cpp-logger/logger.cpp

//
//  logger.cpp
//  logger
//
//  Created by Sam Jaffe on 9/3/16.
//

#include <sys/time.h>

#include <cassert>
#include <cmath>
#include <ctime>
#include <map>
#include <stdexcept>

#include "expect/expect.hpp"
#include "logger.hpp"
#include "properties.hpp"

namespace logging {
#define X(l) \
case logging::L##l: \
return #l;
  
  const char* level_header(log_level l) {
    assert(l != logging::LNONE);
    switch (l) {
        X(FATAL)
        X(CRITICAL)
        X(ERROR)
        X(WARNING)
        X(INFO)
        X(DEBUG)
        X(TRACE)
        X(NONE)
    }
  }
  
#undef X
}

namespace {
  struct timeval now( ) {
    struct timeval tv;
    gettimeofday( &tv, nullptr );
    return tv;
  }
}

namespace logging {
  class multiple_bindings : public std::logic_error {
    using std::logic_error::logic_error;
  };
  
  //  extern logger_impl& _logger_impl_shared_instance();
  extern _binding _default_logger_impl;
  static _binding _impl_binding = nullptr;
  
  bool bind_logger_impl(_binding impl) {
    expects(_impl_binding == nullptr, multiple_bindings,
            "Only one logger implementation may be bound");
    _impl_binding = impl;
    return true;
  }
  
  logger_impl& _i_get_shared_instance() {
    if (_impl_binding == nullptr) {
      return _default_logger_impl();
    } else {
      return _impl_binding();
    }
  }
}

namespace logging {
  logger& logger::instance() {
    static logger instance;
    return instance;
  }
  
  logger& logger::instance(std::string const & name) {
    using p_logger = std::unique_ptr<logger>;
    using store = std::map<std::string, p_logger>;
    static store instances;
    store::iterator it;
    if ((it = instances.find(name)) != instances.end()) {
      return *(it->second);
    }
    return *(instances.emplace(std::make_pair(name, p_logger(new logger(name)))).first->second);
  }
  
  
  logger::logger(std::string const & name)
  : min_level_(LDEBUG)
  , logger_name_(name)
  , impl_(_i_get_shared_instance())
  {
  }
  
  logger::~logger() {
    flush();
  }
  
  void logger::log(log_level ll, location_info info, std::string const & msg) {
    impl_.write({ now( ), ll, info, logger_name_.c_str(), msg });
  }
  
  bool logger::should_log( log_level ll ) const {
    return ll < min_level_ && impl_.should_log( ll );
  }
  
  void logger::flush() {
    impl_.flush();
  }
}

namespace logging {
  
  bool logger_impl::should_log( log_level ll ) const {
    return ll < min_log_level;
  }
}

void test() {
  logging::logger & LOG = logging::logger::instance( );
  LOG.log(logging::LERROR, "{}", 5);
}