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timer_create

Section: C Library Functions (3)
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NAME

timer_create - Allocate a per-process timer  

SYNOPSIS

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

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

PARAMETERS

The type of clock on which the timer is based. The CLOCK_REALTIME clock is supported. A pointer to a sigevent structure, which defines the signal sent to the process on timer expiration. A pointer to the timer ID returned by the call to the timer_create function.  

DESCRIPTION

The timer_create function allocates a per-process timer using the specified clock as the timing base. The timer_create function returns timer_id, which is used to identify the timer in timer requests. The timer ID is unique within the calling process until the timer is deleted. The timer is unarmed when first returned from a call to timer_create. To arm the timer, use the timer_settime function.

The evp argument, if non-NULL, points to a sigevent structure, which defines the asynchronous notification that will occur when the timer expires. If the sigev_notify member of evp is SIGEV_SIGNAL, the structure must contain the signal number and data value to send to the process when the timer expires. If the sigev_notify member is SIGEV_NONE, no notification will be sent.

SIGALRM is the default signal for CLOCK_REALTIME if the evp argument is NULL.

The maximum number of timers supported per process (TIMER_MAX) is defined in the <sys/rt_limits.h> header file, which is indirectly included through <time.h>.

Timers are not inherited across fork calls. An exec call will disarm and delete a timer.  

RETURN VALUES

Upon successful completion, a value of 0 is returned. The timer_create function also returns, in timerid, a pointer to the timer ID that has been created.

An unsuccessful call returns -1, and errno is set to indicate the error type.  

ERRORS

The timer_create function fails under the following conditions:

[EAGAIN]
The system lacks sufficient signal queuing resources to honor the request.

The calling process has already created all of the timers it is allowed.

[EINVAL]
The specified clock ID is not defined.
 

RELATED INFORMATION

Functions: clock_getres(3), clock_gettime(3), clock_settime(3), timer_delete(3), timer_gettime(3), timer_settime(3) delim off


 

Index

NAME
SYNOPSIS
PARAMETERS
DESCRIPTION
RETURN VALUES
ERRORS
RELATED INFORMATION

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Time: 02:41:47 GMT, October 02, 2010