PTHREAD_ONCE(3) BSD Library Functions Manual PTHREAD_ONCE(3)NAMEpthread_once — dynamic package initialization
LIBRARY
POSIX Threads Library (libpthread, -lpthread)
SYNOPSIS
#include <pthread.h>
pthread_once_t once_control = PTHREAD_ONCE_INIT;
int
pthread_once(pthread_once_t *once_control, void (*init_routine)(void));
DESCRIPTION
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.
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 pthread_once() function conforms to ISO/IEC 9945-1:1996 (“POSIX.1”).
BSD April 4, 1996 BSD
