handleEventLoopCallback method

  1. @visibleForTesting
bool handleEventLoopCallback ()
@visibleForTesting

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

Returns true if a task was executed and there are other tasks remaining (even if they are not high-enough priority).

Returns false if no task was executed, which can occur if there are no tasks scheduled, if the scheduler is locked, or if the highest-priority task is of too low a priority given the current schedulingStrategy.

Also returns false if there are no tasks remaining.

Implementation 

@visibleForTesting
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: 'during a task callback',
        informationCollector: (callbackStack == null) ? null : (StringBuffer information) {
          information.writeln(
            '\nThis exception was thrown in the context of a task callback. '
            'When the task callback was _registered_ (as opposed to when the '
            'exception was thrown), this was the stack:'
          );
          FlutterError.defaultStackFilter(callbackStack.toString().trimRight().split('\n')).forEach(information.writeln);
        }
      ));
    }
    return _taskQueue.isNotEmpty;
  }
  return false;
}