Add support for auto-activated keyed singletons

Directory.Build.targets

@@ -33,7 +33,7 @@
     <NoWarn>$(NoWarn);AD0001</NoWarn>
 
     <!-- Experimental warnings are for customers, not for this repo -->
-    <NoWarn>$(NoWarn);EXTEXP0001;EXTEXP0002;EXTEXP0003;EXTEXP0004;EXTEXP0005;EXTEXP0006;EXTEXP0007;EXTEXP0008;EXTEXP0009;EXTEXP0010;EXTEXP0011</NoWarn>
+    <NoWarn>$(NoWarn);EXTEXP0001;EXTEXP0002;EXTEXP0003;EXTEXP0004;EXTEXP0005;EXTEXP0006;EXTEXP0007;EXTEXP0008;EXTEXP0009;EXTEXP0010;EXTEXP0011;EXTEXP0012</NoWarn>
 
     <!-- NU5104: A stable release of a package should not have a prerelease dependency -->
     <NoWarn>$(NoWarn);NU5104</NoWarn>

docs/list-of-diagnostics.md

@@ -25,4 +25,5 @@ if desired.
 | `EXTEXP0008` | Resource monitoring experiments |
 | `EXTEXP0009` | Hosting experiments |
 | `EXTEXP0010` | Object pool experiments |
-
+| `EXTEXP0011` | Document database experiments |
+| `EXTEXP0012` | Auto-activation experiments |

src/Libraries/Microsoft.Extensions.DependencyInjection.AutoActivation/AutoActivationExtensions.cs

@@ -6,44 +6,85 @@
 using System.Diagnostics.CodeAnalysis;
 using System.Linq;
 using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Shared.DiagnosticIds;
 using Microsoft.Shared.Diagnostics;
 
 namespace Microsoft.Extensions.DependencyInjection;
 
 /// <summary>
 /// Extension methods for automatically activating singletons after application starts.
 /// </summary>
-public static class AutoActivationExtensions
+public static partial class AutoActivationExtensions
 {
     /// <summary>
     /// Enforces singleton activation at startup time rather then at runtime.
     /// </summary>
-    /// <typeparam name="TService">The type of the service to add.</typeparam>
+    /// <typeparam name="TService">The type of the service to activate.</typeparam>
     /// <param name="services">The <see cref="IServiceCollection"/> to add the service to.</param>
     /// <returns>A reference to this instance after the operation has completed.</returns>
     public static IServiceCollection Activate<TService>(this IServiceCollection services)
         where TService : class
     {
         _ = Throw.IfNull(services);
 
-        _ = services.AddHostedService<AutoActivationHostedService>()
-                    .AddOptions<AutoActivatorOptions>()
-                    .Configure(ao =>
-                    {
-                        var constructed = typeof(IEnumerable<TService>);
-                        if (ao.AutoActivators.Contains(constructed))
-                        {
-                            return;
-                        }
-
-                        if (ao.AutoActivators.Remove(typeof(TService)))
-                        {
-                            _ = ao.AutoActivators.Add(constructed);
-                            return;
-                        }
-
-                        _ = ao.AutoActivators.Add(typeof(TService));
-                    });
+        _ = services
+            .AddHostedService<AutoActivationHostedService>()
+            .AddOptions<AutoActivatorOptions>()
+            .Configure(ao =>
+            {
+                var constructed = typeof(IEnumerable<TService>);
+                if (ao.AutoActivators.Contains(constructed))
+                {
+                    return;
+                }
+
+                if (ao.AutoActivators.Remove(typeof(TService)))
+                {
+                    _ = ao.AutoActivators.Add(constructed);
+                    return;
+                }
+
+                _ = ao.AutoActivators.Add(typeof(TService));
+            });
+
+        return services;
+    }
+
+    /// <summary>
+    /// Enforces singleton activation at startup time rather then at runtime.
+    /// </summary>
+    /// <param name="services">The <see cref="IServiceCollection"/> to add the service to.</param>
+    /// <param name="serviceType">The type of the service to activate.</param>
+    /// <returns>A reference to this instance after the operation has completed.</returns>
+    [Experimental(diagnosticId: Experiments.AutoActivation, UrlFormat = Experiments.UrlFormat)]
+    [UnconditionalSuppressMessage(
+        "Trimming",
+        "IL2026:Members annotated with 'RequiresUnreferencedCodeAttribute' require dynamic access otherwise can break functionality when trimming application code",
+        Justification = "Addressed with [DynamicallyAccessedMembers]")]
+    public static IServiceCollection Activate(this IServiceCollection services, [DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.PublicConstructors)] Type serviceType)
+    {
+        _ = Throw.IfNull(services);
+        _ = Throw.IfNull(serviceType);
+
+        _ = services
+            .AddHostedService<AutoActivationHostedService>()
+            .AddOptions<AutoActivatorOptions>()
+            .Configure(ao =>
+            {
+                var constructed = typeof(IEnumerable<>).MakeGenericType(serviceType);
+                if (ao.AutoActivators.Contains(constructed))
+                {
+                    return;
+                }
+
+                if (ao.AutoActivators.Remove(serviceType))
+                {
+                    _ = ao.AutoActivators.Add(constructed);
+                    return;
+                }
+
+                _ = ao.AutoActivators.Add(serviceType);
+            });
 
         return services;
     }
@@ -270,34 +311,6 @@ public static void TryAddActivatedSingleton<TService>(this IServiceCollection se
         services.TryAddAndActivate<TService>(ServiceDescriptor.Singleton<TService>(implementationFactory));
     }
 
-    [UnconditionalSuppressMessage(
-        "Trimming",
-        "IL2026:Members annotated with 'RequiresUnreferencedCodeAttribute' require dynamic access otherwise can break functionality when trimming application code",
-        Justification = "Addressed with [DynamicallyAccessedMembers]")]
-    internal static IServiceCollection Activate(this IServiceCollection services, [DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.PublicConstructors)] Type serviceType)
-    {
-        _ = services.AddHostedService<AutoActivationHostedService>()
-                    .AddOptions<AutoActivatorOptions>()
-                    .Configure(ao =>
-                    {
-                        var constructed = typeof(IEnumerable<>).MakeGenericType(serviceType);
-                        if (ao.AutoActivators.Contains(constructed))
-                        {
-                            return;
-                        }
-
-                        if (ao.AutoActivators.Remove(serviceType))
-                        {
-                            _ = ao.AutoActivators.Add(constructed);
-                            return;
-                        }
-
-                        _ = ao.AutoActivators.Add(serviceType);
-                    });
-
-        return services;
-    }
-
     private static void TryAddAndActivate<TService>(this IServiceCollection services, ServiceDescriptor descriptor)
         where TService : class
     {

src/Libraries/Microsoft.Extensions.DependencyInjection.AutoActivation/AutoActivationHostedService.cs

@@ -15,6 +15,7 @@ namespace Microsoft.Extensions.DependencyInjection;
 internal sealed class AutoActivationHostedService : IHostedService
 {
     private readonly Type[] _autoActivators;
+    private readonly (Type, object?)[] _keyedAutoActivators;
     private readonly IServiceProvider _provider;
 
     public AutoActivationHostedService(IServiceProvider provider, IOptions<AutoActivatorOptions> options)
@@ -23,6 +24,7 @@ public AutoActivationHostedService(IServiceProvider provider, IOptions<AutoActiv
         var value = Throw.IfMemberNull(options, options.Value);
 
         _autoActivators = value.AutoActivators.ToArray();
+        _keyedAutoActivators = value.KeyedAutoActivators.ToArray();
     }
 
     public Task StartAsync(CancellationToken cancellationToken)
@@ -32,6 +34,11 @@ public Task StartAsync(CancellationToken cancellationToken)
             _ = _provider.GetRequiredService(singleton);
         }
 
+        foreach (var (serviceType, serviceKey) in _keyedAutoActivators)
+        {
+            _ = _provider.GetRequiredKeyedService(serviceType, serviceKey);
+        }
+
         return Task.CompletedTask;
     }
 

src/Libraries/Microsoft.Extensions.DependencyInjection.AutoActivation/AutoActivatorOptions.cs

@@ -9,4 +9,5 @@ namespace Microsoft.Extensions.DependencyInjection;
 internal sealed class AutoActivatorOptions
 {
     public HashSet<Type> AutoActivators { get; } = new();
+    public HashSet<(Type serviceType, object? serviceKey)> KeyedAutoActivators { get; } = new();
 }

src/Libraries/Microsoft.Extensions.DependencyInjection.AutoActivation/Microsoft.Extensions.DependencyInjection.AutoActivation.csproj

@@ -5,6 +5,10 @@
     <Workstream>Fundamentals</Workstream>
   </PropertyGroup>
 
+  <PropertyGroup>
+    <InjectExperimentalAttributeOnLegacy>true</InjectExperimentalAttributeOnLegacy>
+  </PropertyGroup>
+
   <PropertyGroup>
     <Stage>normal</Stage>
     <MinCodeCoverage>100</MinCodeCoverage>

src/Shared/DiagnosticIds/Experiments.cs

@@ -10,7 +10,7 @@ namespace Microsoft.Shared.DiagnosticIds;
 /// </summary>
 /// <remarks>
 /// When adding a new experiment, add a corresponding suppression to the root <c>Directory.Build.targets</c> file, and add a documentation entry to
-/// <c>docs/Experiments.md</c>.
+/// <c>docs/list-of-diagnostics.md</c>.
 /// </remarks>
 internal static class Experiments
 {
@@ -29,4 +29,5 @@ internal static class Experiments
     internal const string Hosting = "EXTEXP0009";
     internal const string ObjectPool = "EXTEXP0010";
     internal const string DocumentDb = "EXTEXP0011";
+    internal const string AutoActivation = "EXTEXP0012";
 }