Content-type: text/html Man page of pthread_cond_timedwait

pthread_cond_timedwait

Section: C Library Functions (3)
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NAME

pthread_cond_timedwait - Causes a thread to wait for the specified condition 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 standards 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 broadcasted. 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 represented 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 current 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 condition 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 results of this routine are unpredictable if this routine is called without first locking the mutex.

 

RETURN VALUES

If an error condition occurs, this routine returns an integer value indicating 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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Index

NAME
LIBRARY
SYNOPSIS
STANDARDS
PARAMETERS
DESCRIPTION
RETURN VALUES
ERRORS
RELATED INFORMATION

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Time: 02:42:05 GMT, October 02, 2010