foo.rs

#![feature(test)]
extern crate test;
use std::io::Read;

#[bench]
fn read_to_end_1024(b: &mut test::Bencher) {
    let buf = [1u8; 1024];
    let mut src = &buf[..];
    b.iter(|| {
        let mut dst = Vec::with_capacity(1024);
        src.read_to_end(&mut dst)
    });
}

#[bench]
fn read_to_end_64k(b: &mut test::Bencher) {
    let buf = [1u8; 1024 * 64];
    let mut src = &buf[..];
    b.iter(|| {
        let mut dst = Vec::with_capacity(64 * 1024);
        src.read_to_end(&mut dst)
    });
}

#[bench]
fn read_to_end_normal_test(b: &mut test::Bencher) {
    let buf = [1u8; 100000];
    let mut src = &buf[..];
    b.iter(|| {
        let mut dst = Vec::new();
        src.read_to_end(&mut dst)
    });
}

#[bench]
fn read_to_end_small_test(b: &mut test::Bencher) {
    let buf = [1u8; 1000];
    let mut src = &buf[..];
    b.iter(|| {
        let mut dst = Vec::new();
        src.read_to_end(&mut dst)
    });
}

#[test]
fn read_to_end_doesnt_expand_capacity_unless_necessary() {
    const BUF_SIZE: usize = 1024;
    let buf = [1u8; BUF_SIZE];
    let mut src = &buf[..];
    let mut dst = Vec::with_capacity(BUF_SIZE);
    let init_capacity = dst.capacity();
    assert_eq!(src.read_to_end(&mut dst).unwrap(), BUF_SIZE);
    assert_eq!(init_capacity, dst.capacity());
}