module main

import x.atomics

struct SpinLock {
mut:
    state u32 // 0 = unlocked, 1 = locked
}

fn acquire(mut spinlock SpinLock) {
    for !atomics.cas_u32(&spinlock.state, 0, 1) {
        // Busy-wait
    }
}

fn release(mut spinlock SpinLock) {
    atomics.store_u32(&spinlock.state, 0)
}

struct SharedData {
mut:
    spinlock SpinLock
    value    int
}

fn worker(mut data SharedData, iterations int) {
    for _ in 0 .. iterations {
        acquire(mut data.spinlock)
        data.value++
        release(mut data.spinlock)
    }
}

fn main() {
    mut data := &SharedData{}

    num_threads := 4
    iterations_per_thread := 10000

    mut threads := []thread{}

    for _ in 0 .. num_threads {
        threads << spawn worker(mut data, iterations_per_thread)
    }

    threads.wait()

    expected := num_threads * iterations_per_thread
    actual := data.value

    println('Expected: ${expected}')
    println('Actual:   ${actual}')

    if actual == expected {
        println('Spinlock works correctly')
    } else {
        println('Race condition detected')
    }
}