NAME
timer_settime,
timer_gettime,
timer_getoverrun —
process timer manipulation
LIBRARY
library “libc”
SYNOPSIS
#include
<time.h>
int
timer_settime(timer_t
timerid, int flags,
const struct itimerspec *
restrict tim, struct
itimerspec * restrict otim);
int
timer_gettime(timer_t
timerid, struct
itimerspec *tim);
int
timer_getoverrun(timer_t
timerid);
DESCRIPTION
Thetimer_settime()
sets the next expiration time of the timer with ID
timerid to the it_value (see
itimerspec(3)) specified in the tim argument. If
the value is 0, the timer is disarmed. If the argument
otim is not NULL the old timer
settings are returned.
If the flags argument
is set to TIMER_RELTIME then the expiration time is
set to the value in nanoseconds specified in the tim
argument from the time the call to
timer_settime()
was made. If the flags argument is set to
TIMER_ABSTIME then the expiration time is set to be
equal to the difference between the clock associated with this timer, and
the value specified in the tim argument. If that time
has already passed, then the call succeeds, and the expiration notification
occurs.
If the it_interval of the tim argument is non-zero, then the timer reloads upon expiration.
The
timer_gettime()
function returns the current settings of the timer specified by the
timerid argument in the tim
argument.
Only one notification event (signal) can be
pending for a given timer and process. If a timer expires while the signal
is still queued for delivery, then the overrun counter for that timer is
increased. The counter can store values up to
DELAYTIMER_MAX. When the signal is finally delivered
to the process, then the
timer_getoverrun()
function can be used to retrieve the overrun counter for the timer specified
in the timerid argument.
NOTES
Expiration time values are always rounded up to the resolution of
the timer, so a notification will never be sent before the requested time.
Values returned in the otim argument of
timer_settime() or in the tim
argument of timer_gettime() are subject to the above
rounding effect and might not exactly match the requested values by the
user.
RETURN VALUES
If successful, the timer_gettime() and
timer_settime() functions return 0, and the
timer_getoverrun() function returns the expiration
overrun count for the specified timer. Otherwise, the functions return -1,
and set errno to indicate the error.
ERRORS
The timer_gettime(),
timer_getoverrun(), and
timer_settime() functions will fail if:
- [
EINVAL] - The argument timerid does not correspond to a valid
timer id as returned by
timer_create() or that timer id has been deleted bytimer_delete().
The timer_settime() function will fail
if:
- [
EINVAL] - A nanosecond field in the tim structure specified a value less than zero or greater than or equal to 10e9.
SEE ALSO
STANDARDS
IEEE Std 1003.1b-1993 (“POSIX.1b”), IEEE Std 1003.1i-1995 (“POSIX.1i”)