Boost Log 2.0 :日志中的严重级别为空

Question

我使用的是Boost-Log 2.0，它与版本1有一些不同，我很难输出"Severity“属性。

我使用的是"Boost.Format-style“格式化程序

"%TimeStamp% [%Uptime%] (%LineID%) <%Severity%>: %Message%"

TimeStamp、LineID和Message是common_attributes。Uptime是我使用attrs::timer()添加的属性。我以为在使用severity_logger时会自动添加Severity，但显然不是，这就是我的问题所在。我得到的是空洞的严重度，例如：

2013-Apr-06 19:21:52.408974 [00:00:00.001337] (3) <>: A warning severity message

请注意空的<>。我曾尝试使用register_simple_formatter_factory添加严重性，但随后得到编译器错误：

error: no matching function for call to ‘register_simple_formatter_factory(const char [9])’

我不明白为什么。

下面是我的代码：

#include <iostream>


#include <boost/log/common.hpp>
#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/sinks/sync_frontend.hpp>
#include <boost/log/sinks/text_ostream_backend.hpp>
#include <boost/log/utility/setup/file.hpp>
#include <boost/log/utility/setup/common_attributes.hpp>
#include <boost/log/utility/setup/formatter_parser.hpp>
#include <boost/log/sources/severity_logger.hpp>
#include <boost/log/sources/severity_feature.hpp>
#include <boost/log/sources/record_ostream.hpp>

#include <boost/log/attributes.hpp>

using namespace std;

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

enum severity_level
{
    DEBUG,
    INFO,
    WARNING,
    ERROR,
    CRITICAL
};

BOOST_LOG_INLINE_GLOBAL_LOGGER_DEFAULT(my_logger, src::severity_logger_mt< severity_level> )

// The formatting logic for the severity level
template< typename CharT, typename TraitsT >
inline std::basic_ostream< CharT, TraitsT >& operator<< (
    std::basic_ostream< CharT, TraitsT >& strm, severity_level lvl)
{
    static const char* const str[] =
    {
        "DEBUG",
        "INFO",
        "WARNING",
        "ERROR",
        "CRITICAL"
    };
    if (static_cast< std::size_t >(lvl) < (sizeof(str) / sizeof(*str)))
        strm << str[lvl];
    else
        strm << static_cast< int >(lvl);
    return strm;
}

void init() {
    // logging::register_simple_formatter_factory< severity_level >("Severity");
    logging::add_file_log(
            keywords::file_name = "blop.log",
            keywords::auto_flush = true,
            keywords::open_mode = (std::ios::out | std::ios::app),
            keywords::format = "%TimeStamp% [%Uptime%] (%LineID%) <%Severity%>: %Message%"
            );
    logging::add_common_attributes();
    logging::core::get()->add_global_attribute("Uptime", attrs::timer());
}

int main(int argc, const char *argv[]) {
    init();
    src::severity_logger_mt< severity_level > lg = my_logger::get();
    BOOST_LOG_SEV(lg, DEBUG) << "A debug severity message";
    BOOST_LOG_SEV(lg, INFO) << "An informational severity message";
    BOOST_LOG_SEV(lg, WARNING) << "A warning severity message";
    BOOST_LOG_SEV(lg, ERROR) << "An error severity message";
    BOOST_LOG_SEV(lg, CRITICAL) << "A critical severity message";
    return 0;
}

请注意注释掉的行：

// logging::register_simple_formatter_factory< severity_level >("Severity");

这会产生所提到的错误。

我用以下命令编译它：

g++ main.cpp -Wall -DBOOST_ALL_DYN_LINK  -lboost_system -lboost_log_setup -lboost_log -lboost_filesystem -lboost_date_time -lboost_thread -o main

Answer 1

遇到了相同的问题(日志文件中的空白%Severity%和尝试添加寄存器函数时出现的相同编译器错误)。我发现对register_simple_formatter_factory的调用应该是：

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

Answer 2

下面是register_simple_formatter_factory函数模板的原型：

template<typename AttributeValueT, typename CharT>
void register_simple_formatter_factory(attribute_name const &);

这意味着您忘记了typename CharT，所以，下面是正确的一个：

logging::register_simple_formatter_factory<severity_level, char>("Severity");

或其他一些字符类型，如wchar_t。

Answer 3

您可以创建自己的后端，并在其上调用set_formatter。这是我的代码，展示了如何做到这一点，以及一些额外的功能，如日志文件清理和自动刷新：

BOOST_LOG_DECLARE_GLOBAL_LOGGER(db_logger, src::severity_logger_mt< dreambridge::log::LogLevel >);

#define LOGGER(level) BOOST_LOG_STREAM_SEV(db_logger::get(), level)
    void InitializeFileLog(const std::string & logDir)
    {   
        boost::shared_ptr< logging::core > loggingCore = logging::core::get();

        db_logger::get().add_attribute(
            "TimeStamp",
            boost::make_shared< attrs::local_clock >());

        string logPath = logDir + "/DreamBridgeSapi2MrcpTts_%N.log";

        boost::shared_ptr< sinks::text_file_backend > backend =
            boost::make_shared< sinks::text_file_backend >(
                // file name pattern
                keywords::file_name = logPath,
                // rotate the file upon reaching 5 MiB size...
                keywords::rotation_size = 5 * 1024 * 1024,
                // ...or at midnight, whichever comes first
                keywords::time_based_rotation = sinks::file::rotation_at_time_point(0, 0, 0)                    
            );

        backend->auto_flush(true);

        // Wrap it into the frontend and register in the core.
        // The backend requires synchronization in the frontend.
        typedef sinks::synchronous_sink< sinks::text_file_backend > sink_t;
        boost::shared_ptr< sink_t > sink(new sink_t(backend));

        loggingCore->add_sink(sink);

        backend->set_formatter(fmt::stream
                        << fmt::date_time< boost::posix_time::ptime >("TimeStamp")
                        << " : [" << fmt::attr< dreambridge::log::LogLevel >("Severity")
                        << "] " << fmt::message()
                        );

        backend->set_file_collector(sinks::file::make_collector(
            // rotated logs will be moved here
            keywords::target = logDir + "/old_logs",
            // oldest log files will be removed if the total size reaches 100 MiB...
            keywords::max_size = 100 * 1024 * 1024,
            // ...or the free space in the target directory comes down to 50 MiB
            keywords::min_free_space = 50 * 1024 * 1024
        ));

        try
        {
            backend->scan_for_files(sinks::file::scan_all);
        }
        catch(std::exception & e)
        {
            LOGGER(emergency) << "exception during scanning : " << e.what();

        }

    }

您还可以将日志记录级别设置为：

void SetLogLevel(dreambridge::log::LogLevel logLevel)
    {
        boost::shared_ptr< logging::core > loggingCore = logging::core::get();

        loggingCore->set_filter
        (
            flt::attr< dreambridge::log::LogLevel >("Severity") <= logLevel
        );
    }

注意:这段代码来自我自己的存储库。dreamdridge是产品名称，因此有了名称空间。