сон высокого разрешения (high resolution sleep)
Пролог (Prolog)
This manual page is part of the POSIX Programmer's Manual. The
Linux implementation of this interface may differ (consult the
corresponding Linux manual page for details of Linux behavior),
or the interface may not be implemented on Linux.
Имя (Name)
nanosleep — high resolution sleep
Синопсис (Synopsis)
#include <time.h>
int nanosleep(const struct timespec *rqtp, struct timespec *rmtp);
Описание (Description)
The nanosleep() function shall 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 shall
not be less than the time specified by rqtp, as measured by the
system clock CLOCK_REALTIME.
The use of the nanosleep() function has no effect on the action
or blockage of any signal.
Возвращаемое значение (Return value)
If the nanosleep() function returns because the requested time
has elapsed, its return value shall be zero.
If the nanosleep() function returns because it has been
interrupted by a signal, it shall return a value of -1 and set
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). The rqtp and rmtp
arguments can point to the same object. If the rmtp argument is
NULL, the remaining time is not returned.
If nanosleep() fails, it shall return a value of -1 and set errno
to indicate the error.
Ошибки (Error)
The nanosleep() function shall 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.
The following sections are informative.
Примеры (Examples)
None.
Использование в приложениях (Application usage)
None.
Обоснование (Rationale)
It is common to suspend execution of a thread for an interval in
order to poll the status of a non-interrupting function. A large
number of actual needs can be met with a simple extension to
sleep() that provides finer resolution.
In the POSIX.1‐1990 standard and SVR4, it is possible to
implement such a routine, but the frequency of wakeup is limited
by the resolution of the alarm() and sleep() functions. In 4.3
BSD, it is possible to write such a routine using no static
storage and reserving no system facilities. Although it is
possible to write a function with similar functionality to
sleep() using the remainder of the timer_*() functions, such a
function requires the use of signals and the reservation of some
signal number. This volume of POSIX.1‐2017 requires that
nanosleep() be non-intrusive of the signals function.
The nanosleep() function shall return a value of 0 on success and
-1 on failure or if interrupted. This latter case is different
from sleep(). This was done because the remaining time is
returned via an argument structure pointer, rmtp, instead of as
the return value.
Будущие направления (Future directions)
None.
Смотри также (See also)
clock_nanosleep(3p), sleep(3p)
The Base Definitions volume of POSIX.1‐2017, time.h(0p)
