英文:
How to use Polly with Refit?
问题
以下是翻译好的部分：
"我没有在 Startup 中使用服务来配置我的 Refit 客户端。我正在执行以下操作：
public Task<IMyService> GetService()
{
var retryPolicy = HttpPolicyExtensions
.HandleTransientHttpError()
.Or<TimeoutRejectedException>()
.WaitAndRetryAsync(2, _ => TimeSpan.FromMilliseconds(500));
var timeoutPolicy = Policy
.TimeoutAsync<HttpResponseMessage>(TimeSpan.FromMilliseconds(500));
return Task.FromResult(RestService.For<IMyService>(new HttpClient((DelegatingHandler)myHandler)
{
BaseAddress = new Uri(myUrl)
},
new RefitSettings() {}
));
}
我需要将 Polly 策略添加到客户端。在使用 RestService.For<> 创建客户端时，我该如何做呢？"
英文:
I am not configuring my Refit client using the services in Startup. I am doing the following:
public Task<IMyService> GetService()
{
var retryPolicy = HttpPolicyExtensions
.HandleTransientHttpError()
.Or<TimeoutRejectedException>()
.WaitAndRetryAsync(2, _ => TimeSpan.FromMilliseconds(500));
var timeoutPolicy = Policy
.TimeoutAsync<HttpResponseMessage>(TimeSpan.FromMilliseconds(500));
return Task.FromResult(RestService.For<IMyService>(new HttpClient((DelegatingHandler)myHandler)
{
BaseAddress = new Uri(myUrl)
},
new RefitSettings() {}
));
}
I need to add the Polly policies to the client. How can I do this when creating a client with RestService.For<>?
答案1
得分: 0
通常情况下，每当您注册一个被装饰以Polly策略（或一系列策略）的命名/类型化的`HttpClient`时，您会这样做
.AddHttpClient<XYZ>()
.AddPolicyHandler(...);
`AddPolicyHandler` [注册][1] 一个带有指定Polly策略的`PolicyHttpMessageHandler`。 ([ref][2])
所以，您可以在这里做同样的事情：
var combinedPolicy = Policy.WrapAsync(retryPolicy, timeoutPolicy);
var outerHandler = new PolicyHttpMessageHandler(combinedPolicy);
outerHandler.InnerHandler = (DelegatingHandler)myHandler;
然后，您可以在`RestService.For` 调用中使用`outerHandler`
RestService.For<IMyService>(new HttpClient(outerHandler))
*我还没有测试过，但运行时可能需要您将最内部的处理程序设置为一个新的`HttpClientHandler`才能正常工作。*
[1]: https://github.com/dotnet/aspnetcore/blob/a450cb69b5e4549f5515cdb057a68771f56cefd7/src/HttpClientFactory/Polly/src/DependencyInjection/PollyHttpClientBuilderExtensions.cs#L31
[2]: https://learn.microsoft.com/en-us/dotnet/api/microsoft.extensions.dependencyinjection.pollyhttpclientbuilderextensions.addpolicyhandler?view=dotnet-plat-ext-3.1
英文:
Usually whenever you register a named/typed HttpClient which is decorated with a Polly policy (or chain of policies) then you do that like this
.AddHttpClient<XYZ>()
.AddPolicyHandler(...);
The AddPolicyHandler registers a PolicyHttpMessageHandler with the specified Polly policy. (ref)
So, you can do the same here:
var combinedPolicy = Policy.WrapAsync(retryPolicy, timeoutPolicy);
var outerHandler = new PolicyHttpMessageHandler(combinedPolicy);
outerHandler.InnerHandler = (DelegatingHandler)myHandler;
Then you can use the outerHandler in your RestService.For call
RestService.For<IMyService>(new HttpClient(outerHandler))
I haven't tested it but the runtime might require you to set the most inner handler to a new HttpClientHandler to work properly.
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