@Override
public boolean shouldRetry(
AmazonWebServiceRequest originalRequest,
AmazonClientException exception,
int retriesAttempted) {
// Always retry on client exceptions caused by IOException
if (exception.getCause() instanceof IOException) return true;
// Only retry on a subset of service exceptions
if (exception instanceof AmazonServiceException) {
AmazonServiceException ase = (AmazonServiceException) exception;
/*
* 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 (ase.getStatusCode() == HttpStatus.SC_INTERNAL_SERVER_ERROR
|| ase.getStatusCode() == HttpStatus.SC_SERVICE_UNAVAILABLE) {
return true;
}
/*
* Throttling is reported as a 400 error from newer services. To try
* and smooth out an occasional throttling error, we'll pause and
* retry, hoping that the pause is long enough for the request to
* get through the next time.
*/
if (RetryUtils.isThrottlingException(ase)) return true;
/*
* Clock skew exception. If it is then we will get the time offset
* between the device time and the server time to set the clock skew
* and then retry the request.
*/
if (RetryUtils.isClockSkewError(ase)) return true;
}
return false;
}
/** {@inheritDoc} */
@Override
public final long delayBeforeNextRetry(
AmazonWebServiceRequest originalRequest,
AmazonClientException exception,
int retriesAttempted) {
if (retriesAttempted < 0) return 0;
if (retriesAttempted > MAX_RETRIES_BEFORE_MAX_BACKOFF) return MAX_BACKOFF_IN_MILLISECONDS;
int scaleFactor;
if (exception instanceof AmazonServiceException
&& RetryUtils.isThrottlingException((AmazonServiceException) exception)) {
scaleFactor =
THROTTLING_SCALE_FACTOR + random.nextInt(THROTTLING_SCALE_FACTOR_RANDOM_RANGE);
} else {
scaleFactor = SCALE_FACTOR;
}
long delay = (1L << retriesAttempted) * scaleFactor;
delay = Math.min(delay, MAX_BACKOFF_IN_MILLISECONDS);
return delay;
}
