boost log to print source code file name and line number

Question

I'm using Boost(1.55.0) Logging in my C++ application. I have been able to generate log of this format

[2014-Jul-15 10:47:26.137959]: <debug>  A regular message

I want to be able to add source file name and line number where the log is generated.

[2014-Jul-15 10:47:26.137959]: <debug> [filename:line_no] A regular message

example:

[2014-Jul-15 10:47:26.137959]: <debug> [helloworld.cpp : 12] A regular message

Source Code:

#include <boost/log/core.hpp>
#include <boost/log/trivial.hpp>
#include <boost/log/expressions.hpp>
#include <boost/log/sinks/text_file_backend.hpp>
#include <boost/log/utility/setup/file.hpp>
#include <boost/log/utility/setup/common_attributes.hpp>
#include <boost/log/sources/severity_logger.hpp>
#include <boost/log/sources/record_ostream.hpp>
#include <boost/log/expressions.hpp>
#include <boost/log/support/date_time.hpp>
#include <boost/log/attributes/attribute.hpp>
#include <boost/log/attributes/attribute_cast.hpp>
#include <boost/log/attributes/attribute_value.hpp>
#include <boost/make_shared.hpp>
#include <boost/property_tree/ptree.hpp>

namespace logging = boost::log;
namespace src = boost::log::sources;
namespace sinks = boost::log::sinks;
namespace keywords = boost::log::keywords;

void init()
{
    logging::add_file_log
    (
        keywords::file_name = "sample_%N.log",                                        /*< file name pattern >*/
        keywords::rotation_size = 10*1024*1204,                                 /*< rotate files every 10 MiB... >*/
        keywords::time_based_rotation = sinks::file::rotation_at_time_point(0, 0, 0), /*< ...or at midnight >*/
        keywords::format =
        (
            boost::log::expressions::stream
                << boost::log::expressions::format_date_time< boost::posix_time::ptime >("TimeStamp", "%Y-%m-%d_%H:%M:%S.%f")
                << ": <" << boost::log::trivial::severity << "> "
                << boost::log::expressions::smessage
        )
    );
}

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

    using namespace logging::trivial;
    src::severity_logger< severity_level > lg;

    BOOST_LOG_SEV(lg, debug) << "A regular message";
    return 0;
}

Answer 1

As Horus pointed out, you can use attributes to log file and line numbers. However it is best to avoid using multi-statements macros to avoid problems with expressions like this:

if (something)    LOG_FILE_LINE(debug) << "It's true"; // Only the first statement is conditional! 

You can do better creating a macro that leverages the underlying behavior of the Boost Log library. For example, BOOST_LOG_SEV is:

#define BOOST_LOG_SEV(logger, lvl) BOOST_LOG_STREAM_SEV(logger, lvl) #define BOOST_LOG_STREAM_SEV(logger, lvl)\     BOOST_LOG_STREAM_WITH_PARAMS((logger), (::boost::log::keywords::severity = (lvl))) 

Using BOOST_LOG_STREAM_WITH_PARAMS you can set and get more attributes, like this:

// New macro that includes severity, filename and line number #define CUSTOM_LOG(logger, sev) \    BOOST_LOG_STREAM_WITH_PARAMS( \       (logger), \          (set_get_attrib("File", path_to_filename(__FILE__))) \          (set_get_attrib("Line", __LINE__)) \          (::boost::log::keywords::severity = (boost::log::trivial::sev)) \    )  // Set attribute and return the new value template<typename ValueType> ValueType set_get_attrib(const char* name, ValueType value) {    auto attr = logging::attribute_cast<attrs::mutable_constant<ValueType>>(logging::core::get()->get_thread_attributes()[name]);    attr.set(value);    return attr.get(); }  // Convert file path to only the filename std::string path_to_filename(std::string path) {    return path.substr(path.find_last_of("/\\")+1); } 

The complete source code is:

#include <boost/log/trivial.hpp> #include <boost/log/sources/severity_logger.hpp> #include <boost/log/utility/setup/file.hpp> #include <boost/log/utility/setup/console.hpp> #include <boost/log/expressions.hpp> #include <boost/log/utility/setup/common_attributes.hpp> #include <boost/log/attributes/mutable_constant.hpp> #include <boost/date_time/posix_time/posix_time_types.hpp> #include <boost/log/support/date_time.hpp> #include <boost/log/attributes/mutable_constant.hpp>  namespace logging  = boost::log; namespace attrs    = boost::log::attributes; namespace expr     = boost::log::expressions; namespace src      = boost::log::sources; namespace keywords = boost::log::keywords;  // New macro that includes severity, filename and line number #define CUSTOM_LOG(logger, sev) \    BOOST_LOG_STREAM_WITH_PARAMS( \       (logger), \          (set_get_attrib("File", path_to_filename(__FILE__))) \          (set_get_attrib("Line", __LINE__)) \          (::boost::log::keywords::severity = (boost::log::trivial::sev)) \    )  // Set attribute and return the new value template<typename ValueType> ValueType set_get_attrib(const char* name, ValueType value) {    auto attr = logging::attribute_cast<attrs::mutable_constant<ValueType>>(logging::core::get()->get_thread_attributes()[name]);    attr.set(value);    return attr.get(); }  // Convert file path to only the filename std::string path_to_filename(std::string path) {    return path.substr(path.find_last_of("/\\")+1); }  void init() {    // New attributes that hold filename and line number    logging::core::get()->add_thread_attribute("File", attrs::mutable_constant<std::string>(""));    logging::core::get()->add_thread_attribute("Line", attrs::mutable_constant<int>(0));     logging::add_file_log (     keywords::file_name = "sample.log",     keywords::format = (      expr::stream       << expr::format_date_time<boost::posix_time::ptime>("TimeStamp", "%Y-%m-%d_%H:%M:%S.%f")       << ": <" << boost::log::trivial::severity << "> "       << '['   << expr::attr<std::string>("File")                << ':' << expr::attr<int>("Line") << "] "       << expr::smessage     )    );    logging::add_common_attributes(); }  int main(int argc, char* argv[]) {    init();    src::severity_logger<logging::trivial::severity_level> lg;     CUSTOM_LOG(lg, debug) << "A regular message";    return 0; } 

This generate a log like this:

2015-10-15_15:25:12.743153: <debug> [main.cpp:61] A regular message 

Answer 2

As user2943014 pointed out, using scopes prints the line number where you opened that scope, not the line number where you emitted a log message using BOOST_LOG_SEV.

You can use attributes to log the line numbers etc at the place you actually logged.

Register global attributes in your logging initialization function:

using namespace boost::log; core::get()->add_global_attribute("Line", attributes::mutable_constant<int>(5)); core::get()->add_global_attribute("File", attributes::mutable_constant<std::string>("")); core::get()->add_global_attribute("Function", attributes::mutable_constant<std::string>("")); 

Setting these attributes in your logging macro:

#define logInfo(methodname, message)                          \   LOG_LOCATION;                                               \   BOOST_LOG_SEV(_log, boost::log::trivial::severity_level::trace) << message  #define LOG_LOCATION                            \   boost::log::attribute_cast<boost::log::attributes::mutable_constant<int>>(boost::log::core::get()->get_global_attributes()["Line"]).set(__LINE__); \   boost::log::attribute_cast<boost::log::attributes::mutable_constant<std::string>>(boost::log::core::get()->get_global_attributes()["File"]).set(__FILE__); \   boost::log::attribute_cast<boost::log::attributes::mutable_constant<std::string>>(boost::log::core::get()->get_global_attributes()["Function"]).set(__func__); 

Not exactly beautiful, but it works and it was a long way for me. It's a pity boost doesn't offer this feature out of the box.

Answer 3

I would suggest to use the boost::log::add_value() function.

Define:

#define LOG_LOCATION(LEVEL, MSG)      \
  BOOST_LOG_SEV(logger::get(), LEVEL)     \
    << boost::log::add_value("Line", __LINE__)          \
    << boost::log::add_value("File", __FILE__)          \
    << boost::log::add_value("Function", __FUNCTION__) << MSG

And then you can format it as follows:

boost::log::add_common_attributes();

boost::log::register_simple_filter_factory<boost::log::trivial::severity_level, char>("Severity");
boost::log::register_simple_formatter_factory<boost::log::trivial::severity_level, char>("Severity");

auto syslog_format(
    boost::log::expressions::stream <<
        "["   << boost::log::expressions::format_date_time< boost::posix_time::ptime >("TimeStamp", "%Y-%m-%d %H:%M:%S") <<
        "] [" << boost::log::expressions::attr<boost::log::attributes::current_thread_id::value_type>("ThreadID") << 
        "] [" << std::left << std::setw(7) << std::setfill(' ') << boost::log::trivial::severity <<
        "] "  << boost::log::expressions::smessage <<
        " ("  << boost::log::expressions::attr<std::string>("Filename") <<
        ":"   << boost::log::expressions::attr<int>("Line") <<
        ":"   << boost::log::expressions::attr<std::string>("Function") <<
        ")"
);

boost::log::add_file_log(
    boost::log::keywords::file_name  = "sys_%d_%m_%Y.%N.log",
    boost::log::keywords::format = syslog_format
);

No need to add global attributes, and you can format it easily as seen above. I find this is a good compromise between other's solutions and the raw __FILE__ __LINE__ approach.

Full example here.