17 Aug
2010
17 Aug
'10
8:43 p.m.
Hi all,
i am currently trying to use Boost.Log in my application. After fighting the
two last days, I still do not understand how to correctly use the lib. I
would like the result to be the same as the one provided by the example
advanced_use.cpp. So, I wrote a simple class to make some tests.
As I want to use the logging library in a shared library (an application
plugin), I made a simple test: compile the class which uses Log in a shared
library and link an executable against this library. I also have created an
executable which directly compiles the class (so does not link against the
shared library). Basically, I have a test_boost_log class. The constructor
is a copy/paste of the code from the example advanced_use.cpp:
#include "test_boost_log.hpp"
#include <cassert>
#include <iostream>
#include <fstream>
#include <boost/shared_ptr.hpp>
#include <boost/log/common.hpp>
#include <boost/log/filters.hpp>
#include <boost/log/formatters.hpp>
#include <boost/log/attributes.hpp>
#include <boost/log/sinks.hpp>
#include <boost/log/utility/empty_deleter.hpp>
#include <boost/log/utility/scoped_attribute.hpp>
namespace logging = boost::log;
namespace fmt = boost::log::formatters;
namespace flt = boost::log::filters;
namespace sinks = boost::log::sinks;
namespace attrs = boost::log::attributes;
namespace src = boost::log::sources;
namespace keywords = boost::log::keywords;
using boost::shared_ptr;
// Here we define our application severity levels.
enum severity_level
{
normal,
notification,
warning,
error,
critical
};
// 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[] =
{
"normal",
"notification",
"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;
}
int foo(src::logger& lg)
{
BOOST_LOG_FUNCTION();
BOOST_LOG(lg) << "foo is being called";
return 10;
}
test_boost_log::test_boost_log()
{
// For now we only create a text output sink:
typedef sinks::synchronous_sink< sinks::text_ostream_backend > text_sink;
shared_ptr< text_sink > pSink(new text_sink);
{
text_sink::locked_backend_ptr pBackend = pSink->locked_backend();
shared_ptr< std::ostream > pStream(&std::clog,
logging::empty_deleter());
pBackend->add_stream(pStream);
shared_ptr< std::ofstream > pStream2(new std::ofstream("sample.log"));
assert(pStream2->is_open());
pBackend->add_stream(pStream2);
}
logging::core::get()->add_sink(pSink);
src::logger lg;
BOOST_LOG(lg) << "Hello, World!";
pSink->locked_backend()->set_formatter(fmt::stream
<< fmt::attr("LineID") // First an attribute "LineID" is
written to the log
<< " [" << fmt::date_time< boost::posix_time::ptime
>("TimeStamp", "%d.%m.%Y %H:%M:%S.%f")
<< "] [" << fmt::attr< severity_level >("Severity", std::nothrow)
<< "] [" << fmt::time_duration<
boost::posix_time::time_duration >("Uptime")
<< "] [" // then this delimiter separates it from the rest of the line
<< fmt::if_(flt::has_attr("Tag"))
[
fmt::stream << fmt::attr< std::string >("Tag")
<< "] [" // yet another delimiter
]
<< fmt::named_scope("Scope", keywords::iteration = fmt::reverse) << "] "
<< fmt::message()); // here goes the log record text
shared_ptr< logging::attribute > pCounter(new attrs::counter<
unsigned int >(1));
// Since we intend to count all logging records ever made by the
application,
// this attribute should clearly be global.
logging::core::get()->add_global_attribute("LineID", pCounter);
// And similarly add a time stamp
shared_ptr< logging::attribute > pTimeStamp(new attrs::local_clock());
logging::core::get()->add_global_attribute("TimeStamp", pTimeStamp);
// And an up time stopwatch
BOOST_LOG_SCOPED_THREAD_ATTR("Uptime", attrs::timer);
// Let's also track the execution scope from which the records are made
boost::shared_ptr< logging::attribute > pNamedScope(new
attrs::named_scope());
logging::core::get()->add_thread_attribute("Scope", pNamedScope);
// We can mark the current execution scope now - it's the 'main' function
BOOST_LOG_FUNCTION();
// Let's try out the counter attribute and formatting
BOOST_LOG(lg) << "Some log line with a counter";
BOOST_LOG(lg) << "Another log line with the counter";
{
BOOST_LOG_NAMED_SCOPE("Tagging scope");
// Now these lines will be highlighted with the tag
BOOST_LOG(lg) << "Some tagged log line";
BOOST_LOG(lg) << "Another tagged log line";
}
// And this line is not highlighted anymore
BOOST_LOG(lg) << "Now the tag is removed";
pSink->set_filter(
flt::attr< severity_level >("Severity", std::nothrow) >=
warning // Write all records with "warning" severity or higher
|| flt::attr< std::string >("Tag",
std::nothrow).begins_with("IMPORTANT")); // ...or specifically tagged
src::severity_logger< severity_level > slg;
// These two lines test filtering based on severity
BOOST_LOG_SEV(slg, normal) << "A normal severity message, will not
pass to the output";
BOOST_LOG_SEV(slg, error) << "An error severity message, will pass
to the output";
{
// Next we try if the second condition of the filter works
// We mark following lines with a tag
BOOST_LOG_SCOPED_THREAD_TAG("Tag", std::string, "IMPORTANT MESSAGES");
BOOST_LOG(slg) << "Some really urgent line";
}
pSink->reset_filter();
// And moreover, it is possible to nest logging records. For
example, this will
// be processed in the order of evaluation:
BOOST_LOG(lg) << "The result of foo is " << foo(lg);
}
I have added another method to test the logger state:
void test_boost_log::a_test_method_to_see_if_the_logger_is_still_working()
{
src::severity_logger< severity_level > slg;
BOOST_LOG_SEV(slg, error) << "An error severity message, will pass
to the output";
}
My main:
#include "test_boost_log.hpp"
int main(int argc, char** argv)
{
test_boost_log tbl;
tbl.a_test_method_to_see_if_the_logger_is_still_working();
return 0;
}
Here is the output of the program:
Hello, World!
1 [17.08.2010 21:22:43.083302] [] [00:00:00.000076]
[test_boost_log::test_boost_log()] Some log line with a counter
2 [17.08.2010 21:22:43.083445] [] [00:00:00.000217]
[test_boost_log::test_boost_log()] Another log line with the counter
3 [17.08.2010 21:22:43.083484] [] [00:00:00.000256] [Tagged line] [Tagging
scope<-test_boost_log::test_boost_log()] Some tagged log line
4 [17.08.2010 21:22:43.083517] [] [00:00:00.000289] [Tagged line] [Tagging
scope<-test_boost_log::test_boost_log()] Another tagged log line
5 [17.08.2010 21:22:43.083556] [] [00:00:00.000328]
[test_boost_log::test_boost_log()] Now the tag is removed
6 [17.08.2010 21:22:43.083598] [error] [00:00:00.000370]
[test_boost_log::test_boost_log()] An error severity message, will pass to
the output
7 [17.08.2010 21:22:43.083633] [normal] [00:00:00.000405] [IMPORTANT
MESSAGES] [test_boost_log::test_boost_log()] Some really urgent line
9 [17.08.2010 21:22:43.083673] [] [00:00:00.000444] [int
foo(boost::log_mt_posix::sources::logger&)<-test_boost_log::test_boost_log()]
foo is being called
8 [17.08.2010 21:22:43.083668] [] [00:00:00.000440]
[test_boost_log::test_boost_log()] The result of foo is 10
*terminate called after throwing an instance of
'boost::exception_detail::clone_impl<boost::exception_detail::error_info_injector<boost::log_mt_posix::missing_value>
>'*
* what(): Requested attribute value not found*
So, the logger throws, sample.log is created, but empty. The library and the
executable are compiled with
-DBOOST_LOG_USE_CHAR
and
-DBOOST_LOG_DYN_LINK
If someone could help...
Best regards,
Olivier
PS: boost_1.42, log_1.0 (from sourceforge), g++4.3.4, 64bits ubuntu