NAME
timer_settime,
timer_gettime,
timer_getoverrun —
process timer
manipulation
LIBRARY
Standard C Library (libc, -lc)
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
The
timer_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 by
timer_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
clock_gettime(2),
timer_create(2),
timer_delete(2)
STANDARDS
IEEE Std 1003.1b-1993 (“POSIX.1b”),
IEEE Std 1003.1i-1995 (“POSIX.1i”)