PTHREAD_ONCE(3) | Library Functions Manual | PTHREAD_ONCE(3) |
pthread_once
—
dynamic package initialization
#include
<pthread.h>
pthread_once_t once_control =
PTHREAD_ONCE_INIT;
int
pthread_once
(pthread_once_t
*once_control, void
(*init_routine)(void));
The first call to
pthread_once
()
by any thread in a process, with a given once_control,
will call the
init_routine
()
with no arguments. Subsequent calls to
pthread_once
() with the same
once_control will not call the
init_routine
(). On return from
pthread_once
(), it is guaranteed that
init_routine
() has completed. The
once_control parameter is used to determine whether
the associated initialization routine has been called.
The function
pthread_once
()
is not a cancellation point. However, if
init_routine
()
is a cancellation point and is cancelled, the effect on
once_control is as if
pthread_once
() was never called.
The constant PTHREAD_ONCE_INIT is defined by
header <pthread.h>
.
The behavior of
pthread_once
()
is undefined if once_control has automatic storage
duration or is not initialized by
PTHREAD_ONCE_INIT.
If successful, the pthread_once
() function
will return zero. Otherwise an error number will be returned to indicate the
error.
None.
The pthread_once
() function conforms to
ISO/IEC 9945-1:1996 (“POSIX.1”).
April 4, 1996 | macOS 14.6 |