Mastering Rust - Second Edition

Shared ownership with Arc

The preceding code can be made to work with the multi-threaded Arc type as follows:

// thread_arc.rsuse std::thread;use std::sync::Arc;fn main() {    let nums = Arc::new(vec![0, 1, 2, 3, 4]);    let mut childs = vec![];    for n in 0..5 {        let ns = Arc::clone(&nums);        let c = thread::spawn(move || {            println!("{}", ns[n]);        });        childs.push(c);    }    for c in childs {        c.join().unwrap();    }} 

In the preceding code, we simply replaced the wrapper of the vector from Rc to the Arc type. Another change is that, before we reference nums from a child thread, we need to clone it with Arc::clone(), which gives us an owned Arc<Vec<i32>> value that refers to the same Vec. With that change, our program compiles and provides safe access to the ...