logger.hpp

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/*
 * Copyright (C) 2013 Evidence Srl - www.evidence.eu.com
 *
 * Boost Software License - Version 1.0 - August 17th, 2003
 *
 * Permission is hereby granted, free of charge, to any person or organization
 * obtaining a copy of the software and accompanying documentation covered by
 * this license (the "Software") to use, reproduce, display, distribute,
 * execute, and transmit the Software, and to prepare derivative works of the
 * Software, and to permit third-parties to whom the Software is furnished to
 * do so, all subject to the following:
 * 
 * The copyright notices in the Software and this entire statement, including
 * the above license grant, this restriction and the following disclaimer,
 * must be included in all copies of the Software, in whole or in part, and
 * all derivative works of the Software, unless such copies or derivative
 * works are solely in the form of machine-executable object code generated by
 * a source language processor.
 * 
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
 * SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
 * FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 * DEALINGS IN THE SOFTWARE.
 */

#ifndef LOGGER_HPP_
#define LOGGER_HPP_

#include <fstream>
#include <ostream>
#include <string>
#include <sstream>
#include <sys/time.h>
#include <mutex>
#include <chrono>

/**
 * Log levels:
 * 0: no logging
 * 1: log only errors messages
 * 2: log warnings and error messages
 * 3: log debug, warning and error messages
 */
#ifndef LOG_LEVEL
#define LOG_LEVEL 3
#endif

// Uncomment for single-thread log:
#define LOGGER_MULTITHREAD

/**
 * @brief Macro to set the file used for logging.
 *
 * @param Base name of the file used for logging (e.g. "/tmp/myproject")
 *
 * Example of configuration of the Logger: *
 * \code
 *      LOG_FILE("/tmp/myproject);
 * \endcode
 */
#define LOG_FILE(outputFile) { \
        log::Logger::getInstance().setFile(outputFile); \
        }



#if (LOG_LEVEL < 1) || (defined NDEBUG)
        #define ERROR(...)
#else
        /**
         * @brief Macro to print error messages.
         *
         * Example of usage:
         * \code
         *      ERROR("hello " << "world");
         * \endcode
         */
        #define ERROR(msg) { \
                std::ostringstream __debug_stream__; \
                __debug_stream__ << "[ERROR]\t"; \
                __debug_stream__ << msg; \
                log::Logger::getInstance().print(__FILE__, __LINE__, \
                                __debug_stream__.str()); \
                }
#endif

#if (LOG_LEVEL < 2) || (defined NDEBUG)
        #define WARNING(...)
#else
        /**
         * @brief Macro to print warning messages.
         *
         * Example of usage:
         * \code
         *      WARNING("hello " << "world");
         * \endcode
         */
        #define WARNING(msg) { \
                std::ostringstream __debug_stream__; \
                __debug_stream__ << "[WARNING]\t"; \
                __debug_stream__ << msg; \
                log::Logger::getInstance().print(__FILE__, __LINE__, \
                                __debug_stream__.str()); \
                }
#endif




#if (LOG_LEVEL < 3) || (defined NDEBUG)
        #define DEBUG(...)
#else
        /**
         * @brief Macro to print debug messages.
         *
         * Example of usage:
         * \code
         *      DEBUG("hello " << "world");
         * \endcode
         */
        #define DEBUG(msg) { \
                std::ostringstream __debug_stream__; \
                __debug_stream__ << "[DEBUG]\t"; \
                __debug_stream__ << msg; \
                log::Logger::getInstance().print(__FILE__, __LINE__, \
                                __debug_stream__.str()); \
                }
#endif



namespace log {



/**
 * @brief Simple logger to log messages on file and console.
 *
 * This is the implementation of a simple logger in C++. It is implemented 
 * as a Singleton, so it can be easily called through the DEBUG, WARNING
 * and ERROR macros.
 * It is Pthread-safe.
 * It allows to log on both file and screen.
 *
 * Example of configuration of the Logger: *
 * \code
 *      LOG_FILE("/tmp/myproject);
 * \endcode
 *
 * Example of usage of the Logger:
 * \code
 *      DEBUG("hello " << "world");
 * \endcode
 */
class Logger
{
public:
        static Logger& getInstance();

        void print(     const std::string&      sourceFile,
                        const int               codeLine,
                        const std::string&      message);

        void setFile (const std::string&        outputFile);

private:
        Logger();
        ~Logger();

#ifdef LOGGER_MULTITHREAD
        /**
         * @brief Lock for mutual exclusion between different threads
         */
        static std::mutex lock_;
#endif
        
        /**
         * @brief Pointer to the unique Logger (i.e., Singleton)
         */
        static Logger* m_;

        /**
         * @brief Initial part of the name of the file used for Logging.
         *
         * Date and time are automatically appended.
         */
        std::string logFile_;

        /**
         * @brief Stream used when logging on a file
         */
        std::ofstream out_;

        /**
         * @brief Initial time (used to print relative times)
         */
        std::chrono::time_point<std::chrono::system_clock> initialTime_;

        /**
         * @brief Method to lock in case of multithreading
         */
        inline static void lock();

        /**
         * @brief Method to unlock in case of multithreading
         */
        inline static void unlock();
};

} // log

#endif // LOGGER_HPP_