/// <summary>
/// Returns whether a failed request should be retried according to the given request context. In the following
/// circumstances, the request will fail directly without consulting this method:
/// <ul>
/// <li>if it has already reached the max retry limit,
/// <li>if the request contains non-repeatable content,
/// <li>if any RuntimeException or Error is thrown when executing the request.
/// </ul>
/// </summary>
/// <param name="exception"> the exception from the failed request, represented as a BceClientException object. </param>
/// <param name="retriesAttempted"> the number of times the current request has been attempted. </param>
/// <returns> true if the failed request should be retried. </returns>
protected virtual bool ShouldRetry(Exception exception, int retriesAttempted)
{
// Don't retry if stream can not seek.
if (!CanRetry)
{
return(false);
}
// Always retry on client exceptions caused by WebException which has not been converted to
// BceServiceException.
if (exception.InnerException is WebException)
{
log.Debug("Retry for WebException.");
return(true);
}
// Always retry on client exceptions caused by IOException
if (exception.InnerException is IOException)
{
log.Debug("Retry for IOException.");
return(true);
}
// Only retry on a subset of service exceptions
if (exception is BceServiceException)
{
BceServiceException bse = exception as BceServiceException;
/*
* For 500 internal server errors and 503 service unavailable errors, we want to retry, but we need to use
* an exponential back-off strategy so that we don't overload a server with a flood of retries.
*/
if (bse.StatusCode == BceConstants.HttpStatusCode.InternalServerError)
{
log.Debug("Retry for internal server error.");
return(true);
}
if (bse.StatusCode == BceConstants.HttpStatusCode.ServiceUnavailable)
{
log.Debug("Retry for service unavailable.");
return(true);
}
string errorCode = bse.ErrorCode;
if (errorCode == BceConstants.BceErrorCode.RequestExpired)
{
log.Debug("Retry for request expired.");
return(true);
}
}
return(false);
}
/// <summary>
/// convert HttpWebResponse to BceServiceException
/// </summary>
/// <param name="response">the input HttpWebResponse</param>
/// <returns></returns>
public static BceServiceException CreateFromHttpWebResponse(HttpWebResponse response)
{
BceServiceException bse = null;
var content = response.GetResponseStream();
if (content != null)
{
var errorResponse = JsonUtils.ToObject <BceErrorResponse>(new StreamReader(content));
if (errorResponse != null && errorResponse.Message != null)
{
bse = new BceServiceException(errorResponse.Message);
bse.ErrorCode = errorResponse.Code;
bse.RequestId = errorResponse.RequestId;
}
}
if (bse == null)
{
bse = new BceServiceException(response.StatusDescription);
bse.RequestId = response.Headers[BceConstants.HttpHeaders.BceRequestId];
}
bse.StatusCode = (int)response.StatusCode;
return(bse);
}
