Line data    Source code

       1             : // Snap Websites Server -- manage a PID file for a snap service
       2             : // Copyright (c) 2019  Made to Order Software Corp.  All Rights Reserved
       3             : //
       4             : // https://snapwebsites.org/
       5             : // contact@m2osw.com
       6             : //
       7             : // This program is free software; you can redistribute it and/or modify
       8             : // it under the terms of the GNU General Public License as published by
       9             : // the Free Software Foundation; either version 2 of the License, or
      10             : // (at your option) any later version.
      11             : //
      12             : // This program is distributed in the hope that it will be useful,
      13             : // but WITHOUT ANY WARRANTY; without even the implied warranty of
      14             : // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      15             : // GNU General Public License for more details.
      16             : //
      17             : // You should have received a copy of the GNU General Public License
      18             : // along with this program; if not, write to the Free Software
      19             : // Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
      20             : #pragma once
      21             : 
      22             : 
      23             : // self
      24             : //
      25             : #include "snapwebsites/snap_exception.h"
      26             : 
      27             : 
      28             : // snapdev lib
      29             : //
      30             : #include <snapdev/raii_generic_deleter.h>
      31             : 
      32             : 
      33             : 
      34             : /** \file
      35             :  * \brief Declaration of the snap_pid class to manage a PID file.
      36             :  *
      37             :  * This header defines the snap_pid class which we use to manage a PID
      38             :  * file. This is quite practical to make sure only one instance of a
      39             :  * service is running, it also allows us to let systemd know once our
      40             :  * child process is ready and the parent is about to quit (i.e. when
      41             :  * we use detached processes.)
      42             :  *
      43             :  * See the .cpp file for more details.
      44             :  */
      45             : 
      46             : namespace snap
      47             : {
      48             : 
      49             : 
      50             : 
      51           0 : class snap_pid_exception : public snap_exception
      52             : {
      53             : public:
      54             :     explicit snap_pid_exception(char const *        whatmsg) : snap_exception("snap_pid", whatmsg) {}
      55           0 :     explicit snap_pid_exception(std::string const & whatmsg) : snap_exception("snap_pid", whatmsg) {}
      56             :     explicit snap_pid_exception(QString const &     whatmsg) : snap_exception("snap_pid", whatmsg) {}
      57             : };
      58             : 
      59           0 : class snap_pid_exception_io_error : public snap_pid_exception
      60             : {
      61             : public:
      62             :     explicit snap_pid_exception_io_error(char const *        whatmsg) : snap_pid_exception(whatmsg) {}
      63           0 :     explicit snap_pid_exception_io_error(std::string const & whatmsg) : snap_pid_exception(whatmsg) {}
      64             :     explicit snap_pid_exception_io_error(QString const &     whatmsg) : snap_pid_exception(whatmsg) {}
      65             : };
      66             : 
      67           0 : class snap_pid_exception_invalid_parameter : public snap_pid_exception
      68             : {
      69             : public:
      70             :     explicit snap_pid_exception_invalid_parameter(char const *        whatmsg) : snap_pid_exception(whatmsg) {}
      71           0 :     explicit snap_pid_exception_invalid_parameter(std::string const & whatmsg) : snap_pid_exception(whatmsg) {}
      72             :     explicit snap_pid_exception_invalid_parameter(QString const &     whatmsg) : snap_pid_exception(whatmsg) {}
      73             : };
      74             : 
      75             : 
      76             : 
      77             : 
      78             : 
      79             : 
      80             : class snap_pid
      81             : {
      82             : public:
      83             :     typedef std::shared_ptr<snap_pid>   pointer_t;
      84             : 
      85             :                     snap_pid(std::string const & service_name);
      86             :                     ~snap_pid();
      87             : 
      88             :     void            create_pid_file();
      89             :     bool            wait_signal();
      90             : 
      91             : private:
      92             :     void            generate_filename(std::string const & service_name);
      93             :     void            unlink_pid_file();
      94             :     void            close_pipes();
      95             :     void            send_signal(bool result);
      96             : 
      97             :     std::string     f_service_name = std::string();
      98             :     int             f_pipes[2];
      99             :     std::string     f_pid_filename = std::string();
     100             :     raii_fd_t       f_safe_fd = raii_fd_t();
     101             :     bool            f_child_process = false;
     102             :     char            f_result = static_cast<char>(false);
     103             : };
     104             : 
     105             : } // namespace snap
     106             : // vim: ts=4 sw=4 et