Rust bench 実行時間測定

rustである関数の実行時間を測定したいときがあったのでメモ

環境

rustc --version
rustc 1.24.0-nightly (f8af59d95 2017-12-13)

rustc-testクレートが必要なのでCargo.tomlに記述する。

extern crate test;

use test::test::Bencher;

struct Fx {
    a: f64,
    b: f64,
    dx: f64,
    f: fn(f64) -> f64,
}

impl Fx {
    fn new(a: f64, b: f64, step: u64, f: fn(f64) -> f64) -> Fx {
        Fx {
            a: a,
            b: b,
            dx: (b - a) / (step as f64),
            f: f,
        }
    }
}

fn integral(prim: &Fx) -> f64 {
    let a = prim.a;
    let b = prim.b;
    let dx = prim.dx;
    let f = prim.f;
    let step = ((b - a) / dx) as u32;

    let mut sum = 0.0;

    for n in 0..step {
        let x = a + dx * (n as f64);
        let bar = f(x) * dx;
        sum = sum + bar;
    }
    sum
}

#[cfg(test)]
mod tests {
    use super::*;

    fn f(x: f64) -> f64 {
        x * x + 1.0
    }

    #[test]
    fn int_test() {
        let f = f;
        let prim = Fx::new(0.0, 1.0, 1000000, f);
        println!("{}", integral(&prim));
    }

    #[bench]
    fn int_bench(b: &mut Bencher) {
        let f = f;
        let prim = Fx::new(0.0, 1.0, 1000000, f);

        b.iter(|| {
            let p = test::black_box(&prim);
            integral(p);
        });
    }
}

fn main() {
        println!("Hello, thread World!");
}