pthread_once3
Dynamic package initialization
Usage
#include <pthread.h>
pthread_once_t once_control = PTHREAD_ONCE_INIT;
int
pthread_once(pthread_once_t *once_control, void (*init_routine)(void));
Library
POSIX Threads Library (libpthread, -lpthread)
Overview
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.
Releases
80 releases since FreeBSD 2.2.7-RELEASE; the text changed 46 times.