mirror of
https://github.com/jart/cosmopolitan.git
synced 2025-02-07 15:03:34 +00:00
36 lines
1.4 KiB
C
36 lines
1.4 KiB
C
|
#ifndef NSYNC_ONCE_H_
|
||
|
|
#define NSYNC_ONCE_H_
|
||
|
|
#include "third_party/nsync/atomic.h"
|
||
|
|
COSMOPOLITAN_C_START_
|
||
|
|
|
||
|
|
/* An nsync_once allows a function to be called exactly once, when first
|
||
|
|
referenced. */
|
||
|
|
typedef nsync_atomic_uint32_ nsync_once;
|
||
|
|
|
||
|
|
/* An initializer for nsync_once; it is guaranteed to be all zeroes. */
|
||
|
|
#define NSYNC_ONCE_INIT NSYNC_ATOMIC_UINT32_INIT_
|
||
|
|
|
||
|
|
/* The first time nsync_run_once() or nsync_run_once_arg() is applied to
|
||
|
|
*once, the supplied function is run (with argument, in the case of
|
||
|
|
nsync_run_once_arg()). Other callers will wait until the run of the
|
||
|
|
function is complete, and then return without running the function
|
||
|
|
again. */
|
||
|
|
void nsync_run_once(nsync_once *once, void (*f)(void));
|
||
|
|
void nsync_run_once_arg(nsync_once *once, void (*farg)(void *arg), void *arg);
|
||
|
|
|
||
|
|
/* Same as nsync_run_once()/nsync_run_once_arg() but uses a spinloop.
|
||
|
|
Can be used on the same nsync_once as
|
||
|
|
nsync_run_once/nsync_run_once_arg().
|
||
|
|
|
||
|
|
These *_spin variants should be used only in contexts where normal
|
||
|
|
blocking is disallowed, such as within user-space schedulers, when
|
||
|
|
the runtime is not fully initialized, etc. They provide no
|
||
|
|
significant performance benefit, and they should be avoided in normal
|
||
|
|
code. */
|
||
|
|
void nsync_run_once_spin(nsync_once *once, void (*f)(void));
|
||
|
|
void nsync_run_once_arg_spin(nsync_once *once, void (*farg)(void *arg),
|
||
|
|
void *arg);
|
||
|
|
|
||
|
|
COSMOPOLITAN_C_END_
|
||
|
|
#endif /* NSYNC_ONCE_H_ */
|