f64 の to_string のベンチマーク（通常の to_string vs Ryu を使った to_string）

to_string_bench.rs

#![feature(test)]
fn main() {
    println!("Hello, world!");
}

fn from_f64_to_string(value: f64) -> String {
    value.to_string()
}

fn from_f64_to_string_by_ryu(value: f64) -> String {
    let mut buffer = ryu::Buffer::new();
    let printed = buffer.format(value);
    printed.to_string()
}

fn from_i64_to_string(value: i64) -> String {
    value.to_string()
}

#[cfg(test)]
mod tests {
    extern crate test;

    use super::*;
    use test::Bencher;

    // 適切に比較できているのかは自信ない…

    #[bench]
    fn bench_f64_to_string(b: &mut Bencher) {
        b.iter(|| from_f64_to_string(1.23));
    }

    #[bench]
    fn bench_f64_to_string_by_ryu(b: &mut Bencher) {
        b.iter(|| from_f64_to_string_by_ryu(1.23));
    }

    #[bench]
    fn bench_i64_to_string(b: &mut Bencher) {
        b.iter(|| from_i64_to_string(123));
    }
}