handleEventLoopCallback method

  1. @visibleForTesting
bool handleEventLoopCallback()

Execute the highest-priority task, if it is of a high enough priority.

Returns false if the scheduler is locked, or if there are no tasks remaining.

Returns true otherwise, including when no task is executed due to priority being too low.

Implementation

@visibleForTesting
@pragma('vm:notify-debugger-on-exception')
bool handleEventLoopCallback() {
  if (_taskQueue.isEmpty || locked) {
    return false;
  }
  final _TaskEntry<dynamic> entry = _taskQueue.first;
  if (schedulingStrategy(priority: entry.priority, scheduler: this)) {
    try {
      _taskQueue.removeFirst();
      entry.run();
    } catch (exception, exceptionStack) {
      StackTrace? callbackStack;
      assert(() {
        callbackStack = entry.debugStack;
        return true;
      }());
      FlutterError.reportError(FlutterErrorDetails(
        exception: exception,
        stack: exceptionStack,
        library: 'scheduler library',
        context: ErrorDescription('during a task callback'),
        informationCollector: (callbackStack == null) ? null : () {
          return <DiagnosticsNode>[
            DiagnosticsStackTrace(
              '\nThis exception was thrown in the context of a scheduler callback. '
              'When the scheduler callback was _registered_ (as opposed to when the '
              'exception was thrown), this was the stack',
              callbackStack,
            ),
          ];
        },
      ));
    }
    return _taskQueue.isNotEmpty;
  }
  return true;
}