GApplication.cpp

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/***************************************************************************
 *             GApplication.cpp - GammaLib application base class          *
 * ----------------------------------------------------------------------- *
 *  copyright (C) 2010-2022 by Juergen Knoedlseder                         *
 * ----------------------------------------------------------------------- *
 *                                                                         *
 *  This program is free software: you can redistribute it and/or modify   *
 *  it under the terms of the GNU General Public License as published by   *
 *  the Free Software Foundation, either version 3 of the License, or      *
 *  (at your option) any later version.                                    *
 *                                                                         *
 *  This program is distributed in the hope that it will be useful,        *
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of         *
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the          *
 *  GNU General Public License for more details.                           *
 *                                                                         *
 *  You should have received a copy of the GNU General Public License      *
 *  along with this program.  If not, see <http://www.gnu.org/licenses/>.  *
 *                                                                         *
 ***************************************************************************/
/**
 * @file GApplication.cpp
 * @brief GammaLib application base class
 * @author Juergen Knoedlseder
 */

/* __ Includes ___________________________________________________________ */
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
#include <fcntl.h>         // for file locking
#include <unistd.h>        // access() function
#include <cstdlib>         // exit() function
#include <cstdio>          // std::fopen(), etc. functions
#include <signal.h>        // signal() function
#include "GApplication.hpp"
#include "GTools.hpp"
#include "GFits.hpp"
#include "GFitsHDU.hpp"
#include "GFilename.hpp"
#include "GDaemon.hpp"

/* __ OpenMP section _____________________________________________________ */
#ifdef _OPENMP
#include <omp.h>
#endif

/* __ Constants __________________________________________________________ */

/* __ Globals ____________________________________________________________ */

/* __ Method name definitions ____________________________________________ */

/* __ Macros _____________________________________________________________ */

/* __ Coding definitions _________________________________________________ */

/* __ Debug definitions __________________________________________________ */


/*==========================================================================
 =                                                                         =
 =                         Constructors/destructors                        =
 =                                                                         =
 ==========================================================================*/

/***********************************************************************//**
 * @brief Void constructor
 *
 * Constructs an empty application.
 ***************************************************************************/
GApplication::GApplication(void)
{
    // Initialise members
    init_members();

    // Set statistics
    set_statistics();

    // Return
    return;
}


/***********************************************************************//**
 * @brief Application constructor
 *
 * @param[in] name Application name.
 * @param[in] version Application version.
 *
 * Constructs an application from an application @p name and @p version. The
 * constructor will set the parameter filename to "<name>.par" and the log
 * filename to "<name>".log. The parameters will be loaded from the parameter
 * file.
 *
 * No log file will be opened. To open the log file an explicit call to the
 * logFileOpen() method is required.
 *
 * This constructor should be used for Python scripts.
 ***************************************************************************/
GApplication::GApplication(const std::string& name, const std::string& version)
{
    // Initialise members
    init_members();

    // Set application name and version
    m_name    = name;
    m_version = version;

    // Set default parfile and logfile name
    m_parfile = name+".par";
    m_logfile = name+".log";

    // Load application parameters
    m_pars.load(par_filename());

    // Signal that application parameters have been loaded
    m_pars_loaded = true;

    // Set log filename and chattiness
    set_log_filename();
    set_log_chatter();

    // Set statistics
    set_statistics();

    // Return
    return;
}


/***********************************************************************//**
 * @brief Application constructor
 *
 * @param[in] name Application name.
 * @param[in] version Application version.
 * @param[in] pars Application parameters.
 *
 * Constructs an application from an application @p name and @p version. The
 * constructor will set the parameter filename to "<name>.par" and the log
 * filename to "<name>".log. The parameters will be loaded from the parameter
 * file.
 *
 * No log file will be opened. To open the log file an explicit call to the
 * logFileOpen() method is required.
 *
 * This constructor should be used for Python scripts.
 ***************************************************************************/
GApplication::GApplication(const std::string&      name,
                           const std::string&      version,
                           const GApplicationPars& pars)
{
    // Initialise members
    init_members();

    // Set application name and version
    m_name    = name;
    m_version = version;

    // Set default parfile and logfile name
    m_parfile = name+".par";
    m_logfile = name+".log";

    // Set application parameters
    m_pars = pars;

    // Signal that application parameters have been loaded
    m_pars_loaded = true;

    // Set log filename and chattiness
    set_log_filename();
    set_log_chatter();

    // Set statistics
    set_statistics();

    // Return
    return;
}


/***********************************************************************//**
 * @brief Application constructor
 *
 * @param[in] name Application name.
 * @param[in] version Application version.
 * @param[in] argc Number of command line arguments
 * @param[in] argv Command line arguments
 *
 * Constructs an application from an application @p name, @p version and a
 * number @p argc of command line arguments @p argv.
 *
 * This constructor should be used for C++ applications.
 ***************************************************************************/
GApplication::GApplication(const std::string& name,
                           const std::string& version,
                           int                argc,
                           char*              argv[])
{
    // Initialise members
    init_members();

    // Set application name and version
    m_name    = name;
    m_version = version;

    // Set default parfile and logfile name
    m_parfile = name+".par";
    m_logfile = name+".log";

    // Put arguments in vector string
    m_args.clear();
    for (int i = 0; i < argc; ++i) {
        m_args.push_back(gammalib::strip_whitespace(argv[i]));
    }

    // Catch --help option before doing anything else. The actual action
    // needs to be done by the client, but we skip the loading of the
    // parameter file and the opening of the logger if the help option
    // was specified.
    m_need_help = false;
    if (m_args.size() >= 2) {
        if (m_args[1] == "--help") {
            m_need_help = true;
        }
    }

    // If no --help option has been specified then proceed with loading
    // the parameter file and opening the logger
    if (!m_need_help) {

        // Initialise application parameters
        m_pars.load(par_filename(), m_args);

        // Signal that application parameters have been loaded
        m_pars_loaded = true;

        // Set log filename and chattiness
        set_log_filename();
        set_log_chatter();

    } // endif: no --help option specified

    // Set statistics
    set_statistics();

    // Return
    return;
}


/***********************************************************************//**
 * @brief Copy constructor
 *
 * @param[in] app Application.
 ***************************************************************************/
GApplication::GApplication(const GApplication& app)
{
    // Initialise members
    init_members();

    // Copy members
    copy_members(app);

    // Set statistics
    set_statistics();

    // Return
    return;
}


/***********************************************************************//**
 * @brief Destructor
 ***************************************************************************/
GApplication::~GApplication(void)
{
    // Free members
    free_members();

    // Return
    return;
}


/*==========================================================================
 =                                                                         =
 =                                Operators                                =
 =                                                                         =
 ==========================================================================*/

/***********************************************************************//**
 * @brief Assignment operator
 *
 * @param[in] app Application.
 * @return Application.
 ***************************************************************************/
GApplication& GApplication::operator=(const GApplication& app)
{
    // Execute only if object is not identical
    if (this != &app) {

        // Free members
        free_members();

        // Initialise private members for clean destruction
        init_members();

        // Copy members
        copy_members(app);

        // Set statistics
        set_statistics();

    } // endif: object was not identical

    // Return
    return *this;
}


/*==========================================================================
 =                                                                         =
 =                             Public methods                              =
 =                                                                         =
 ==========================================================================*/

/***********************************************************************//**
 * @brief Clear application
 ***************************************************************************/
void GApplication::clear(void)
{
    // Save application name and version as we need them to reconstruct
    // the application after freeing and initialising its members
    std::string name    = m_name;
    std::string version = m_version;

    // Free members
    free_members();

    // Initialise members
    init_members();

    // Recover saved application name and version
    m_name    = name;
    m_version = version;

    // Set default parfile and logfile name
    m_parfile = name+".par";
    m_logfile = name+".log";

    // Initialise application parameters
    m_pars.load(par_filename());

    // Signal that application parameters have been loaded
    m_pars_loaded = true;

    // Set log filename and chattiness
    set_log_filename();
    set_log_chatter();

    // Return
    return;
}


/***********************************************************************//**
 * @brief Clone application
 *
 * @return Pointer to deep copy of application.
 ***************************************************************************/
GApplication* GApplication::clone(void) const
{
    // Clone application
    return new GApplication(*this);
}


/***********************************************************************//**
 * @brief Return application elapsed time in calendar seconds
 *
 * @return Application elapsed time in calendar seconds.
 ***************************************************************************/
double GApplication::telapse(void) const
{
    // Get actual time
    std::time_t acttime;
    std::time(&acttime);

    // Compute elapsed time
    double telapse = difftime(acttime, m_tstart);

    // Return elapsed time
    return telapse;
}


/***********************************************************************//**
 * @brief Return application elapsed time in CPU seconds
 *
 * @return Application elapsed time in CPU seconds.
 *
 * Returns the CPU seconds that were consumed by the application. The
 * content of @p m_celapse is added to the measurement which allows tracking
 * of additional CPU seconds from child processes that are not properly
 * tracked otherwise.
 ***************************************************************************/
double GApplication::celapse(void) const
{
    // Compute elapsed CPU clock time
    #ifdef _OPENMP
    double celapse = omp_get_wtime() - m_cstart;
    #else
    double celapse = (double(clock()) - m_cstart) / (double)CLOCKS_PER_SEC;
    #endif

    // Add CPU seconds of internal counter
    celapse += m_celapse;

    // Return elapsed time
    return celapse;
}


/***********************************************************************//**
 * @brief Return application equivalent CO2 footprint (units: g CO2e)
 *
 * @param[in] country Country where computation is performed.
 * @return Application equivalent CO2 footprint (g CO2e).
 *
 * The method returns the equivalent CO2 footprint in grams after the
 * currently elpased CPU time, as returned by celapse(). The method assumes
 * an emission factor of 4.68 g CO2e / CPU hour as estimated by Berthoud et
 * al. (2020) (https://hal.archives-ouvertes.fr/hal-02549565v4/document),
 * where 2.43 g CO2e / CPU hour are due to electricity use and 2.25
 * g CO2e / CPU hour are due to fabrication and personnel. Specifically
 * the footprint estimated includes
 *
 * * server fabrication
 * * server environment
 * * server usage (electricity)
 * * travelling of personnel in the context of their work
 * * travelling of personnel from home to office
 * * personnel equipment
 * * personnel energy
 *
 * The emission factors are based on an estimate done for the DAHU cluster
 * of the UMS GRICAD in 2019. Note that the electricity footprint a carbon
 * intensity of 108 g eCO2 / kWh was assumed.
 *
 * The method tries to determine the appropriate carbon intensity from the
 * two-digit country code and then computes the applicable emission factor
 * \f$EF\f$ in units of g CO2e / CPU hour using
 *
 * \f[
 *    EF = 2.25 + 2.43 \frac{CI}{108}
 * \f]
 *
 * where \f$CI\f$ is the country specific carbon intensity of electricity
 * generation, given in units of g eCO2 / kWh.
 *
 * The equivalent CO2 footprint is then computed by multiplying \f$EF\f$
 * by the number of CPU hours.
 *
 * Country specific carbon intensities are specified by the file
 * @p share/refdata/emission-factors.fits.
 ***************************************************************************/
double GApplication::gCO2e(const std::string& country) const
{
    // Initialise constants
    const double ef_total       = 4.68;
    const double ef_electricity = 2.43;
    const double ef_other       = ef_total - ef_electricity;
    const double ef_kWh         = 108.0;

    // Initialise vectors of country codes and emission factors
    static bool                     has_data = true;
    static std::vector<std::string> code;
    static std::vector<double>      ef;
    static std::string              last_code = "";
    static double                   last_ef   = 0.0;

    // Initialise equivalent CO2 footprint
    double gCO2e = 0.0;

    // If there is a country code then try to find the country specific
    // equivalent CO2 footprint
    if (!country.empty()) {

        // If there are data but no country codes then load the country
        // codes and emission factors from the FITS file. This is only
        // attempted once, and if it fails the has_data flag will be set
        // "false"
        if (has_data && code.empty()) {

            // Signal that we attempted loading the data
            has_data = false;

            // Initialise filename
            GFilename filename("$GAMMALIB/share/refdata/emission-factors.fits");

            // If file does not exist then it may not yet be installed,
            // possibly because a unit test is performed. Therefore try to
            // get file in the source directory.
            if (!filename.is_fits()) {
                filename = GFilename("$TEST_SRCDIR/refdata/emission-factors.fits");
            }

            // If file exists then load the data
            if (filename.is_fits()) {

                // Open FITS file
                GFits fits(filename);

                // Get first table
                const GFitsTable* table = fits.table(1);

                // Extract number of rows in FITS file
                int num = table->nrows();

                // Continue if there are data
                if (num > 0) {

                    // Reserve data
                    code.reserve(num);
                    ef.reserve(num);

                    // Get column pointers
                    const GFitsTableCol* ptr_code = (*table)["CODE"];
                    const GFitsTableCol* ptr_ef   = (*table)["EF"];

                    // Extract data
                    for (int i = 0; i < num; ++i) {

                        // Get code and emission factor
                        std::string val_code = ptr_code->string(i,0);
                        double      val_ef   = ptr_ef->real(i,0);

                        // Store code and emission factor
                        code.push_back(val_code);
                        ef.push_back(val_ef);

                        // Update last code and emission factor
                        if (val_code == country) {
                            last_code = val_code;
                            last_ef   = val_ef;
                        }

                    } // endfor: extracted data

                } // endif: loaded data

            } // endif: FITS file existed

        } // endif: loaded emission data

        // If there are data then try to find the country dependent
        // equivalent CO2 footprint
        if (!code.empty()) {

            // Initialise Berthoud et al. (2020) emission factor
            double val_ef = ef_kWh;

            // If country is identical to last code then get the last
            // emission factor
            if (country == last_code) {
                val_ef = last_ef;
            }

            // ... otherwise search emission factor in table
            else {
                int size = code.size();
                for (int i = 0; i < size; ++i) {
                    if (code[i] == country) {
                        val_ef    = ef[i];
                        last_code = code[i];
                        last_ef   = val_ef;
                        break;
                    }
                }
            }

            // Get elapsed time in CPU jours
            double cpu_hours = celapse() / 3600.0;

            // Compute effective emission factor
            double eff_ef = ef_other + ef_electricity * val_ef / ef_kWh;

            // Convert into g eCO2
            gCO2e = eff_ef * cpu_hours;

        } // endif: there were codes

    } // endif: country code specified

    // If equivalent CO2 footprint is not yet set then use the emission
    // factor of Berthoud et al. (2020)
    if (gCO2e == 0.0) {

        // Get elapsed time in CPU jours
        double cpu_hours = celapse() / 3600.0;

        // Convert into g eCO2
        gCO2e = ef_total * cpu_hours;

    }
 
    // Return equivalent CO2 footprint
    return gCO2e;
}


/***********************************************************************//**
 * @brief Open log file
 *
 * @param[in] clobber Overwrite (true) or append (false) to existing file
 *                    (defaults to true)
 *
 * Opens application log file and sets the logger chattiness dependent on
 * the chatter parameter of the application.
 ***************************************************************************/
void GApplication::logFileOpen(const bool& clobber)
{
    // Open logger only if filename is non-empty
    if (!log_filename().empty()) {

        // Initialise the application logger
        log.open(log_filename(), clobber);

        // If we're in debug mode then all output is also dumped on the
        // screen
        if (has_par("debug")) {
            if (logDebug()) {
                log.cout(true);
            }
        }

        // Write header into log file
        log_header();

    } // endif: file name was not empty

    // Set logger chattiness
    set_log_chatter();

    // Return
    return;
}


/***********************************************************************//**
 * @brief Close log file
 *
 * Close the log file. In case that some characters have been written
 * through the logger a trailer will be appended to the logger before
 * closing the log file. The trailer informs about the computation time
 * used by the application.
 ***************************************************************************/
void GApplication::logFileClose(void)
{
    // Continue only if log file is open and if something has been written
    // through this logger. This avoid writing trailers for logger than
    // have not been used.
    if (log.is_open() && (log.written_size() > 0)) {

        // Write line feed before trailer into logger
        log << std::endl;

        // Write trailer into logger
        log_trailer();

        // Close log file
        log.close();

    } // endif: log file was open

    // Return
    return;
}


/***********************************************************************//**
 * @brief Signal terse logging
 *
 * @return True if at least terse logging is requested.
 *
 * The terse level is used for the most crucial application information that
 * should be logged in all cases (chatter >= 1).
 ***************************************************************************/
bool GApplication::logTerse(void) const
{
    // Get chatter level (circumvent const correctness)
    int chatter = const_cast<GApplicationPar*>(&m_pars["chatter"])->integer();

    // Return terse logging condition
    return (chatter > 0);
}


/***********************************************************************//**
 * @brief Signal normal logging
 *
 * @return True if at least normal logging is requested.
 *
 * The normal level is used for standard application information that should
 * be logged in normal operations (chatter >= 2).
 ***************************************************************************/
bool GApplication::logNormal(void) const
{
    // Get chatter level (circumvent const correctness)
    int chatter = const_cast<GApplicationPar*>(&m_pars["chatter"])->integer();

    // Return normal logging condition
    return (chatter > 1);
}


/***********************************************************************//**
 * @brief Signal explicit logging
 *
 * @return True if at least explicit logging is requested.
 *
 * The explicit level is used for detailed application information that
 * should be logged in detailed studies (chatter >= 3).
 ***************************************************************************/
bool GApplication::logExplicit(void) const
{
    // Get chatter level (circumvent const correctness)
    int chatter = const_cast<GApplicationPar*>(&m_pars["chatter"])->integer();

    // Return explicit logging condition
    return (chatter > 2);
}


/***********************************************************************//**
 * @brief Signal verbose logging
 *
 * @return True if verbose logging is requested.
 *
 * The verbose level is used for full application information (chatter >= 4).
 ***************************************************************************/
bool GApplication::logVerbose(void) const
{
    // Get chatter level (circumvent const correctness)
    int chatter = const_cast<GApplicationPar*>(&m_pars["chatter"])->integer();

    // Return verbose logging condition
    return (chatter > 3);
}


/***********************************************************************//**
 * @brief Signal debug logging
 *
 * @return True if the debugging mode has been selected.
 *
 * The debug level is used for application debugging.
 ***************************************************************************/
bool GApplication::logDebug(void) const
{
    // Get debug condition (circumvent const correctness)
    bool debug = const_cast<GApplicationPar*>(&m_pars["debug"])->boolean();

    // Return debug condition
    return (debug);
}


/***********************************************************************//**
 * @brief Return clobber
 *
 * @return True if the clobber parameter is true.
 *
 * The clobber indicates if existing files should be overwritten.
 ***************************************************************************/
bool GApplication::clobber(void) const
{
    // Get clobber condition (circumvent const correctness)
    bool clobber = const_cast<GApplicationPar*>(&m_pars["clobber"])->boolean();

    // Return clobber condition
    return (clobber);
}


/***********************************************************************//**
 * @brief Write application header in log file
 *
 * Dump the application header into the log file. The header is composed of
 * a fixed width block delimined by "*" characters that contains information
 * about the application name and version.
 ***************************************************************************/
void GApplication::log_header(void)
{
    // Set header width
    const int header_width = 80;

    // Reset any indentation
    log.indent(0);

    // Dump header
    log << gammalib::fill("*", header_width) << std::endl;
    log << "*" << gammalib::centre(m_name, header_width-2) << "*" << std::endl;
    log << "* " << gammalib::fill("-", header_width-4) << " *" << std::endl;
    log << "* Version: " << gammalib::left(m_version, header_width-12) << "*" << std::endl;
    log << gammalib::fill("*", header_width) << std::endl;

    // Return
    return;
}


/***********************************************************************//**
 * @brief Write application trailer in log file
 *
 * The application trailer gives the total number of elapsed calendar and
 * CPU seconds, as well as the carbon footprint of the application execution.
 ***************************************************************************/
void GApplication::log_trailer(void)
{
    // Reset any indentation
    log.indent(0);

    // Get application statistics
    double telapse = this->telapse();
    double celapse = this->celapse();
    double gCO2e   = this->gCO2e(gammalib::host_country());

    // Dump trailer
    log << "Application \"" << m_name << "\" terminated after ";
    log << telapse << " wall clock seconds, consuming ";
    log << celapse << " seconds of CPU time and generating a carbon";
    log << " footprint of " << gCO2e << " g eCO2.";
    if (gCO2e >= 1000.0) {
        log << " Please watch your carbon footprint.";
    }
    if (telapse < 0.1) {
        log << " This was rather quick and economic!";
    }
    if (telapse > 86400.0) {
        log << " Hope it was worth waiting ...";
    }
    log << std::endl;

    // Return
    return;
}


/***********************************************************************//**
 * @brief Write string in log file
 *
 * @param[in] chatter Minimum required chattiness
 * @param[in] string String
 * @param[in] linefeed Terminate string with linefeed?
 *
 * Writes a string into the log file if chattiness is at least @p chatter.
 * If @p linefeed is true the string is terminated with a linefeed.
 ***************************************************************************/
void GApplication::log_string(const GChatter&    chatter,
                              const std::string& string,
                              const bool&        linefeed)
{
    // Get chattiness of application
    GChatter chattiness = static_cast<GChatter>((&m_pars["chatter"])->integer());

    // Only write message if chattiness is at least equal to the minimum
    // required chattiness
    if (chattiness >= chatter) {
        log << string;
        if (linefeed) {
            log << std::endl;
        }
    }

    // Return
    return;
}


/***********************************************************************//**
 * @brief Write parameter value in log file
 *
 * @param[in] chatter Minimum required chattiness
 * @param[in] name Parameter name string
 * @param[in] value Value string
 *
 * Writes a parameter value into the log file if chattiness is at least
 * @p chatter.
 ***************************************************************************/
void GApplication::log_value(const GChatter&    chatter,
                             const std::string& name,
                             const std::string& value)
{
    // Get chattiness of application
    GChatter chattiness = static_cast<GChatter>((&m_pars["chatter"])->integer());

    // Only write message if chattiness is at least equal to the minimum
    // required chattiness
    if (chattiness >= chatter) {
        log << gammalib::parformat(name);
        log << value << std::endl;
    }

    // Return
    return;
}


/***********************************************************************//**
 * @brief Write parameter value in log file
 *
 * @param[in] chatter Minimum required chattiness
 * @param[in] name Parameter name string
 * @param[in] value Integer value
 *
 * Writes a parameter value into the log file if chattiness is at least
 * @p chatter.
 ***************************************************************************/
void GApplication::log_value(const GChatter&    chatter,
                             const std::string& name,
                             const int&         value)
{
    // Get chattiness of application
    GChatter chattiness = static_cast<GChatter>((&m_pars["chatter"])->integer());

    // Only write message if chattiness is at least equal to the minimum
    // required chattiness
    if (chattiness >= chatter) {
        log << gammalib::parformat(name);
        log << value << std::endl;
    }

    // Return
    return;
}


/***********************************************************************//**
 * @brief Write parameter value in log file
 *
 * @param[in] chatter Minimum required chattiness
 * @param[in] name Parameter name string
 * @param[in] value Floating point value
 *
 * Writes a parameter value into the log file if chattiness is at least
 * @p chatter.
 ***************************************************************************/
void GApplication::log_value(const GChatter&    chatter,
                             const std::string& name,
                             const double&      value)
{
    // Get chattiness of application
    GChatter chattiness = static_cast<GChatter>((&m_pars["chatter"])->integer());

    // Only write message if chattiness is at least equal to the minimum
    // required chattiness
    if (chattiness >= chatter) {
        log << gammalib::parformat(name);
        log << value << std::endl;
    }

    // Return
    return;
}


/***********************************************************************//**
 * @brief Write header 1 in log file
 *
 * @param[in] chatter Minimum required chattiness
 * @param[in] header Header string
 *
 * Writes a header of level 1 into the log file if chattiness is at least
 * @p chatter.
 ***************************************************************************/
void GApplication::log_header1(const GChatter&    chatter,
                               const std::string& header)
{
    // Get chattiness of application
    GChatter chattiness = static_cast<GChatter>((&m_pars["chatter"])->integer());

    // Only write message if chattiness is at least equal to the minimum
    // required chattiness
    if (chattiness >= chatter) {
        log << std::endl;
        log.header1(header);
    }

    // Return
    return;
}


/***********************************************************************//**
 * @brief Write header 2 in log file
 *
 * @param[in] chatter Minimum required chattiness
 * @param[in] header Header string
 *
 * Writes a header of level 2 into the log file if chattiness is at least
 * @p chatter.
 ***************************************************************************/
void GApplication::log_header2(const GChatter&    chatter,
                               const std::string& header)
{
    // Get chattiness of application
    GChatter chattiness = static_cast<GChatter>((&m_pars["chatter"])->integer());

    // Only write message if chattiness is at least equal to the minimum
    // required chattiness
    if (chattiness >= chatter) {
        log.header2(header);
    }

    // Return
    return;
}


/***********************************************************************//**
 * @brief Write header 3 in log file
 *
 * @param[in] chatter Minimum required chattiness
 * @param[in] header Header string
 *
 * Writes a header of level 3 into the log file if chattiness is at least
 * @p chatter.
 ***************************************************************************/
void GApplication::log_header3(const GChatter&    chatter,
                               const std::string& header)
{
    // Get chattiness of application
    GChatter chattiness = static_cast<GChatter>((&m_pars["chatter"])->integer());

    // Only write message if chattiness is at least equal to the minimum
    // required chattiness
    if (chattiness >= chatter) {
        log.header3(header);
    }

    // Return
    return;
}


/***********************************************************************//**
 * @brief Write application parameters in log file
 *
 * @param[in] chatter Minimum required chattiness
 *
 * Writes all application parameters in the log file. For parameters that
 * have not yet been queried the method does not write the current value
 * but signals [not queried].
 ***************************************************************************/
void GApplication::log_parameters(const GChatter& chatter)
{
    // Get chattiness of application
    GChatter chattiness = static_cast<GChatter>((&m_pars["chatter"])->integer());

    // Only write parameters if the chattiness is at least equal to the
    // minimum required chattiness
    if (chattiness >= chatter) {

        // Write header
        log.header1("Parameters");

        // Write parameters in logger
        for (int i = 0; i < m_pars.size(); ++i) {

            // Set parameter name
            std::string name = " " + m_pars.m_pars[i].name() + " ";
            name = name + gammalib::fill(".", 28-name.length()) + ": ";

            // Write parameter
            if (m_pars.m_pars[i].is_query() &&
                !m_pars.m_pars[i].was_queried()) {
                log << name << "[not queried]" << std::endl;
            }
            else {
                log << name << m_pars.m_pars[i].m_value << std::endl;
            }

        } // endfor: looped over all parameters

    } // endif: chattiness satisfied minimum required level

    // Return
    return;
}


/***********************************************************************//**
 * @brief Stamp FITS header with provenance information
 *
 * @param[in] hdu FITS header.
 *
 * Write provenance information into a FITS header.
 ***************************************************************************/
void GApplication::stamp(GFitsHDU& hdu) const
{
    // Set provenance information
    std::string creator = name() + " v" + version();

    // Write provenance information
    hdu.card("CREATOR", creator, "Program which created the file");

    // Return
    return;
}


/***********************************************************************//**
 * @brief Stamp all headers in FITS object with provenance information
 *
 * @param[in] fits FITS object.
 *
 * Write provenance information into all headers of FITS object.
 ***************************************************************************/
void GApplication::stamp(GFits& fits) const
{
    // Loop over FITS headers
    for (int i = 0; i < fits.size(); ++i) {
        stamp(*fits[i]);
    }

    // Return
    return;
}


/***********************************************************************//**
 * @brief Stamp all headers in FITS file with provenance information
 *
 * @param[in] filename FITS file name.
 *
 * Write provenance information into all headers of FITS file.
 ***************************************************************************/
void GApplication::stamp(const GFilename& filename) const
{
    // Open FITS file
    GFits fits(filename);

    // Stamp headers
    stamp(fits);

    // Save FITS file
    fits.save(true);

    // Return
    return;
}


/***********************************************************************//**
 * @brief Print application
 *
 * @param[in] chatter Chattiness.
 * @return String containing application information.
 ***************************************************************************/
std::string GApplication::print(const GChatter& chatter) const
{
    // Initialise result string
    std::string result;

    // Continue only if chatter is not silent
    if (chatter != SILENT) {

        // Append header
        result.append("=== GApplication ===");

        // Append application name, version and arguments
        result.append("\n"+gammalib::parformat("Name")+name());
        result.append("\n"+gammalib::parformat("Version")+version());
        result.append("\n"+gammalib::parformat("Running instances"));
        result.append(gammalib::str(running()));
        for (int i = 0; i < m_args.size(); ++i) {
            if (i == 0) {
                result.append("\n"+gammalib::parformat("Command")+m_args[i]);
            }
            else if (i == 1) {
                result.append("\n"+gammalib::parformat("Arguments")+m_args[i]);
            }
            else {
                result.append("\n"+gammalib::parformat("                           ")+m_args[i]);
            }
        }

        // Append parameters
        for (int i = 0; i < m_pars.size(); ++i) {
            result.append("\n"+gammalib::parformat(m_pars.m_pars[i].name()) +
                          m_pars.m_pars[i].m_value);
        }

    } // endif: chatter was not silent

    // Return result
    return result;
}


/*==========================================================================
 =                                                                         =
 =                             Private methods                             =
 =                                                                         =
 ==========================================================================*/

/***********************************************************************//**
 * @brief Initialise class members
 ***************************************************************************/
void GApplication::init_members(void)
{
    // Initialise public members
    log.clear();

    // Initialise protected members
    m_name.clear();
    m_version.clear();
    m_parfile.clear();
    m_logfile.clear();
    m_args.clear();
    m_pars.clear();
    m_pars_loaded = false;
    m_need_help   = false;
    m_statistics  = true;

    // Save the execution calendar start time
    std::time(&m_tstart);

    // Save the execution start clock
    #ifdef _OPENMP
    m_cstart = omp_get_wtime();
    #else
    m_cstart = double(clock());
    #endif

    // Initialise internal CPU seconds counter
    m_celapse = 0.0;

    // Return
    return;
}


/***********************************************************************//**
 * @brief Copy class members
 *
 * @param[in] app Application.
 *
 * Copies all class members.
 ***************************************************************************/
void GApplication::copy_members(const GApplication& app)
{
    // Copy public attributes
    log = app.log;

    // Copy protected attributes
    m_name        = app.m_name;
    m_version     = app.m_version;
    m_parfile     = app.m_parfile;
    m_logfile     = app.m_logfile;
    m_args        = app.m_args;
    m_tstart      = app.m_tstart;
    m_cstart      = app.m_cstart;
    m_celapse     = app.m_celapse;
    m_pars        = app.m_pars;
    m_pars_loaded = app.m_pars_loaded;
    m_need_help   = app.m_need_help;
    m_statistics  = app.m_statistics;

    // Return
    return;
}


/***********************************************************************//**
 * @brief Delete class members
 ***************************************************************************/
void GApplication::free_members(void)
{
    // Save application parameters if they have been loaded
    if (m_pars_loaded) {
        m_pars.save(par_filename());
    }

    // Close log file
    logFileClose();

    // Write statistics
    write_statistics();

    // Return
    return;
}


/***********************************************************************//**
 * @brief Set statistics according to parent child status
 *
 * Makes sure that application statistics are only written for the parent
 * which is the first running instances. If this instance signals that an
 * instance is already running, this instance is a child process that was
 * started by another running instance.
 ***************************************************************************/
void GApplication::set_statistics(void)
{
    // Determine whether instance is a parent
    bool parent = (running() < 1);

    // Enable statistics only for parents
    statistics(parent);

    // Return
    return;
}


/***********************************************************************//**
 * @brief Set chattiness of logger
 ***************************************************************************/
void GApplication::set_log_chatter(void)
{
    // Get chattiness from application parameter
    int chatter = m_pars["chatter"].integer();

    // Make sure that chatter is within valid range
    if (chatter < 0) {
        chatter = 0;
    }
    else if (chatter > 4) {
        chatter = 4;
    }

    // Set logger chatter
    log.chatter((GChatter)chatter);

    // Return
    return;
}


/***********************************************************************//**
 * @brief Set log filename from "logfile" parameter
 *
 * If the application parameters contain a "logfile" parameter then set the
 * file name of the log file from this parameter.
 *
 * In case that the file name is not valid, the file name will be set to an
 * empty string, which will prevent opening a log file.
 ***************************************************************************/
void GApplication::set_log_filename(void)
{
    // Continue only if logfile parameter exists
    if (m_pars.contains("logfile")) {

        // Get log filename from application parameter
        if (m_pars["logfile"].is_valid()) {
            m_logfile = m_pars["logfile"].filename();
        }
        else {
            m_logfile = "";
        }

    }

    // Return
    return;
}


/***********************************************************************//**
 * @brief Write application statistics
 *
 * Write application statistics in a global ASCII file.
 ***************************************************************************/
void GApplication::write_statistics(void)
{
    // Continue only if statistics should be written
    if (m_statistics) {

        // Get statistics ASCII file name
        GFilename filename = gammalib::gamma_filename("statistics.csv");

        // Make sure that file exists and that it contains a header line
        if (access(filename.url().c_str(), R_OK) != 0) {

            // OpenMP critical zone to write header in case that the file
            // does not yet exist
            #pragma omp critical(GApplication_write_statistics)
            {

            // Open statistics file, and in case of success, write header
            // line
            FILE* fptr = fopen(filename.url().c_str(), "w");
            if (fptr != NULL) {
                fprintf(fptr, "Date,"
                              "GammaLib version,"
                              "Country,"
                              "Application,"
                              "Version,"
                              "Wall clock seconds,"
                              "CPU seconds,"
                              "g eCO2\n");
                fclose(fptr);
            }

            } // end of OMP critial zone

        } // endif: no statistics file existed

        // OpenMP critical zone to write statitics
        #pragma omp critical(GApplication_write_statistics)
        {

        // Get file lock. Continue only in case of success
        struct flock lock;
        lock.l_type   = F_WRLCK;  // Want a write lock
        lock.l_whence = SEEK_SET; // Want beginning of file
        lock.l_start  = 0;        // No offset, lock entire file ...
        lock.l_len    = 0;        // ... to the end
        lock.l_pid    = getpid(); // Current process ID
        int fd        = open(filename.url().c_str(), O_WRONLY);
        if (fd != -1) {

            // Lock file
            fcntl(fd, F_SETLKW, &lock);

            // Open statistics file, and in case of success, write
            // statistics
            FILE* fptr = fopen(filename.url().c_str(), "a");
            if (fptr != NULL) {

                // Get host country
                std::string country = gammalib::host_country();

                // Write statistics string
                fprintf(fptr, "%s,%s,%s,%s,%s,%e,%e,%e\n",
                              gammalib::strdate().c_str(), VERSION,
                              country.c_str(),
                              name().c_str(), version().c_str(),
                              telapse(), celapse(), gCO2e(country));

                // Close file
                fclose(fptr);
            }

            // Unlock file
            lock.l_type = F_UNLCK;
            fcntl(fd, F_SETLK, &lock);

            // Close file
            close(fd);

        } // endif: file locking successful

        } // end of OMP critial zone

    } // endif: statistics should be written

    // Return
    return;
}