Avoid allocating on a per-request basis

Author: javiercn

src/Components/Components/src/PersistentState/PersistentServicesRegistry.cs

@@ -26,9 +26,8 @@ internal sealed class PersistentServicesRegistry
 
     public PersistentServicesRegistry(IServiceProvider serviceProvider)
     {
-        var registrations = serviceProvider.GetRequiredService<IEnumerable<IPersistentServiceRegistration>>();
         _serviceProvider = serviceProvider;
-        _registrations = ResolveRegistrations(registrations);
+        _registrations = ResolveRegistrations(serviceProvider.GetRequiredService<RegisteredPersistentServiceRegistrationCollection>().Registrations);
     }
 
     internal IComponentRenderMode? RenderMode { get; set; }
@@ -140,7 +139,7 @@ private static void RestoreInstanceState(object instance, Type type, PersistentC
         }
     }
 
-    private static IPersistentServiceRegistration[] ResolveRegistrations(IEnumerable<IPersistentServiceRegistration> registrations) => [.. registrations.DistinctBy(r => (r.Assembly, r.FullTypeName)).OrderBy(r => r.Assembly).ThenBy(r => r.FullTypeName)];
+    internal static IPersistentServiceRegistration[] ResolveRegistrations(IEnumerable<IPersistentServiceRegistration> registrations) => [.. registrations.DistinctBy(r => (r.Assembly, r.FullTypeName)).OrderBy(r => r.Assembly).ThenBy(r => r.FullTypeName)];
 
     private static Type? ResolveType(IPersistentServiceRegistration registration)
     {

src/Components/Components/src/PersistentState/RegisteredPersistentServiceRegistrationCollection.cs

@@ -0,0 +1,12 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+namespace Microsoft.AspNetCore.Components.Infrastructure;
+
+internal class RegisteredPersistentServiceRegistrationCollection(IEnumerable<IPersistentServiceRegistration> registrations)
+{
+    private readonly IEnumerable<IPersistentServiceRegistration> _registrations =
+        PersistentServicesRegistry.ResolveRegistrations(registrations);
+
+    public IEnumerable<IPersistentServiceRegistration> Registrations => _registrations;
+}

src/Components/Components/src/RegisterPersistentComponentStateServiceCollectionExtensions.cs

@@ -36,6 +36,7 @@ public static class RegisterPersistentComponentStateServiceCollectionExtensions
         // We resolve the service from the DI container.
         // We loop through the properties in the type and try to restore the properties that have SupplyParameterFromPersistentComponentState on them.
         services.TryAddEnumerable(ServiceDescriptor.Singleton<IPersistentServiceRegistration>(new PersistentServiceRegistration<TService>(componentRenderMode)));
+        services.TryAddSingleton<RegisteredPersistentServiceRegistrationCollection>();
 
         return services;
     }