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28.\" $FreeBSD: src/share/man/man3/pthread_cond_wait.3,v 1.22 2007/10/22 10:08:00 ru Exp $
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30.Dd February 22, 2018
31.Dt PTHREAD_COND_WAIT 3
32.Os
33.Sh NAME
34.Nm pthread_cond_wait
35.Nd wait on a condition variable
36.Sh LIBRARY
37.Lb libpthread
38.Sh SYNOPSIS
39.In pthread.h
40.Ft int
41.Fn pthread_cond_wait "pthread_cond_t * restrict cond" "pthread_mutex_t * restrict mutex"
42.Sh DESCRIPTION
43The
44.Fn pthread_cond_wait
45function atomically blocks the current thread waiting on the condition
46variable specified by
47.Fa cond ,
48and releases the mutex specified by
49.Fa mutex .
50The waiting thread unblocks only after another thread calls
51.Xr pthread_cond_signal 3 ,
52or
53.Xr pthread_cond_broadcast 3
54with the same condition variable, and the current thread reacquires the lock
55on
56.Fa mutex .
57.Sh RETURN VALUES
58If successful, the
59.Fn pthread_cond_wait
60function will return zero.
61Otherwise an error number will be returned to
62indicate the error.
63.Sh ERRORS
64The
65.Fn pthread_cond_wait
66function will fail if:
67.Bl -tag -width Er
68.It Bq Er EINVAL
69The value specified by
70.Fa cond
71or the value specified by
72.Fa mutex
73is invalid.
74.\".It Bq Er EPERM
75.\"The specified
76.\".Fa mutex
77.\"was not locked by the calling thread.
78.El
79.Sh SEE ALSO
80.Xr pthread_cond_broadcast 3 ,
81.Xr pthread_cond_destroy 3 ,
82.Xr pthread_cond_init 3 ,
83.Xr pthread_cond_signal 3 ,
84.Xr pthread_cond_timedwait 3
85.Sh STANDARDS
86The
87.Fn pthread_cond_wait
88function conforms to
89.St -p1003.1-96 .
90