immich_mirror/mobile/lib/utils/async_mutex.dart

import 'dart:async';

/// Async mutex to guarantee actions are performed sequentially and do not interleave
class AsyncMutex {
  Future _running = Future.value(null);
  int _enqueued = 0;

  // ignore: unused-code
  int get enqueued => _enqueued;

  /// Execute [operation] exclusively, after any currently running operations.
  /// Returns a [Future] with the result of the [operation].
  Future<T> run<T>(Future<T> Function() operation) {
    final completer = Completer<T>();
    _enqueued++;
    unawaited(
      _running.whenComplete(() {
        _enqueued--;
        completer.complete(Future<T>.sync(operation));
      }),
    );
    return _running = completer.future;
  }
}