ホットリスタートをした回数分だけfirebaseのDBアクセスが重複問題 – 開発日記(86)

Error: TypeError: Instance of '_Exception': type '_Exception' is not a subtype of type 'JavaScriptObject'

class _FirebaseStream<T> extends Stream<T> {
  final Stream<T> inner;

  _FirebaseStream(this.inner);

  // during regular execution this variable doesn't change, only hot restart could affect it
  static final _timestamp = DateTime.now();

  @override
  StreamSubscription<T> listen(void Function(T event)? onData, {Function? onError, void Function()? onDone, bool? cancelOnError}) {
    StreamSubscription<T>? subscription;
    final timestamp = _timestamp;

    subscription = inner.listen(
          (event) {
        if (timestamp == _timestamp) {
          onData?.call(event);
        } else {
          subscription?.cancel();
        }
      },
      onError: (error) {
        if (timestamp == _timestamp) {
          onError?.call(error);
        } else {
          subscription?.cancel();
        }
      },
      onDone: onDone,
      cancelOnError: cancelOnError,
    );
    return subscription;
  }
}

extension FirebaseStreamWorkaround<T> on Stream<T> {
  Stream<T> get usingFirebaseWorkaround {
    if (kReleaseMode) {
      return this;
    } else {
      return _FirebaseStream(this);
    }
  }
}