Unsafe multi-threaded buffer output

Published 410d ago

See C++ version: https://gist.github.com/ayebear/7ee6c64c387413a90532da8f838f32d6 Both rust and c++ versions seem to work.

use rayon::prelude::*;

// source: https://stackoverflow.com/a/64502824
struct EvilPtr<T> {
    ptr: *mut T,
}
impl<T> EvilPtr<T> {
    fn new(inp: &mut T) -> Self {
        EvilPtr { ptr: inp as *mut T }
    }
    unsafe fn deref(&self) -> *mut T {
        self.ptr
    }
}

unsafe impl<T> Sync for EvilPtr<T> {}
unsafe impl<T> Send for EvilPtr<T> {}

fn main() {
    const COUNT: usize = 1000;
    let mut arr: Vec<i32> = (0..COUNT as i32).collect();
    let e = EvilPtr::new(&mut arr[0]);
    unsafe {
        (0..COUNT).into_par_iter().for_each(|x| {
            *e.deref().add(x) = x as i32;
        });
    }
    println!("{:?}", arr);
}