.\" Portions Copyright (c) 2001 Apple Computer, Inc. All Rights Reserved.
.\" Copyright (c) 1997 Brian Cully <shmit@kublai.com>
.\" All rights reserved.
.\"
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.\" modification, are permitted provided that the following conditions
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.\" 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
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.\" $FreeBSD: src/lib/libc_r/man/pthread_cond_wait.3,v 1.8.2.4 2001/08/17 15:42:51 ru Exp $
.\"
.Dd November 5, 2001
.Dt PTHREAD_COND_WAIT 3
.Os Darwin
.Sh NAME
.Nm pthread_cond_wait
.Nd wait on a condition variable
.Sh SYNOPSIS
.Fd #include <pthread.h>
.Ft int
.Fo pthread_cond_wait
.Fa "pthread_cond_t *restrict cond"
.Fa "pthread_mutex_t *restrict mutex"
.Fc
.Sh DESCRIPTION
The
.Fn pthread_cond_wait
function atomically unlocks the 
.Fa mutex 
and blocks the current thread on the condition specified by the
.Fa cond
argument.
The current thread unblocks only after another thread calls
.Xr pthread_cond_signal 3 
or
.Xr pthread_cond_broadcast 3
with the same condition variable.
The
.Fa mutex
must be locked before calling this function, otherwise the behavior is
undefined. Before
.Fn pthread_cond_wait
returns to the calling function, it re-acquires the
.Fa mutex .
.Sh RETURN VALUES
If successful, the
.Fn pthread_cond_wait
function will return zero; otherwise, an error number will be returned to
indicate the error.
.Sh ERRORS
.Fn pthread_cond_wait
will fail if:
.Bl -tag -width Er
.It Bq Er EINVAL
The value specified by
.Fa cond
or the value specified by
.Fa mutex
is invalid.
.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_timedwait 3
.Sh STANDARDS
.Fn pthread_cond_wait
conforms to
.St -p1003.1-96 .