Polly 策略的扩展方法

Question

I am trying to find the best way to write an extension method for Polly Policy

I have the following

public static async Task<IPollyDto> RunAsync(this IPolicy dtoClass, Func<Task<IDto>> action)
{
    return
        await Policy
            .Handle<ApiException>(ex => ex.StatusCode == HttpStatusCode.RequestTimeout)
            .RetryAsync(3,
                async (exception, retryCount) => await Task.Delay(200))
            .ExecuteAsync(async () => await action.Invoke().ConfigureAwait(false))
            .ConfigureAwait(false);
}

public interface IPollyDto {}
public interface IPolicy {}

Then I call the code as follows

public class DtoTest : IPollyDto
{
}

public class TestA
{
    public static async Task<DtoTest> GetItem(string datasetName)
    {
        return await Task.Run(() => new DtoTest()) ;
    }
}

public class PollyTest : IPolicy
{
    public async Task<DtoTest> TestMe(string dataset)
    {
       return (DtoTest) await this.RunAsync(() => Task.Run(() => (IPollyDto) TestA.GetItem(dataset)));
    }
}

I get an error resolving types.

Answer 1

You are missing async-await in your this.RunAsync(() => Task.Run(() => (IPollyDto) TestA.GetItem(dataset))) call. Change it to:

this.RunAsync(() => Task.Run(async () => (IPollyDto)(await TestA.GetItem(dataset))));

Or just:

this.RunAsync(async () => (IPollyDto)(await TestA.GetItem(dataset)))