NAME
pthread_once —
dynamic package
initialization
LIBRARY
library “libpthread”
SYNOPSIS
#include
<pthread.h>
int
pthread_once(pthread_once_t
*once_control, void
(*init_routine)(void));
pthread_once_t once_control
=
PTHREAD_ONCE_INIT;
DESCRIPTION
The first call topthread_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 initializes the static once
synchronization control structure once_control to be
used with
pthread_once().
The behavior of pthread_once() is undefined if
once_control has automatic storage duration or is not
initialized by PTHREAD_ONCE_INIT.
RETURN VALUES
If successful, the pthread_once() function
will return zero. Otherwise an error number will be returned to indicate the
error.
ERRORS
None.
STANDARDS
The function conforms to IEEE Std 1003.1-2001 (“POSIX.1”).