POSIX_TIMERS

POSIX Timers option group. More...

Macros
#define	CLOCK_REALTIME   ((clockid_t)SYS_CLOCK_REALTIME)
	Clock measuring real (wall-clock) time.
#define	CLOCKS_PER_SEC   1000000
	Number of clock ticks per second as seen by clock().
#define	TIMER_ABSTIME   SYS_TIMER_ABSTIME
	Flag for clock_nanosleep() and timer_settime(): interpret time as absolute.

Functions
int	clock_getres (clockid_t clock_id, struct timespec *ts)
	Get the resolution of a clock.
int	clock_gettime (clockid_t clock_id, struct timespec *ts)
	Get the current time of a clock.
int	clock_settime (clockid_t clock_id, const struct timespec *ts)
	Set the time of a clock.
int	nanosleep (const struct timespec *rqtp, struct timespec *rmtp)
	Sleep for a specified number of nanoseconds (high-resolution sleep).
int	timer_create (clockid_t clockId, struct sigevent *ZRESTRICT evp, timer_t *ZRESTRICT timerid)
	Create a per-process timer.
int	timer_delete (timer_t timerid)
	Delete a per-process timer.
int	timer_getoverrun (timer_t timerid)
	Get the number of timer overruns since the last timer expiration notification.
int	timer_gettime (timer_t timerid, struct itimerspec *its)
	Get the time remaining until the next timer expiration.
int	timer_settime (timer_t timerid, int flags, const struct itimerspec *value, struct itimerspec *ovalue)
	Arm or disarm a per-process timer.

Detailed Description

POSIX Timers option group.

Macro Definition Documentation

CLOCK_REALTIME

#define CLOCK_REALTIME   ((clockid_t)SYS_CLOCK_REALTIME)

Clock measuring real (wall-clock) time.

Definition at line 107 of file time.h.

CLOCKS_PER_SEC

#define CLOCKS_PER_SEC   1000000

Number of clock ticks per second as seen by clock().

Definition at line 113 of file time.h.

TIMER_ABSTIME

#define TIMER_ABSTIME   SYS_TIMER_ABSTIME

Flag for clock_nanosleep() and timer_settime(): interpret time as absolute.

Definition at line 142 of file time.h.

Function Documentation

clock_getres()

int clock_getres	(	clockid_t	clock_id,
		struct timespec *	ts
	)

Get the resolution of a clock.

Parameters

clock_id	Clock to query.
ts	Output: resolution (smallest representable interval).

Returns

0 on success, or -1 with errno set on failure.

See also

https://pubs.opengroup.org/onlinepubs/9699919799/functions/clock_getres.html

clock_gettime()

int clock_gettime	(	clockid_t	clock_id,
		struct timespec *	ts
	)

Get the current time of a clock.

Parameters

clock_id	Clock to read.
ts	Output: current time.

Returns

0 on success, or -1 with errno set on failure.

See also

https://pubs.opengroup.org/onlinepubs/9699919799/functions/clock_gettime.html

clock_settime()

int clock_settime	(	clockid_t	clock_id,
		const struct timespec *	ts
	)

Set the time of a clock.

Parameters

clock_id	Clock to set.
ts	New time value.

Returns

0 on success, or -1 with errno set on failure.

See also

https://pubs.opengroup.org/onlinepubs/9699919799/functions/clock_settime.html

nanosleep()

int nanosleep	(	const struct timespec *	rqtp,
		struct timespec *	rmtp
	)

Sleep for a specified number of nanoseconds (high-resolution sleep).

Parameters

rqtp	Requested sleep duration.
rmtp	Output: remaining time if the call was interrupted, or NULL.

Returns

0 on success, or a positive error number on failure.

See also

https://pubs.opengroup.org/onlinepubs/9699919799/functions/nanosleep.html

timer_create()

int timer_create	(	clockid_t	clockId,
		struct sigevent *ZRESTRICT	evp,
		timer_t *ZRESTRICT	timerid
	)

Create a per-process timer.

Parameters

clockId	Clock to base the timer on.
evp	Notification specification, or NULL for SIGALRM delivery.
timerid	Output: new timer ID.

Returns

0 on success, or -1 with errno set on failure.

See also

https://pubs.opengroup.org/onlinepubs/9699919799/functions/timer_create.html

timer_delete()

int timer_delete

(

timer_t

timerid

)

Delete a per-process timer.

Parameters

timerid

Timer to delete.

Returns

0 on success, or -1 with errno set on failure.

See also

https://pubs.opengroup.org/onlinepubs/9699919799/functions/timer_delete.html

timer_getoverrun()

int timer_getoverrun

(

timer_t

timerid

)

Get the number of timer overruns since the last timer expiration notification.

Parameters

timerid

Timer to query.

Returns

Overrun count on success, or -1 with errno set on failure.

See also

https://pubs.opengroup.org/onlinepubs/9699919799/functions/timer_getoverrun.html

timer_gettime()

int timer_gettime	(	timer_t	timerid,
		struct itimerspec *	its
	)

Get the time remaining until the next timer expiration.

Parameters

timerid	Timer to query.
its	Output: current timer value and interval.

Returns

0 on success, or -1 with errno set on failure.

See also

https://pubs.opengroup.org/onlinepubs/9699919799/functions/timer_gettime.html

timer_settime()

int timer_settime	(	timer_t	timerid,
		int	flags,
		const struct itimerspec *	value,
		struct itimerspec *	ovalue
	)

Arm or disarm a per-process timer.

Parameters

timerid	Timer to set.
flags	0 for a relative time, TIMER_ABSTIME for an absolute time.
value	New expiration time and interval; set it_value to zero to disarm.
ovalue	Output: previous timer value, or NULL.

Returns

0 on success, or -1 with errno set on failure.

See also

https://pubs.opengroup.org/onlinepubs/9699919799/functions/timer_settime.html