109 lines
3.9 KiB
Groff
109 lines
3.9 KiB
Groff
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY
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.\" $FreeBSD$
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.\"
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.Dd Sep 11, 2000
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.Dt TIMER_CREATE 2
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.Os
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.Sh NAME
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.Nm timer_create
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.Nd create a per-process timer (REALTIME)
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.Sh LIBRARY
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.Lb libc
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.Sh SYNOPSIS
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.In time.h
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.Ft int
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.Fn timer_create "clockid_t clockid" "struct sigevent *restrict evp" "timer_t *restrict timerid"
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.Sh DESCRIPTION
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The
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.Fn timer_create
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function creates a per-process timer using the specified clock,
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.Fa clock_id ,
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as the timing base. The
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.Fn timer_create
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function returns, in the location referenced by
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.Fa timerid ,
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a timer ID of type timer_t used to identify the timer in timer requests.
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This timer ID is unique within the calling process until the timer is deleted.
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The particular clock,
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.Fa clock_id ,
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is defined in
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.In time.h .
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The timer whose ID is returned is in a disarmed state upon return from
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.Fn timer_create .
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.Pp
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The
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.Fa evp
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argument, if non-NULL, points to a sigevent structure. This structure,
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allocated by the application, defines the asynchronous notification to occur
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when the timer expires. If the
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.Fa evp
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argument is NULL, the effect is as if the evp argument pointed to a sigevent
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structure with the sigev_notify member having the value SIGEV_SIGNAL, the
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sigev_signo having a default signal number, and the sigev_value member having
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the value of the timer ID.
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.Pp
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The implementations supports a clock_id of CLOCK_REALTIME or CLOCK_MONOTONIC.
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.Pp
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If evp->sigev_sigev_notify is SIGEV_THREAD and sev->sigev_notify_attributes
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is not NULL, if the attribute pointed to by sev->sigev_notify_attributes has
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a thread stack address specified by a call to
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.Fn pthread_attr_setstack
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or
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.Fn pthread_attr_setstackaddr ,
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the results are unspecified if the signal is generated more than once.
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.Sh RETURN VALUES
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If the call succeeds,
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.Fn timer_create
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returns zero and update the location referenced by
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.Fa timerid
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to a timer_t, which can be passed to the per-process timer calls. If an error
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occurs, the function shall return a value of -1 and set errno to indicate the
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error. The value of timerid is undefined if an error occurs.
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.Sh ERRORS
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The
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.Fn timer_create
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will fail if:
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.Bl -tag -width Er
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.It Bq Er EAGAIN
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The calling process has already created all of the timers it is allowed by
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this implementation
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.It Bq Er EINVAL
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The specified clock ID is not supported.
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.It Bq Er EFAULT
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Any arguments point outside the allocated address space or there is a
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memory protection fault.
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.El
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.Sh SEE ALSO
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.Xr clock_getres 2 ,
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.Xr timer_delete 2 ,
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.Xr timer_getoverun 2
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.Sh STANDARDS
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The
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.Fn timer_create
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function conforms to
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.St -p1003.1-96 .
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