Tag Archives: boost log

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Using Boost Logging

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Simple std::cout works great but there are few problems:

  1. Logging output only goes to console
  2. If program runs for a long time via cron / scheduler then output has to be redirected to a file
  3. Doing so might cause a large log with filesystem lock for which the program has to be stopped before it can be cleaned

Here’s how to use the Boost Logging library:

#include 

#include "boost/log/trivial.hpp"
#include "boost/log/utility/setup.hpp"

using namespace std;

int main() {
  // Output message to console
  boost::log::add_console_log(
    cout, 
    boost::log::keywords::format = "[%TimeStamp%]: %Message%",
    boost::log::keywords::auto_flush = true
  );

  // Output message to file, rotates when file reached 1mb or at midnight every day. Each log file
  // is capped at 1mb and total is 20mb
  boost::log::add_file_log (
    boost::log::keywords::file_name = "MyApp_%3N.log",
    boost::log::keywords::rotation_size = 1 * 1024 * 1024,
    boost::log::keywords::max_size = 20 * 1024 * 1024,
    boost::log::keywords::time_based_rotation = boost::log::sinks::file::rotation_at_time_point(0, 0, 0),
    boost::log::keywords::format = "[%TimeStamp%]: %Message%",
    boost::log::keywords::auto_flush = true
  );

  boost::log::add_common_attributes();

  // Only output message with INFO or higher severity
  boost::log::core::get()->set_filter(
    boost::log::trivial::severity >= boost::log::trivial::info
  );

  // Output some simple log message
  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";
}

See Also