187 lines
6.8 KiB
Groff
187 lines
6.8 KiB
Groff
|
.\"
|
||
|
|
.\" Redistribution and use in source and binary forms, with or without
|
||
|
|
.\" modification, are permitted provided that the following conditions
|
||
|
|
.\" are met:
|
||
|
|
.\" 1. Redistributions of source code must retain the above copyright
|
||
|
|
.\" notice(s), this list of conditions and the following disclaimer as
|
||
|
|
.\" the first lines of this file unmodified other than the possible
|
||
|
|
.\" addition of one or more copyright notices.
|
||
|
|
.\" 2. Redistributions in binary form must reproduce the above copyright
|
||
|
|
.\" notice(s), this list of conditions and the following disclaimer in
|
||
|
|
.\" the documentation and/or other materials provided with the
|
||
|
|
.\" distribution.
|
||
|
|
.\"
|
||
|
|
.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY
|
||
|
|
.\" EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
||
|
|
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
|
||
|
|
.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE
|
||
|
|
.\" LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
|
||
|
|
.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
|
||
|
|
.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
|
||
|
|
.\" BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
|
||
|
|
.\" WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
|
||
|
|
.\" OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
|
||
|
|
.\" EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
|
||
|
|
.\"
|
||
|
|
.\" $FreeBSD$
|
||
|
|
.\"
|
||
|
|
.Dd Sep 11, 2000
|
||
|
|
.Dt TIMER_SETTIME 2
|
||
|
|
.Os
|
||
|
|
.Sh NAME
|
||
|
|
.Nm timer_getoverrun
|
||
|
|
.Nm timer_gettime
|
||
|
|
.Nm timer_settime
|
||
|
|
.Nd per-process timers (REALTIME)
|
||
|
|
.Sh LIBRARY
|
||
|
|
.Lb libc
|
||
|
|
.Sh SYNOPSIS
|
||
|
|
.In time.h
|
||
|
|
.Ft int
|
||
|
|
.Fn timer_getoverrun "timer_t timerid"
|
||
|
|
.Ft int
|
||
|
|
.Fn timer_gettime "timer_t timerid" "struct itimerspec *value"
|
||
|
|
.Ft int
|
||
|
|
.Fn timer_settime "timer_t timerid" "int flags" "const struct itimerspec *restrict value" "struct itimerspec *restrict ovalue"
|
||
|
|
.Sh DESCRIPTION
|
||
|
|
The
|
||
|
|
.Fn timer_gettime
|
||
|
|
function stores the amount of time until the specified timer,
|
||
|
|
.Fa timerid ,
|
||
|
|
expires and the reload value of the timer into the space pointed to by the
|
||
|
|
.Fa value
|
||
|
|
argument. The it_value member of this structure contains the amount of time
|
||
|
|
before the timer expires, or zero if the timer is disarmed. This value is
|
||
|
|
returned as the interval until timer expiration, even if the timer was armed
|
||
|
|
with absolute time. The it_interval member of value contains the reload
|
||
|
|
value last set by
|
||
|
|
.Fn timer_settime .
|
||
|
|
.Pp
|
||
|
|
The
|
||
|
|
.Fn timer_settime
|
||
|
|
function sets the time until the next expiration of the timer specified
|
||
|
|
by
|
||
|
|
.Fa timerid
|
||
|
|
from the it_value member of the value argument and arm the timer if the
|
||
|
|
it_value member of value is non-zero. If the specified timer was already
|
||
|
|
armed when
|
||
|
|
.Fn timer_settime
|
||
|
|
is called, this call resets the time until next expiration to the value
|
||
|
|
specified. If the it_value member of value is zero, the timer is disarmed.
|
||
|
|
If the timer is disarmed, then pending signal is removed.
|
||
|
|
.Pp
|
||
|
|
If the flag TIMER_ABSTIME is not set in the argument
|
||
|
|
.Fa flags ,
|
||
|
|
.Fn timer_settime
|
||
|
|
behaves as if the time until next expiration is set to
|
||
|
|
be equal to the interval specified by the it_value member of value. That is,
|
||
|
|
the timer expires in it_value nanoseconds from when the call is made. If the
|
||
|
|
flag TIMER_ABSTIME is set in the argument flags,
|
||
|
|
.Fn timer_settime
|
||
|
|
behaves as if the time until next expiration is set to be equal to the
|
||
|
|
difference between the absolute time specified by the it_value member of
|
||
|
|
value and the current value of the clock associated with
|
||
|
|
.Fa timerid .
|
||
|
|
That is, the timer expires when the clock reaches the value specified by the
|
||
|
|
it_value member of value. If the specified time has already passed, the
|
||
|
|
function succeeds and the expiration notification is made.
|
||
|
|
.Pp
|
||
|
|
The reload value of the timer is set to the value specified by the it_interval
|
||
|
|
member of value. When a timer is armed with a non-zero it_interval, a periodic
|
||
|
|
(or repetitive) timer is specified.
|
||
|
|
.Pp
|
||
|
|
Time values that are between two consecutive non-negative integer multiples of
|
||
|
|
the resolution of the specified timer is rounded up to the larger multiple of
|
||
|
|
the resolution. Quantization error will not cause the timer to expire earlier
|
||
|
|
than the rounded time value.
|
||
|
|
.Pp
|
||
|
|
If the argument ovalue is not NULL, the
|
||
|
|
.Fn timer_settime
|
||
|
|
function stores, in the location referenced by ovalue, a value representing
|
||
|
|
the previous amount of time before the timer would have expired, or zero if the
|
||
|
|
timer was disarmed, together with the previous timer reload value. Timers is not
|
||
|
|
expire before their scheduled time.
|
||
|
|
.Pp
|
||
|
|
Only a single signal is queued to the process for a given timer at any point in
|
||
|
|
time. When a timer for which a signal is still pending expires, no signal is
|
||
|
|
queued, and a timer overrun will occur. When a timer expiration signal is
|
||
|
|
accepted by a process, the
|
||
|
|
.Fn timer_getoverrun
|
||
|
|
function returns the timer expiration overrun count for the specified timer.
|
||
|
|
The overrun count returned contains the number of extra timer expirations that
|
||
|
|
occurred between the time the signal was generated (queued) and when it was
|
||
|
|
accepted, up to but not including an maximum of {DELAYTIMER_MAX}. If the number of
|
||
|
|
such extra expirations is greater than or equal to {DELAYTIMER_MAX}, then the
|
||
|
|
overrun count is set to {DELAYTIMER_MAX}. The value returned by
|
||
|
|
.Fn timer_getoverrun
|
||
|
|
applies to the most recent expiration signal acceptance for the timer. If no
|
||
|
|
expiration signal has been delivered for the timer, the return value of
|
||
|
|
.Fn timer_getoverrun
|
||
|
|
is unspecified.
|
||
|
|
.Sh RETURN VALUES
|
||
|
|
If the
|
||
|
|
.Fn timer_getoverrun
|
||
|
|
function succeeds, it returns the timer expiration overrun count as explained
|
||
|
|
above.
|
||
|
|
.Pp
|
||
|
|
If the
|
||
|
|
.Fn timer_gettime
|
||
|
|
or
|
||
|
|
.Fn timer_settime
|
||
|
|
functions succeed, a value of 0 is returned.
|
||
|
|
.Pp
|
||
|
|
If an error occurs for any of these functions, the value -1 is returned, and
|
||
|
|
errno set to indicate the error.
|
||
|
|
.Sh ERRORS
|
||
|
|
The
|
||
|
|
.Fn timer_settime
|
||
|
|
will fail if:
|
||
|
|
.Bl -tag -width Er
|
||
|
|
.It Bq Er EINVAL
|
||
|
|
A value structure specified a nanosecond value less than zero or greater than
|
||
|
|
or equal to 1000 million, and the it_value member of that structure did not
|
||
|
|
specify zero seconds and nanoseconds.
|
||
|
|
.El
|
||
|
|
.Pp
|
||
|
|
These functions may fail if:
|
||
|
|
.Bl -tag -width Er
|
||
|
|
.It Bq Er EINVAL
|
||
|
|
The
|
||
|
|
.Fa timerid
|
||
|
|
argument does not correspond to an ID returned by
|
||
|
|
.Fn timer_create
|
||
|
|
but not yet deleted by
|
||
|
|
.Fn timer_delete .
|
||
|
|
.El
|
||
|
|
.Pp
|
||
|
|
The timer_settime() function may fail if:
|
||
|
|
.Bl -tag -width Er
|
||
|
|
.It Bq Er EINVAL
|
||
|
|
The it_interval member of value is not zero and the timer was created with
|
||
|
|
notification by creation of a new thread ( sigev_sigev_notify was SIGEV_THREAD)
|
||
|
|
and a fixed stack address has been set in the thread attribute pointed to by
|
||
|
|
sigev_notify_attributes.
|
||
|
|
.El
|
||
|
|
.Pp
|
||
|
|
The
|
||
|
|
.Fn timer_gettime
|
||
|
|
and
|
||
|
|
.Fn timer_settime
|
||
|
|
may fail if:
|
||
|
|
.Bl -tag -width Er
|
||
|
|
.It Bq Er EFAULT
|
||
|
|
Any arguments point outside the allocated address space or there is a
|
||
|
|
memory protection fault.
|
||
|
|
.El
|
||
|
|
.Sh SEE ALSO
|
||
|
|
.Xr clock_getres 2 ,
|
||
|
|
.Xr timer_create 2
|
||
|
|
.Sh STANDARDS
|
||
|
|
The
|
||
|
|
.Fn timer_getoverrun ,
|
||
|
|
.Fn timer_gettime ,
|
||
|
|
and
|
||
|
|
.Fn timer_settime
|
||
|
|
function conform to
|
||
|
|
.St -p1003.1-96 .
|