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timer_create(3c)

timer_create(3C)         Standard C Library Functions         timer_create(3C)

NAME
       timer_create - create a timer

SYNOPSIS
       #include <signal.h>
       #include <time.h>

       int timer_create(clockid_t clock_id,
            struct sigevent *restrict evp, timer_t *restrict timerid);

DESCRIPTION
       The  timer_create() function creates a timer using the specified clock,
       clock_id, as the timing base. The timer_create() function  returns,  in
       the  location referenced by timerid, a timer ID of type timer_t used to
       identify the timer in timer requests. This  timer  ID  will  be  unique
       within  the  calling process until the timer is deleted. The particular
       clock, clock_id, is defined in <time.h>. The timer whose ID is returned
       will be in a disarmed state upon return from timer_create().


       The evp argument, if non-null, points to  a  sigevent  structure.  This
       structure, allocated by the application, defines the asynchronous noti‐
       fication  that  will  occur when the timer expires (see signal.h(3HEAD)
       for event notification details). If the evp argument is NULL,  the  ef‐
       fect is as if the evp argument pointed to a sigevent structure with the
       sigev_notify member having the value SIGEV_SIGNAL, the sigev_signo hav‐
       ing  the value SIGALARM, and the sigev_value member having the value of
       the timer ID.


       If the sigev_notify member of  the  sigeven  structure  has  the  value
       SIGEV_SIGNAL_THR,  the  signal  number specified in sigev_signo will be
       sent to the calling thread. When the thread exits, this timer  will  be
       deleted automatically.


       The system defines a set of clocks that can be used as timing bases for
       per-process timers. The following values for clock_id are supported:

       CLOCK_REALTIME              wall clock


       CLOCK_VIRTUAL               user CPU usage clock


       CLOCK_PROF                  user and system CPU usage clock


       CLOCK_HIGHRES               non-adjustable, high-resolution clock


       CLOCK_PROCESS_CPUTIME_ID    process CPU time clock


       CLOCK_THREAD_CPUTIME_ID     thread CPU time clock



       As  well as the above values, clock_id can be specified as the Clock ID
       returned by clock_getcpuclockid(3C) or pthread_getcpuclockid(3C).


       For timers created with a clock_id of CLOCK_HIGHRES,  the  system  will
       attempt to use an optimal hardware source. This may include, but is not
       limited  to,  per-CPU timer sources. The actual hardware source used is
       transparent to the user and may change over the lifetime of the  timer.
       For  example,  if  the caller that created the timer were to change its
       processor binding or its processor set, the system may elect  to  drive
       the  timer with a hardware source that better reflects the new binding.
       Timers based on a clock_id of CLOCK_HIGHRES are ideally suited for  in‐
       terval timers that have minimal jitter tolerance.


       Timers  are  not  inherited by a child process across a fork(2) and are
       disarmed and deleted by a call  to  one  of  the  exec  functions  (see
       exec(2)).

RETURN VALUES
       Upon  successful  completion,  timer_create() returns 0 and updates the
       location referenced by timerid to a timer_t, which can be passed to the
       per-process timer calls. If an error occurs, the  function  returns  −1
       and sets errno to indicate the error. The value of timerid is undefined
       if an error occurs.

ERRORS
       The timer_create() function will fail if:

       EAGAIN    The system lacks sufficient signal queuing resources to honor
                 the  request,  or the calling process has already created all
                 of the timers it is allowed by the system.


       EINVAL    The specified clock ID, clock_id, is not defined.


       EPERM     The specified clock ID, clock_id, is  CLOCK_HIGHRES  and  the
                 {PRIV_PROC_CLOCK_HIGHRES}  is  not  asserted in the effective
                 set of the calling process.


ATTRIBUTES
       See attributes(7) for descriptions of the following attributes:

       tab() box; cw(2.75i) |cw(2.75i) lw(2.75i) |lw(2.75i) ATTRIBUTE  TYPEAT‐
       TRIBUTE VALUE _ Interface StabilityCommitted _ MT-LevelMT-Safe with ex‐
       ceptions _ StandardSee standards(7).


SEE ALSO
       exec(2),  fork(2), time(2), clock_settime(3C), clock_getcpuclockid(3C),
       pthread_getcpuclockid(3C),  signal(3C),  timer_delete(3C),   timer_set‐
       time(3C),  signal.h(3HEAD), attributes(7), privileges(7), resource-con‐
       trols(7), standards(7)

Oracle Solaris 11.4               22 Jan 2019                 timer_create(3C)
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