lock method

Future<void> lock(Future<void> criticalSection())

Implementation

Future<void> lock(Future<void> Function() criticalSection) async { // Changed to Future<void> Function()
  while (_completer != null) {
    await _completer!.future;
  }
  _completer = Completer<void>();
  try {
    await criticalSection();
  } finally {
    if (_completer != null && !_completer!.isCompleted) {
      _completer!.complete();
    }
    _completer = null;
  }
}