.\" Copyright (c) 1997 Brian Cully <shmit@kublai.com>
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.Dd July 28, 1998
.Dt PTHREAD_COND_WAIT 3
.Os BSD 4
.Sh NAME
.Nm pthread_cond_wait
.Nd wait on a condition variable
.Sh SYNOPSIS
.Fd #include <pthread.h>
.Ft int
.Fn pthread_cond_wait "pthread_cond_t *cond" "pthread_mutex_t *mutex"
.Sh DESCRIPTION
The
.Fn pthread_cond_wait
function atomically blocks the current thread waiting on the condition
variable specified by
.Fa cond ,
and unblocks 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, and the current thread reaquires the lock
on
.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 attr
is invalid.
.El
.Pp
.Sh SEE ALSO
.Xr pthreads 3 ,
.Xr pthread_cond_init 3 ,
.Xr pthread_cond_destroy 3 ,
.Xr pthread_cond_timedwait 3 ,
.Xr pthread_cond_signal 3 ,
.Xr pthread_cond_broadcast 3
.Sh STANDARDS
.Fn pthread_cond_wait
conforms to ISO/IEC 9945-1 ANSI/IEEE
.Pq Dq Tn POSIX
Std 1003.1 Second Edition 1996-07-12.