boost log file cannot create sample.log file

Question

I've been struggling with boost log for a while now - I got their simple example writing to a log file (http://boost-log.sourceforge.net/libs/log/example/doc/tutorial_file.cpp).The problem is when I use this part of the code ...

void init()
{
    logging::add_file_log("sample.log");

    logging::core::get()->set_filter
    (
        logging::trivial::severity >= logging::trivial::info
    );
}

Instead of sample.log file, 00000.log file is created. And when I use this part of the code ...

void init()
{
    logging::add_file_log
    (
        keywords::file_name = "sample_%N.log",
        keywords::rotation_size = 10 * 1024 * 1024,
        keywords::time_based_rotation = sinks::file::rotation_at_time_point(0, 0, 0),
        keywords::format = "[%TimeStamp%]: %Message%"
    );

    logging::core::get()->set_filter
    (
        logging::trivial::severity >= logging::trivial::info
    );
}

I get the following error message: Exception thrown at 0x00007FF787AD0393 in Boost_log_sample.exe: 0xC0000005: Access violation reading location 0x00003BBA20597184.

I'm on win10 64bit and used VS2015,boost_1_71_0.Installing Boost With NuGet (https://www.scalyr.com/blog/getting-started-quickly-c-logging/)

I don't have this problem with boost_1_66_0.

Here's my 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>

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 * 1024,                                   /*< rotate files every 10 MiB... >*/
        keywords::time_based_rotation = sinks::file::rotation_at_time_point(0, 0, 0), /*< ...or at midnight >*/
        keywords::format = "[%TimeStamp%]: %Message%"                                 /*< log record format >*/
    );

    logging::core::get()->set_filter
    (
        logging::trivial::severity >= logging::trivial::info
    );
}


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

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

    BOOST_LOG_SEV(lg, trace) << "A trace severity message";
    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, fatal) << "A fatal severity message";

    return 0;
}

I get the following error message: Exception thrown at 0x00007FF787AD0393 in Boost_log_sample.exe: 0xC0000005: Access violation reading location 0x00003BBA20597184. -- What does the call stack tell you? You should be able to tell where the offending line of code that led to the error by looking at the call stack. — PaulMcKenzie
header file wchar.h, line247: 'return (wchar_t*)memmove(_S1, _S2, _N*sizeof(wchar_t));' — Mohsen Ghahremani Manesh
And what line in your code leads to this error? The purpose of the call stack is to see what series of calls led to the error, not where the error ultimately happens to be. — PaulMcKenzie
@MohsenGhahremaniManesh Sounds like a good place to start debugging. — Ted Lyngmo
Put the line(s) of code in the post, not in the comment section. — PaulMcKenzie

user2580621 user2580621 · Accepted Answer · 2020-03-03T13:58:17

I also stumbled upon the problem of the log being called 00000.log while following the Boost.Log tutorial on a system with Boost 1.72.0 installed, using the code in the tutorial, i.e.:

logging::add_file_log("sample.log");

Additionally, as explained in the question, I could not reproduce the problem on a system with an older version of Boost, 1.67.0 to be precise. The log was named sample.log there.

After some experimentation, I found that on the system with 1.72.0, by using the target_file_name parameter, the log is written to sample.log as desired:

// DO NOT USE IN PRODUCTION, SEE BELOW
logging::add_file_log
(
    keywords::file_name = "sample.log",
    keywords::target_file_name = "sample.log"
);

While I am not too familiar with Boost.Log, it appears that the documentation for the target_file_name parameter implies that this should not be necessary in this case, so the above should likely be seen as a workaround. The target_file_name parameter also doesn't exist on Boost 1.67.0 and below so this workaround will also cause compilation problems there.

So this looks like either a regression or a poorly documented breaking change. It would be interesting if someone more familiar with the library could shed further light on the issue.

EDIT: I have opened an issue upstream: https://github.com/boostorg/log/issues/104

(Unfortunately, I can't reproduce the crash problem in the second half of the question)

boost log file cannot create sample.log file

1 Answers