Support resolving application services from singleton internal services

Fixes #13540

Scoped and transient internal services can obtain application services using the `DbContext` as a service locator. Singleton services cannot do this since they do not have access to the `DbContext`. This change allows the root application service provider to be registered as an `ISingletonOption` such that singleton internal services can resolve singleton and transient application services.

src/EFCore/DbContextOptionsBuilder.cs

@@ -446,6 +446,41 @@ public virtual DbContextOptionsBuilder UseInternalServiceProvider(IServiceProvid
     public virtual DbContextOptionsBuilder UseApplicationServiceProvider(IServiceProvider? serviceProvider)
         => WithOption(e => e.WithApplicationServiceProvider(serviceProvider));
 
+    /// <summary>
+    ///     Sets the root <see cref="IServiceProvider" /> from which singleton application services can be obtained from singleton
+    ///     internal services.
+    /// </summary>
+    /// <remarks>
+    ///     <para>
+    ///         This is an advanced option that is rarely needed by normal applications. Calling this method will result in a new internal
+    ///         service provider being created for every different root application service provider.
+    ///     </para>
+    ///     <para>
+    ///         See <see href="https://aka.ms/efcore-docs-dbcontext-options">Using DbContextOptions</see> for more information and examples.
+    ///     </para>
+    /// </remarks>
+    /// <param name="rootServiceProvider">The service provider to be used.</param>
+    /// <returns>The same builder instance so that multiple calls can be chained.</returns>
+    public virtual DbContextOptionsBuilder UseRootApplicationServiceProvider(IServiceProvider? rootServiceProvider)
+        => WithOption(e => e.WithRootApplicationServiceProvider(rootServiceProvider));
+
+    /// <summary>
+    ///     Resolves the root <see cref="IServiceProvider" /> from from the scoped application service provider. The root provider can
+    ///     be used to obtain singleton application services from singleton internal services.
+    /// </summary>
+    /// <remarks>
+    ///     <para>
+    ///         This is an advanced option that is rarely needed by normal applications. Calling this method will result in a new internal
+    ///         service provider being created for every different root application service provider.
+    ///     </para>
+    ///     <para>
+    ///         See <see href="https://aka.ms/efcore-docs-dbcontext-options">Using DbContextOptions</see> for more information and examples.
+    ///     </para>
+    /// </remarks>
+    /// <returns>The same builder instance so that multiple calls can be chained.</returns>
+    public virtual DbContextOptionsBuilder ResolveRootApplicationServiceProvider()
+        => WithOption(e => e.WithAutoResolveRootApplicationServiceProvider(true));
+
     /// <summary>
     ///     Enables application data to be included in exception messages, logging, etc. This can include the
     ///     values assigned to properties of your entity instances, parameter values for commands being sent

src/EFCore/DbContextOptionsBuilder`.cs

@@ -365,6 +365,41 @@ public DbContextOptionsBuilder(DbContextOptions<TContext> options)
     public new virtual DbContextOptionsBuilder<TContext> UseApplicationServiceProvider(IServiceProvider? serviceProvider)
         => (DbContextOptionsBuilder<TContext>)base.UseApplicationServiceProvider(serviceProvider);
 
+    /// <summary>
+    ///     Sets the root <see cref="IServiceProvider" /> from which singleton application services can be obtained from singleton
+    ///     internal services.
+    /// </summary>
+    /// <remarks>
+    ///     <para>
+    ///         This is an advanced option that is rarely needed by normal applications. Calling this method will result in a new internal
+    ///         service provider being created for every different root application service provider.
+    ///     </para>
+    ///     <para>
+    ///         See <see href="https://aka.ms/efcore-docs-dbcontext-options">Using DbContextOptions</see> for more information and examples.
+    ///     </para>
+    /// </remarks>
+    /// <param name="rootServiceProvider">The service provider to be used.</param>
+    /// <returns>The same builder instance so that multiple calls can be chained.</returns>
+    public new virtual DbContextOptionsBuilder<TContext> UseRootApplicationServiceProvider(IServiceProvider? rootServiceProvider)
+        => (DbContextOptionsBuilder<TContext>)base.UseRootApplicationServiceProvider(rootServiceProvider);
+
+    /// <summary>
+    ///     Resolves the root <see cref="IServiceProvider" /> from from the scoped application service provider. The root provider can
+    ///     be used to obtain singleton application services from singleton internal services.
+    /// </summary>
+    /// <remarks>
+    ///     <para>
+    ///         This is an advanced option that is rarely needed by normal applications. Calling this method will result in a new internal
+    ///         service provider being created for every different root application service provider.
+    ///     </para>
+    ///     <para>
+    ///         See <see href="https://aka.ms/efcore-docs-dbcontext-options">Using DbContextOptions</see> for more information and examples.
+    ///     </para>
+    /// </remarks>
+    /// <returns>The same builder instance so that multiple calls can be chained.</returns>
+    public new virtual DbContextOptionsBuilder<TContext> ResolveRootApplicationServiceProvider()
+        => (DbContextOptionsBuilder<TContext>)base.ResolveRootApplicationServiceProvider();
+
     /// <summary>
     ///     Enables application data to be included in exception messages, logging, etc. This can include the
     ///     values assigned to properties of your entity instances, parameter values for commands being sent

src/EFCore/Extensions/EntityFrameworkServiceCollectionExtensions.cs

@@ -1040,6 +1040,8 @@ private static void AddCoreServices<TContextImplementation>(
         ServiceLifetime optionsLifetime)
         where TContextImplementation : DbContext
     {
+        serviceCollection.TryAddSingleton<ServiceProviderAccessor>();
+
         serviceCollection.TryAdd(
             new ServiceDescriptor(
                 typeof(DbContextOptions<TContextImplementation>),

src/EFCore/Infrastructure/CoreOptionsExtension.cs

@@ -25,6 +25,8 @@ public class CoreOptionsExtension : IDbContextOptionsExtension
 {
     private IServiceProvider? _internalServiceProvider;
     private IServiceProvider? _applicationServiceProvider;
+    private IServiceProvider? _rootApplicationServiceProvider;
+    private bool _autoResolveResolveRootProvider;
     private IModel? _model;
     private ILoggerFactory? _loggerFactory;
     private IDbContextLogger? _contextLogger;
@@ -66,6 +68,8 @@ protected CoreOptionsExtension(CoreOptionsExtension copyFrom)
     {
         _internalServiceProvider = copyFrom.InternalServiceProvider;
         _applicationServiceProvider = copyFrom.ApplicationServiceProvider;
+        _rootApplicationServiceProvider = copyFrom.RootApplicationServiceProvider;
+        _autoResolveResolveRootProvider = copyFrom.AutoResolveRootProvider;
         _model = copyFrom.Model;
         _loggerFactory = copyFrom.LoggerFactory;
         _contextLogger = copyFrom.DbContextLogger;
@@ -130,6 +134,36 @@ public virtual CoreOptionsExtension WithApplicationServiceProvider(IServiceProvi
         return clone;
     }
 
+    /// <summary>
+    ///     Creates a new instance with all options the same as for this instance, but with the given option changed.
+    ///     It is unusual to call this method directly. Instead use <see cref="DbContextOptionsBuilder" />.
+    /// </summary>
+    /// <param name="rootApplicationServiceProvider">The option to change.</param>
+    /// <returns>A new instance with the option changed.</returns>
+    public virtual CoreOptionsExtension WithRootApplicationServiceProvider(IServiceProvider? rootApplicationServiceProvider)
+    {
+        var clone = Clone();
+
+        clone._rootApplicationServiceProvider = rootApplicationServiceProvider;
+
+        return clone;
+    }
+
+    /// <summary>
+    ///     Creates a new instance with all options the same as for this instance, but with the given option changed.
+    ///     It is unusual to call this method directly. Instead use <see cref="DbContextOptionsBuilder" />.
+    /// </summary>
+    /// <param name="autoResolve">The option to change.</param>
+    /// <returns>A new instance with the option changed.</returns>
+    public virtual CoreOptionsExtension WithAutoResolveRootApplicationServiceProvider(bool autoResolve = true)
+    {
+        var clone = Clone();
+
+        clone._autoResolveResolveRootProvider = autoResolve;
+
+        return clone;
+    }
+
     /// <summary>
     ///     Creates a new instance with all options the same as for this instance, but with the given option changed.
     ///     It is unusual to call this method directly. Instead use <see cref="DbContextOptionsBuilder" />.
@@ -420,6 +454,21 @@ public virtual IServiceProvider? InternalServiceProvider
     public virtual IServiceProvider? ApplicationServiceProvider
         => _applicationServiceProvider;
 
+    /// <summary>
+    ///     The option set from the <see cref="DbContextOptionsBuilder.UseRootApplicationServiceProvider" /> method.
+    /// </summary>
+    public virtual IServiceProvider? RootApplicationServiceProvider
+        => _rootApplicationServiceProvider
+            ?? (_autoResolveResolveRootProvider
+                ? _applicationServiceProvider?.GetService<ServiceProviderAccessor>()?.RootServiceProvider
+                : null);
+
+    /// <summary>
+    ///     The option set from the <see cref="DbContextOptionsBuilder.UseRootApplicationServiceProvider" /> method.
+    /// </summary>
+    public virtual bool AutoResolveRootProvider
+        => _autoResolveResolveRootProvider;
+
     /// <summary>
     ///     The options set from the <see cref="DbContextOptionsBuilder.ConfigureWarnings" /> method.
     /// </summary>
@@ -647,6 +696,7 @@ public override int GetServiceProviderHashCode()
                 hashCode.Add(Extension.GetMemoryCache());
                 hashCode.Add(Extension._sensitiveDataLoggingEnabled);
                 hashCode.Add(Extension._detailedErrorsEnabled);
+                hashCode.Add(Extension.RootApplicationServiceProvider);
                 hashCode.Add(Extension._threadSafetyChecksEnabled);
                 hashCode.Add(Extension._warningsConfiguration.GetServiceProviderHashCode());
 
@@ -677,6 +727,7 @@ public override bool ShouldUseSameServiceProvider(DbContextOptionsExtensionInfo
                 && Extension.GetMemoryCache() == otherInfo.Extension.GetMemoryCache()
                 && Extension._sensitiveDataLoggingEnabled == otherInfo.Extension._sensitiveDataLoggingEnabled
                 && Extension._detailedErrorsEnabled == otherInfo.Extension._detailedErrorsEnabled
+                && Extension.RootApplicationServiceProvider == otherInfo.Extension.RootApplicationServiceProvider
                 && Extension._threadSafetyChecksEnabled == otherInfo.Extension._threadSafetyChecksEnabled
                 && Extension._warningsConfiguration.ShouldUseSameServiceProvider(otherInfo.Extension._warningsConfiguration)
                 && (Extension._replacedServices == otherInfo.Extension._replacedServices

src/EFCore/Infrastructure/ICoreSingletonOptions.cs

@@ -28,4 +28,9 @@ public interface ICoreSingletonOptions : ISingletonOptions
     ///     Reflects the option set by <see cref="DbContextOptionsBuilder.EnableThreadSafetyChecks" />.
     /// </summary>
     bool AreThreadSafetyChecksEnabled { get; }
+
+    /// <summary>
+    ///     The root service provider for the application, if available. />.
+    /// </summary>
+    IServiceProvider? RootApplicationServiceProvider { get; }
 }

src/EFCore/Infrastructure/Internal/CoreSingletonOptions.cs

@@ -23,6 +23,7 @@ public virtual void Initialize(IDbContextOptions options)
 
         AreDetailedErrorsEnabled = coreOptions.DetailedErrorsEnabled;
         AreThreadSafetyChecksEnabled = coreOptions.ThreadSafetyChecksEnabled;
+        RootApplicationServiceProvider = coreOptions.RootApplicationServiceProvider;
     }
 
     /// <summary>
@@ -54,6 +55,14 @@ public virtual void Validate(IDbContextOptions options)
                     nameof(DbContextOptionsBuilder.EnableThreadSafetyChecks),
                     nameof(DbContextOptionsBuilder.UseInternalServiceProvider)));
         }
+
+        if (RootApplicationServiceProvider != coreOptions.RootApplicationServiceProvider)
+        {
+            throw new InvalidOperationException(
+                CoreStrings.SingletonOptionChanged(
+                    nameof(DbContextOptionsBuilder.UseRootApplicationServiceProvider),
+                    nameof(DbContextOptionsBuilder.UseInternalServiceProvider)));
+        }
     }
 
     /// <summary>
@@ -71,4 +80,12 @@ public virtual void Validate(IDbContextOptions options)
     ///     doing so can result in application failures when updating to a new Entity Framework Core release.
     /// </summary>
     public virtual bool AreThreadSafetyChecksEnabled { get; private set; }
+
+    /// <summary>
+    ///     This is an internal API that supports the Entity Framework Core infrastructure and not subject to
+    ///     the same compatibility standards as public APIs. It may be changed or removed without notice in
+    ///     any release. You should only use it directly in your code with extreme caution and knowing that
+    ///     doing so can result in application failures when updating to a new Entity Framework Core release.
+    /// </summary>
+    public virtual IServiceProvider? RootApplicationServiceProvider { get; private set; }
 }

src/EFCore/Infrastructure/ServiceProviderAccessor.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.
+
+namespace Microsoft.EntityFrameworkCore.Infrastructure;
+
+/// <summary>
+///     This type is added as a singleton service to the application service provider to provide access to the
+///     root service provider.
+/// </summary>
+public class ServiceProviderAccessor
+{
+    /// <summary>
+    ///     Initializes a new instance of the <see cref="ServiceProviderAccessor" /> class.
+    /// </summary>
+    /// <param name="rootServiceProvider">The injected service provider.</param>
+    public ServiceProviderAccessor(IServiceProvider rootServiceProvider)
+    {
+        RootServiceProvider = rootServiceProvider;
+    }
+
+    /// <summary>
+    ///     The injected service provider.
+    /// </summary>
+    public virtual IServiceProvider RootServiceProvider { get; }
+}