/* Watchdog and associated classes' declaration and inline functions.
   Copyright (C) 2002-2004 Roberto Bagnara <bagnara@cs.unipr.it>

This file is part of the Parma Watchdog Library (PWL).

The PWL 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 2 of the License, or (at your
option) any later version.

The PWL 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, write to the Free Software
Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
USA.

For the most up-to-date information see
http://www.cs.unipr.it/Software/ . */

#ifndef PWL_Watchdog_defs_hh
#define PWL_Watchdog_defs_hh 1

#include "Watchdog.types.hh"
#include "Time.defs.hh"
#include "Handler.types.hh"
#include "Pending_List.defs.hh"
#include <cassert>

#ifdef HAVE_SYS_TIME_H
# include <sys/time.h>
#endif

namespace Parma_Watchdog_Library {

// Set linkage now to declare it friend later.
extern "C" void PWL_handle_timeout(int signum);

//! A watchdog timer.
class Watchdog {
public:
  template <typename Flag_Base, typename Flag>
  Watchdog(int units, const Flag_Base* volatile& holder, Flag& flag);

  Watchdog(int units, void (*function)());
  ~Watchdog();


private:
  friend class Init;
  static void initialize();
  static void finalize();

  bool expired;
  const Handler& handler;
  Pending_List::Iterator pending_position;

private:
  // Just to prevent their use.
  Watchdog(const Watchdog&);
  Watchdog& operator=(const Watchdog&);

  // Pass this to getitimer.
  static itimerval current_timer_status;

  // Get the timer value.
  static void get_timer(Time& time);

  // Pass this to setitimer.
  static itimerval signal_once;

  // Last time value we set the timer to.
  static Time last_time_requested;

  // Set the timer value.
  static void set_timer(const Time& time);

  // Stops the timer.
  static void stop_timer();

  // Quick reschedule to avoid race conditions.
  static void reschedule();

  // Used by the above.
  static Time reschedule_time;

  // Records the time elapsed since last fresh start.
  static Time time_so_far;

  //! The ordered queue of pending watchdog events.
  static Pending_List pending;

  //! The actual signal handler.
  static void handle_timeout(int);

  // Handle the addition of a new watchdog event.
  static Pending_List::Iterator new_watchdog_event(int units,
						   const Handler& handler,
						   bool& expired_flag);

  // Handle the removal of a watchdog event.
  void remove_watchdog_event(Pending_List::Iterator position);

  // Whether the alarm clock is running.
  static volatile bool alarm_clock_running;

  // Whether we are changing data which is also changed by the signal handler.
  static volatile bool in_critical_section;

  friend void Parma_Watchdog_Library::PWL_handle_timeout(int signum);
};

class Init {
private:
  //! Count the number of objects created.
  static unsigned int count;

public:
  //! Initializes the PWL.
  Init();

  //! Finalizes the PWL.
  ~Init();
};

} // namespace Parma_Watchdog_Library

#include "Watchdog.inlines.hh"

namespace {

Parma_Watchdog_Library::Init Parma_Watchdog_Library_initializer;

} // namespace

#endif // !defined(PWL_Watchdog_defs_hh)