如何使用dotnetcore和Polly添加动态重试策略

我有一个dotnetcore(2.1)控制台应用程序,我正在使用Polly用重试策略包装代码段。这在下面显示的一个简单用例中运行良好:

private void ProcessRun() 
{
    var policy = Policy.Handle<SocketException>().WaitAndRetryAsync(
                 retryCount: 3
                 sleepDurationProvider: attempt => TimeSpan.FromSeconds(10),
                 onRetry: (exception, calculatedWaitDuration) => 
                 {
                    Console.WriteLine($"Retry policy executed for type SocketException");
                 });

    try
    {
        CancellationTokenSource _cts = new CancellationTokenSource()

        PollyRetryWaitPolicy.ExecuteAsync(async token => {
           MyOperation(token);
        }, _cts.Token)
        .ContinueWith(p => {
           if (p.IsFaulted || p.Status == TaskStatus.Canceled)
           {
                Console.WriteLine("faulted or was cancelled");
           }
        })
        .ConfigureAwait(false);
    }
    catch (Exception ex) {
     Console.WriteLine($"Exception has occurred: {ex.Message}");
    }
}

然后使用以下代码进行测试:

private void MyOperation() 
{
    Thread.Sleep(2000);
    throw new SocketException();
}

我在寻找一种灵活的方法,用多个策略而不是一个策略来包装代码。我修改了代码,动态地添加了许多打包的Polly重试策略,以允许捕获多个错误类型,并轻松地更改我正在查找的异常。我把代码改成:

internal PolicyWrap PollyRetryWaitPolicy;

public void AddRetryWaitPolicy<T>(int waitTimeInSeconds, int retryAttempts)
    where T: Exception
{

    // Setup the polly policy that will be added to the executing code.
    var policy = Policy.Handle<T>().WaitAndRetryAsync(
                retryCount: retryAttempts, 
                sleepDurationProvider: attempt => TimeSpan.FromSeconds(waitTimeInSeconds), 
                onRetry: (exception, calculatedWaitDuration) => 
                {
                    Console.WriteLine($"Retry policy executed for type {typeof(T).Name}");
                });

    if (host.PollyRetryWaitPolicy == null)
    {
        // NOTE: Only add this timeout policy as it seems to need at least one
        // policy before it can wrap! (suppose that makes sense).
        var timeoutPolicy = Policy
            .TimeoutAsync(TimeSpan.FromSeconds(waitTimeInSeconds), TimeoutStrategy.Pessimistic);
        PollyRetryWaitPolicy = policy.WrapAsync(timeoutPolicy);
    }
    else
    {
        PollyRetryWaitPolicy.WrapAsync(policy);
    }
}

private void ProcessRun() 
{
    AddRetryWaitPolicy<SocketException>(10, 5);
    AddRetryWaitPolicy<InvalidOperationException>(5, 2);

    try
    {
        Console.WriteLine($"Calling HostedProcess.Run() method. AwaitResult: {awaitResult}");

        CancellationTokenSource _cts = new CancellationTokenSource()

        PollyRetryWaitPolicy.ExecuteAsync(async token => {
           MyOperation(token);
        }, _cts.Token)
        .ContinueWith(p => {
           if (p.IsFaulted || p.Status == TaskStatus.Canceled)
           {
                Console.WriteLine("Process has faulted or was cancelled");
           }
        })
        .ConfigureAwait(false);
    }
    catch (Exception ex) {
     Console.WriteLine($"Exception has occurred: {ex.Message}");
    }
}

当我使用此代码进行测试时,上面的代码按预期工作,并重试5次。

私有void MyOperation()
睡眠(2000);
抛出新的SocketException();

但当我尝试以下操作时,它不会按预期重试2次(它根本不会重试):

private void MyOperation() 
{
    Thread.Sleep(2000);
    throw new InvalidOperationException();
}

提前谢谢你的指点!