This example shows the use of rwlock, arc and threading.

rwlock_example.rs

// share ownership across multiple threads
// https://doc.rust-lang.org/book/ch16-03-shared-state.html
//
use std::thread;
use std::sync::{Arc,RwLock};

struct User {
    index: u32,
}

fn main() {
    let counter = Arc::new(RwLock::new(User {
        index : 0,
    }));

    let counter_cloned = counter.clone();

    let handle = thread::spawn(move || {
        let num = counter_cloned.write().unwrap();

        // derefence the variable
        //*num.index +=1;
        let mut user = num;
        user.index += 1;

        println!("hi number {} from the spawned thread!", user.index);
    });

    handle.join().unwrap();
    let mut user2 = counter.write().unwrap();
    user2.index += 1;

    println!("Hello, world! {}", user2.index);
}