I am using boost log in my application, and while it has been tricky to configure it is generally working well.
Now however, I would like to add some more advanced filtering logic to my application, and I can't figure it out.
What I would like is to have two "levels" of filtering:
- I am already using a "severity logger" with different levels like
debug,warn,noteetc. This is setup and working. - I would like to add an additional way to filter records by looking at the "named scope" that the record emanates from.
So I would like for instance to be able to see only the records with severity >= note, AND within a NAMED_SCOPE of monthly.
I have successfully been able to use the BOOST_LOG_NAMED_SCOPE() macro and can see the scope stack in the log messages.
I have tried implementing a custom filter with boost::phoenix, but I can't get it to work.
The code I have pasted here compiles in my application (I am working on stripping this down so I can include a complete working minimal example here), but nothing appears to happen in the my_filter(..) function. I think that I am not correctly passing the scope stack into the bound function, because if I put a std::cout statement within the loop over the scope stack, I do not see anything printed.
Minimal example here:
// Excerpt from MyLogger.cpp class
bool my_filter(attrs::named_scope_list const& scopeList) {
for (attrs::named_scope_list::const_iterator iter = scopeList.begin(); iter != scopeList.end(); ++iter) {
if ( (*iter).scope_name == "monthly") {
return true;
}
}
return false;
}
void setup_logging(std::string lvl) {
logging::core::get()->add_global_attribute(
"Scope", attrs::named_scope()
);
logging::add_console_log(
std::clog,
keywords::format = (
expr::stream
<< "[" << severity << "] "
<< "[" << named_scope << "] "
<< expr::smessage
)
);
try {
// set the severity level...
EnumParser<severity_level> parser;
logging::core::get()->set_filter(
(
severity >= parser.parseEnum(lvl) &&
( expr::has_attr("Scope") && ( boost::phoenix::bind(&my_filter, attrs::named_scope::get_scopes() ) ) )
)
);
} catch (std::runtime_error& e) {
std::cout << e.what() << std::endl;
std::cout << "'" << lvl << "' is an invalid --log-level! Must be one of "
<< "[debug, info, note, warn, err, fatal]\n";
exit(-1);
}
}
EDIT Updated with minimal working example:
TEMLogger.h
#ifndef _TEMLOGGER_H_
#define _TEMLOGGER_H_
#include <string>
#include <iostream>
#include <sstream>
#include <cstdlib>
#include <exception>
#include <map>
#include <iomanip>
#include <boost/log/core.hpp>
#include <boost/log/trivial.hpp>
#include <boost/log/sources/global_logger_storage.hpp>
#include <boost/log/sources/severity_feature.hpp>
#include <boost/log/sources/severity_logger.hpp>
#include <boost/log/expressions.hpp>
#include <boost/log/utility/setup/console.hpp>
#include <boost/log/attributes/current_process_id.hpp>
#include <boost/log/attributes/scoped_attribute.hpp>
namespace logging = boost::log;
namespace src = boost::log::sources;
namespace attrs = boost::log::attributes;
namespace keywords = boost::log::keywords;
namespace expr = boost::log::expressions;
namespace sinks = boost::log::sinks;
/** Define the "severity levels" for Boost::Log's severity logger. */
enum severity_level {
debug, info, note, warn, err, fatal
};
/** Convert from string to enum integer value.
*
* Inspired by: http://stackoverflow.com/questions/726664/string-to-enum-in-c
*/
template <typename T>
class EnumParser {
std::map <std::string, T> enumMap;
public:
EnumParser(){};
T parseEnum(const std::string &value) {
typename std::map<std::string, T>::const_iterator iValue = enumMap.find(value);
if (iValue == enumMap.end())
throw std::runtime_error("Value not found in enum!");
return iValue->second;
}
};
BOOST_LOG_GLOBAL_LOGGER(my_logger, src::severity_logger< severity_level >);
/** Send string representing an enum value to stream
*/
std::ostream& operator<< (std::ostream& strm, severity_level lvl);
void setup_logging(std::string lvl);
#endif /* _TEMLOGGER_H_ */
TEMLogger.cpp
#include <boost/log/expressions/formatters/named_scope.hpp>
#include <boost/log/expressions.hpp>
#include <boost/phoenix.hpp>
#include "TEMLogger.h"
// Create the global logger object
src::severity_logger< severity_level > glg;
// Add a bunch of attributes to it
BOOST_LOG_ATTRIBUTE_KEYWORD(severity, "Severity", severity_level)
BOOST_LOG_ATTRIBUTE_KEYWORD(named_scope, "Scope", attrs::named_scope::value_type)
/** Initialize the enum parser map from strings to the enum levels.*/
template<>
EnumParser< severity_level >::EnumParser() {
enumMap["debug"] = debug;
enumMap["info"] = info;
enumMap["note"] = note;
enumMap["warn"] = warn;
enumMap["err"] = err;
enumMap["fatal"] = fatal;
}
std::ostream& operator<< (std::ostream& strm, severity_level level) {
static const char* strings[] = {
"debug", "info", "note", "warn", "err", "fatal"
};
if (static_cast< std::size_t >(level) < sizeof(strings) / sizeof(*strings))
strm << strings[level];
else
strm << static_cast< int >(level);
return strm;
}
bool my_filter(boost::log::value_ref< attrs::named_scope > const& theNamedScope) {
// I think I want something like this:
// for (attrs::named_scope_list::const_iterator iter = scopeList.begin(); iter != scopeList.end(); ++iter) {
// if ( (*iter).scope_name == "monthly"){
// return true;
// }
// }
return true;
}
void setup_logging(std::string lvl) {
logging::core::get()->add_global_attribute(
"Scope", attrs::named_scope()
);
logging::add_console_log(
std::clog,
keywords::format = (
expr::stream
<< "[" << severity << "] "
<< "[" << named_scope << "] "
<< expr::smessage
)
);
try {
// set the severity level...
EnumParser<severity_level> parser;
logging::core::get()->set_filter(
(
severity >= parser.parseEnum(lvl) &&
( expr::has_attr("Scope") && ( boost::phoenix::bind(&my_filter, expr::attr< attrs::named_scope >("Scope").or_none()) ) )
)
);
} catch (std::runtime_error& e) {
std::cout << e.what() << std::endl;
std::cout << "'" << lvl << "' is an invalid --log-level! Must be one of "
<< "[debug, info, note, warn, err, fatal]\n";
exit(-1);
}
}
Main Program
#include "TEMLogger.h"
extern src::severity_logger< severity_level > glg;
void func1() {
BOOST_LOG_NAMED_SCOPE("monthly");
for (int i=0; i<5; ++i) {
BOOST_LOG_SEV(glg, note) << "doing iteration " << i << "within monthly scope!";
}
}
int main(int argc, char* argv[]) {
std::cout << "Setting up logging...\n";
setup_logging("debug");
BOOST_LOG_SEV(glg, note) << "Some message in the main scope";
func1();
BOOST_LOG_SEV(glg, note) << "Another message in the main scope";
return 0;
}
Compile
(I am on a Mac, and due to the way I installed Boost I have to specify the compiler, and the method of linking the Boost libs. YMMV)
g++-4.8 -o TEMLogger.o -c -g -DBOOST_ALL_DYN_LINK TEMLogger.cpp
g++-4.8 -o log-filter-example.o -c -g -DBOOST_ALL_DYN_LINK log-filter-example.cpp
g++-4.8 -o a.out log-filter-example.o TEMLogger.o -L/usr/local/lib -lboost_system-mt -lboost_filesystem-mt -lboost_thread-mt -lboost_log-mt
Run
$ ./a.out
Setting up logging...
[note] [] Some message in the main scope
[note] [monthly] doing iteration 0within monthly scope!
[note] [monthly] doing iteration 1within monthly scope!
[note] [monthly] doing iteration 2within monthly scope!
[note] [monthly] doing iteration 3within monthly scope!
[note] [monthly] doing iteration 4within monthly scope!
[note] [] Another message in the main scope
