references.rs

use std::{rc::Rc, time::Instant};

struct Foo {
    val: usize,
}

impl Foo {
    fn new(val: usize) -> Self {
        Foo { val }
    }
}

fn main() {
    let original = Foo::new(0);
    let runs = 1_000_000_000;

    let start = Instant::now();
    {
        let mut vec_ref: Vec<&Foo> = Vec::with_capacity(runs);
        for _ in 0..runs {
            vec_ref.push(&original);
        }
    } // the vector is destroyed here.
    println!("Took {:#?}", start.elapsed());

    let orig_rc = Rc::new(original);

    let start = Instant::now();
    {
        let mut vec_ref: Vec<Rc<Foo>> = Vec::with_capacity(runs);
        for _ in 0..runs {
            vec_ref.push(orig_rc.clone());
        }
    } // the vector is destroyed here.
    println!("Took {:#?}", start.elapsed());
}