using System;

using System.Net;

using System.Net.Http;

using System.Threading.Tasks;

using Microsoft.Extensions.DependencyInjection;

using Polly;

public class Program

{

    public static async Task Main()

    {

        var collection = new ServiceCollection();

        collection.AddHttpClient();

        collection.AddHttpClient("A")

            .AddPolicyHandler(GetCircuitBreakerPolicy());

        var sp = collection.BuildServiceProvider();

        var factory = sp.GetRequiredService<IHttpClientFactory>();

        for(int i=0; i < 10; i++)

        {

            var client = factory.CreateClient("A");

            var res = await client.GetAsync("http://httpstat.us/500");

            res.StatusCode.Dump();

        }

    }

    static IAsyncPolicy<HttpResponseMessage> GetCircuitBreakerPolicy()

        => Policy<HttpResponseMessage>

            .HandleResult(res => res.StatusCode == HttpStatusCode.InternalServerError)

            .CircuitBreakerAsync(1, TimeSpan.FromSeconds(2));

}