retry<T> function

Future<T> retry<T>(FutureOr<T> fn(), { Duration delayFactor = const Duration(milliseconds: 200), double randomizationFactor = 0.25, Duration maxDelay = const Duration(seconds: 30), int maxAttempts = 8, FutureOr<bool> retryIf(Exception)?, FutureOr<void> onRetry(Exception)?, })

Call fn retrying so long as retryIf return true for the exception thrown, up-to maxAttempts times.

Defaults to 8 attempts, sleeping as following after 1st, 2nd, 3rd, ..., 7th attempt:

1. 400 ms +/- 25%
2. 800 ms +/- 25%
3. 1600 ms +/- 25%
4. 3200 ms +/- 25%
5. 6400 ms +/- 25%
6. 12800 ms +/- 25%
7. 25600 ms +/- 25%

final response = await retry(
  // Make a GET request
  () => http.get('https://google.com').timeout(Duration(seconds: 5)),
  // Retry on SocketException or TimeoutException
  retryIf: (e) => e is SocketException || e is TimeoutException,
);
print(response.body);

If no retryIf function is given this will retry any for any Exception thrown. To retry on an Error, the error must be caught and rethrown as an Exception.

Implementation

Future<T> retry<T>(
  FutureOr<T> Function() fn, {
  Duration delayFactor = const Duration(milliseconds: 200),
  double randomizationFactor = 0.25,
  Duration maxDelay = const Duration(seconds: 30),
  int maxAttempts = 8,
  FutureOr<bool> Function(Exception)? retryIf,
  FutureOr<void> Function(Exception)? onRetry,
}) =>
    RetryOptions(
      delayFactor: delayFactor,
      randomizationFactor: randomizationFactor,
      maxDelay: maxDelay,
      maxAttempts: maxAttempts,
    ).retry(fn, retryIf: retryIf, onRetry: onRetry);