Future generateAndRun()

in build_runner/lib/src/build_script_generate/bootstrap.dart [29:124]
88 lines of code
10 McCabe index (conditional complexity)

Future<int> generateAndRun(
  List<String> args, {
  Logger? logger,
  Future<String> Function() generateBuildScript = generateBuildScript,
  void Function(Object error, StackTrace stackTrace) handleUncaughtError =
      _defaultHandleUncaughtError,
}) async {
  logger ??= _logger;
  ReceivePort? exitPort;
  ReceivePort? errorPort;
  ReceivePort? messagePort;
  StreamSubscription? errorListener;
  int? scriptExitCode;

  var tryCount = 0;
  var succeeded = false;
  while (tryCount < 2 && !succeeded) {
    tryCount++;
    exitPort?.close();
    errorPort?.close();
    messagePort?.close();
    await errorListener?.cancel();

    try {
      var buildScript = File(scriptLocation);
      var oldContents = '';
      if (buildScript.existsSync()) {
        oldContents = buildScript.readAsStringSync();
      }
      var newContents = await generateBuildScript();
      // Only trigger a build script update if necessary.
      if (newContents != oldContents) {
        buildScript
          ..createSync(recursive: true)
          ..writeAsStringSync(newContents);
      }
    } on CannotBuildException {
      return ExitCode.config.code;
    }

    scriptExitCode = await _createKernelIfNeeded(logger);
    if (scriptExitCode != 0) return scriptExitCode!;

    exitPort = ReceivePort();
    errorPort = ReceivePort();
    messagePort = ReceivePort();
    errorListener = errorPort.listen((e) {
      final error = e[0] as Object? ?? NullThrownError();
      final trace = Trace.parse(e[1] as String).terse;

      handleUncaughtError(error, trace);
      if (scriptExitCode == 0) scriptExitCode = 1;
    });
    try {
      await Isolate.spawnUri(Uri.file(p.absolute(scriptKernelLocation)), args,
          messagePort.sendPort,
          errorsAreFatal: true,
          onExit: exitPort.sendPort,
          onError: errorPort.sendPort);
      succeeded = true;
    } on IsolateSpawnException catch (e) {
      if (tryCount > 1) {
        logger.severe(
            'Failed to spawn build script after retry. '
            'This is likely due to a misconfigured builder definition. '
            'See the generated script at $scriptLocation to find errors.',
            e);
        messagePort.sendPort.send(ExitCode.config.code);
        exitPort.sendPort.send(null);
      } else {
        logger.warning(
            'Error spawning build script isolate, this is likely due to a Dart '
            'SDK update. Deleting precompiled script and retrying...');
      }
      await File(scriptKernelLocation).rename(scriptKernelCachedLocation);
    }
  }

  StreamSubscription? exitCodeListener;
  exitCodeListener = messagePort!.listen((isolateExitCode) {
    if (isolateExitCode is int) {
      scriptExitCode = isolateExitCode;
    } else {
      throw StateError(
          'Bad response from isolate, expected an exit code but got '
          '$isolateExitCode');
    }
    exitCodeListener!.cancel();
    exitCodeListener = null;
  });
  await exitPort?.first;
  await errorListener?.cancel();
  await exitCodeListener?.cancel();

  return scriptExitCode ?? 1;
}