Subj : Re: double-checked locking in C
To   : comp.programming.threads
From : Alexander Terekhov
Date : Thu Jul 07 2005 07:33 pm


Joe Seigh wrote:
[...]
> memcpy() of a static pthread_once_t initialized with PTHREAD_ONCE_INIT
> for pthread_once_init().  

Undefined behavior (as soon as you call pthread_once() on a "cloned" 
thing). Because pthread_once_t is noncopyable, just like any other 
synchronization objects.

"The behavior of pthread_once() is undefined if once_control has 
 automatic storage duration or is not initialized by 
 PTHREAD_ONCE_INIT."

> I don't even know what pthread_once_reset() even means.

Effect is the same as pthread_once_destroy()+pthread_once_init()
(with pthread_once_destroy() invoking optional destructor function)
except that it is throw()-nothing operation (vs pthread_once_init() 
that can throw).

regards,
alexander.

.