_lwp_cond_timedwait(2) _lwp_cond_timedwait(2)
NAME
_lwp_cond_timedwait - wait on a condition variable for a
limited time
SYNOPSIS
#include <synch.h>
#include <sys/time.h>
int _lwp_cond_timedwait(lwp_cond_t *cond, lwp_mutex_t *mutex,
timestruc_t *abstime);
Parameters
cond pointer to the condition variable to wait for
mutex pointer to a locked mutex
abstime absolute time at which to time out
DESCRIPTION
_lwp_cond_timedwait, similar to _lwp_cond_wait, waits for the
occurrence of a condition associated with the given object
cond. However, if the absolute time specified by abstime has
passed, and the indicated condition is not signaled, the
operation returns ETIME to the caller. The calling
lightweight process (LWP) must lock the mutual exclusion lock
(mutex) pointed to by mutex before calling cond_timedwait,
otherwise the behavior is unpredictable.
_lwp_timedwait automatically releases the mutex before
blocking on the condition variable. When the condition is
signalled, the time expires or the wait is interrupted,
_lwp_cond_timedwait reacquires the mutex and returns to the
caller. If the wait is interrupted, The mutex is reacquired
before a signal handler or any other user code can be
executed.
A wait on _lwp_cond_timedwait is interruptible. If
_lwp_cond_timedwait is interrupted the function always fails.
The calling LWP is allowed to resume execution when the
condition is signaled or broadcast, timeout occurs, or when
interrupted.
User-visible timers are not affected by a call to
_lwp_cond_timedwait.
Copyright 1994 Novell, Inc. Page 1
_lwp_cond_timedwait(2) _lwp_cond_timedwait(2)
cond Parameter
The condition variable denoted by cond must previously have
been statically initialized (zero-filled).
mutex Parameter
mutex is a mutual exclusion variable protecting a shared
resource associated with the condition represented by the
condition variable, cond. The calling LWP must lock mutex
before calling _lwp_cond_timedwait, otherwise the behavior is
unpredictable.
abstime Parameter
abstime represents the time at which _lwp_cond_timedwait
should time out. The time is expressed in elapsed seconds and
nanoseconds since Universal Coordinated Time, January 1, 1970.
gettimeofday(2) returns the current time, but in seconds and
microseconds. To construct abstime, convert the current time
to a timestruc_t, and add to that the waiting time.
Return Values
_lwp_cond_timedwait returns zero on success or an error number
on failure, as described below.
Errors
If any of the following conditions is detected,
_lwp_cond_timedwait fails and returns the corresponding value:
EINVAL The condition variable pointed to by cond or the
mutex pointed to by mutex is invalid.
EINVAL abstime is NULL.
EFAULT Either cond, mutex, or abstime points to an illegal
address. (This error may not be detected; a SIGSEGV
signal may be posted to the faulting LWP if an
illegal address is used.)
If any of the following conditions occurs, _lwp_cond_timedwait
fails and returns the corresponding value:
ETIME Time specified by abstime has passed.
EINTR The operation was interrupted by a signal or a fork
operation.
Copyright 1994 Novell, Inc. Page 2
_lwp_cond_timedwait(2) _lwp_cond_timedwait(2)
USAGE
See the description of how to use condition variables under
USAGE on cond_init(3synch).
Because the condition can change between the time the
condition is signaled and the mutex is re-locked, the calling
LWP must always re-check the condition upon return from
_lwp_cond_timedwait.
REFERENCES
_lwp_cond_broadcast(2), _lwp_cond_signal(2),
_lwp_cond_wait(2), cond_broadcast(3synch),
cond_destroy(3synch), cond_init(3synch), cond_signal(3synch),
cond_timedwait(3synch), cond_wait(3synch)
NOTICES
Lightweight processes (LWPs) are internal interfaces and are
subject to change. Their use should be avoided.
Copyright 1994 Novell, Inc. Page 3