NAME

pthread_once − dynamic package initialization

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

If any thread in a process with a once_control parameter makes a call to pthread_once(), the first call will summon the init_routine(), but subsequent calls will not.  The once_control parameter determines whether the associated initialization routine has been called.  The init_routine() is complete upon return of pthread_once(). 

pthread_once() is not a cancellation point; however, if the function init_routine() is a cancellation point and is canceled, the effect on once_control is the same as if pthread_once() had never been called. 

The constant PTHREAD_ONCE_INIT is defined in the <pthread.h> header. 

If once_control has automatic storage duration or is not initialized by PTHREAD_ONCE_INIT, the behavior of pthread_once() is undefined. 

RETURN VALUES

pthread_once() returns 0 upon successful completion; otherwise, an error number is returned. 

ERRORS

EINVAL once_control or init_routine is NULL. 

ATTRIBUTES

See attributes(5) for descriptions of the following attributes:

SEE ALSO

attributes(5)

NOTES

Solaris threads do not offer this functionality. 

SunOS 5.6  —  Last change: 30 Dec 1996