/* Definitions for POSIX timer implementation on top of NPTL.

   Copyright (C) 2000-2018 Free Software Foundation, Inc.

   This file is part of the GNU C Library.

   Contributed by Kaz Kylheku <kaz@ashi.footprints.net>.

   The GNU C Library is free software; you can redistribute it and/or

   modify it under the terms of the GNU Lesser General Public License as

   published by the Free Software Foundation; either version 2.1 of the

   License, or (at your option) any later version.

   The GNU C Library 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

   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public

   License along with the GNU C Library; see the file COPYING.LIB.  If

   not, see <http://www.gnu.org/licenses/>.  */

#include <limits.h>

#include <signal.h>

#include <list.h>

/* Forward declaration.  */

struct timer_node;

/* Definitions for an internal thread of the POSIX timer implementation.  */

struct thread_node

{

  struct list_head links;

  pthread_attr_t attr;

  pthread_t id;

  unsigned int exists;

  struct list_head timer_queue;

  pthread_cond_t cond;

  struct timer_node *current_timer;

  pthread_t captured;

  clockid_t clock_id;

};

/* Internal representation of a timer.  */

struct timer_node

{

  struct list_head links;

  struct sigevent event;

  clockid_t clock;

  struct itimerspec value;

  struct timespec expirytime;

  pthread_attr_t attr;

  unsigned int abstime;

  unsigned int armed;

  enum {

    TIMER_FREE, TIMER_INUSE, TIMER_DELETED

  } inuse;

  struct thread_node *thread;

  pid_t creator_pid;

  int refcount;

  int overrun_count;

};

/* The limit is not published if we are compiled with kernel timer support.

   But we still compiled in this implementation with its limit unless built

   to require the kernel support.  */

#ifndef TIMER_MAX

# define TIMER_MAX 256

#endif

/* Static array with the structures for all the timers.  */

extern struct timer_node __timer_array[TIMER_MAX];

/* Global lock to protect operation on the lists.  */

extern pthread_mutex_t __timer_mutex;

/* Variable to protext initialization.  */

extern pthread_once_t __timer_init_once_control;

/* Nonzero if initialization of timer implementation failed.  */

extern int __timer_init_failed;

/* Node for the thread used to deliver signals.  */

extern struct thread_node __timer_signal_thread_rclk;

/* Return pointer to timer structure corresponding to ID.  */

#define timer_id2ptr(timerid) ((struct timer_node *) timerid)

#define timer_ptr2id(timerid) ((timer_t) timerid)

/* Check whether timer is valid; global mutex must be held. */

static inline int

timer_valid (struct timer_node *timer)

{

  return timer && timer->inuse == TIMER_INUSE;

}

/* Timer refcount functions; need global mutex. */

extern void __timer_dealloc (struct timer_node *timer);

static inline void

timer_addref (struct timer_node *timer)

{

  timer->refcount++;

}

static inline void

timer_delref (struct timer_node *timer)

{

  if (--timer->refcount == 0)

    __timer_dealloc (timer);

}

/* Timespec helper routines.  */

static inline int

__attribute ((always_inline))

timespec_compare (const struct timespec *left, const struct timespec *right)

{

  if (left->tv_sec < right->tv_sec)

    return -1;

  if (left->tv_sec > right->tv_sec)

    return 1;

  if (left->tv_nsec < right->tv_nsec)

    return -1;

  if (left->tv_nsec > right->tv_nsec)

    return 1;

  return 0;

}

static inline void

timespec_add (struct timespec *sum, const struct timespec *left,

	      const struct timespec *right)

{

  sum->tv_sec = left->tv_sec + right->tv_sec;

  sum->tv_nsec = left->tv_nsec + right->tv_nsec;

  if (sum->tv_nsec >= 1000000000)

    {

      ++sum->tv_sec;

      sum->tv_nsec -= 1000000000;

    }

}

static inline void

timespec_sub (struct timespec *diff, const struct timespec *left,

	      const struct timespec *right)

{

  diff->tv_sec = left->tv_sec - right->tv_sec;

  diff->tv_nsec = left->tv_nsec - right->tv_nsec;

  if (diff->tv_nsec < 0)

    {

      --diff->tv_sec;

      diff->tv_nsec += 1000000000;

    }

}

/* We need one of the list functions in the other modules.  */

static inline void

list_unlink_ip (struct list_head *list)

{

  struct list_head *lnext = list->next, *lprev = list->prev;

  lnext->prev = lprev;

  lprev->next = lnext;

  /* The suffix ip means idempotent; list_unlink_ip can be called

   * two or more times on the same node.

   */

  list->next = list;

  list->prev = list;

}

/* Functions in the helper file.  */

extern void __timer_mutex_cancel_handler (void *arg);

extern void __timer_init_once (void);

extern struct timer_node *__timer_alloc (void);

extern int __timer_thread_start (struct thread_node *thread);

extern struct thread_node *__timer_thread_find_matching (const pthread_attr_t *desired_attr, clockid_t);

extern struct thread_node *__timer_thread_alloc (const pthread_attr_t *desired_attr, clockid_t);

extern void __timer_thread_dealloc (struct thread_node *thread);

extern int __timer_thread_queue_timer (struct thread_node *thread,

				       struct timer_node *insert);

extern void __timer_thread_wakeup (struct thread_node *thread);