runPreciseIntervalAsync<T> function

Future<void> runPreciseIntervalAsync<T>(Duration interval, FutureOr<T> callback(T state), { required Completer<void> completer, dynamic state, Duration startBusyAt = const Duration(milliseconds: 1), Stopwatch? sw, })

Run a callback at precise intervals asynchronously. This is a less precise version of runPreciseInterval that uses Future.delayed instead of sleep to reduce the impact on the main thread. The tradeoff is that the callback may be called slightly later than the specified interval.

Implementation

@pragma('vm:unsafe:no-bounds-checks')
Future<void> runPreciseIntervalAsync<T>(
  Duration interval,
  FutureOr<T> Function(T state) callback, {
  required Completer<void> completer,
  dynamic state,
  Duration startBusyAt = const Duration(milliseconds: 1),
  Stopwatch? sw,
}) async {
  sw ??= dartStopwatch;
  sw.start();

  for (int i = 1; true; i++) {
    final nextAwake = interval * i;
    final toSleep = (nextAwake - sw.elapsed) - startBusyAt;
    if (toSleep > Duration.zero) {
      await Future.delayed(toSleep);
    }

    while (sw.elapsed < nextAwake) {}
    // Await to allow the implementer to pause the loop if needed
    state = await callback(state);
    if (completer.isCompleted) {
      return;
    }
  }
}