Odin/core/sync/sync.odin

package sync

import "core:intrinsics"

cpu_relax :: inline proc "contextless" () {
	intrinsics.cpu_relax();
}

Condition_Mutex_Ptr :: union{^Mutex, ^Blocking_Mutex};


Ticket_Mutex :: struct {
	ticket:  u64,
	serving: u64,
}

ticket_mutex_init :: proc(m: ^Ticket_Mutex) {
	atomic_store(&m.ticket,  0, .Relaxed);
	atomic_store(&m.serving, 0, .Relaxed);
}

ticket_mutex_lock :: inline proc(m: ^Ticket_Mutex) {
	ticket := atomic_add(&m.ticket, 1, .Relaxed);
	for ticket != atomic_load(&m.serving, .Acquire) {
		intrinsics.cpu_relax();
	}
}

ticket_mutex_unlock :: inline proc(m: ^Ticket_Mutex) {
	atomic_add(&m.serving, 1, .Relaxed);
}


Benaphore :: struct {
	counter: int,
	sema: Semaphore,
}

benaphore_init :: proc(b: ^Benaphore) {
	intrinsics.atomic_store(&b.counter, 0);
	semaphore_init(&b.sema);
}

benaphore_destroy :: proc(b: ^Benaphore) {
	semaphore_destroy(&b.sema);
}

benaphore_lock :: proc(b: ^Benaphore) {
	if intrinsics.atomic_add_acq(&b.counter, 1) > 1 {
		semaphore_wait_for(&b.sema);
	}
}

benaphore_try_lock :: proc(b: ^Benaphore) -> bool {
	v, _ := intrinsics.atomic_cxchg_acq(&b.counter, 1, 0);
	return v == 0;
}

benaphore_unlock :: proc(b: ^Benaphore) {
	if intrinsics.atomic_sub_rel(&b.counter, 1) > 0 {
		semaphore_post(&b.sema);
	}
}