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Command: pthread_cond_timedwait | Section: 3 | Source: Digital UNIX | File: pthread_cond_timedwait.3.gz
pthread_cond_timedwait(3) Library Functions Manual pthread_cond_timedwait(3)
NAME
pthread_cond_timedwait - Causes a thread to wait for the specified con-
dition variable to be signaled or broadcasted, such that it will awake
after a specified period of time.
LIBRARY
DECthreads POSIX 1003.1c Library (libpthread.so)
SYNOPSIS
#include <pthread.h>
int pthread_cond_timedwait(
pthread_cond_t *cond,
pthread_mutex_t *mutex,
const struct timespec *abstime);
STANDARDS
Interfaces documented on this reference page conform to industry stan-
dards as follows:
IEEE Std 1003.1c-1995, POSIX System Application Program Interface
PARAMETERS
Condition variable that the calling thread waits on. Mutex associated
with the condition variable specified in cond. Absolute time at which
the wait expires, if the condition has not been signaled or broad-
casted. See the pthread_get_expiration_np(3) routine, which is used to
obtain a value for this argument. The abstime argument is specified in
Universal Coordinated Time (UTC). In the UTC-based model, time is rep-
resented as seconds since the Epoch. The Epoch is defined as the time
0 hours, 0 minutes, 0 seconds, January 1st, 1970 UTC. Seconds since
the Epoch is a value interpreted as the number of seconds between a
specified time and the Epoch.
DESCRIPTION
This routine causes a thread to wait until one of the following occurs:
The specified condition variable is signaled or broadcasted. The cur-
rent system clock time is greater than or equal to the time specified
by the abstime argument. This routine is identical to
pthread_cond_wait(3), except that this routine can return before a con-
dition variable is signaled or broadcasted; specifically, when the
specified time expires. For more information, see the
pthread_cond_wait(3) description.
This routine atomically releases the mutex and causes the calling
thread to wait on the condition. The atomicity is important, because
it means the thread cannot miss a wakeup while the mutex is unlocked.
When the timer expires or when the wait is satisfied as a result of
some thread calling thread_cond_signal(3) or pthread_cond_broadcast(3),
the mutex is reacquired before returning to the caller.
If the current time equals or exceeds the expiration time, this routine
returns immediately, releasing and reacquiring the mutex. It might
cause the calling thread to yield (see the sched_yield(3) description).
Your code should check the return status whenever this routine returns
and take the appropriate action. Otherwise, waiting on the condition
variable can become a nonblocking loop.
Call this routine after you lock the mutex specified in mutex. The re-
sults of this routine are unpredictable if this routine is called with-
out first locking the mutex.
RETURN VALUES
If an error condition occurs, this routine returns an integer value in-
dicating the type of error. Possible return values are as follows:
Successful completion. The value specified by cond, mutex, or abstime
is invalid, or: Different mutexes are supplied for concurrent pthread_
cond_timedwait(3) operations or pthread_cond_wait(3) operations on the
same condition variable, or: The mutex was not owned by the calling
thread at the time of the call. The time specified by abstime expired.
DECthreads cannot acquire memory needed to block using a statically
initialized condition variable.
ERRORS
None
RELATED INFORMATION
Functions: pthread_cond_broadcast(3), pthread_cond_destroy(3),
pthread_cond_init(3), pthread_cond_signal(3), pthread_cond_wait(3),
pthread_get_expiration_np(3)
Manuals: Guide to DECthreads and Programmer's Guide
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pthread_cond_timedwait(3)