polly断路器策略与基于asp.net核心api的httpclient

我在设置波利的断路器时遇到问题 HttpClient .

明确地, CircuitBreaker 和 HTTP客户端 用于以下链接的ASP.NET Core Web API控制器:

https://docs.microsoft.com/en-us/aspnet/core/fundamentals/http-requests

https://github.com/App-vNext/Polly/wiki/Polly-and-HttpClientFactory

下面是我想要的

• 重试策略:如果存在暂时性错误,则对每个请求重试3次。

• 电路断路器策略:如果所有请求中发生五个瞬时错误,则生效。

问题

尽管重试策略工作正常,但断路器策略不工作。

在发生来自HttpClient.SendAsync()的5个异常之后,Carcontroller仍然接收请求,并且在30秒内没有暂停(请求由控制器立即处理)。

破裂前处理事件:5

断裂秒持续时间:30

我是不是丢了什么东西?

配置服务

配置polly重试和断路器策略,以及单独的自定义httpclient, HttpClientService

    public void ConfigureServices(IServiceCollection services)
        {
           services.AddHttpClient();
           services.AddHttpClient<IHttpClientService, HttpClientService>()                                
                        .AddPolicyHandler((service, request) =>
                            HttpPolicyExtensions.HandleTransientHttpError()
                                .WaitAndRetryAsync(3,
                                    retryCount => TimeSpan.FromSeconds(Math.Pow(2, retryCount)),
                onRetry: (outcome, timespan, retryCount, context) =>
                                {
                                    service.GetService<ILog>().Error("Delaying for {delay}ms, then making retry {retry}.",
                                        timespan.TotalMilliseconds, retryCount);
                                }
                            )
)
                        )
                       .AddPolicyHandler((service, request) =>                      
                                HttpPolicyExtensions.HandleTransientHttpError()
                                    //Further external requests are blocked for 30 seconds if five failed attempts occur sequentially.
                                    //Circuit breaker policies are stateful.All calls through this client share the same circuit state.
                                    .CircuitBreakerAsync(5,
                                                 TimeSpan.FromSeconds(30), 
                                                 (result, timeSpan, context)=>
                                                            service.GetService<ILog>().Error("CircuitBreaker onBreak for {delay}ms", timeSpan.TotalMilliseconds),
                                                  context =>
                                                      service.GetService<ILog>().Error("CircuitBreaker onReset")));

         }

汽车控制器

IHttpClientService 在中的polly策略中指定 ConfigureServices . HttpClientService服务 使用 HTTP客户端 .

断路器不工作:即使发生五个瞬态错误(例如 HttpRequestException 从 _httpClient.SendAsync() ,carcontroller仍然可以接收请求,并且不会暂停30秒。

 [ApiVersion("1")]
    [Route("api/v{version:apiVersion}/[controller]")]
    [ApiController]
    public class CarController : ControllerBase
    {
        private readonly ILog _logger;
        private readonly IHttpClientService _httpClientService;
        private readonly IOptions<Config> _config;

        public CarController(ILog logger, IHttpClientService httpClientService, IOptions<Config> config)
        {
            _logger = logger;
            _httpClientService = httpClientService;
            _config = config;
        }

        [HttpPost]
        public async Task<ActionResult> Post()
        {  

            using (StreamReader reader = new StreamReader(Request.Body, Encoding.UTF8))
            {
                string body = reader.ReadToEnd();

                    var statusCode = await _httpClientService.PostAsync(
                        "url",
                        new Dictionary<string, string>
                        {
                            {"headerID", "Id"}                           
                        },
                        body);
                    return StatusCode((int)statusCode);               
            }
        }
      }

HttpClientService服务

似乎httpclient在请求之间不是有状态的。

断路器不工作:即使发生五个瞬态错误(例如 httprequestexception 从 _ HttpClient.SendAsync() ,carcontroller仍然可以接收请求,并且不会暂停30秒。

 public class HttpClientService
{
    private readonly HttpClient _httpClient;
    public HttpClientService(HttpClient client)
    {
        _httpClient = client;
    }

    public async Task<HttpStatusCode> PostAsync(string url, Dictionary<string, string> headers, string body)
    {
        using (var content = new StringContent(body, Encoding.UTF8, "application/json"))
        {
            foreach (var keyValue in headers)
            {
                content.Headers.Add(keyValue.Key, keyValue.Value);
            }

             var request = new HttpRequestMessage(HttpMethod.Post, url)
                                    {
                                        Content = content
                                    };

            var response = await _httpClient.SendAsync(request);

            response.EnsureSuccessStatusCode();
            return response.StatusCode;
        }

    }

ASP.NET核心API 2.2

更新 已更新setwaitandretrypolicy扩展方法以使用iserviceprovider。