PTHREAD_MUTEX_TIMEDLOCK(P) POSIX Programmer's ManualPTHREAD_MUTEX_TIMEDLOCK(P)NAMEpthread_mutex_timedlock - lock a mutex (ADVANCED REALTIME)
SYNOPSIS
#include <pthread.h>
#include <time.h>
int pthread_mutex_timedlock(pthread_mutex_t *restrict mutex,
const struct timespec *restrict abs_timeout);
DESCRIPTION
The pthread_mutex_timedlock() function shall lock the mutex object ref‐
erenced by mutex. If the mutex is already locked, the calling thread
shall block until the mutex becomes available as in the
pthread_mutex_lock() function. If the mutex cannot be locked without
waiting for another thread to unlock the mutex, this wait shall be ter‐
minated when the specified timeout expires.
The timeout shall expire when the absolute time specified by abs_time‐
out passes, as measured by the clock on which timeouts are based (that
is, when the value of that clock equals or exceeds abs_timeout), or if
the absolute time specified by abs_timeout has already been passed at
the time of the call.
If the Timers option is supported, the timeout shall be based on the
CLOCK_REALTIME clock; if the Timers option is not supported, the time‐
out shall be based on the system clock as returned by the time() func‐
tion.
The resolution of the timeout shall be the resolution of the clock on
which it is based. The timespec data type is defined in the <time.h>
header.
Under no circumstance shall the function fail with a timeout if the
mutex can be locked immediately. The validity of the abs_timeout param‐
eter need not be checked if the mutex can be locked immediately.
As a consequence of the priority inheritance rules (for mutexes ini‐
tialized with the PRIO_INHERIT protocol), if a timed mutex wait is ter‐
minated because its timeout expires, the priority of the owner of the
mutex shall be adjusted as necessary to reflect the fact that this
thread is no longer among the threads waiting for the mutex.
RETURN VALUE
If successful, the pthread_mutex_timedlock() function shall return
zero; otherwise, an error number shall be returned to indicate the
error.
ERRORS
The pthread_mutex_timedlock() function shall fail if:
EINVAL The mutex was created with the protocol attribute having the
value PTHREAD_PRIO_PROTECT and the calling thread's priority is
higher than the mutex' current priority ceiling.
EINVAL The process or thread would have blocked, and the abs_timeout
parameter specified a nanoseconds field value less than zero or
greater than or equal to 1000 million.
ETIMEDOUT
The mutex could not be locked before the specified timeout
expired.
The pthread_mutex_timedlock() function may fail if:
EINVAL The value specified by mutex does not refer to an initialized
mutex object.
EAGAIN The mutex could not be acquired because the maximum number of
recursive locks for mutex has been exceeded.
EDEADLK
The current thread already owns the mutex.
This function shall not return an error code of [EINTR].
The following sections are informative.
EXAMPLES
None.
APPLICATION USAGE
The pthread_mutex_timedlock() function is part of the Threads and Time‐
outs options and need not be provided on all implementations.
RATIONALE
None.
FUTURE DIRECTIONS
None.
SEE ALSOpthread_mutex_destroy() , pthread_mutex_lock() , pthread_mutex_try‐
lock() , time() , the Base Definitions volume of IEEE Std 1003.1-2001,
<pthread.h>, <time.h>
COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
Electrical and Electronics Engineers, Inc and The Open Group. In the
event of any discrepancy between this version and the original IEEE and
The Open Group Standard, the original IEEE and The Open Group Standard
is the referee document. The original Standard can be obtained online
at http://www.opengroup.org/unix/online.html .
IEEE/The Open Group 2003 PTHREAD_MUTEX_TIMEDLOCK(P)
