#![feature(box_syntax)]

use crossbeam_utils::thread;
use std::time::Instant;

const MAP_WIDTH: usize = 8192;
const MAP_ARRAY_SIZE: usize = MAP_WIDTH * MAP_WIDTH;
const NUM_CORES: usize = 4;

fn main() {
    let t1_a = Instant::now();

    let mut a: Box<[u64; MAP_ARRAY_SIZE]> = box [0x00; MAP_ARRAY_SIZE];

    assert_eq!(MAP_ARRAY_SIZE % NUM_CORES, 0);

    thread::scope(|scope_handle| {
        for chunk in a.chunks_mut(MAP_ARRAY_SIZE / 4) {
            scope_handle.spawn(move |_| {
                do_stuff(chunk, 0x01);
            });
        }
    }).unwrap();

    assert_eq!((*a)[0], 1);

    let t2_a = Instant::now();
    println!("chunks {:?}", t2_a - t1_a);

    /////////////////////////////////////

    let t1_b = Instant::now();
    let mut b: Box<[u64; MAP_ARRAY_SIZE]> = box [0x00; MAP_ARRAY_SIZE];
    do_stuff(&mut (*b), 0x01);
    assert_eq!((*b)[0], 1);
    let t2_b = Instant::now();
    println!("linear {:?}", t2_b - t1_b);
}

fn do_stuff(a: &mut [u64], n: u64) {
    for x in a.iter_mut() {
        *x = n;
    }
}