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/AutoActivationHostedService.cs

@@ -2,10 +2,8 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using System;
-using System.Linq;
 using System.Threading;
 using System.Threading.Tasks;
-using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Hosting;
 using Microsoft.Extensions.Options;
 using Microsoft.Shared.Diagnostics;
@@ -14,24 +12,27 @@ namespace Microsoft.Extensions.DependencyInjection;
 
 internal sealed class AutoActivationHostedService : IHostedService
 {
-    private readonly Type[] _autoActivators;
+    private readonly AutoActivatorOptions _options;
     private readonly IServiceProvider _provider;
 
     public AutoActivationHostedService(IServiceProvider provider, IOptions<AutoActivatorOptions> options)
     {
         _provider = provider;
-        var value = Throw.IfMemberNull(options, options.Value);
-
-        _autoActivators = value.AutoActivators.ToArray();
+        _options = Throw.IfMemberNull(options, options.Value);
     }
 
     public Task StartAsync(CancellationToken cancellationToken)
     {
-        foreach (var singleton in _autoActivators)
+        foreach (var singleton in _options.AutoActivators)
         {
             _ = _provider.GetRequiredService(singleton);
         }
 
+        foreach (var (serviceType, serviceKey) in _options.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";
 }