {
+ argumentTypes = new Type[parameters.Length];
+ for (int i = 0; i < argumentTypes.Length; i++)
+ {
+ argumentTypes[i] = parameters[i]?.GetType();
+ }
  }
 
  FindApplicableConstructor(instanceType, argumentTypes, out ConstructorInfo constructorInfo, out int?[] parameterMap);
- var constructorMatcher = new ConstructorMatcher(constructorInfo);
+
+ // Find the ConstructorInfoEx from the given constructorInfo.
+ constructor = null;
+ foreach (ConstructorInfoEx ctor in constructors)
+ {
+ if (ReferenceEquals(ctor.Info, constructorInfo))
+ {
+ constructor = ctor;
+ break;
+ }
+ }
+
+ Debug.Assert(constructor != null);
+
+ var constructorMatcher = new ConstructorMatcher(constructor);
  constructorMatcher.MapParameters(parameterMap, parameters);
  return constructorMatcher.CreateInstance(provider);
  }
 
+#if NETCOREAPP
+ private static ConstructorInfoEx[] GetOrAddConstructors(
+ [DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.PublicConstructors)] Type type)
+ {
+ // Not found. Do the slower work of checking for the value in the correct cache.
+ // Null and non-collectible load contexts use the default cache.
+ if (!type.Assembly.IsCollectible)
+ {
+ return s_constructorInfos.GetOrAdd(type, CreateConstructorInfoExs(type));
+ }
+
+ // Collectible load contexts should use the ConditionalWeakTable so they can be unloaded.
+ if (s_collectibleConstructorInfos.Value.TryGetValue(type, out ConstructorInfoEx[]? value))
+ {
+ return value;
+ }
+
+ value = CreateConstructorInfoExs(type);
+
+ // ConditionalWeakTable doesn't support GetOrAdd() so use AddOrUpdate(). This means threads
+ // can have different instances for the same type, but that is OK since they are equivalent.
+ s_collectibleConstructorInfos.Value.AddOrUpdate(type, value);
+ return value;
+ }
+#endif // NETCOREAPP
+
+ private static ConstructorInfoEx[] CreateConstructorInfoExs(
+ [DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.PublicConstructors)] Type type)
+ {
+ ConstructorInfo[] constructors = type.GetConstructors();
+ ConstructorInfoEx[]? value = new ConstructorInfoEx[constructors.Length];
+ for (int i = 0; i < constructors.Length; i++)
+ {
+ value[i] = new ConstructorInfoEx(constructors[i]);
+ }
+
+ return value;
+ }
+
  /// <summary>
  /// Create a delegate that will instantiate a type with constructor arguments provided directly
  /// and/or from an <see cref="IServiceProvider"/>.
@@ -551,58 +637,82 @@ private static bool TryCreateParameterMap(ParameterInfo[] constructorParameters,
  return true;
  }
 
- private static object? GetService(IServiceProvider serviceProvider, ParameterInfo parameterInfo)
+ private sealed class ConstructorInfoEx
  {
- // Handle keyed service
- if (TryGetServiceKey(parameterInfo, out object? key))
+ public readonly ConstructorInfo Info;
+ public readonly ParameterInfo[] Parameters;
+ public readonly bool IsPreferred;
+ private readonly object?[]? _parameterKeys;
+
+ public ConstructorInfoEx(ConstructorInfo constructor)
  {
- if (serviceProvider is IKeyedServiceProvider keyedServiceProvider)
+ Info = constructor;
+ Parameters = constructor.GetParameters();
+ IsPreferred = constructor.IsDefined(typeof(ActivatorUtilitiesConstructorAttribute), inherit: false);
+
+ for (int i = 0; i < Parameters.Length; i++)
  {
- return keyedServiceProvider.GetKeyedService(parameterInfo.ParameterType, key);
+ FromKeyedServicesAttribute? attr = (FromKeyedServicesAttribute?)
+ Attribute.GetCustomAttribute(Parameters[i], typeof(FromKeyedServicesAttribute), inherit: false);
+
+ if (attr is not null)
+ {
+ _parameterKeys ??= new object?[Parameters.Length];
+ _parameterKeys[i] = attr.Key;
+ }
  }
- throw new InvalidOperationException(SR.KeyedServicesNotSupported);
  }
- // Try non keyed service
- return serviceProvider.GetService(parameterInfo.ParameterType);
- }
 
- private static bool IsService(IServiceProviderIsService serviceProviderIsService, ParameterInfo parameterInfo)
- {
- // Handle keyed service
- if (TryGetServiceKey(parameterInfo, out object? key))
+ public bool IsService(IServiceProviderIsService serviceProviderIsService, int parameterIndex)
  {
- if (serviceProviderIsService is IServiceProviderIsKeyedService serviceProviderIsKeyedService)
+ ParameterInfo parameterInfo = Parameters[parameterIndex];
+
+ // Handle keyed service
+ object? key = _parameterKeys?[parameterIndex];
+ if (key is not null)
  {
- return serviceProviderIsKeyedService.IsKeyedService(parameterInfo.ParameterType, key);
+ if (serviceProviderIsService is IServiceProviderIsKeyedService serviceProviderIsKeyedService)
+ {
+ return serviceProviderIsKeyedService.IsKeyedService(parameterInfo.ParameterType, key);
+ }
+
+ throw new InvalidOperationException(SR.KeyedServicesNotSupported);
  }
- throw new InvalidOperationException(SR.KeyedServicesNotSupported);
+
+ // Use non-keyed service
+ return serviceProviderIsService.IsService(parameterInfo.ParameterType);
  }
- // Try non keyed service
- return serviceProviderIsService.IsService(parameterInfo.ParameterType);
- }
 
- private static bool TryGetServiceKey(ParameterInfo parameterInfo, out object? key)
- {
- foreach (var attribute in parameterInfo.GetCustomAttributes<FromKeyedServicesAttribute>(false))
+ public object? GetService(IServiceProvider serviceProvider, int parameterIndex)
  {
- key = attribute.Key;
- return true;
+ ParameterInfo parameterInfo = Parameters[parameterIndex];
+
+ // Handle keyed service
+ object? key = _parameterKeys?[parameterIndex];
+ if (key is not null)
+ {
+ if (serviceProvider is IKeyedServiceProvider keyedServiceProvider)
+ {
+ return keyedServiceProvider.GetKeyedService(parameterInfo.ParameterType, key);
+ }
+
+ throw new InvalidOperationException(SR.KeyedServicesNotSupported);
+ }
+
+ // Use non-keyed service
+ return serviceProvider.GetService(parameterInfo.ParameterType);
  }
- key = null;
- return false;
  }
 
  private readonly struct ConstructorMatcher
  {
- private readonly ConstructorInfo _constructor;
- private readonly ParameterInfo[] _parameters;
+ private readonly ConstructorInfoEx _constructor;
  private readonly object?[] _parameterValues;
 
- public ConstructorMatcher(ConstructorInfo constructor)
+ public ConstructorMatcher(ConstructorInfoEx constructor)
  {
  _constructor = constructor;
- _parameters = _constructor.GetParameters();
- _parameterValues = new object?[_parameters.Length];
+ _parameterValues = new object[constructor.Parameters.Length];
  }
 
  public int Match(object[] givenParameters, IServiceProviderIsService serviceProviderIsService)
@@ -612,10 +722,10 @@ public int Match(object[] givenParameters, IServiceProviderIsService serviceProv
  Type? givenType = givenParameters[givenIndex]?.GetType();
  bool givenMatched = false;
 
- for (int applyIndex = 0; applyIndex < _parameters.Length; applyIndex++)
+ for (int applyIndex = 0; applyIndex < _constructor.Parameters.Length; applyIndex++)
  {
  if (_parameterValues[applyIndex] == null &&
-_parameters[applyIndex].ParameterType.IsAssignableFrom(givenType))
+_constructor.Parameters[applyIndex].ParameterType.IsAssignableFrom(givenType))
  {
  givenMatched = true;
  _parameterValues[applyIndex] = givenParameters[givenIndex];
@@ -630,12 +740,12 @@ public int Match(object[] givenParameters, IServiceProviderIsService serviceProv
  }
 
  // confirms the rest of ctor arguments match either as a parameter with a default value or as a service registered
- for (int i = 0; i < _parameters.Length; i++)
+ for (int i = 0; i < _constructor.Parameters.Length; i++)
  {
  if (_parameterValues[i] == null &&
- !IsService(serviceProviderIsService, _parameters[i]))
+ !_constructor.IsService(serviceProviderIsService, i))
  {
- if (ParameterDefaultValue.TryGetDefaultValue(_parameters[i], out object? defaultValue))
+ if (ParameterDefaultValue.TryGetDefaultValue(_constructor.Parameters[i], out object? defaultValue))
  {
  _parameterValues[i] = defaultValue;
  }
@@ -646,21 +756,21 @@ public int Match(object[] givenParameters, IServiceProviderIsService serviceProv
  }
  }
 
- return _parameters.Length;
+ return _constructor.Parameters.Length;
  }
 
  public object CreateInstance(IServiceProvider provider)
  {
- for (int index = 0; index < _parameters.Length; index++)
+ for (int index = 0; index < _constructor.Parameters.Length; index++)
  {
  if (_parameterValues[index] == null)
  {
- object? value = GetService(provider, _parameters[index]);
+ object? value = _constructor.GetService(provider, index);
  if (value == null)
  {
- if (!ParameterDefaultValue.TryGetDefaultValue(_parameters[index], out object? defaultValue))
+ if (!ParameterDefaultValue.TryGetDefaultValue(_constructor.Parameters[index], out object? defaultValue))
  {
- throw new InvalidOperationException(SR.Format(SR.UnableToResolveService, _parameters[index].ParameterType, _constructor.DeclaringType));
+ throw new InvalidOperationException(SR.Format(SR.UnableToResolveService, _constructor.Parameters[index].ParameterType, _constructor.Info.DeclaringType));
  }
  else
  {
@@ -677,7 +787,7 @@ public object CreateInstance(IServiceProvider provider)
 #if NETFRAMEWORK || NETSTANDARD2_0
  try
  {
- return _constructor.Invoke(_parameterValues);
+ return _constructor.Info.Invoke(_parameterValues);
  }
  catch (TargetInvocationException ex) when (ex.InnerException != null)
  {
@@ -686,13 +796,13 @@ public object CreateInstance(IServiceProvider provider)
  throw;
  }
 #else
- return _constructor.Invoke(BindingFlags.DoNotWrapExceptions, binder: null, parameters: _parameterValues, culture: null);
+ return _constructor.Info.Invoke(BindingFlags.DoNotWrapExceptions, binder: null, parameters: _parameterValues, culture: null);
 #endif
  }
 
  public void MapParameters(int?[] parameterMap, object[] givenParameters)
  {
- for (int i = 0; i < _parameters.Length; i++)
+ for (int i = 0; i < _constructor.Parameters.Length; i++)
  {
  if (parameterMap[i] != null)
  {
@@ -974,5 +1084,20 @@ private static object ReflectionFactoryCanonical(
  return constructor.Invoke(BindingFlags.DoNotWrapExceptions, binder: null, constructorArguments, culture: null);
  }
 #endif // NET8_0_OR_GREATER
+
+#if NETCOREAPP
+ internal static class ActivatorUtilitiesUpdateHandler
+ {
+ public static void ClearCache(Type[]? _)
+ {
+ // Ignore the Type[] argument; just clear the caches.
+ s_constructorInfos.Clear();
+ if (s_collectibleConstructorInfos.IsValueCreated)
+ {
+ s_collectibleConstructorInfos.Value.Clear();
+ }
+ }
+ }
+#endif
  }
 }

src/libraries/Microsoft.Extensions.DependencyInjection/tests/CollectibleAssembly/CollectableClasses.cs

@@ -0,0 +1,25 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using Microsoft.Extensions.DependencyInjection;
+
+namespace CollectibleAssembly
+{
+ public class ClassToCreate
+ {
+ public object ClassAsCtorArgument { get; set; }
+
+ public ClassToCreate(ClassAsCtorArgument obj) { ClassAsCtorArgument = obj; }
+
+ public static object Create(ServiceProvider provider)
+ {
+ // Both the type to create (ClassToCreate) and the ctor's arg type (ClassAsCtorArgument) are
+ // located in this assembly, so both types need to be GC'd for this assembly to be collected.
+ return ActivatorUtilities.CreateInstance<ClassToCreate>(provider, new ClassAsCtorArgument());
+ }
+ }
+
+ public class ClassAsCtorArgument
+ {
+ }
+}

src/libraries/Microsoft.Extensions.DependencyInjection.Abstractions/src/ActivatorUtilities.cs

@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using System;
+using System.Collections.Concurrent;
 using System.Diagnostics;
 using System.Diagnostics.CodeAnalysis;
 using System.Linq.Expressions;
@@ -10,13 +11,25 @@
 using System.Runtime.ExceptionServices;
 using Microsoft.Extensions.Internal;
 
+#if NETCOREAPP
+[assembly: System.Reflection.Metadata.MetadataUpdateHandler(typeof(Microsoft.Extensions.DependencyInjection.ActivatorUtilities.ActivatorUtilitiesUpdateHandler))]
+#endif
+
 namespace Microsoft.Extensions.DependencyInjection
 {
  /// <summary>
  /// Helper code for the various activator services.
  /// </summary>
  public static class ActivatorUtilities
  {
+#if NETCOREAPP
+ // Support caching of constructor metadata for the common case of types in non-collectible assemblies.
+ private static readonly ConcurrentDictionary<Type, ConstructorInfoEx[]> s_constructorInfos = new();
+
+ // Support caching of constructor metadata for types in collectible assemblies.
+ private static readonly Lazy<ConditionalWeakTable<Type, ConstructorInfoEx[]>> s_collectibleConstructorInfos = new();
+#endif
+
 #if NET8_0_OR_GREATER
  // Maximum number of fixed arguments for ConstructorInvoker.Invoke(arg1, etc).
  private const int FixedArgumentThreshold = 4;
@@ -47,6 +60,17 @@ public static object CreateInstance(
  throw new InvalidOperationException(SR.CannotCreateAbstractClasses);
  }
 
+ ConstructorInfoEx[]? constructors;
+#if NETCOREAPP
+ if (!s_constructorInfos.TryGetValue(instanceType, out constructors))
+ {
+ constructors = GetOrAddConstructors(instanceType);
+ }
+#else
+ constructors = CreateConstructorInfoExs(instanceType);
+#endif
+
+ ConstructorInfoEx? constructor;
  IServiceProviderIsService? serviceProviderIsService = provider.GetService<IServiceProviderIsService>();
  // if container supports using IServiceProviderIsService, we try to find the longest ctor that
  // (a) matches all parameters given to CreateInstance
@@ -61,10 +85,11 @@ public static object CreateInstance(
  ConstructorMatcher bestMatcher = default;
  bool multipleBestLengthFound = false;
 
-foreach (ConstructorInfo? constructor in instanceType.GetConstructors())
+for (int i = 0; i < constructors.Length; i++)
  {
- var matcher = new ConstructorMatcher(constructor);
- bool isPreferred = constructor.IsDefined(typeof(ActivatorUtilitiesConstructorAttribute), false);
+ constructor = constructors[i];
+ ConstructorMatcher matcher = new(constructor);
+ bool isPreferred = constructor.IsPreferred;
  int length = matcher.Match(parameters, serviceProviderIsService);
 
  if (isPreferred)
@@ -105,18 +130,79 @@ public static object CreateInstance(
  }
  }
 
- Type?[] argumentTypes = new Type[parameters.Length];
-for (int i = 0; i < argumentTypes.Length; i++)
+ Type?[] argumentTypes;
+if (parameters.Length == 0)
  {
- argumentTypes[i] = parameters[i]?.GetType();
+ argumentTypes = Type.EmptyTypes;
+ }
+ else
+ {
+ argumentTypes = new Type[parameters.Length];
+ for (int i = 0; i < argumentTypes.Length; i++)
+ {
+ argumentTypes[i] = parameters[i]?.GetType();
+ }
  }
 
  FindApplicableConstructor(instanceType, argumentTypes, out ConstructorInfo constructorInfo, out int?[] parameterMap);
- var constructorMatcher = new ConstructorMatcher(constructorInfo);
+
+ // Find the ConstructorInfoEx from the given constructorInfo.
+ constructor = null;
+ foreach (ConstructorInfoEx ctor in constructors)
+ {
+ if (ReferenceEquals(ctor.Info, constructorInfo))
+ {
+ constructor = ctor;
+ break;
+ }
+ }
+
+ Debug.Assert(constructor != null);
+
+ var constructorMatcher = new ConstructorMatcher(constructor);
  constructorMatcher.MapParameters(parameterMap, parameters);
  return constructorMatcher.CreateInstance(provider);
  }
 
+#if NETCOREAPP
+ private static ConstructorInfoEx[] GetOrAddConstructors(
+ [DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.PublicConstructors)] Type type)
+ {
+ // Not found. Do the slower work of checking for the value in the correct cache.
+ // Null and non-collectible load contexts use the default cache.
+ if (!type.Assembly.IsCollectible)
+ {
+ return s_constructorInfos.GetOrAdd(type, CreateConstructorInfoExs(type));
+ }
+
+ // Collectible load contexts should use the ConditionalWeakTable so they can be unloaded.
+ if (s_collectibleConstructorInfos.Value.TryGetValue(type, out ConstructorInfoEx[]? value))
+ {
+ return value;
+ }
+
+ value = CreateConstructorInfoExs(type);
+
+ // ConditionalWeakTable doesn't support GetOrAdd() so use AddOrUpdate(). This means threads
+ // can have different instances for the same type, but that is OK since they are equivalent.
+ s_collectibleConstructorInfos.Value.AddOrUpdate(type, value);
+ return value;
+ }
+#endif // NETCOREAPP
+
+ private static ConstructorInfoEx[] CreateConstructorInfoExs(
+ [DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.PublicConstructors)] Type type)
+ {
+ ConstructorInfo[] constructors = type.GetConstructors();
+ ConstructorInfoEx[]? value = new ConstructorInfoEx[constructors.Length];
+ for (int i = 0; i < constructors.Length; i++)
+ {
+ value[i] = new ConstructorInfoEx(constructors[i]);
+ }
+
+ return value;
+ }
+
  /// <summary>
  /// Create a delegate that will instantiate a type with constructor arguments provided directly
  /// and/or from an <see cref="IServiceProvider"/>.
@@ -551,58 +637,82 @@ private static bool TryCreateParameterMap(ParameterInfo[] constructorParameters,
  return true;
  }
 
- private static object? GetService(IServiceProvider serviceProvider, ParameterInfo parameterInfo)
+ private sealed class ConstructorInfoEx
  {
- // Handle keyed service
- if (TryGetServiceKey(parameterInfo, out object? key))
+ public readonly ConstructorInfo Info;
+ public readonly ParameterInfo[] Parameters;
+ public readonly bool IsPreferred;
+ private readonly object?[]? _parameterKeys;
+
+ public ConstructorInfoEx(ConstructorInfo constructor)
  {
- if (serviceProvider is IKeyedServiceProvider keyedServiceProvider)
+ Info = constructor;
+ Parameters = constructor.GetParameters();
+ IsPreferred = constructor.IsDefined(typeof(ActivatorUtilitiesConstructorAttribute), inherit: false);
+
+ for (int i = 0; i < Parameters.Length; i++)
  {
- return keyedServiceProvider.GetKeyedService(parameterInfo.ParameterType, key);
+ FromKeyedServicesAttribute? attr = (FromKeyedServicesAttribute?)
+ Attribute.GetCustomAttribute(Parameters[i], typeof(FromKeyedServicesAttribute), inherit: false);
+
+ if (attr is not null)
+ {
+ _parameterKeys ??= new object?[Parameters.Length];
+ _parameterKeys[i] = attr.Key;
+ }
  }
- throw new InvalidOperationException(SR.KeyedServicesNotSupported);
  }
- // Try non keyed service
- return serviceProvider.GetService(parameterInfo.ParameterType);
- }
 
- private static bool IsService(IServiceProviderIsService serviceProviderIsService, ParameterInfo parameterInfo)
- {
- // Handle keyed service
- if (TryGetServiceKey(parameterInfo, out object? key))
+ public bool IsService(IServiceProviderIsService serviceProviderIsService, int parameterIndex)
  {
- if (serviceProviderIsService is IServiceProviderIsKeyedService serviceProviderIsKeyedService)
+ ParameterInfo parameterInfo = Parameters[parameterIndex];
+
+ // Handle keyed service
+ object? key = _parameterKeys?[parameterIndex];
+ if (key is not null)
  {
- return serviceProviderIsKeyedService.IsKeyedService(parameterInfo.ParameterType, key);
+ if (serviceProviderIsService is IServiceProviderIsKeyedService serviceProviderIsKeyedService)
+ {
+ return serviceProviderIsKeyedService.IsKeyedService(parameterInfo.ParameterType, key);
+ }
+
+ throw new InvalidOperationException(SR.KeyedServicesNotSupported);
  }
- throw new InvalidOperationException(SR.KeyedServicesNotSupported);
+
+ // Use non-keyed service
+ return serviceProviderIsService.IsService(parameterInfo.ParameterType);
  }
- // Try non keyed service
- return serviceProviderIsService.IsService(parameterInfo.ParameterType);
- }
 
- private static bool TryGetServiceKey(ParameterInfo parameterInfo, out object? key)
- {
- foreach (var attribute in parameterInfo.GetCustomAttributes<FromKeyedServicesAttribute>(false))
+ public object? GetService(IServiceProvider serviceProvider, int parameterIndex)
  {
- key = attribute.Key;
- return true;
+ ParameterInfo parameterInfo = Parameters[parameterIndex];
+
+ // Handle keyed service
+ object? key = _parameterKeys?[parameterIndex];
+ if (key is not null)
+ {
+ if (serviceProvider is IKeyedServiceProvider keyedServiceProvider)
+ {
+ return keyedServiceProvider.GetKeyedService(parameterInfo.ParameterType, key);
+ }
+
+ throw new InvalidOperationException(SR.KeyedServicesNotSupported);
+ }
+
+ // Use non-keyed service
+ return serviceProvider.GetService(parameterInfo.ParameterType);
  }
- key = null;
- return false;
  }
 
  private readonly struct ConstructorMatcher
  {
- private readonly ConstructorInfo _constructor;
- private readonly ParameterInfo[] _parameters;
+ private readonly ConstructorInfoEx _constructor;
  private readonly object?[] _parameterValues;
 
- public ConstructorMatcher(ConstructorInfo constructor)
+ public ConstructorMatcher(ConstructorInfoEx constructor)
  {
  _constructor = constructor;
- _parameters = _constructor.GetParameters();
- _parameterValues = new object?[_parameters.Length];
+ _parameterValues = new object[constructor.Parameters.Length];
  }
 
  public int Match(object[] givenParameters, IServiceProviderIsService serviceProviderIsService)
@@ -612,10 +722,10 @@ public int Match(object[] givenParameters, IServiceProviderIsService serviceProv
  Type? givenType = givenParameters[givenIndex]?.GetType();
  bool givenMatched = false;
 
- for (int applyIndex = 0; applyIndex < _parameters.Length; applyIndex++)
+ for (int applyIndex = 0; applyIndex < _constructor.Parameters.Length; applyIndex++)
  {
  if (_parameterValues[applyIndex] == null &&
-_parameters[applyIndex].ParameterType.IsAssignableFrom(givenType))
+_constructor.Parameters[applyIndex].ParameterType.IsAssignableFrom(givenType))
  {
  givenMatched = true;
  _parameterValues[applyIndex] = givenParameters[givenIndex];
@@ -630,12 +740,12 @@ public int Match(object[] givenParameters, IServiceProviderIsService serviceProv
  }
 
  // confirms the rest of ctor arguments match either as a parameter with a default value or as a service registered
- for (int i = 0; i < _parameters.Length; i++)
+ for (int i = 0; i < _constructor.Parameters.Length; i++)
  {
  if (_parameterValues[i] == null &&
- !IsService(serviceProviderIsService, _parameters[i]))
+ !_constructor.IsService(serviceProviderIsService, i))
  {
- if (ParameterDefaultValue.TryGetDefaultValue(_parameters[i], out object? defaultValue))
+ if (ParameterDefaultValue.TryGetDefaultValue(_constructor.Parameters[i], out object? defaultValue))
  {
  _parameterValues[i] = defaultValue;
  }
@@ -646,21 +756,21 @@ public int Match(object[] givenParameters, IServiceProviderIsService serviceProv
  }
  }
 
- return _parameters.Length;
+ return _constructor.Parameters.Length;
  }
 
  public object CreateInstance(IServiceProvider provider)
  {
- for (int index = 0; index < _parameters.Length; index++)
+ for (int index = 0; index < _constructor.Parameters.Length; index++)
  {
  if (_parameterValues[index] == null)
  {
- object? value = GetService(provider, _parameters[index]);
+ object? value = _constructor.GetService(provider, index);
  if (value == null)
  {
- if (!ParameterDefaultValue.TryGetDefaultValue(_parameters[index], out object? defaultValue))
+ if (!ParameterDefaultValue.TryGetDefaultValue(_constructor.Parameters[index], out object? defaultValue))
  {
- throw new InvalidOperationException(SR.Format(SR.UnableToResolveService, _parameters[index].ParameterType, _constructor.DeclaringType));
+ throw new InvalidOperationException(SR.Format(SR.UnableToResolveService, _constructor.Parameters[index].ParameterType, _constructor.Info.DeclaringType));
  }
  else
  {
@@ -677,7 +787,7 @@ public object CreateInstance(IServiceProvider provider)
 #if NETFRAMEWORK || NETSTANDARD2_0
  try
  {
- return _constructor.Invoke(_parameterValues);
+ return _constructor.Info.Invoke(_parameterValues);
  }
  catch (TargetInvocationException ex) when (ex.InnerException != null)
  {
@@ -686,13 +796,13 @@ public object CreateInstance(IServiceProvider provider)
  throw;
  }
 #else
- return _constructor.Invoke(BindingFlags.DoNotWrapExceptions, binder: null, parameters: _parameterValues, culture: null);
+ return _constructor.Info.Invoke(BindingFlags.DoNotWrapExceptions, binder: null, parameters: _parameterValues, culture: null);
 #endif
  }
 
  public void MapParameters(int?[] parameterMap, object[] givenParameters)
  {
- for (int i = 0; i < _parameters.Length; i++)
+ for (int i = 0; i < _constructor.Parameters.Length; i++)
  {
  if (parameterMap[i] != null)
  {
@@ -974,5 +1084,20 @@ private static object ReflectionFactoryCanonical(
  return constructor.Invoke(BindingFlags.DoNotWrapExceptions, binder: null, constructorArguments, culture: null);
  }
 #endif // NET8_0_OR_GREATER
+
+#if NETCOREAPP
+ internal static class ActivatorUtilitiesUpdateHandler
+ {
+ public static void ClearCache(Type[]? _)
+ {
+ // Ignore the Type[] argument; just clear the caches.
+ s_constructorInfos.Clear();
+ if (s_collectibleConstructorInfos.IsValueCreated)
+ {
+ s_collectibleConstructorInfos.Value.Clear();
+ }
+ }
+ }
+#endif
  }
 }

src/libraries/Microsoft.Extensions.DependencyInjection/tests/CollectibleAssembly/CollectableClasses.cs

@@ -0,0 +1,25 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using Microsoft.Extensions.DependencyInjection;
+
+namespace CollectibleAssembly
+{
+ public class ClassToCreate
+ {
+ public object ClassAsCtorArgument { get; set; }
+
+ public ClassToCreate(ClassAsCtorArgument obj) { ClassAsCtorArgument = obj; }
+
+ public static object Create(ServiceProvider provider)
+ {
+ // Both the type to create (ClassToCreate) and the ctor's arg type (ClassAsCtorArgument) are
+ // located in this assembly, so both types need to be GC'd for this assembly to be collected.
+ return ActivatorUtilities.CreateInstance<ClassToCreate>(provider, new ClassAsCtorArgument());
+ }
+ }
+
+ public class ClassAsCtorArgument
+ {
+ }
+}

src/libraries/Microsoft.Extensions.DependencyInjection.Abstractions/src/ActivatorUtilities.cs

@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using System;
+using System.Collections.Concurrent;
 using System.Diagnostics;
 using System.Diagnostics.CodeAnalysis;
 using System.Linq.Expressions;
@@ -10,13 +11,25 @@
 using System.Runtime.ExceptionServices;
 using Microsoft.Extensions.Internal;
 
+#if NETCOREAPP
+[assembly: System.Reflection.Metadata.MetadataUpdateHandler(typeof(Microsoft.Extensions.DependencyInjection.ActivatorUtilities.ActivatorUtilitiesUpdateHandler))]
+#endif
+
 namespace Microsoft.Extensions.DependencyInjection
 {
  /// <summary>
  /// Helper code for the various activator services.
  /// </summary>
  public static class ActivatorUtilities
  {
+#if NETCOREAPP
+ // Support caching of constructor metadata for the common case of types in non-collectible assemblies.
+ private static readonly ConcurrentDictionary<Type, ConstructorInfoEx[]> s_constructorInfos = new();
+
+ // Support caching of constructor metadata for types in collectible assemblies.
+ private static readonly Lazy<ConditionalWeakTable<Type, ConstructorInfoEx[]>> s_collectibleConstructorInfos = new();
+#endif
+
 #if NET8_0_OR_GREATER
  // Maximum number of fixed arguments for ConstructorInvoker.Invoke(arg1, etc).
  private const int FixedArgumentThreshold = 4;
@@ -47,6 +60,17 @@ public static object CreateInstance(
  throw new InvalidOperationException(SR.CannotCreateAbstractClasses);
  }
 
+ ConstructorInfoEx[]? constructors;
+#if NETCOREAPP
+ if (!s_constructorInfos.TryGetValue(instanceType, out constructors))
+ {
+ constructors = GetOrAddConstructors(instanceType);
+ }
+#else
+ constructors = CreateConstructorInfoExs(instanceType);
+#endif
+
+ ConstructorInfoEx? constructor;
  IServiceProviderIsService? serviceProviderIsService = provider.GetService<IServiceProviderIsService>();
  // if container supports using IServiceProviderIsService, we try to find the longest ctor that
  // (a) matches all parameters given to CreateInstance
@@ -61,10 +85,11 @@ public static object CreateInstance(
  ConstructorMatcher bestMatcher = default;
  bool multipleBestLengthFound = false;
 
-foreach (ConstructorInfo? constructor in instanceType.GetConstructors())
+for (int i = 0; i < constructors.Length; i++)
  {
- var matcher = new ConstructorMatcher(constructor);
- bool isPreferred = constructor.IsDefined(typeof(ActivatorUtilitiesConstructorAttribute), false);
+ constructor = constructors[i];
+ ConstructorMatcher matcher = new(constructor);
+ bool isPreferred = constructor.IsPreferred;
  int length = matcher.Match(parameters, serviceProviderIsService);
 
  if (isPreferred)
@@ -105,18 +130,79 @@ public static object CreateInstance(
  }
  }
 
- Type?[] argumentTypes = new Type[parameters.Length];
-for (int i = 0; i < argumentTypes.Length; i++)
+ Type?[] argumentTypes;
+if (parameters.Length == 0)
  {
- argumentTypes[i] = parameters[i]?.GetType();
+ argumentTypes = Type.EmptyTypes;
+ }
+ else
+ {
+ argumentTypes = new Type[parameters.Length];
+ for (int i = 0; i < argumentTypes.Length; i++)
+ {
+ argumentTypes[i] = parameters[i]?.GetType();
+ }
  }
 
  FindApplicableConstructor(instanceType, argumentTypes, out ConstructorInfo constructorInfo, out int?[] parameterMap);
- var constructorMatcher = new ConstructorMatcher(constructorInfo);
+
+ // Find the ConstructorInfoEx from the given constructorInfo.
+ constructor = null;
+ foreach (ConstructorInfoEx ctor in constructors)
+ {
+ if (ReferenceEquals(ctor.Info, constructorInfo))
+ {
+ constructor = ctor;
+ break;
+ }
+ }
+
+ Debug.Assert(constructor != null);
+
+ var constructorMatcher = new ConstructorMatcher(constructor);
  constructorMatcher.MapParameters(parameterMap, parameters);
  return constructorMatcher.CreateInstance(provider);
  }
 
+#if NETCOREAPP
+ private static ConstructorInfoEx[] GetOrAddConstructors(
+ [DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.PublicConstructors)] Type type)
+ {
+ // Not found. Do the slower work of checking for the value in the correct cache.
+ // Null and non-collectible load contexts use the default cache.
+ if (!type.Assembly.IsCollectible)
+ {
+ return s_constructorInfos.GetOrAdd(type, CreateConstructorInfoExs(type));
+ }
+
+ // Collectible load contexts should use the ConditionalWeakTable so they can be unloaded.
+ if (s_collectibleConstructorInfos.Value.TryGetValue(type, out ConstructorInfoEx[]? value))
+ {
+ return value;
+ }
+
+ value = CreateConstructorInfoExs(type);
+
+ // ConditionalWeakTable doesn't support GetOrAdd() so use AddOrUpdate(). This means threads
+ // can have different instances for the same type, but that is OK since they are equivalent.
+ s_collectibleConstructorInfos.Value.AddOrUpdate(type, value);
+ return value;
+ }
+#endif // NETCOREAPP
+
+ private static ConstructorInfoEx[] CreateConstructorInfoExs(
+ [DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.PublicConstructors)] Type type)
+ {
+ ConstructorInfo[] constructors = type.GetConstructors();
+ ConstructorInfoEx[]? value = new ConstructorInfoEx[constructors.Length];
+ for (int i = 0; i < constructors.Length; i++)
+ {
+ value[i] = new ConstructorInfoEx(constructors[i]);
+ }
+
+ return value;
+ }
+
  /// <summary>
  /// Create a delegate that will instantiate a type with constructor arguments provided directly
  /// and/or from an <see cref="IServiceProvider"/>.
@@ -551,58 +637,82 @@ private static bool TryCreateParameterMap(ParameterInfo[] constructorParameters,
  return true;
  }
 
- private static object? GetService(IServiceProvider serviceProvider, ParameterInfo parameterInfo)
+ private sealed class ConstructorInfoEx
  {
- // Handle keyed service
- if (TryGetServiceKey(parameterInfo, out object? key))
+ public readonly ConstructorInfo Info;
+ public readonly ParameterInfo[] Parameters;
+ public readonly bool IsPreferred;
+ private readonly object?[]? _parameterKeys;
+
+ public ConstructorInfoEx(ConstructorInfo constructor)
  {
- if (serviceProvider is IKeyedServiceProvider keyedServiceProvider)
+ Info = constructor;
+ Parameters = constructor.GetParameters();
+ IsPreferred = constructor.IsDefined(typeof(ActivatorUtilitiesConstructorAttribute), inherit: false);
+
+ for (int i = 0; i < Parameters.Length; i++)
  {
- return keyedServiceProvider.GetKeyedService(parameterInfo.ParameterType, key);
+ FromKeyedServicesAttribute? attr = (FromKeyedServicesAttribute?)
+ Attribute.GetCustomAttribute(Parameters[i], typeof(FromKeyedServicesAttribute), inherit: false);
+
+ if (attr is not null)
+ {
+ _parameterKeys ??= new object?[Parameters.Length];
+ _parameterKeys[i] = attr.Key;
+ }
  }
- throw new InvalidOperationException(SR.KeyedServicesNotSupported);
  }
- // Try non keyed service
- return serviceProvider.GetService(parameterInfo.ParameterType);
- }
 
- private static bool IsService(IServiceProviderIsService serviceProviderIsService, ParameterInfo parameterInfo)
- {
- // Handle keyed service
- if (TryGetServiceKey(parameterInfo, out object? key))
+ public bool IsService(IServiceProviderIsService serviceProviderIsService, int parameterIndex)
  {
- if (serviceProviderIsService is IServiceProviderIsKeyedService serviceProviderIsKeyedService)
+ ParameterInfo parameterInfo = Parameters[parameterIndex];
+
+ // Handle keyed service
+ object? key = _parameterKeys?[parameterIndex];
+ if (key is not null)
  {
- return serviceProviderIsKeyedService.IsKeyedService(parameterInfo.ParameterType, key);
+ if (serviceProviderIsService is IServiceProviderIsKeyedService serviceProviderIsKeyedService)
+ {
+ return serviceProviderIsKeyedService.IsKeyedService(parameterInfo.ParameterType, key);
+ }
+
+ throw new InvalidOperationException(SR.KeyedServicesNotSupported);
  }
- throw new InvalidOperationException(SR.KeyedServicesNotSupported);
+
+ // Use non-keyed service
+ return serviceProviderIsService.IsService(parameterInfo.ParameterType);
  }
- // Try non keyed service
- return serviceProviderIsService.IsService(parameterInfo.ParameterType);
- }
 
- private static bool TryGetServiceKey(ParameterInfo parameterInfo, out object? key)
- {
- foreach (var attribute in parameterInfo.GetCustomAttributes<FromKeyedServicesAttribute>(false))
+ public object? GetService(IServiceProvider serviceProvider, int parameterIndex)
  {
- key = attribute.Key;
- return true;
+ ParameterInfo parameterInfo = Parameters[parameterIndex];
+
+ // Handle keyed service
+ object? key = _parameterKeys?[parameterIndex];
+ if (key is not null)
+ {
+ if (serviceProvider is IKeyedServiceProvider keyedServiceProvider)
+ {
+ return keyedServiceProvider.GetKeyedService(parameterInfo.ParameterType, key);
+ }
+
+ throw new InvalidOperationException(SR.KeyedServicesNotSupported);
+ }
+
+ // Use non-keyed service
+ return serviceProvider.GetService(parameterInfo.ParameterType);
  }
- key = null;
- return false;
  }
 
  private readonly struct ConstructorMatcher
  {
- private readonly ConstructorInfo _constructor;
- private readonly ParameterInfo[] _parameters;
+ private readonly ConstructorInfoEx _constructor;
  private readonly object?[] _parameterValues;
 
- public ConstructorMatcher(ConstructorInfo constructor)
+ public ConstructorMatcher(ConstructorInfoEx constructor)
  {
  _constructor = constructor;
- _parameters = _constructor.GetParameters();
- _parameterValues = new object?[_parameters.Length];
+ _parameterValues = new object[constructor.Parameters.Length];
  }
 
  public int Match(object[] givenParameters, IServiceProviderIsService serviceProviderIsService)
@@ -612,10 +722,10 @@ public int Match(object[] givenParameters, IServiceProviderIsService serviceProv
  Type? givenType = givenParameters[givenIndex]?.GetType();
  bool givenMatched = false;
 
- for (int applyIndex = 0; applyIndex < _parameters.Length; applyIndex++)
+ for (int applyIndex = 0; applyIndex < _constructor.Parameters.Length; applyIndex++)
  {
  if (_parameterValues[applyIndex] == null &&
-_parameters[applyIndex].ParameterType.IsAssignableFrom(givenType))
+_constructor.Parameters[applyIndex].ParameterType.IsAssignableFrom(givenType))
  {
  givenMatched = true;
  _parameterValues[applyIndex] = givenParameters[givenIndex];
@@ -630,12 +740,12 @@ public int Match(object[] givenParameters, IServiceProviderIsService serviceProv
  }
 
  // confirms the rest of ctor arguments match either as a parameter with a default value or as a service registered
- for (int i = 0; i < _parameters.Length; i++)
+ for (int i = 0; i < _constructor.Parameters.Length; i++)
  {
  if (_parameterValues[i] == null &&
- !IsService(serviceProviderIsService, _parameters[i]))
+ !_constructor.IsService(serviceProviderIsService, i))
  {
- if (ParameterDefaultValue.TryGetDefaultValue(_parameters[i], out object? defaultValue))
+ if (ParameterDefaultValue.TryGetDefaultValue(_constructor.Parameters[i], out object? defaultValue))
  {
  _parameterValues[i] = defaultValue;
  }
@@ -646,21 +756,21 @@ public int Match(object[] givenParameters, IServiceProviderIsService serviceProv
  }
  }
 
- return _parameters.Length;
+ return _constructor.Parameters.Length;
  }
 
  public object CreateInstance(IServiceProvider provider)
  {
- for (int index = 0; index < _parameters.Length; index++)
+ for (int index = 0; index < _constructor.Parameters.Length; index++)
  {
  if (_parameterValues[index] == null)
  {
- object? value = GetService(provider, _parameters[index]);
+ object? value = _constructor.GetService(provider, index);
  if (value == null)
  {
- if (!ParameterDefaultValue.TryGetDefaultValue(_parameters[index], out object? defaultValue))
+ if (!ParameterDefaultValue.TryGetDefaultValue(_constructor.Parameters[index], out object? defaultValue))
  {
- throw new InvalidOperationException(SR.Format(SR.UnableToResolveService, _parameters[index].ParameterType, _constructor.DeclaringType));
+ throw new InvalidOperationException(SR.Format(SR.UnableToResolveService, _constructor.Parameters[index].ParameterType, _constructor.Info.DeclaringType));
  }
  else
  {
@@ -677,7 +787,7 @@ public object CreateInstance(IServiceProvider provider)
 #if NETFRAMEWORK || NETSTANDARD2_0
  try
  {
- return _constructor.Invoke(_parameterValues);
+ return _constructor.Info.Invoke(_parameterValues);
  }
  catch (TargetInvocationException ex) when (ex.InnerException != null)
  {
@@ -686,13 +796,13 @@ public object CreateInstance(IServiceProvider provider)
  throw;
  }
 #else
- return _constructor.Invoke(BindingFlags.DoNotWrapExceptions, binder: null, parameters: _parameterValues, culture: null);
+ return _constructor.Info.Invoke(BindingFlags.DoNotWrapExceptions, binder: null, parameters: _parameterValues, culture: null);
 #endif
  }
 
  public void MapParameters(int?[] parameterMap, object[] givenParameters)
  {
- for (int i = 0; i < _parameters.Length; i++)
+ for (int i = 0; i < _constructor.Parameters.Length; i++)
  {
  if (parameterMap[i] != null)
  {
@@ -974,5 +1084,20 @@ private static object ReflectionFactoryCanonical(
  return constructor.Invoke(BindingFlags.DoNotWrapExceptions, binder: null, constructorArguments, culture: null);
  }
 #endif // NET8_0_OR_GREATER
+
+#if NETCOREAPP
+ internal static class ActivatorUtilitiesUpdateHandler
+ {
+ public static void ClearCache(Type[]? _)
+ {
+ // Ignore the Type[] argument; just clear the caches.
+ s_constructorInfos.Clear();
+ if (s_collectibleConstructorInfos.IsValueCreated)
+ {
+ s_collectibleConstructorInfos.Value.Clear();
+ }
+ }
+ }
+#endif
  }
 }

src/libraries/Microsoft.Extensions.DependencyInjection/tests/CollectibleAssembly/CollectableClasses.cs

@@ -0,0 +1,25 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using Microsoft.Extensions.DependencyInjection;
+
+namespace CollectibleAssembly
+{
+ public class ClassToCreate
+ {
+ public object ClassAsCtorArgument { get; set; }
+
+ public ClassToCreate(ClassAsCtorArgument obj) { ClassAsCtorArgument = obj; }
+
+ public static object Create(ServiceProvider provider)
+ {
+ // Both the type to create (ClassToCreate) and the ctor's arg type (ClassAsCtorArgument) are
+ // located in this assembly, so both types need to be GC'd for this assembly to be collected.
+ return ActivatorUtilities.CreateInstance<ClassToCreate>(provider, new ClassAsCtorArgument());
+ }
+ }
+
+ public class ClassAsCtorArgument
+ {
+ }
+}

src/libraries/Microsoft.Extensions.DependencyInjection.Abstractions/src/ActivatorUtilities.cs

@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using System;
+using System.Collections.Concurrent;
 using System.Diagnostics;
 using System.Diagnostics.CodeAnalysis;
 using System.Linq.Expressions;
@@ -10,13 +11,25 @@
 using System.Runtime.ExceptionServices;
 using Microsoft.Extensions.Internal;
 
+#if NETCOREAPP
+[assembly: System.Reflection.Metadata.MetadataUpdateHandler(typeof(Microsoft.Extensions.DependencyInjection.ActivatorUtilities.ActivatorUtilitiesUpdateHandler))]
+#endif
+
 namespace Microsoft.Extensions.DependencyInjection
 {
  /// <summary>
  /// Helper code for the various activator services.
  /// </summary>
  public static class ActivatorUtilities
  {
+#if NETCOREAPP
+ // Support caching of constructor metadata for the common case of types in non-collectible assemblies.
+ private static readonly ConcurrentDictionary<Type, ConstructorInfoEx[]> s_constructorInfos = new();
+
+ // Support caching of constructor metadata for types in collectible assemblies.
+ private static readonly Lazy<ConditionalWeakTable<Type, ConstructorInfoEx[]>> s_collectibleConstructorInfos = new();
+#endif
+
 #if NET8_0_OR_GREATER
  // Maximum number of fixed arguments for ConstructorInvoker.Invoke(arg1, etc).
  private const int FixedArgumentThreshold = 4;
@@ -47,6 +60,17 @@ public static object CreateInstance(
  throw new InvalidOperationException(SR.CannotCreateAbstractClasses);
  }
 
+ ConstructorInfoEx[]? constructors;
+#if NETCOREAPP
+ if (!s_constructorInfos.TryGetValue(instanceType, out constructors))
+ {
+ constructors = GetOrAddConstructors(instanceType);
+ }
+#else
+ constructors = CreateConstructorInfoExs(instanceType);
+#endif
+
+ ConstructorInfoEx? constructor;
  IServiceProviderIsService? serviceProviderIsService = provider.GetService<IServiceProviderIsService>();
  // if container supports using IServiceProviderIsService, we try to find the longest ctor that
  // (a) matches all parameters given to CreateInstance
@@ -61,10 +85,11 @@ public static object CreateInstance(
  ConstructorMatcher bestMatcher = default;
  bool multipleBestLengthFound = false;
 
-foreach (ConstructorInfo? constructor in instanceType.GetConstructors())
+for (int i = 0; i < constructors.Length; i++)
  {
- var matcher = new ConstructorMatcher(constructor);
- bool isPreferred = constructor.IsDefined(typeof(ActivatorUtilitiesConstructorAttribute), false);
+ constructor = constructors[i];
+ ConstructorMatcher matcher = new(constructor);
+ bool isPreferred = constructor.IsPreferred;
  int length = matcher.Match(parameters, serviceProviderIsService);
 
  if (isPreferred)
@@ -105,18 +130,79 @@ public static object CreateInstance(
  }
  }
 
- Type?[] argumentTypes = new Type[parameters.Length];
-for (int i = 0; i < argumentTypes.Length; i++)
+ Type?[] argumentTypes;
+if (parameters.Length == 0)
  {
- argumentTypes[i] = parameters[i]?.GetType();
+ argumentTypes = Type.EmptyTypes;
+ }
+ else
+ {
+ argumentTypes = new Type[parameters.Length];
+ for (int i = 0; i < argumentTypes.Length; i++)
+ {
+ argumentTypes[i] = parameters[i]?.GetType();
+ }
  }
 
  FindApplicableConstructor(instanceType, argumentTypes, out ConstructorInfo constructorInfo, out int?[] parameterMap);
- var constructorMatcher = new ConstructorMatcher(constructorInfo);
+
+ // Find the ConstructorInfoEx from the given constructorInfo.
+ constructor = null;
+ foreach (ConstructorInfoEx ctor in constructors)
+ {
+ if (ReferenceEquals(ctor.Info, constructorInfo))
+ {
+ constructor = ctor;
+ break;
+ }
+ }
+
+ Debug.Assert(constructor != null);
+
+ var constructorMatcher = new ConstructorMatcher(constructor);
  constructorMatcher.MapParameters(parameterMap, parameters);
  return constructorMatcher.CreateInstance(provider);
  }
 
+#if NETCOREAPP
+ private static ConstructorInfoEx[] GetOrAddConstructors(
+ [DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.PublicConstructors)] Type type)
+ {
+ // Not found. Do the slower work of checking for the value in the correct cache.
+ // Null and non-collectible load contexts use the default cache.
+ if (!type.Assembly.IsCollectible)
+ {
+ return s_constructorInfos.GetOrAdd(type, CreateConstructorInfoExs(type));
+ }
+
+ // Collectible load contexts should use the ConditionalWeakTable so they can be unloaded.
+ if (s_collectibleConstructorInfos.Value.TryGetValue(type, out ConstructorInfoEx[]? value))
+ {
+ return value;
+ }
+
+ value = CreateConstructorInfoExs(type);
+
+ // ConditionalWeakTable doesn't support GetOrAdd() so use AddOrUpdate(). This means threads
+ // can have different instances for the same type, but that is OK since they are equivalent.
+ s_collectibleConstructorInfos.Value.AddOrUpdate(type, value);
+ return value;
+ }
+#endif // NETCOREAPP
+
+ private static ConstructorInfoEx[] CreateConstructorInfoExs(
+ [DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.PublicConstructors)] Type type)
+ {
+ ConstructorInfo[] constructors = type.GetConstructors();
+ ConstructorInfoEx[]? value = new ConstructorInfoEx[constructors.Length];
+ for (int i = 0; i < constructors.Length; i++)
+ {
+ value[i] = new ConstructorInfoEx(constructors[i]);
+ }
+
+ return value;
+ }
+
  /// <summary>
  /// Create a delegate that will instantiate a type with constructor arguments provided directly
  /// and/or from an <see cref="IServiceProvider"/>.
@@ -551,58 +637,82 @@ private static bool TryCreateParameterMap(ParameterInfo[] constructorParameters,
  return true;
  }
 
- private static object? GetService(IServiceProvider serviceProvider, ParameterInfo parameterInfo)
+ private sealed class ConstructorInfoEx
  {
- // Handle keyed service
- if (TryGetServiceKey(parameterInfo, out object? key))
+ public readonly ConstructorInfo Info;
+ public readonly ParameterInfo[] Parameters;
+ public readonly bool IsPreferred;
+ private readonly object?[]? _parameterKeys;
+
+ public ConstructorInfoEx(ConstructorInfo constructor)
  {
- if (serviceProvider is IKeyedServiceProvider keyedServiceProvider)
+ Info = constructor;
+ Parameters = constructor.GetParameters();
+ IsPreferred = constructor.IsDefined(typeof(ActivatorUtilitiesConstructorAttribute), inherit: false);
+
+ for (int i = 0; i < Parameters.Length; i++)
  {
- return keyedServiceProvider.GetKeyedService(parameterInfo.ParameterType, key);
+ FromKeyedServicesAttribute? attr = (FromKeyedServicesAttribute?)
+ Attribute.GetCustomAttribute(Parameters[i], typeof(FromKeyedServicesAttribute), inherit: false);
+
+ if (attr is not null)
+ {
+ _parameterKeys ??= new object?[Parameters.Length];
+ _parameterKeys[i] = attr.Key;
+ }
  }
- throw new InvalidOperationException(SR.KeyedServicesNotSupported);
  }
- // Try non keyed service
- return serviceProvider.GetService(parameterInfo.ParameterType);
- }
 
- private static bool IsService(IServiceProviderIsService serviceProviderIsService, ParameterInfo parameterInfo)
- {
- // Handle keyed service
- if (TryGetServiceKey(parameterInfo, out object? key))
+ public bool IsService(IServiceProviderIsService serviceProviderIsService, int parameterIndex)
  {
- if (serviceProviderIsService is IServiceProviderIsKeyedService serviceProviderIsKeyedService)
+ ParameterInfo parameterInfo = Parameters[parameterIndex];
+
+ // Handle keyed service
+ object? key = _parameterKeys?[parameterIndex];
+ if (key is not null)
  {
- return serviceProviderIsKeyedService.IsKeyedService(parameterInfo.ParameterType, key);
+ if (serviceProviderIsService is IServiceProviderIsKeyedService serviceProviderIsKeyedService)
+ {
+ return serviceProviderIsKeyedService.IsKeyedService(parameterInfo.ParameterType, key);
+ }
+
+ throw new InvalidOperationException(SR.KeyedServicesNotSupported);
  }
- throw new InvalidOperationException(SR.KeyedServicesNotSupported);
+
+ // Use non-keyed service
+ return serviceProviderIsService.IsService(parameterInfo.ParameterType);
  }
- // Try non keyed service
- return serviceProviderIsService.IsService(parameterInfo.ParameterType);
- }
 
- private static bool TryGetServiceKey(ParameterInfo parameterInfo, out object? key)
- {
- foreach (var attribute in parameterInfo.GetCustomAttributes<FromKeyedServicesAttribute>(false))
+ public object? GetService(IServiceProvider serviceProvider, int parameterIndex)
  {
- key = attribute.Key;
- return true;
+ ParameterInfo parameterInfo = Parameters[parameterIndex];
+
+ // Handle keyed service
+ object? key = _parameterKeys?[parameterIndex];
+ if (key is not null)
+ {
+ if (serviceProvider is IKeyedServiceProvider keyedServiceProvider)
+ {
+ return keyedServiceProvider.GetKeyedService(parameterInfo.ParameterType, key);
+ }
+
+ throw new InvalidOperationException(SR.KeyedServicesNotSupported);
+ }
+
+ // Use non-keyed service
+ return serviceProvider.GetService(parameterInfo.ParameterType);
  }
- key = null;
- return false;
  }
 
  private readonly struct ConstructorMatcher
  {
- private readonly ConstructorInfo _constructor;
- private readonly ParameterInfo[] _parameters;
+ private readonly ConstructorInfoEx _constructor;
  private readonly object?[] _parameterValues;
 
- public ConstructorMatcher(ConstructorInfo constructor)
+ public ConstructorMatcher(ConstructorInfoEx constructor)
  {
  _constructor = constructor;
- _parameters = _constructor.GetParameters();
- _parameterValues = new object?[_parameters.Length];
+ _parameterValues = new object[constructor.Parameters.Length];
  }
 
  public int Match(object[] givenParameters, IServiceProviderIsService serviceProviderIsService)
@@ -612,10 +722,10 @@ public int Match(object[] givenParameters, IServiceProviderIsService serviceProv
  Type? givenType = givenParameters[givenIndex]?.GetType();
  bool givenMatched = false;
 
- for (int applyIndex = 0; applyIndex < _parameters.Length; applyIndex++)
+ for (int applyIndex = 0; applyIndex < _constructor.Parameters.Length; applyIndex++)
  {
  if (_parameterValues[applyIndex] == null &&
-_parameters[applyIndex].ParameterType.IsAssignableFrom(givenType))
+_constructor.Parameters[applyIndex].ParameterType.IsAssignableFrom(givenType))
  {
  givenMatched = true;
  _parameterValues[applyIndex] = givenParameters[givenIndex];
@@ -630,12 +740,12 @@ public int Match(object[] givenParameters, IServiceProviderIsService serviceProv
  }
 
  // confirms the rest of ctor arguments match either as a parameter with a default value or as a service registered
- for (int i = 0; i < _parameters.Length; i++)
+ for (int i = 0; i < _constructor.Parameters.Length; i++)
  {
  if (_parameterValues[i] == null &&
- !IsService(serviceProviderIsService, _parameters[i]))
+ !_constructor.IsService(serviceProviderIsService, i))
  {
- if (ParameterDefaultValue.TryGetDefaultValue(_parameters[i], out object? defaultValue))
+ if (ParameterDefaultValue.TryGetDefaultValue(_constructor.Parameters[i], out object? defaultValue))
  {
  _parameterValues[i] = defaultValue;
  }
@@ -646,21 +756,21 @@ public int Match(object[] givenParameters, IServiceProviderIsService serviceProv
  }
  }
 
- return _parameters.Length;
+ return _constructor.Parameters.Length;
  }
 
  public object CreateInstance(IServiceProvider provider)
  {
- for (int index = 0; index < _parameters.Length; index++)
+ for (int index = 0; index < _constructor.Parameters.Length; index++)
  {
  if (_parameterValues[index] == null)
  {
- object? value = GetService(provider, _parameters[index]);
+ object? value = _constructor.GetService(provider, index);
  if (value == null)
  {
- if (!ParameterDefaultValue.TryGetDefaultValue(_parameters[index], out object? defaultValue))
+ if (!ParameterDefaultValue.TryGetDefaultValue(_constructor.Parameters[index], out object? defaultValue))
  {
- throw new InvalidOperationException(SR.Format(SR.UnableToResolveService, _parameters[index].ParameterType, _constructor.DeclaringType));
+ throw new InvalidOperationException(SR.Format(SR.UnableToResolveService, _constructor.Parameters[index].ParameterType, _constructor.Info.DeclaringType));
  }
  else
  {
@@ -677,7 +787,7 @@ public object CreateInstance(IServiceProvider provider)
 #if NETFRAMEWORK || NETSTANDARD2_0
  try
  {
- return _constructor.Invoke(_parameterValues);
+ return _constructor.Info.Invoke(_parameterValues);
  }
  catch (TargetInvocationException ex) when (ex.InnerException != null)
  {
@@ -686,13 +796,13 @@ public object CreateInstance(IServiceProvider provider)
  throw;
  }
 #else
- return _constructor.Invoke(BindingFlags.DoNotWrapExceptions, binder: null, parameters: _parameterValues, culture: null);
+ return _constructor.Info.Invoke(BindingFlags.DoNotWrapExceptions, binder: null, parameters: _parameterValues, culture: null);
 #endif
  }
 
  public void MapParameters(int?[] parameterMap, object[] givenParameters)
  {
- for (int i = 0; i < _parameters.Length; i++)
+ for (int i = 0; i < _constructor.Parameters.Length; i++)
  {
  if (parameterMap[i] != null)
  {
@@ -974,5 +1084,20 @@ private static object ReflectionFactoryCanonical(
  return constructor.Invoke(BindingFlags.DoNotWrapExceptions, binder: null, constructorArguments, culture: null);
  }
 #endif // NET8_0_OR_GREATER
+
+#if NETCOREAPP
+ internal static class ActivatorUtilitiesUpdateHandler
+ {
+ public static void ClearCache(Type[]? _)
+ {
+ // Ignore the Type[] argument; just clear the caches.
+ s_constructorInfos.Clear();
+ if (s_collectibleConstructorInfos.IsValueCreated)
+ {
+ s_collectibleConstructorInfos.Value.Clear();
+ }
+ }
+ }
+#endif
  }
 }

src/libraries/Microsoft.Extensions.DependencyInjection/tests/CollectibleAssembly/CollectableClasses.cs

@@ -0,0 +1,25 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using Microsoft.Extensions.DependencyInjection;
+
+namespace CollectibleAssembly
+{
+ public class ClassToCreate
+ {
+ public object ClassAsCtorArgument { get; set; }
+
+ public ClassToCreate(ClassAsCtorArgument obj) { ClassAsCtorArgument = obj; }
+
+ public static object Create(ServiceProvider provider)
+ {
+ // Both the type to create (ClassToCreate) and the ctor's arg type (ClassAsCtorArgument) are
+ // located in this assembly, so both types need to be GC'd for this assembly to be collected.
+ return ActivatorUtilities.CreateInstance<ClassToCreate>(provider, new ClassAsCtorArgument());
+ }
+ }
+
+ public class ClassAsCtorArgument
+ {
+ }
+}

src/libraries/Microsoft.Extensions.DependencyInjection.Abstractions/src/ActivatorUtilities.cs

@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using System;
+using System.Collections.Concurrent;
 using System.Diagnostics;
 using System.Diagnostics.CodeAnalysis;
 using System.Linq.Expressions;
@@ -10,13 +11,25 @@
 using System.Runtime.ExceptionServices;
 using Microsoft.Extensions.Internal;
 
+#if NETCOREAPP
+[assembly: System.Reflection.Metadata.MetadataUpdateHandler(typeof(Microsoft.Extensions.DependencyInjection.ActivatorUtilities.ActivatorUtilitiesUpdateHandler))]
+#endif
+
 namespace Microsoft.Extensions.DependencyInjection
 {
  /// <summary>
  /// Helper code for the various activator services.
  /// </summary>
  public static class ActivatorUtilities
  {
+#if NETCOREAPP
+ // Support caching of constructor metadata for the common case of types in non-collectible assemblies.
+ private static readonly ConcurrentDictionary<Type, ConstructorInfoEx[]> s_constructorInfos = new();
+
+ // Support caching of constructor metadata for types in collectible assemblies.
+ private static readonly Lazy<ConditionalWeakTable<Type, ConstructorInfoEx[]>> s_collectibleConstructorInfos = new();
+#endif
+
 #if NET8_0_OR_GREATER
  // Maximum number of fixed arguments for ConstructorInvoker.Invoke(arg1, etc).
  private const int FixedArgumentThreshold = 4;
@@ -47,6 +60,17 @@ public static object CreateInstance(
  throw new InvalidOperationException(SR.CannotCreateAbstractClasses);
  }
 
+ ConstructorInfoEx[]? constructors;
+#if NETCOREAPP
+ if (!s_constructorInfos.TryGetValue(instanceType, out constructors))
+ {
+ constructors = GetOrAddConstructors(instanceType);
+ }
+#else
+ constructors = CreateConstructorInfoExs(instanceType);
+#endif
+
+ ConstructorInfoEx? constructor;
  IServiceProviderIsService? serviceProviderIsService = provider.GetService<IServiceProviderIsService>();
  // if container supports using IServiceProviderIsService, we try to find the longest ctor that
  // (a) matches all parameters given to CreateInstance
@@ -61,10 +85,11 @@ public static object CreateInstance(
  ConstructorMatcher bestMatcher = default;
  bool multipleBestLengthFound = false;
 
-foreach (ConstructorInfo? constructor in instanceType.GetConstructors())
+for (int i = 0; i < constructors.Length; i++)
  {
- var matcher = new ConstructorMatcher(constructor);
- bool isPreferred = constructor.IsDefined(typeof(ActivatorUtilitiesConstructorAttribute), false);
+ constructor = constructors[i];
+ ConstructorMatcher matcher = new(constructor);
+ bool isPreferred = constructor.IsPreferred;
  int length = matcher.Match(parameters, serviceProviderIsService);
 
  if (isPreferred)
@@ -105,18 +130,79 @@ public static object CreateInstance(
  }
  }
 
- Type?[] argumentTypes = new Type[parameters.Length];
-for (int i = 0; i < argumentTypes.Length; i++)
+ Type?[] argumentTypes;
+if (parameters.Length == 0)
  {
- argumentTypes[i] = parameters[i]?.GetType();
+ argumentTypes = Type.EmptyTypes;
+ }
+ else
+ {
+ argumentTypes = new Type[parameters.Length];
+ for (int i = 0; i < argumentTypes.Length; i++)
+ {
+ argumentTypes[i] = parameters[i]?.GetType();
+ }
  }
 
  FindApplicableConstructor(instanceType, argumentTypes, out ConstructorInfo constructorInfo, out int?[] parameterMap);
- var constructorMatcher = new ConstructorMatcher(constructorInfo);
+
+ // Find the ConstructorInfoEx from the given constructorInfo.
+ constructor = null;
+ foreach (ConstructorInfoEx ctor in constructors)
+ {
+ if (ReferenceEquals(ctor.Info, constructorInfo))
+ {
+ constructor = ctor;
+ break;
+ }
+ }
+
+ Debug.Assert(constructor != null);
+
+ var constructorMatcher = new ConstructorMatcher(constructor);
  constructorMatcher.MapParameters(parameterMap, parameters);
  return constructorMatcher.CreateInstance(provider);
  }
 
+#if NETCOREAPP
+ private static ConstructorInfoEx[] GetOrAddConstructors(
+ [DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.PublicConstructors)] Type type)
+ {
+ // Not found. Do the slower work of checking for the value in the correct cache.
+ // Null and non-collectible load contexts use the default cache.
+ if (!type.Assembly.IsCollectible)
+ {
+ return s_constructorInfos.GetOrAdd(type, CreateConstructorInfoExs(type));
+ }
+
+ // Collectible load contexts should use the ConditionalWeakTable so they can be unloaded.
+ if (s_collectibleConstructorInfos.Value.TryGetValue(type, out ConstructorInfoEx[]? value))
+ {
+ return value;
+ }
+
+ value = CreateConstructorInfoExs(type);
+
+ // ConditionalWeakTable doesn't support GetOrAdd() so use AddOrUpdate(). This means threads
+ // can have different instances for the same type, but that is OK since they are equivalent.
+ s_collectibleConstructorInfos.Value.AddOrUpdate(type, value);
+ return value;
+ }
+#endif // NETCOREAPP
+
+ private static ConstructorInfoEx[] CreateConstructorInfoExs(
+ [DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.PublicConstructors)] Type type)
+ {
+ ConstructorInfo[] constructors = type.GetConstructors();
+ ConstructorInfoEx[]? value = new ConstructorInfoEx[constructors.Length];
+ for (int i = 0; i < constructors.Length; i++)
+ {
+ value[i] = new ConstructorInfoEx(constructors[i]);
+ }
+
+ return value;
+ }
+
  /// <summary>
  /// Create a delegate that will instantiate a type with constructor arguments provided directly
  /// and/or from an <see cref="IServiceProvider"/>.
@@ -551,58 +637,82 @@ private static bool TryCreateParameterMap(ParameterInfo[] constructorParameters,
  return true;
  }
 
- private static object? GetService(IServiceProvider serviceProvider, ParameterInfo parameterInfo)
+ private sealed class ConstructorInfoEx
  {
- // Handle keyed service
- if (TryGetServiceKey(parameterInfo, out object? key))
+ public readonly ConstructorInfo Info;
+ public readonly ParameterInfo[] Parameters;
+ public readonly bool IsPreferred;
+ private readonly object?[]? _parameterKeys;
+
+ public ConstructorInfoEx(ConstructorInfo constructor)
  {
- if (serviceProvider is IKeyedServiceProvider keyedServiceProvider)
+ Info = constructor;
+ Parameters = constructor.GetParameters();
+ IsPreferred = constructor.IsDefined(typeof(ActivatorUtilitiesConstructorAttribute), inherit: false);
+
+ for (int i = 0; i < Parameters.Length; i++)
  {
- return keyedServiceProvider.GetKeyedService(parameterInfo.ParameterType, key);
+ FromKeyedServicesAttribute? attr = (FromKeyedServicesAttribute?)
+ Attribute.GetCustomAttribute(Parameters[i], typeof(FromKeyedServicesAttribute), inherit: false);
+
+ if (attr is not null)
+ {
+ _parameterKeys ??= new object?[Parameters.Length];
+ _parameterKeys[i] = attr.Key;
+ }
  }
- throw new InvalidOperationException(SR.KeyedServicesNotSupported);
  }
- // Try non keyed service
- return serviceProvider.GetService(parameterInfo.ParameterType);
- }
 
- private static bool IsService(IServiceProviderIsService serviceProviderIsService, ParameterInfo parameterInfo)
- {
- // Handle keyed service
- if (TryGetServiceKey(parameterInfo, out object? key))
+ public bool IsService(IServiceProviderIsService serviceProviderIsService, int parameterIndex)
  {
- if (serviceProviderIsService is IServiceProviderIsKeyedService serviceProviderIsKeyedService)
+ ParameterInfo parameterInfo = Parameters[parameterIndex];
+
+ // Handle keyed service
+ object? key = _parameterKeys?[parameterIndex];
+ if (key is not null)
  {
- return serviceProviderIsKeyedService.IsKeyedService(parameterInfo.ParameterType, key);
+ if (serviceProviderIsService is IServiceProviderIsKeyedService serviceProviderIsKeyedService)
+ {
+ return serviceProviderIsKeyedService.IsKeyedService(parameterInfo.ParameterType, key);
+ }
+
+ throw new InvalidOperationException(SR.KeyedServicesNotSupported);
  }
- throw new InvalidOperationException(SR.KeyedServicesNotSupported);
+
+ // Use non-keyed service
+ return serviceProviderIsService.IsService(parameterInfo.ParameterType);
  }
- // Try non keyed service
- return serviceProviderIsService.IsService(parameterInfo.ParameterType);
- }
 
- private static bool TryGetServiceKey(ParameterInfo parameterInfo, out object? key)
- {
- foreach (var attribute in parameterInfo.GetCustomAttributes<FromKeyedServicesAttribute>(false))
+ public object? GetService(IServiceProvider serviceProvider, int parameterIndex)
  {
- key = attribute.Key;
- return true;
+ ParameterInfo parameterInfo = Parameters[parameterIndex];
+
+ // Handle keyed service
+ object? key = _parameterKeys?[parameterIndex];
+ if (key is not null)
+ {
+ if (serviceProvider is IKeyedServiceProvider keyedServiceProvider)
+ {
+ return keyedServiceProvider.GetKeyedService(parameterInfo.ParameterType, key);
+ }
+
+ throw new InvalidOperationException(SR.KeyedServicesNotSupported);
+ }
+
+ // Use non-keyed service
+ return serviceProvider.GetService(parameterInfo.ParameterType);
  }
- key = null;
- return false;
  }
 
  private readonly struct ConstructorMatcher
  {
- private readonly ConstructorInfo _constructor;
- private readonly ParameterInfo[] _parameters;
+ private readonly ConstructorInfoEx _constructor;
  private readonly object?[] _parameterValues;
 
- public ConstructorMatcher(ConstructorInfo constructor)
+ public ConstructorMatcher(ConstructorInfoEx constructor)
  {
  _constructor = constructor;
- _parameters = _constructor.GetParameters();
- _parameterValues = new object?[_parameters.Length];
+ _parameterValues = new object[constructor.Parameters.Length];
  }
 
  public int Match(object[] givenParameters, IServiceProviderIsService serviceProviderIsService)
@@ -612,10 +722,10 @@ public int Match(object[] givenParameters, IServiceProviderIsService serviceProv
  Type? givenType = givenParameters[givenIndex]?.GetType();
  bool givenMatched = false;
 
- for (int applyIndex = 0; applyIndex < _parameters.Length; applyIndex++)
+ for (int applyIndex = 0; applyIndex < _constructor.Parameters.Length; applyIndex++)
  {
  if (_parameterValues[applyIndex] == null &&
-_parameters[applyIndex].ParameterType.IsAssignableFrom(givenType))
+_constructor.Parameters[applyIndex].ParameterType.IsAssignableFrom(givenType))
  {
  givenMatched = true;
  _parameterValues[applyIndex] = givenParameters[givenIndex];
@@ -630,12 +740,12 @@ public int Match(object[] givenParameters, IServiceProviderIsService serviceProv
  }
 
  // confirms the rest of ctor arguments match either as a parameter with a default value or as a service registered
- for (int i = 0; i < _parameters.Length; i++)
+ for (int i = 0; i < _constructor.Parameters.Length; i++)
  {
  if (_parameterValues[i] == null &&
- !IsService(serviceProviderIsService, _parameters[i]))
+ !_constructor.IsService(serviceProviderIsService, i))
  {
- if (ParameterDefaultValue.TryGetDefaultValue(_parameters[i], out object? defaultValue))
+ if (ParameterDefaultValue.TryGetDefaultValue(_constructor.Parameters[i], out object? defaultValue))
  {
  _parameterValues[i] = defaultValue;
  }
@@ -646,21 +756,21 @@ public int Match(object[] givenParameters, IServiceProviderIsService serviceProv
  }
  }
 
- return _parameters.Length;
+ return _constructor.Parameters.Length;
  }
 
  public object CreateInstance(IServiceProvider provider)
  {
- for (int index = 0; index < _parameters.Length; index++)
+ for (int index = 0; index < _constructor.Parameters.Length; index++)
  {
  if (_parameterValues[index] == null)
  {
- object? value = GetService(provider, _parameters[index]);
+ object? value = _constructor.GetService(provider, index);
  if (value == null)
  {
- if (!ParameterDefaultValue.TryGetDefaultValue(_parameters[index], out object? defaultValue))
+ if (!ParameterDefaultValue.TryGetDefaultValue(_constructor.Parameters[index], out object? defaultValue))
  {
- throw new InvalidOperationException(SR.Format(SR.UnableToResolveService, _parameters[index].ParameterType, _constructor.DeclaringType));
+ throw new InvalidOperationException(SR.Format(SR.UnableToResolveService, _constructor.Parameters[index].ParameterType, _constructor.Info.DeclaringType));
  }
  else
  {
@@ -677,7 +787,7 @@ public object CreateInstance(IServiceProvider provider)
 #if NETFRAMEWORK || NETSTANDARD2_0
  try
  {
- return _constructor.Invoke(_parameterValues);
+ return _constructor.Info.Invoke(_parameterValues);
  }
  catch (TargetInvocationException ex) when (ex.InnerException != null)
  {
@@ -686,13 +796,13 @@ public object CreateInstance(IServiceProvider provider)
  throw;
  }
 #else
- return _constructor.Invoke(BindingFlags.DoNotWrapExceptions, binder: null, parameters: _parameterValues, culture: null);
+ return _constructor.Info.Invoke(BindingFlags.DoNotWrapExceptions, binder: null, parameters: _parameterValues, culture: null);
 #endif
  }
 
  public void MapParameters(int?[] parameterMap, object[] givenParameters)
  {
- for (int i = 0; i < _parameters.Length; i++)
+ for (int i = 0; i < _constructor.Parameters.Length; i++)
  {
  if (parameterMap[i] != null)
  {
@@ -974,5 +1084,20 @@ private static object ReflectionFactoryCanonical(
  return constructor.Invoke(BindingFlags.DoNotWrapExceptions, binder: null, constructorArguments, culture: null);
  }
 #endif // NET8_0_OR_GREATER
+
+#if NETCOREAPP
+ internal static class ActivatorUtilitiesUpdateHandler
+ {
+ public static void ClearCache(Type[]? _)
+ {
+ // Ignore the Type[] argument; just clear the caches.
+ s_constructorInfos.Clear();
+ if (s_collectibleConstructorInfos.IsValueCreated)
+ {
+ s_collectibleConstructorInfos.Value.Clear();
+ }
+ }
+ }
+#endif
  }
 }

src/libraries/Microsoft.Extensions.DependencyInjection/tests/CollectibleAssembly/CollectableClasses.cs

@@ -0,0 +1,25 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using Microsoft.Extensions.DependencyInjection;
+
+namespace CollectibleAssembly
+{
+ public class ClassToCreate
+ {
+ public object ClassAsCtorArgument { get; set; }
+
+ public ClassToCreate(ClassAsCtorArgument obj) { ClassAsCtorArgument = obj; }
+
+ public static object Create(ServiceProvider provider)
+ {
+ // Both the type to create (ClassToCreate) and the ctor's arg type (ClassAsCtorArgument) are
+ // located in this assembly, so both types need to be GC'd for this assembly to be collected.
+ return ActivatorUtilities.CreateInstance<ClassToCreate>(provider, new ClassAsCtorArgument());
+ }
+ }
+
+ public class ClassAsCtorArgument
+ {
+ }
+}