Tribblix: manual page: nanosleep.3c

NANOSLEEP(3C) Standard C Library Functions NANOSLEEP(3C)

NAME

nanosleep, thrd_sleep - high resolution sleep

SYNOPSIS

#include <time.h>

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

#include <threads.h>

int thrd_sleep(const struct timespec *rqtp,
struct timespec *rmtp);

DESCRIPTION

The nanosleep() and thrd_sleep() functions cause the current thread
to be suspended from execution until either the time interval
specified by the rqtp argument has elapsed or a signal is delivered
to the calling thread and its action is to invoke a signal-catching
function or to terminate the process. The suspension time may be
longer than requested because the argument value is rounded up to an
integer multiple of the sleep resolution or because of the scheduling
of other activity by the system. But, except for the case of being
interrupted by a signal, the suspension time will not be less than
the time specified by rqtp, as measured by the system clock,
CLOCK_REALTIME.

The use of the nanosleep() and thrd_sleep() functions has no effect
on the action or blockage of any signal.

RETURN VALUES

If the nanosleep() or thrd_sleep() function returns because the
requested time has elapsed, its return value is 0.

If the nanosleep() function returns because it has been interrupted
by a signal, the function returns a value of -1 and sets errno to
indicate the interruption. If the rmtp argument is non-NULL, the
timespec structure referenced by it is updated to contain the amount
of time remaining in the interval (the requested time minus the time
actually slept). If the rmtp argument is NULL, the remaining time is
not returned.

If nanosleep() fails, it returns -1 and sets errno to indicate the
error.

The thrd_sleep() function may fail for identical reasons as the
nanosleep() function and returns -1; however, the C11 standard does
not define that errno should be set, therefore callers of
thrd_sleep() cannot rely on errno being set or staying the same
across a call to thrd_sleep() .

ERRORS

The nanosleep() function will fail if:

EINTR
The nanosleep() function was interrupted by a signal.

EINVAL
The rqtp argument specified a nanosecond value less than
zero or greater than or equal to 1000 million.

ENOSYS
The nanosleep() function is not supported by this
implementation.