run<T> method

Future<T> run<T>(String? key, Future<T> operation(), { DeduplicationPolicy policy = DeduplicationPolicy.reuseInFlight, })

Runs operation under key according to policy.

If key is null, operation always runs — deduplication is opt-in per call.

Implementation

Future<T> run<T>(
  String? key,
  Future<T> Function() operation, {
  DeduplicationPolicy policy = DeduplicationPolicy.reuseInFlight,
}) {
  if (key == null) return operation();

  final existing = _inFlight[key];
  if (existing != null) {
    switch (policy) {
      case DeduplicationPolicy.reuseInFlight:
        return existing.then((value) => value as T);
      case DeduplicationPolicy.ignoreNew:
        return Future.error(
          StateError('A request with key "$key" is already in flight.'),
        );
      case DeduplicationPolicy.replacePrevious:
        _inFlight.remove(key);
        break;
    }
  }

  final future = operation();
  _inFlight[key] = future.then<Object?>((v) => v).whenComplete(() {
    if (identical(_inFlight[key], _inFlight[key])) {
      _inFlight.remove(key);
    }
  });
  return future;
}