public async Task <IReadOnlyCollection <Vacancy> > GetHotVacancies() { var key = $"hot_vacancies"; const int size = 5; var result = _cache.Get(key) as IReadOnlyCollection <Vacancy>; if (result == null) { result = await _repository.GetHotVacancies(size); _cache.Set(key, result, GetMemoryCacheEntryOptions()); } return(result); }