private RetryParams ComputeAdalRetry(Exception ex)
{
if (ex is AdalServiceException)
{
AdalServiceException adalServiceException = (AdalServiceException)ex;
// When the Service Token Server (STS) is too busy because of “too many requests”,
// it returns an HTTP error 429 with a hint about when you can try again (Retry-After response field) as a delay in seconds
if (adalServiceException.ErrorCode == AdalError.ServiceUnavailable || adalServiceException.StatusCode == 429)
{
RetryConditionHeaderValue retryAfter = adalServiceException.Headers.RetryAfter;
// Depending on the service, the recommended retry time may be in retryAfter.Delta or retryAfter.Date. Check both.
if (retryAfter != null && retryAfter.Delta.HasValue)
{
return(new RetryParams(retryAfter.Delta.Value));
}
else if (retryAfter != null && retryAfter.Date.HasValue)
{
return(new RetryParams(retryAfter.Date.Value.Offset));
}
// We got a 429 but didn't get a specific back-off time. Use the default
return(RetryParams.DefaultBackOff(0));
}
}
return(RetryParams.DefaultBackOff(0));
}
private RetryParams HandleAdalException(Exception ex, int currentRetryCount)
{
if (IsAdalServiceUnavailable(ex))
{
return(ComputeAdalRetry(ex));
}
else if (ex is ThrottleException)
{
// This is an exception that we threw, with knowledge that
// one of our threads is trying to acquire a token from the server
// Use the retry parameters recommended in the exception
ThrottleException throttlException = (ThrottleException)ex;
return(throttlException.RetryParams ?? RetryParams.DefaultBackOff(currentRetryCount));
}
else
{
// We end up here is the exception is not an ADAL exception. An example, is under high traffic
// where we could have a timeout waiting to acquire a token, waiting on the semaphore.
// If we hit a timeout, we want to retry a reasonable number of times.
return(RetryParams.DefaultBackOff(currentRetryCount));
}
}