timers.2 (2010 09)

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timers(2) timers(2)

NAME

timers: timer_create(), timer_delete(), timer_getoverrun(), timer_gettime(), timer_settime() - timer opera-

tions

SYNOPSIS

#include <time.h>

int timer_create(

clockid_t clock_id,

struct sigevent *evp,

timer_t *timerid

);

int timer_delete(

timer_t timerid

);

int timer_getoverrun(

timer_t timerid

);

int timer_gettime(

timer_t timerid,

struct itimerspec *value

);

int timer_settime(

timer_t timerid,

int flags,

const struct itimerspec *value,

struct itimerspec *ovalue

);

DESCRIPTION

timer_create()

The timer_create() function creates a per-process 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 cal-

ling 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. If the sigev_notify member of evp is

SIGEV_SIGNAL, then the structure should also specify the signal number to be sent to the process on

timer expiration. The signal to be sent is speciﬁed in the sigev_signo ﬁeld of evp. If the sigev_notify

member of evp is

SIGEV_NONE, no notiﬁcation is sent. If evp is NULL, then a default signal is sent to

the process. The defaults for the clocks CLOCK_REALTIME, CLOCK_VIRTUAL

, and CLOCK_PROFILE

are SIGALRM, SIGVTALRM, and SIGPROF.

Per-process timers are not inherited by a child process across a

fork() and are disarmed and deleted by

an exec().

timer_delete()

The

timer_delete() function deletes the speciﬁed timer, timerid, previously created by the

timer_create() function. If the timer is armed when timer_delete()

is called, the behavior is as

if the timer is automatically disarmed before removal. Any pending notiﬁcations from the timer remain.

timer_settime()

The

timer_settime() function sets the time until the next expiration of the timer speciﬁed by timerid

from the it_value member of the value argument and arms the timer if the it_value member of value is

non-zero. If the speciﬁed timer was already armed when 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. Any pending notiﬁcations from the timer remain.

If the ﬂag

TIMER_ABSTIME is not set in the argument ﬂags, timer_settime() behaves as if the time

until next expiration is set equal to the interval speciﬁed by the it_value member of value. That is, the

timer will expire in it_value nanoseconds from when the call is made.

HP-UX 11i Version 3: September 2010 − 1 − Hewlett-Packard Company 1

Summary of content (4 pages)

PAGE 1
timers(2) timers(2) NAME timers: timer_create(), timer_delete(), timer_getoverrun(), timer_gettime(), timer_settime() - timer operations SYNOPSIS #include
PAGE 2
timers(2) timers(2) If the flag TIMER_ABSTIME is set in the argument flags, timer_settime() behaves as if the time until next expiration is set 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 timerid . That is, the timer will expire when the clock reaches the value specified by the it_value member of value .
PAGE 3
timers(2) timers(2) [EFAULT] The timerid or evp argument points to an invalid address. [ENOSYS] The function timer_create() is not supported by this implementation. If any of the following conditions occur, the timer_delete() function returns −1 and sets errno to the corresponding value: [EINVAL] The timer ID specified by timerid is not a valid timer ID. [ENOSYS] The function timer_delete() is not supported by this implementation.
PAGE 4
timers(2) timers(2) if (timer_create(CLOCK_REALTIME, &sigev, &timerid) == -1) { perror("timer_create"); exit(1); } if (timer_settime(timerid, 0, &one_minute, (struct itimerspec *)NULL) == -1) { perror("timer_create"); exit(1); } pause(); if (timer_delete(timerid) == -1) { perror("timer_delete"); exit(1); } return 0; } AUTHOR timer_create(), timer_delete(), timer_settime(), timer_gettime(), timer_getoverrun() were derived from the proposed IEEE POSIX P1003.4 standard, draft 14.