[apple/libpthread.git] / man / pthread_cond_timedwait.3

.\" Copyright (c) 1997 Brian Cully <shmit@kublai.com>
.\" All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\" 3. Neither the name of the author nor the names of any co-contributors
.\"    may be used to endorse or promote products derived from this software
.\"    without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.\" $FreeBSD$
.\"
.Dd May 9, 2010
.Dt PTHREAD_COND_TIMEDWAIT 3
.Os
.Sh NAME
.Nm pthread_cond_timedwait
.Nd "wait on a condition variable for a specific amount of time"
.Sh SYNOPSIS
.In pthread.h
.Ft int
.Fn pthread_cond_timedwait "pthread_cond_t *cond" "pthread_mutex_t *mutex" "const struct timespec *abstime"
.Sh DESCRIPTION
The
.Fn pthread_cond_timedwait
function atomically blocks the current thread waiting on the condition
variable specified by
.Fa cond ,
and releases the mutex specified by
.Fa mutex .
The waiting thread unblocks only after another thread calls
.Xr pthread_cond_signal 3 ,
or
.Xr pthread_cond_broadcast 3
with the same condition variable, or if the system time reaches the
time specified in
.Fa abstime ,
and the current thread reacquires the lock on
.Fa mutex .
.Pp 
Values for struct timespec can be obtained by adding the required
time interval to the  the current time obtained using 
.Xr gettimeofday 2 .
.Pp
.Fa Note 
that struct timeval and struct timespec use different units to specify
the time. Hence, the user should always take care to perform the time unit 
conversions accordingly.
.Sh EXAMPLE
.Pp
   struct timeval tv;
   struct timespec ts;
   gettimeofday(&tv, NULL);
   ts.tv_sec = tv.tv_sec + 0;
   ts.tv_nsec = 0;
.Pp
.Sh RETURN VALUES
If successful, the
.Fn pthread_cond_timedwait
function will return zero.
Otherwise an error number will be returned to
indicate the error.
.Sh ERRORS
The
.Fn pthread_cond_timedwait
function will fail if:
.Bl -tag -width Er
.It Bq Er EINVAL
The value specified by
.Fa cond ,
.Fa mutex
or
.Fa abstime
is invalid.
.It Bq Er ETIMEDOUT
The system time has reached or exceeded the time specified in
.Fa abstime .
.El
.Sh SEE ALSO
.Xr pthread_cond_broadcast 3 ,
.Xr pthread_cond_destroy 3 ,
.Xr pthread_cond_init 3 ,
.Xr pthread_cond_signal 3 ,
.Xr pthread_cond_wait 3 ,
.Xr gettimeofday 2
.Sh STANDARDS
The
.Fn pthread_cond_timedwait
function conforms to
.St -p1003.1-96 .
Commit	Line	Data
f1a1da6c A	1	.\" Copyright (c) 1997 Brian Cully <shmit@kublai.com>
	2	.\" All rights reserved.
	3	.\"
	4	.\" Redistribution and use in source and binary forms, with or without
	5	.\" modification, are permitted provided that the following conditions
	6	.\" are met:
	7	.\" 1. Redistributions of source code must retain the above copyright
	8	.\" notice, this list of conditions and the following disclaimer.
	9	.\" 2. Redistributions in binary form must reproduce the above copyright
	10	.\" notice, this list of conditions and the following disclaimer in the
	11	.\" documentation and/or other materials provided with the distribution.
	12	.\" 3. Neither the name of the author nor the names of any co-contributors
	13	.\" may be used to endorse or promote products derived from this software
	14	.\" without specific prior written permission.
	15	.\"
	16	.\" THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND
	17	.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	18	.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	19	.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
	20	.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	21	.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	22	.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	23	.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	24	.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	25	.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	26	.\" SUCH DAMAGE.
	27	.\"
2546420a	28	.\" $FreeBSD$
f1a1da6c	29	.\"
2546420a	30	.Dd May 9, 2010
f1a1da6c A	31	.Dt PTHREAD_COND_TIMEDWAIT 3
	32	.Os
	33	.Sh NAME
	34	.Nm pthread_cond_timedwait
	35	.Nd "wait on a condition variable for a specific amount of time"
	36	.Sh SYNOPSIS
2546420a	37	.In pthread.h
f1a1da6c	38	.Ft int
2546420a	39	.Fn pthread_cond_timedwait "pthread_cond_t cond" "pthread_mutex_t mutex" "const struct timespec *abstime"
f1a1da6c A	40	.Sh DESCRIPTION
	41	The
	42	.Fn pthread_cond_timedwait
	43	function atomically blocks the current thread waiting on the condition
	44	variable specified by
2546420a A	45	.Fa cond ,
2546420a A	46	and releases the mutex specified by
f1a1da6c A	47	.Fa mutex .
	48	The waiting thread unblocks only after another thread calls
	49	.Xr pthread_cond_signal 3 ,
	50	or
	51	.Xr pthread_cond_broadcast 3
	52	with the same condition variable, or if the system time reaches the
	53	time specified in
	54	.Fa abstime ,
	55	and the current thread reacquires the lock on
	56	.Fa mutex .
	57	.Pp
	58	Values for struct timespec can be obtained by adding the required
	59	time interval to the the current time obtained using
	60	.Xr gettimeofday 2 .
	61	.Pp
	62	.Fa Note
	63	that struct timeval and struct timespec use different units to specify
	64	the time. Hence, the user should always take care to perform the time unit
	65	conversions accordingly.
	66	.Sh EXAMPLE
	67	.Pp
	68	struct timeval tv;
	69	struct timespec ts;
	70	gettimeofday(&tv, NULL);
	71	ts.tv_sec = tv.tv_sec + 0;
	72	ts.tv_nsec = 0;
	73	.Pp
	74	.Sh RETURN VALUES
	75	If successful, the
	76	.Fn pthread_cond_timedwait
	77	function will return zero.
2546420a	78	Otherwise an error number will be returned to
f1a1da6c A	79	indicate the error.
f1a1da6c A	80	.Sh ERRORS
2546420a	81	The
f1a1da6c	82	.Fn pthread_cond_timedwait
2546420a	83	function will fail if:
f1a1da6c A	84	.Bl -tag -width Er
	85	.It Bq Er EINVAL
	86	The value specified by
	87	.Fa cond ,
	88	.Fa mutex
	89	or
	90	.Fa abstime
	91	is invalid.
	92	.It Bq Er ETIMEDOUT
	93	The system time has reached or exceeded the time specified in
	94	.Fa abstime .
	95	.El
	96	.Sh SEE ALSO
	97	.Xr pthread_cond_broadcast 3 ,
	98	.Xr pthread_cond_destroy 3 ,
	99	.Xr pthread_cond_init 3 ,
	100	.Xr pthread_cond_signal 3 ,
	101	.Xr pthread_cond_wait 3 ,
	102	.Xr gettimeofday 2
	103	.Sh STANDARDS
2546420a	104	The
f1a1da6c	105	.Fn pthread_cond_timedwait
2546420a	106	function conforms to
f1a1da6c	107	.St -p1003.1-96 .