timer_settime(2) [netbsd man page]
TIMER_SETTIME(2) BSD System Calls Manual TIMER_SETTIME(2) NAME
timer_settime, timer_gettime, timer_getoverrun -- process timer manipulation LIBRARY
Standard C Library (libc, -lc) SYNOPSIS
#include <time.h> int timer_settime(timer_t timerid, int flags, const struct itimerspec * restrict tim, struct itimerspec * restrict otim); int timer_gettime(timer_t timerid, struct itimerspec *tim); int timer_getoverrun(timer_t timerid); DESCRIPTION
The timer_settime() sets the next expiration time of the timer with ID timerid to the it_value (see itimerspec(3)) specified in the tim argu- ment. If the value is 0, the timer is disarmed. If the argument otim is not NULL the old timer settingas are returned. If the flags argument is set to TIMER_RELTIME then the expiration time is set to the value in nanoseconds specified in the tim argument from the time the call to timer_settime() was made. If the flags argument is set to TIMER_ABSTIME then the expiration time is set to be equal to the difference between the clock associated with this timer, and the value specified in the tim argument. If that time has already passed, then the call succeeds, and the expiration notification occurs. If the it_interval of the tim argument is non-zero, then the timer reloads upon expiration. The timer_gettime() function returns the current settings of the timer specified by the timerid argument in the tim argument. Only one notification event (signal) can be pending for a given timer and process. If a timer expires while the signal is still queued for delivery, then the overrun counter for that timer is increased. The counter can store values up to DELAYTIMER_MAX. When the signal is finally delivered to the process, then the timer_getoverrun() function can be used to retrieve the overrun counter for the timer specified in the timerid argument. NOTES
Expiration time values are always rounded up to the resolution of the timer, so a notification will never be sent before the requested time. Values returned in the otim argument of timer_settime() or in the tim argment of timer_gettime() are subject to the above rounding effect and might not exactly match the requested values by the user. RETURN VALUES
If successful, the timer_gettime() and timer_settime() functions return 0, and the timer_getoverrun() function returns the expiration overrun count for the specified timer. Otherwise, the functions return -1, and set errno to indicate the error. ERRORS
The timer_gettime(), timer_getoverrun(), and timer_settime() functions will fail if: [EINVAL] The argument timerid does not correspond to a valid timer id as returned by timer_create() or that timer id has been deleted by timer_delete(). The timer_settime() function will fail if: [EINVAL] A nanosecond field in the tim structure specified a value less than zero or greater than or equal to 10e9. SEE ALSO
clock_gettime(2), timer_create(2), timer_delete(2) STANDARDS
IEEE Std 1003.1b-1993 (``POSIX.1''), IEEE Std 1003.1i-1995 (``POSIX.1'') BSD
May 17, 2010 BSD
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timer_settime(3C) Standard C Library Functions timer_settime(3C) NAME
timer_settime, timer_gettime, timer_getoverrun - per-process timers SYNOPSIS
#include <time.h> int timer_settime(timer_t timerid, int flags, const struct itimerspec *restrict value, struct itimerspec *restrict ovalue); int timer_gettime(timer_t timerid, struct itimerspec *value); int timer_getoverrun(timer_t timerid); DESCRIPTION
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 arm 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 0, the timer is dis- armed. The effect of disarming or resetting a timer on pending expiration notifications is unspecified. If the flag TIMER_ABSTIME is not set in the argument flags, 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, 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 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. 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. Time values that are between two consecutive non-negative integer multiples of the resolution of the specified timer will be rounded up to the larger multiple of the resolution. Quantization error will not cause the timer to expire earlier than the rounded time value. If the argument ovalue is not NULL, the function timer_settime() stores, in the location referenced by ovalue, a value representing the previous amount of time before the timer would have expired or 0 if the timer was disarmed, together with the previous timer reload value. The members of ovalue are subject to the resolution of the timer, and they are the same values that would be returned by a timer_gettime() call at that point in time. The timer_gettime() function stores the amount of time until the specified timer, timerid, expires and the reload value of the timer into the space pointed to by the value argument. The it_value member of this structure contains the amount of time before the timer expires, or 0 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 timer_settime(). Only a single signal will be 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 will be queued, and a timer overrun occurs. When a timer expiration signal is delivered to or accepted by a process, the 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 delivered or accepted, up to but not including an implementation-dependent maximum of DELAYTIMER_MAX. If the number of such extra expirations is greater than or equal to DELAYTIMER_MAX, then the overrun count will be set to DELAYTIMER_MAX. The value returned by timer_getoverrun() applies to the most recent expiration signal delivery or acceptance for the timer. If no expiration signal has been delivered for the timer, the meaning of the overrun count returned is undefined. RETURN VALUES
If the timer_settime() or timer_gettime() functions succeed, 0 is returned. If an error occurs for either of these functions, -1 is returned, and errno is set to indicate the error. If the timer_getoverrun() function succeeds, it returns the timer expiration overrun count as explained above. ERRORS
The timer_settime(), timer_gettime() and timer_getoverrun() functions will fail if: EINVAL The timerid argument does not correspond to a timer returned by timer_create(3C) but not yet deleted by timer_delete(3C). ENOSYS The timer_settime(), timer_gettime(), and timer_getoverrun() functions are not supported by the system. The timer_settime() function will fail if: EINVAL A value structure specified a nanosecond value less than zero or greater than or equal to 1000 million. ATTRIBUTES
See attributes(5) for descriptions of the following attributes: +-----------------------------+-----------------------------+ |ATTRIBUTE TYPE |ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |Interface Stability |Committed | +-----------------------------+-----------------------------+ |MT-Level |Async-Signal-Safe | +-----------------------------+-----------------------------+ |Standard |See standards(5). | +-----------------------------+-----------------------------+ SEE ALSO
time.h(3HEAD), clock_settime(3C), timer_create(3C), timer_delete(3C), attributes(5), standards(5) SunOS 5.11 5 Feb 2008 timer_settime(3C)