DTK_NANOSLEEP(3) Draw Toolkit manual DTK_NANOSLEEP(3)NAME
dtk_nanosleep - high-resolution sleep
SYNOPSIS
#include <dtk_time.h>
int dtk_nanosleep(int abs, const struct dtk_timespec* req,
struct dtk_timespec* rem);
DESCRIPTION
The function dtk_nanosleep() allows the caller to sleep for an interval with nanosecond precision. If the argument abs is zero, the speci-
fied interval is interpretated as a relative value, otherwise an absolute value. The interval is specified by the req argument which is a
pointer to a dtk_timespec structure defined as:
struct dtk_timespec {
long sec; /* seconds */
long nsec; /* nanoseconds */
};
If interpreted as an absolute value, it represents seconds and nanoseconds since the Epoch, 1970-01-01 00:00:00 +0000 (UTC).
dtk_nanosleep() suspends the execution of the calling thread until either at least the time specified by req has elapsed, or a signal is
delivered that causes a signal handler to be called or that terminates the process.
If the call is interrupted by a signal handler, dtk_nanosleep() returns -1, and sets errno to EINTR. In addition, if rem is not NULL, and
abs is zero, it returns the remaining unslept time in rem. This value can then be used to call dtk_nanosleep() again and complete a (rela-
tive) sleep.
RETURN VALUE
On successfully sleeping for the requested interval, dtk_nanosleep() returns 0. If the call is interrupted by a signal handler or encoun-
ters an error, then it returns -1 and errno is set appropriately.
ERRORS
dtk_nanosleep() will fail if:
EINTR The sleep was interrupted by a signal handler.
EINVAL The value in the nsec field was not in the range 0 to 999999999 or sec was negative.
NOTE
This function is a wrapper to clock_nanosleep(2) if it is provided by the system. Otherwise, it implements the function by using the sleep
function with the highest precision available on the system.
SEE ALSO dtk_nanosleep(3), clock_nanosleep(2)EPFL 2011 DTK_NANOSLEEP(3)
Check Out this Related Man Page
CLOCK_NANOSLEEP(2) Linux Programmer's Manual CLOCK_NANOSLEEP(2)NAME
clock_nanosleep - high-resolution sleep with specifiable clock
SYNOPSIS
#include <time.h>
int clock_nanosleep(clockid_t clock_id, int flags,
const struct timespec *request,
struct timespec *remain);
Link with -lrt (only for glibc versions before 2.17).
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
clock_nanosleep():
_XOPEN_SOURCE >= 600 || _POSIX_C_SOURCE >= 200112L
DESCRIPTION
Like nanosleep(2), clock_nanosleep() allows the calling thread to sleep for an interval specified with nanosecond precision. It differs in
allowing the caller to select the clock against which the sleep interval is to be measured, and in allowing the sleep interval to be speci-
fied as either an absolute or a relative value.
The time values passed to and returned by this call are specified using timespec structures, defined as follows:
struct timespec {
time_t tv_sec; /* seconds */
long tv_nsec; /* nanoseconds [0 .. 999999999] */
};
The clock_id argument specifies the clock against which the sleep interval is to be measured. This argument can have one of the following
values:
CLOCK_REALTIME A settable system-wide real-time clock.
CLOCK_MONOTONIC A nonsettable, monotonically increasing clock that measures time since some unspecified point in the past that does not
change after system startup.
CLOCK_PROCESS_CPUTIME_ID
A settable per-process clock that measures CPU time consumed by all threads in the process.
See clock_getres(2) for further details on these clocks.
If flags is 0, then the value specified in request is interpreted as an interval relative to the current value of the clock specified by
clock_id.
If flags is TIMER_ABSTIME, then request is interpreted as an absolute time as measured by the clock, clock_id. If request is less than or
equal to the current value of the clock, then clock_nanosleep() returns immediately without suspending the calling thread.
clock_nanosleep() suspends the execution of the calling thread until either at least the time specified by request has elapsed, or a signal
is delivered that causes a signal handler to be called or that terminates the process.
If the call is interrupted by a signal handler, clock_nanosleep() fails with the error EINTR. In addition, if remain is not NULL, and
flags was not TIMER_ABSTIME, it returns the remaining unslept time in remain. This value can then be used to call clock_nanosleep() again
and complete a (relative) sleep.
RETURN VALUE
On successfully sleeping for the requested interval, clock_nanosleep() returns 0. If the call is interrupted by a signal handler or
encounters an error, then it returns one of the positive error number listed in ERRORS.
ERRORS
EFAULT request or remain specified an invalid address.
EINTR The sleep was interrupted by a signal handler.
EINVAL The value in the tv_nsec field was not in the range 0 to 999999999 or tv_sec was negative.
EINVAL clock_id was invalid. (CLOCK_THREAD_CPUTIME_ID is not a permitted value for clock_id.)
VERSIONS
The clock_nanosleep() system call first appeared in Linux 2.6. Support is available in glibc since version 2.1.
CONFORMING TO
POSIX.1-2001.
NOTES
If the interval specified in request is not an exact multiple of the granularity underlying clock (see time(7)), then the interval will be
rounded up to the next multiple. Furthermore, after the sleep completes, there may still be a delay before the CPU becomes free to once
again execute the calling thread.
Using an absolute timer is useful for preventing timer drift problems of the type described in nanosleep(2). (Such problems are exacer-
bated in programs that try to restart a relative sleep that is repeatedly interrupted by signals.) To perform a relative sleep that avoids
these problems, call clock_gettime(2) for the desired clock, add the desired interval to the returned time value, and then call
clock_nanosleep() with the TIMER_ABSTIME flag.
clock_nanosleep() is never restarted after being interrupted by a signal handler, regardless of the use of the sigaction(2) SA_RESTART
flag.
The remain argument is unused, and unnecessary, when flags is TIMER_ABSTIME. (An absolute sleep can be restarted using the same request
argument.)
POSIX.1 specifies that clock_nanosleep() has no effect on signals dispositions or the signal mask.
POSIX.1 specifies that after changing the value of the CLOCK_REALTIME clock via clock_settime(2), the new clock value shall be used to
determine the time at which a thread blocked on an absolute clock_nanosleep() will wake up; if the new clock value falls past the end of
the sleep interval, then the clock_nanosleep() call will return immediately.
POSIX.1 specifies that changing the value of the CLOCK_REALTIME clock via clock_settime(2) shall have no effect on a thread that is blocked
on a relative clock_nanosleep().
SEE ALSO clock_getres(2), nanosleep(2), restart_syscall(2), timer_create(2), sleep(3), usleep(3), time(7)COLOPHON
This page is part of release 3.53 of the Linux man-pages project. A description of the project, and information about reporting bugs, can
be found at http://www.kernel.org/doc/man-pages/.
Linux 2013-07-30 CLOCK_NANOSLEEP(2)