Pool: native error on network cable break.

[PROGrand]

Flutter

Flutter 3.27.2 • channel stable • https://github.com/flutter/flutter.git
Framework • revision 68415ad1d9 (11 days ago) • 2025-01-13 10:22:03 -0800
Engine • revision e672b006cb
Tools • Dart 3.6.1 • DevTools 2.40.2

Probem

Pool does not handle network cable break properly. Native error pass try/catch when network break occurs while there are no executing connections in pool.

Steps to reproduce

1. Connect PC with ethernet cable.
2. Run attached program (replace endpoint args with non-local postges's credentials).
3. Let execute sql couple times.
4. On prompt try disconnect cable in 10 seconds...: disconnect ethernet cable.
5. Loop should continue, but program fails with uncatched error.

Program

pubspec.yaml

name: postgres_exploit
description: postgres_exploit
version: 1.0.0
publish_to: none

environment:
  sdk: ^3.6.1

dependencies:
  postgres: ^3.0.0

dev_dependencies:
  lints: ^4.0.0
  test: ^1.24.0

postgres_exploit.dart:

import 'package:postgres/postgres.dart';

Future<void> main(List<String> arguments) async {
  final pool = Pool.withSelector(
    (context) async => EndpointSelection(
        endpoint: Endpoint(
      host: 'host.com',
      port: 5432,
      database: 'postgres',
      username: 'user',
      password: 'password',
    )),
    settings: PoolSettings(sslMode: SslMode.disable, maxConnectionCount: 1),
  );

  while (true) {
    print('----- ${DateTime.now()}');

    final result = await pool
        .execute(Sql.named('SELECT pg_sleep(1), version()'))
        .then(
          (result) => 'OK: ${result.first}',
        )
        .onError(
      (error, stackTrace) {
        print('Error: $error, $stackTrace');
        return '$error';
      },
    );

    print('Result: $result');

    print('try disconnect cable in 10 seconds...');

    await Future.delayed(Duration(seconds: 10));
  }
}

C:/Programs/flutter/bin/cache/dart-sdk/bin/dart.exe --enable-asserts --no-serve-devtools D:\work\flutter\postgres_exploit\lib\postgres_exploit.dart
----- 2025-01-24 21:01:25.457665
Result: OK: [null, PostgreSQL 13.16 on x86_64-pc-linux-gnu, compiled by Debian clang version 12.0.1, 64-bit]
try disconnect cable in 10 seconds...
----- 2025-01-24 21:01:37.435116
Result: OK: [null, PostgreSQL 13.16 on x86_64-pc-linux-gnu, compiled by Debian clang version 12.0.1, 64-bit]
try disconnect cable in 10 seconds...
----- 2025-01-24 21:01:48.873554
Unhandled exception:
type '(Object, StackTrace) => void' is not a subtype of type '(dynamic) => dynamic' in type cast
#0      _CancelOnErrorSubscriptionWrapper.onError.<anonymous closure>.<anonymous closure> (package:async/src/subscription_stream.dart:82:24)
#1      _RootZone.run (dart:async/zone.dart:1670:54)
#2      _FutureListener.handleWhenComplete (dart:async/future_impl.dart:247:18)
#3      Future._propagateToListeners.handleWhenCompleteCallback (dart:async/future_impl.dart:872:39)
#4      Future._propagateToListeners (dart:async/future_impl.dart:928:11)
#5      Future._addListener.<anonymous closure> (dart:async/future_impl.dart:513:9)
#6      _microtaskLoop (dart:async/schedule_microtask.dart:40:21)
#7      _startMicrotaskLoop (dart:async/schedule_microtask.dart:49:5)
#8      _runPendingImmediateCallback (dart:isolate-patch/isolate_patch.dart:118:13)
#9      _RawReceivePort._handleMessage (dart:isolate-patch/isolate_patch.dart:185:5)

Process finished with exit code 255

[PROGrand]

Problem lies in async package: dart-lang/core#855

[PROGrand]

Fixed in dart-lang/core#855