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.\" Portions Copyright (c) 2007, Sun Microsystems, Inc. All Rights Reserved.
.\"
.TH PTHREAD_MUTEX_TIMEDLOCK 3C "Jun 5, 2007"
.SH NAME
pthread_mutex_timedlock, pthread_mutex_reltimedlock_np \- lock a mutex
.SH SYNOPSIS
.LP
.nf
cc \fB-mt\fR [ \fIflag\fR... ] \fIfile\fR... [ \fIlibrary\fR... ]
#include <pthread.h>
#include <time.h>
\fBint\fR \fBpthread_mutex_timedlock\fR(\fBpthread_mutex_t *restrict\fR \fImutex\fR,
\fBconst struct timespec *restrict\fR \fIabs_timeout\fR);
.fi
.LP
.nf
\fBint\fR \fBpthread_mutex_reltimedlock_np\fR(\fBpthread_mutex_t *restrict\fR \fImutex\fR,
\fBconst struct timespec *restrict\fR \fIrel_timeout\fR);
.fi
.SH DESCRIPTION
.sp
.LP
The \fBpthread_mutex_timedlock()\fR function locks the mutex object referenced
by \fImutex\fR. If the mutex is already locked, the calling thread blocks until
the mutex becomes available as in the \fBpthread_mutex_lock\fR(3C). If the
mutex cannot be locked without waiting for another thread to unlock the mutex,
this wait is terminated when the specified timeout expires.
.sp
.LP
The \fBpthread_mutex_reltimedlock_np()\fR function is identical to the
\fBpthread_mutex_timedlock()\fR function, except that the timeout is specified
as a relative time interval.
.sp
.LP
For \fBpthread_mutex_timedlock()\fR, the timeout expires when the absolute time
specified by \fIabs_timeout\fR passes, as measured by the clock on which
timeouts are based (that is, when the value of that clock equals or exceeds
\fIabs_timeout\fR), or if the absolute time specified by \fIabs_timeout\fR has
already been passed at the time of the call.
.sp
.LP
For \fBpthread_mutex_reltimedlock_np()\fR, the timeout expires when the time
interval specified by \fIrel_timeout\fR passes, as measured by the
\fBCLOCK_REALTIME\fR clock, or if the time interval specified by
\fIrel_timeout\fR is negative at the time of the call.
.sp
.LP
The resolution of the timeout is the resolution of the \fBCLOCK_REALTIME\fR
clock. The \fBtimespec\fR data type is defined in the \fB<time.h>\fRheader.
.sp
.LP
Under no circumstance will either function fail with a timeout if the mutex can
be locked immediately. The validity of the \fItimeout\fR parameter is not
checked if the mutex can be locked immediately.
.sp
.LP
As a consequence of the priority inheritance rules (for mutexes initialized
with the \fBPRIO_INHERIT\fR protocol), if a timed mutex wait is terminated
because its timeout expires, the priority of the owner of the mutex is adjusted
as necessary to reflect the fact that this thread is no longer among the
threads waiting for the mutex.
.SH RETURN VALUES
.sp
.LP
Upon successful completion, the \fBpthread_mutex_timedlock()\fR and
\fBpthread_mutex_reltimedlock_np()\fR functions return 0. Otherwise, an error
number is returned to indicate the error.
.SH ERRORS
.sp
.LP
The \fBpthread_mutex_timedlock()\fR and \fBpthread_mutex_reltimedlock_np()\fR
functions will fail for the same reasons as \fBpthread_mutex_lock\fR(3C). In
addition, they will fail if:
.sp
.ne 2
.na
\fB\fBEINVAL\fR\fR
.ad
.RS 13n
The caller would have blocked and the \fItimeout\fR parameter specified a
nanoseconds field value less than zero or greater than or equal to 1,000
million.
.RE
.sp
.ne 2
.na
\fB\fBETIMEDOUT\fR\fR
.ad
.RS 13n
The mutex could not be locked before the specified \fItimeout\fR expired.
.RE
.SH ATTRIBUTES
.sp
.LP
See \fBattributes\fR(5) for descriptions of the following attributes:
.sp
.sp
.TS
box;
c | c
l | l .
ATTRIBUTE TYPE ATTRIBUTE VALUE
_
Interface Stability See below.
_
MT-Level MT-Safe
.TE
.sp
.LP
The \fBpthread_mutex_timedlock()\fR is Standard. The
\fBpthread_mutex_reltimedlock_np()\fR function is Stable.
.SH SEE ALSO
.sp
.LP
\fBtime\fR(2), \fBpthread_mutex_destroy\fR(3C), \fBpthread_mutex_lock\fR(3C),
\fBpthread_mutex_trylock\fR(3C), \fBattributes\fR(5), \fBstandards\fR(5)
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