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_lwp_cond_broadcast(2)

_lwp_cond_reltimedwait(2)

_lwp_cond_signal(2)

_lwp_cond_timedwait(2)

_lwp_mutex_trylock(2)

_lwp_mutex_unlock(2)

_lwp_self(2)

_lwp_sema_init(2)

_lwp_sema_post(2)

_lwp_sema_trywait(2)

__sparc_utrap_install(2)

_lwp_cond_wait

, _lwp_cond_timedwait

, _lwp_cond_reltimedwait

- wait on a condition variable

Synopsis

#include <sys/lwp.h>int_lwp_cond_wait(lwp_cond_t *cvp,lwp_mutex_t *mp);

int_lwp_cond_timedwait(lwp_cond_t *cvp,lwp_mutex_t *mp,timestruc_t *abstime);

int_lwp_cond_reltimedwait(lwp_cond_t *cvp,lwp_mutex_t *mp,timestruc_t *reltime);

Description

These functions are used to wait for the occurrence of a conditionrepresented by an LWP condition variable. LWP condition variables must be initializedto 0 before use.

The_lwp_cond_wait() function atomically releases the LWP mutex pointed to bympand causes the calling LWP to block on the LWP condition variablepointed to bycvp. The blocked LWP may be awakened by_lwp_cond_signal(2),_lwp_cond_broadcast(2), or when interrupted by delivery of a signal. Any change invalue of a condition associated with the condition variable cannot be inferredby the return of_lwp_cond_wait() and any such condition must be re-evaluated.

The_lwp_cond_timedwait() function is similar to_lwp_cond_wait(), except that the calling LWPwill not block past the time of day specified byabstime. Ifthe time of day becomes greater thanabstime,_lwp_cond_timedwait() returns with theerror codeETIME.

The_lwp_cond_reltimedwait() function is similar to_lwp_cond_wait(), except that the calling LWPwill not block past the relative time specified byreltime. If thetime of day becomes greater than the starting time of day plusreltime,_lwp_cond_reltimedwait() returns with the error codeETIME.

The_lwp_cond_wait(),_lwp_cond_timedwait(), and_lwp_cond_reltimedwait() functions always return with the mutex lockedand owned by the calling lightweight process.

Return Values

Upon successful completion,0 is returned. A non-zero value indicates an error.

Errors

If any of the following conditions are detected,_lwp_cond_wait(),_lwp_cond_timedwait(), and_lwp_cond_reltimedwait()fail and return the corresponding value:

EINVAL: Thecvp argument points to an invalid LWP condition variable or themp argument points to an invalid LWP mutex.
EFAULT: Themp,cvp, orabstime argument points to an illegal address.

If any of the following conditions occur,_lwp_cond_wait(),_lwp_cond_timedwait(), and_lwp_cond_reltimedwait() failand return the corresponding value:

EINTR: The call was interrupted by a signal orfork(2).

If any of the following conditions occur,_lwp_cond_timedwait() and_lwp_cond_reltimedwait() fail andreturn the corresponding value:

ETIME: The time specified inabstime orreltime has passed.

Examples

Example 1 Use the_lwp_cond_wait() function in a loop testing some condition.

The_lwp_cond_wait() function is normally used in a loop testing some condition,as follows:

lwp_mutex_t m;lwp_cond_t cv;int cond;(void) _lwp_mutex_lock(&m);while (cond == FALSE) {        (void) _lwp_cond_wait(&cv, &m);}(void) _lwp_mutex_unlock(&m);

Example 2 Use the_lwp_cond_timedwait() function in a loop testing some condition.

The_lwp_cond_timedwait() function is also normally used in a loop testing somecondition. It uses an absolute timeout value as follows:

timestruc_t to;lwp_mutex_t m;lwp_cond_t cv;int cond, err;(void) _lwp_mutex_lock(&m);to.tv_sec = time(NULL) + TIMEOUT;to.tv_nsec = 0;while (cond == FALSE) {        err = _lwp_cond_timedwait(&cv, &m, &to);        if (err == ETIME) {                /* timeout, do something */                break;        SENDwhom}}(void) _lwp_mutex_unlock(&m);

This example sets a bound on the total wait time even thoughthe_lwp_cond_timedwait() may return several times due to the condition being signalledor the wait being interrupted.

Example 3 Use the_lwp_cond_reltimedwait() function in a loop testing some condition.

The_lwp_cond_reltimedwait() function is also normally used in a loop testing somecondition. It uses a relative timeout value as follows:

timestruc_t to;lwp_mutex_t m;lwp_cond_t cv;int cond, err;(void) _lwp_mutex_lock(&m);while (cond == FALSE) {        to.tv_sec = TIMEOUT;        to.tv_nsec = 0;        err = _lwp_cond_reltimedwait(&cv, &m, &to);        if (err == ETIME) {                /* timeout, do something */                break;        }}(void) _lwp_mutex_unlock(&m);

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