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/* Definitions for POSIX timer implementation on top of NPTL.
Copyright (C) 2000-2023 Free Software Foundation, Inc.
This file is part of the GNU C Library.
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 <https://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);
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