Boost.Log - コンソール画面とファイルにロギング

Boost.Log で add_file_log を使ってログをファイル出力するように変更すると，コンソール画面への出力が無くなってしまいます．コンソール画面とファイルの両方に出力したい場合には，下記のようにそれぞれの sink を作成し，追加してあげる必要があります．

下記のプログラムを実行するとコンソール画面とファイルそれぞれに出力されます．

#include <boost/log/core.hpp>
#include <boost/log/expressions.hpp>
#include <boost/log/trivial.hpp>
#include <boost/log/sinks/sync_frontend.hpp>
#include <boost/log/sinks/text_file_backend.hpp>
#include <boost/log/sinks/text_ostream_backend.hpp>
#include <boost/log/support/date_time.hpp>
#include <boost/log/utility/empty_deleter.hpp>
#include <boost/log/utility/setup/common_attributes.hpp>
#include <boost/log/utility/setup/common_attributes.hpp>
#include <boost/log/utility/setup/file.hpp>

void InitLogging()
{
  namespace logging  = boost::log;
  namespace expr     = boost::log::expressions;
  namespace sinks    = boost::log::sinks;
  namespace keywords = boost::log::keywords;

  logging::add_common_attributes();

  boost::shared_ptr<logging::core> core = logging::core::get();

  boost::shared_ptr<sinks::text_ostream_backend> ostream_backend =
    boost::make_shared<sinks::text_ostream_backend>();
  ostream_backend->add_stream(
      boost::shared_ptr<std::ostream>(&std::clog, logging::empty_deleter()));
  ostream_backend->auto_flush(true);

  typedef sinks::synchronous_sink<sinks::text_ostream_backend> sink_ostream_t;
  boost::shared_ptr<sink_ostream_t> sink_ostream(new sink_ostream_t(ostream_backend));
  sink_ostream->set_formatter(
    expr::format("[%1%] [%2%]\t%3%")
      % expr::format_date_time<boost::posix_time::ptime>("TimeStamp", "%Y-%m-%d %H:%M:%S.%f")
      % logging::trivial::severity
      % expr::message);

  core->add_sink(sink_ostream);

  boost::shared_ptr<sinks::text_file_backend> text_backend =
    boost::make_shared<sinks::text_file_backend>(
      keywords::file_name = "log/%Y-%m-%d_%H-%M.log",
      keywords::rotation_size = 10 * 1024 * 1024,
      keywords::time_based_rotation = sinks::file::rotation_at_time_point(0, 0, 0));

  text_backend->auto_flush(true);

  typedef sinks::synchronous_sink<sinks::text_file_backend> sink_text_t;
  boost::shared_ptr<sink_text_t> sink_text(new sink_text_t(text_backend));

  sink_text->set_formatter(
    expr::format("[%1%] [%2%]\t%3%")
      % expr::format_date_time<boost::posix_time::ptime>("TimeStamp", "%Y-%m-%d %H:%M:%S.%f")
      % logging::trivial::severity
      % expr::message);

  core->add_sink(sink_text);
}

int main() {

  InitLogging();

  BOOST_LOG_TRIVIAL(trace) << "A trace severity message";
  BOOST_LOG_TRIVIAL(debug) << "A debug severity message";
  BOOST_LOG_TRIVIAL(info) << "An informational severity message";
  BOOST_LOG_TRIVIAL(warning) << "A warning severity message";
  BOOST_LOG_TRIVIAL(error) << "An error severity message";
  BOOST_LOG_TRIVIAL(fatal) << "A fatal severity message";

  return 0;
}