How to add timezone info for log entries and log filename

[lijh8]

Hi, how can i add timezone info for log entries:

% expr::attr< boost::posix_time::ptime >("TimeStamp")

and for log filename:

` auto pattern = "_%Y%m%d_%H%M%S_%5N.log"; `

Thanks

log entries:

2023-Jul-02 07:40:38.952122: main.cpp:39: trace msg!
2023-Jul-02 07:40:38.952363: main.cpp:40: debug msg!
2023-Jul-02 07:40:38.952670: main.cpp:41: info msg!
2023-Jul-02 07:40:38.953011: main.cpp:42: warning msg!
2023-Jul-02 07:40:38.953460: main.cpp:43: error msg!
2023-Jul-02 07:40:38.954591: main.cpp:44: fatal msg!

---

filename pattern:

 foo_20230702_074038_00000.log
 foo_20230702_074320_00001.log
 foo_20230702_074320_00002.log
 foo_20230702_074320_00003.log
 foo_20230702_074320_00004.log

---

// log.h:

#ifndef log_h
#define log_h

#include <string>
#include <boost/log/trivial.hpp>

// Andrey Semashev, 2016
// https://stackoverflow.com/questions/35895199/boost-log-and-severity-local-attributes/35919119#35919119
// #define LOG(lg, sev) \
//     BOOST_LOG_SEV(lg, sev) << "[" << __FILE__ << ":" << __LINE__ << "]: "

#define LOG(severity) \
    BOOST_LOG_TRIVIAL(severity) << __FILE__ << ":" << __LINE__ << ": "

void boost_log_init(const std::string log_dir, const std::string name);

#endif

---

// log.cpp

// ../boost_1_82_0/libs/log/example/rotating_file/main.cpp

// $ export LD_LIBRARY_PATH=/home/ljh/Downloads/boost_1_82_0/stage/lib

// #define BOOST_LOG_DYN_LINK 1

#include <stdexcept>
#include <string>
#include <iostream>
#include <memory>
#include <boost/smart_ptr/shared_ptr.hpp>
#include <boost/shared_ptr.hpp>
#include <boost/date_time/posix_time/posix_time.hpp>

#include <boost/log/common.hpp>
#include <boost/log/expressions.hpp>
#include <boost/log/attributes.hpp>
#include <boost/log/sources/logger.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/core/null_deleter.hpp>

#include "log.h"

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

using boost::shared_ptr;

// enum { LOG_RECORDS_TO_WRITE = 10000 };

void boost_log_init(const std::string log_dir, const std::string name) {

    auto format = expr::format("%1%: %2%")
            % expr::attr< boost::posix_time::ptime >("TimeStamp")
            % expr::smessage;

    // Create a text file sink
    typedef sinks::synchronous_sink< sinks::text_file_backend > file_sink;
    auto pattern = "_%Y%m%d_%H%M%S_%5N.log";
    shared_ptr< file_sink > sink(new file_sink(
        keywords::file_name = log_dir + "/" + name + pattern,   // file name pattern
        keywords::target_file_name = name + pattern,            // file name pattern
        keywords::rotation_size = 30 * 1024                     // rotation size, in characters
        ));

    // Set up where the rotated files will be stored
    sink->locked_backend()->set_file_collector(sinks::file::make_collector(
        keywords::target = log_dir,                             // where to store rotated files
        keywords::max_size = 16 * 1024 * 1024,                  // maximum total size of the stored files, in bytes
        keywords::min_free_space = 100 * 1024 * 1024,           // minimum free space on the drive, in bytes
        keywords::max_files = 7                                 // maximum number of stored files
        ));

    // Upon restart, scan the target directory for files matching the file_name pattern
    sink->locked_backend()->scan_for_files();
    sink->set_formatter(format);

    // Add it to the core
    logging::core::get()->add_sink(sink);

    // Add a console sink
    typedef sinks::synchronous_sink< sinks::text_ostream_backend > console_sink;
    shared_ptr< console_sink > consoleSink(new console_sink());
    consoleSink->locked_backend()->add_stream(boost::shared_ptr<std::ostream>(&std::clog, boost::null_deleter()));
    consoleSink->set_formatter(format);

    consoleSink->set_filter(logging::trivial::severity >= logging::trivial::trace);
    logging::core::get()->add_sink(consoleSink);

    // Add some attributes too
    logging::core::get()->add_global_attribute("TimeStamp", attrs::local_clock());

}

[Lastique]

You can't, because Boost.DateTime currently does not provide a way to obtain the current timezone from the system. I'm actually not sure there is a more or less standard way to do this.

If you have a timezone through some external means, you could create an attribute that generates boost::local_time::local_date_time with the time zone, and then use its locale facet to format the date and time with the timezone. You can use the basic_clock attribute with your own traits (see here for examples of clock traits).

There is no workaround for file names. This was already reported in #210.

[lijh8]

#define LOG(severity) \
    now = time(NULL); \
    strftime(tz, sizeof(tz), "%z", localtime(&now)); \
    BOOST_LOG_TRIVIAL(severity) << " " << tz << " " << __FILE__ << ":" << __LINE__ << ": "

I tried adding the timezone in the LOG macro which was written by you in 2016. But it outputs the timezone after severity +0800. It also calls extra functions time() and strftime(). I don't think you'll like it.

2023-Jul-02 20:52:01.079777 [info   ]  +0800 main.cpp:45: info msg!
2023-Jul-02 20:52:01.080239 [warning]  +0800 main.cpp:46: warning msg!
2023-Jul-02 20:52:01.098602 [error  ]  +0800 main.cpp:47: error msg!

[Lastique]

I didn't mean to modify the logging macro, I meant to add your own attribute for timestamps instead of attrs::local_clock, which would contain time zone information, and then format it.