below is some code example using DI:

public class Program {
   public static void Main(string[] args) {
      var services = new ServiceCollection();                

      services.AddScoped<IXXX, XXX>();    
 
      ServiceProvider rootContainer = services.BuildServiceProvider(true);    

      using (IServiceScope scope = rootContainer.CreateScope) { /
         IXXX sth= scope.ServiceProvider.GetRequiredService<XXX>();  
      }
   }
}

and the source code of CreateScope() is

public static class ServiceProviderServiceExtensions {
   // ...
   public static IServiceScope CreateScope(this IServiceProvider provider) {
      return provider.GetRequiredService<IServiceScopeFactory>().CreateScope();   
   }
}

how does IServiceScopeFactory get registered? and what is the concrete implementation for IServiceScopeFactory?

CodePudding user response：

how does IServiceScopeFactory get registered?

It is registered internally within the ServiceProvider when it is initialised.

//...

CallSiteFactory.Add(typeof(IServiceScopeFactory), new ConstantCallSite(typeof(IServiceScopeFactory), Root));

//...

Source

and what is the concrete implementation for IServiceScopeFactory?

In the above registration, the Root is a property

internal ServiceProviderEngineScope Root { get; }

Source

of the internal type ServiceProviderEngineScope

internal sealed class ServiceProviderEngineScope : IServiceScope, IServiceProvider, IAsyncDisposable, IServiceScopeFactory

Source