Benchmark test: Box<str> vs String

boxed_str_vs_string.rs

#![feature(test)]

extern crate test;

use std::collections::HashMap;
use test::Bencher;

const KEY0: &str = "A benchmark test";
const KEY1: &str = "for";
const KEY2: &str = "`Box<str>` and `String`";
const KEY3: &str = "as keys";
const KEY4: &str = "of a map.";
const KEY5: &str = "A long key. Long long long LONG key. Blah blah long blah key blah bench blah blah";

#[bench]
fn boxed_str(b: &mut Bencher) {
    let mut map = HashMap::new();
    b.iter(|| {
        map.insert(KEY0.to_owned().into_boxed_str(), 0);
        map.insert(KEY1.to_owned().into_boxed_str(), 1);
        map.insert(KEY2.to_owned().into_boxed_str(), 2);
        map.insert(KEY3.to_owned().into_boxed_str(), 3);
        map.insert(KEY4.to_owned().into_boxed_str(), 4);
        map.insert(KEY5.to_owned().into_boxed_str(), 5);
    });
}

#[bench]
fn string(b: &mut Bencher) {
    let mut map = HashMap::new();
    b.iter(|| {
        map.insert(KEY0.to_owned(), 0);
        map.insert(KEY1.to_owned(), 1);
        map.insert(KEY2.to_owned(), 2);
        map.insert(KEY3.to_owned(), 3);
        map.insert(KEY4.to_owned(), 4);
        map.insert(KEY5.to_owned(), 5);
    });
}

// running 2 tests
// test boxed_str ... bench:         546 ns/iter (+/- 22)
// test string    ... bench:         569 ns/iter (+/- 47)
//
// test result: ok. 0 passed; 0 failed; 0 ignored; 2 measured; 0 filtered out