CND(3) FreeBSD Library Functions Manual CND(3)
NAME
cnd - condition variable functions
LIBRARY
POSIX Threads Library (libpthread, -lpthread)
SYNOPSIS
#include <threads.h>
int
cnd_broadcast(cnd_t *cond);
void
cnd_destroy(cnd_t *cond);
int
cnd_init(cnd_t *cond);
int
cnd_signal(cnd_t *cond);
int
cnd_timedwait(cnd_t * __restrict cond, mtx_t * __restrict mtx,
const struct timespec * __restrict ts);
int
cnd_wait(cnd_t *cond, mtx_t *mtx);
DESCRIPTION
The cnd_broadcast() function unblocks all threads that are blocked on a
condition variable cond at the time of the call. If no thread is blocked
on the cond condition variable at the time of the call, the function does
nothing and returns success.
The cnd_destroy() function destroys the cond condition variable.
The cnd_init() function initializes a new cond variable.
The cnd_signal() function unblock one thread that currently waits on the
cond variable. If there are no threads blocked, cnd_signal() does
nothing and returns success.
The cnd_timedwait() function atomically unlocks the mutex mtx and blocks
on the condition variable cond until a thread is signalled by a call to
cnd_signal() or cnd_broadcast() or timeout ts has been reached. The ts
parameter is specified as TIME_UTC based calendar time. If the mutex is
not locked by the calling thread then behavior is undefined.
The cnd_wait() function atomically unlocks the mutex mtx and tries to
block on the conditional variable cond until a thread is signalled by a
call to cnd_signal() or cnd_broadcast(). The mtx mutex is locked again
before the function returns. If the mutex is not locked by the calling
thread then behavior is undefined.
RETURN VALUES
The cnd_broadcast() function returns thrd_success on success or
thrd_error on failure.
The cnd_destroy() function returns no value.
The cnd_init() function returns thrd_success on success or thrd_error on
failure.
The cnd_signal() function returns thrd_success on success or thrd_error
on failure.
The cnd_timedwait() function returns thrd_success on success, otherwise
thrd_timedout to indicate that system time has reached or exceeded the
time specified in ts, or thrd_error on failure.
The cnd_wait() function returns thrd_success on success or thrd_error on
failure.
SEE ALSO
pthread_cond(3), threads(3)
STANDARDS
The cnd interface conforms to ISO/IEC 9899:2011 ("ISO C11").
HISTORY
This interface first appeared in NetBSD 9.
AUTHORS
Kamil Rytarowski <
[email protected]>
FreeBSD 14.1-RELEASE-p8 October 16, 2016 FreeBSD 14.1-RELEASE-p8