#pragma once

#include <rt/atomic.h>
#include <rt/mutex.h>

#ifdef __cplusplus
extern "C" {
#endif

struct rt_once;

/* Call fn exactly once among all callers using the same struct rt_once.
 * Regardless of which caller actually executes fn, rt_once_call only returns
 * for any caller after fn has returned. */
void rt_once_call(struct rt_once *once, void (*fn)(void));

struct rt_once
{
    rt_atomic_int done;
    struct rt_mutex mutex;
};

#define RT_ONCE_INIT(name)                                                     \
    {                                                                          \
        .done = 0,                                                             \
        .mutex = RT_MUTEX_INIT(name.mutex),                                    \
    }

#define RT_ONCE(name) struct rt_once name = RT_ONCE_INIT(name)

#ifdef __cplusplus
}
#endif