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PTHREAD_ONCE(3)       DragonFly Library Functions Manual       PTHREAD_ONCE(3)


pthread_once - dynamic package initialization


POSIX Threads Library (libpthread, -lpthread)


#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.




The pthread_once() function conforms to ISO/IEC 9945-1:1996 ("POSIX.1"). DragonFly 5.9-DEVELOPMENT July 10, 2009 DragonFly 5.9-DEVELOPMENT

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