c# - 在C#异常处理中，有没有一种方法可以检测瞬时错误？

Question

我正在使用Azure，但有一个简单的try catch块
我现在正在做的是，当我们遇到任何错误时，我现在将通过电子邮件将错误消息发送给我，我想检测暂时性错误，而忽略为他们发送电子邮件

private void SomeMethod()
{
    try
    {
        // Do stuff
    }
    catch (Exception ex) 
    {         
         HandleError(ex);
         return RedirectToAction("Index", "Error");
    }
}

protected void HandleError(Exception ex) 
{
      //and here i want to check if the cause of exception is not a transient      error then write a code to email the error details 
}

Answer 1

根据您刚刚发布的链接，并提供以下代码示例:

// Define your retry strategy: retry 3 times, 1 second apart.
var retryStrategy = new FixedInterval(3, TimeSpan.FromSeconds(1));

// Define your retry policy using the retry strategy and the Azure storage
// transient fault detection strategy.
var retryPolicy = 
  new RetryPolicy<StorageTransientErrorDetectionStrategy>(retryStrategy);

// Do some work that may result in a transient fault.
try
{
  // Call a method that uses Azure storage and which may
  // throw a transient exception.
  retryPolicy.ExecuteAction(
    () =>
    {
        this.queue.CreateIfNotExist();
    });
}
catch (Exception)
{
  // All of the retries failed.
}

根据该文档，在之前，不会引发 异​​常，它不再是重试策略所定义的临时错误。实际上，利用 transient 故障处理应用程序块已经可以完成您在问题中的要求。重试将以静默方式重试(无异常(exception))，直到发生引发异常的时间点-当重试已超出您的重试策略时。

以下内容不应视为“好代码”，它仅仅是TFHAB 如何确定 transient 错误的一个示例。

private void DoStuff()
{
    try
    {
        this.DoSomethingThatCouldPotentiallyCauseTransientErrors(5);
    }
    catch (Exception ex)
    {
        // This would not be caught until the "retries" have occurred.
        this.HandleException(ex);
        return RedirectToAction("Index", "Error");
    }
}

private void DoSomethingThatCouldPotentiallyCauseTransientErrors(int retryAttemptsBeforeExceptionThrown)
{
    // Note that this will *always throw an exception*, 
    // I'm (attempting to) simply demonstrate my point of how the transient errors could be defined.

    for (int i = 0; i < retryAttemptsBeforeExceptionThrown)
    {
        try    
        {
            int x = 0;
            int y = 0;

            int result = x / y;
        }
        catch (Exception)
        {
            if (i < retryAttemptsBeforeExceptionThrown-1)
            {
                // Swallow/ignore the exception, and retry
                // Note that anything hitting this block would be considered a "transient error", 
                // as we are not raising an exception
            }
            else
            {
                // Too many failed attempts have occurred, ***now*** we raise an exception to the caller
                throw;
            }
        }
    }
}

private void HandleException(Exception ex)
{
    // Implementation
}

希望这种回答可以在造成“暂时性错误”的背景下回答约翰的问题