Class ServiceProviderExtensions

Provides a set of extension methods for IServiceProvider. These methods extend the functionality of IServiceProvider to offer enhanced and simplified service resolution capabilities, enabling the retrieval and management of service instances in a more flexible manner.

Inheritance

object

ServiceProviderExtensions

Inherited Members

object.Equals(object)

object.Equals(object, object)

object.GetHashCode()

object.GetType()

object.MemberwiseClone()

object.ReferenceEquals(object, object)

object.ToString()

Namespace: Coree.NETStandard.HostedServicesCollection

Assembly: Coree.NETStandard.dll

Syntax

public static class ServiceProviderExtensions

Methods

GetHostedServiceCollectionOfTypeLazy<T>(IServiceProvider)

Provides a lazy-initialized collection of hosted services of the specified type T, designed to be used in scenarios where direct service resolution in constructors may lead to race conditions.

Declaration

public static Lazy<IEnumerable<T>> GetHostedServiceCollectionOfTypeLazy<T>(this IServiceProvider serviceProvider)

Parameters

Type	Name	Description
IServiceProvider	serviceProvider	The IServiceProvider from which to retrieve the services.

Returns

Type	Description
Lazy<IEnumerable<T>>	A Lazy<T> object that, when evaluated, provides an IEnumerable<T> representing the collection of services of the specified type T. If no services of the specified type are registered, an empty enumerable is returned. This allows safe and deferred resolution of services, ideal for use within method implementations to avoid race conditions in service stacks.

Type Parameters

Name	Description
T	The type of the hosted service to retrieve. This type parameter is contravariant.

Remarks

This method is particularly useful in complex dependency scenarios, where some services may not be fully initialized at the time of a constructor's execution. By deferring the service resolution to the actual execution time of a method, it mitigates the risk of encountering race conditions within the service initialization stack. It leverages Lazy<T> to ensure that the service collection is resolved only when it is first needed, thereby enhancing reliability and performance by avoiding unnecessary upfront service resolution and instantiation.

Examples

This example demonstrates using GetHostedServiceCollectionOfTypeLazy<T>(IServiceProvider) within a service constructor to defer the resolution of dependent services, mitigating race conditions:

public class MyService :BackgroundService
{
    private readonly Lazy<IEnumerable<MyDependentService>> _dependentServices;

    public MyService(IServiceProvider serviceProvider)
    {
        _dependentServices = serviceProvider.GetHostedServiceCollectionOfTypeLazy<MyDependentService>();
    }

    protected override async Task ExecuteAsync(CancellationToken stoppingToken)
    {
        while (!stoppingToken.IsCancellationRequested)
        {
            // The dependent services are resolved here, when first needed, avoiding race conditions.
            foreach(var service in _dependentServices.Value)
            {
                // Interact with the service
            }
        }
    }
}