= nng_cv_wake1(3supp)
//
// Copyright 2018 Staysail Systems, Inc. <info@staysail.tech>
// Copyright 2018 Capitar IT Group BV <info@capitar.com>
//
// This document is supplied under the terms of the MIT License, a
// copy of which should be located in the distribution where this
// file was obtained (LICENSE.txt).  A copy of the license may also be
// found online at https://opensource.org/licenses/MIT.
//

== NAME

nng_cv_wake1 - wake one waiter

== SYNOPSIS

[source, c]
----
#include <nng/nng.h>
#include <nng/supplemental/util/platform.h>

void nng_cv_wake1(nng_cv *cv);
----

== DESCRIPTION

The `nng_cv_wake1()` wakes at most one thread waiting for the condition
variable _cv_
to be signaled in the xref:nng_cv_wait.3supp.adoc[`nng_cv_wait()`] or
xref:nng_cv_until.3supp.adoc[`nng_cv_until()`] functions.

The caller must have have ownership of the mutex that was used when
_cv_ was allocated.

NOTE: The caller should already have set the condition that the waiters
will check, while holding the mutex.

TIP: While this function avoids the "`thundering herd`" problem, the
caller cannot predict which waiter will be woken, and so the design must
ensure that it is sufficient that _any_ waiter be woken.
When in doubt, it is safer to use xref:nng_cv_wake.3supp.adoc[`nng_cv_wake()`].

== RETURN VALUES

None.

== ERRORS

None.

== SEE ALSO

[.text-left]
xref:nng_cv_alloc.3supp.adoc[nng_cv_alloc(3supp)],
xref:nng_cv_until.3supp.adoc[nng_cv_until(3supp)],
xref:nng_cv_wait.3supp.adoc[nng_cv_wait(3supp)],
xref:nng_cv_wake.3supp.adoc[nng_cv_wake(3supp)],
xref:nng_mtx_alloc.3supp.adoc[nng_mtx_alloc(3supp)],
xref:nng_mtx_lock.3supp.adoc[nng_mtx_lock(3supp)],
xref:nng_mtx_unlock.3supp.adoc[nng_mtx_unlock(3supp)],
xref:nng.7.adoc[nng(7)]