Boost C++ Libraries

libs/log/example/doc/tutorial_attributes.cpp

/*
 *          Copyright Andrey Semashev 2007 - 2015.
 * Distributed under the Boost Software License, Version 1.0.
 *    (See accompanying file LICENSE_1_0.txt or copy at
 *          http://www.boost.org/LICENSE_1_0.txt)
 */

#include <cstddef>
#include <string>
#include <ostream>
#include <fstream>
#include <iomanip>
#include <boost/smart_ptr/shared_ptr.hpp>
#include <boost/smart_ptr/make_shared_object.hpp>
#include <boost/date_time/posix_time/posix_time.hpp>
#include <boost/log/core.hpp>
#include <boost/log/expressions.hpp>
#include <boost/log/attributes.hpp>
#include <boost/log/sources/basic_logger.hpp>
#include <boost/log/sources/severity_logger.hpp>
#include <boost/log/sources/record_ostream.hpp>
#include <boost/log/sinks/sync_frontend.hpp>
#include <boost/log/sinks/text_ostream_backend.hpp>
#include <boost/log/attributes/scoped_attribute.hpp>
#include <boost/log/utility/setup/common_attributes.hpp>

namespace logging = boost::log;
namespace src = boost::log::sources;
namespace expr = boost::log::expressions;
namespace sinks = boost::log::sinks;
namespace attrs = boost::log::attributes;
namespace keywords = boost::log::keywords;

// We define our own severity levels
enum severity_level
{
    normal,
    notification,
    warning,
    error,
    critical
};

BOOST_LOG_ATTRIBUTE_KEYWORD(line_id, "LineID", unsigned int)
BOOST_LOG_ATTRIBUTE_KEYWORD(severity, "Severity", severity_level)
BOOST_LOG_ATTRIBUTE_KEYWORD(tag_attr, "Tag", std::string)
BOOST_LOG_ATTRIBUTE_KEYWORD(scope, "Scope", attrs::named_scope::value_type)
BOOST_LOG_ATTRIBUTE_KEYWORD(timeline, "Timeline", attrs::timer::value_type)

void logging_function()
{
    src::severity_logger< severity_level > slg;

    BOOST_LOG_SEV(slg, normal) << "A regular message";
    BOOST_LOG_SEV(slg, warning) << "Something bad is going on but I can handle it";
    BOOST_LOG_SEV(slg, critical) << "Everything crumbles, shoot me now!";
}

//[ example_tutorial_attributes_named_scope
void named_scope_logging()
{
    BOOST_LOG_NAMED_SCOPE("named_scope_logging");

    src::severity_logger< severity_level > slg;

    BOOST_LOG_SEV(slg, normal) << "Hello from the function named_scope_logging!";
}
//]

//[ example_tutorial_attributes_tagged_logging
void tagged_logging()
{
    src::severity_logger< severity_level > slg;
    slg.add_attribute("Tag", attrs::constant< std::string >("My tag value"));

    BOOST_LOG_SEV(slg, normal) << "Here goes the tagged record";
}
//]

//[ example_tutorial_attributes_timed_logging
void timed_logging()
{
    BOOST_LOG_SCOPED_THREAD_ATTR("Timeline", attrs::timer());

    src::severity_logger< severity_level > slg;
    BOOST_LOG_SEV(slg, normal) << "Starting to time nested functions";

    logging_function();

    BOOST_LOG_SEV(slg, normal) << "Stopping to time nested functions";
}
//]

// The operator puts a human-friendly representation of the severity level to the stream
std::ostream& operator<< (std::ostream& strm, severity_level level)
{
    static const char* strings[] =
    {
        "normal",
        "notification",
        "warning",
        "error",
        "critical"
    };

    if (static_cast< std::size_t >(level) < sizeof(strings) / sizeof(*strings))
        strm << strings[level];
    else
        strm << static_cast< int >(level);

    return strm;
}

void init()
{
    typedef sinks::synchronous_sink< sinks::text_ostream_backend > text_sink;
    boost::shared_ptr< text_sink > sink = boost::make_shared< text_sink >();

    sink->locked_backend()->add_stream(
        boost::make_shared< std::ofstream >("sample.log"));

    sink->set_formatter
    (
        expr::stream
            << std::hex << std::setw(8) << std::setfill('0') << line_id << std::dec << std::setfill(' ')
            << ": <" << severity << ">\t"
            << "(" << scope << ") "
            << expr::if_(expr::has_attr(tag_attr))
               [
                    expr::stream << "[" << tag_attr << "] "
               ]
            << expr::if_(expr::has_attr(timeline))
               [
                    expr::stream << "[" << timeline << "] "
               ]
            << expr::smessage
    );

    logging::core::get()->add_sink(sink);

    // Add attributes
    logging::add_common_attributes();
    logging::core::get()->add_global_attribute("Scope", attrs::named_scope());
}

int main(int, char*[])
{
    init();

    named_scope_logging();
    tagged_logging();
    timed_logging();

    return 0;
}