问Boost日志v2中旋转日志的限制大小

EN

void setup_logging( channel_settings_t const& settings
                , std::string const& log_file
                , std::string const& log_level
                )
{
  config_logger_attributes(logging::core::get(), settings, log_level);

  using namespace logging::aux::default_attribute_names;

  //add logging to file (which implicitly deletes the default console logger)
  logging::add_file_log
  (
    keywords::auto_flush = true,
    keywords::open_mode = std::ios::out | std::ios::app,
    keywords::file_name = log_file+"_%N.log",
    keywords::rotation_size = 50 * 1024, // Just for test limit to 50K
    keywords::format = //"%TimeStamp%: [%Channel%] |ThreadId| <%Severity%> %Message%"
      expr::format("%1% : [%2%] |%3%| <%4%> %5%")
      % expr::attr< boost::posix_time::ptime >(timestamp())
      % expr::attr<std::string>(channel())
      % expr::attr<attrs::current_thread_id::value_type>(thread_id())
      % trivial::severity
     % expr::smessage
  )->locked_backend()->set_file_collector
     ( sinks::file::make_collector
       ( keywords::target = "logs"
       , keywords::max_size = 200 * 1024 // just for test limit to 200K
       )
     )
  ;
}