Copying memory

main.rs

extern crate time;

use std::env;
use std::ptr;

use time::Duration;


const SIZE: usize = 10 * 1024 * 1024;


fn copy_iter(src: &[u8], dst: &mut Vec<u8>) {
    for &byte in src {
        dst.push(byte);
    }
}

fn copy_index(src: &[u8], dst: &mut Vec<u8>) {
    let mut index = 0;
    unsafe { dst.set_len(SIZE); }
    while index < src.len() {
        dst[index] = src[index];
        index += 1;
    }
}

fn copy_push_all(src: &[u8], dst: &mut Vec<u8>) {
    dst.extend_from_slice(src);
}

fn copy_ptr(src: &[u8], dst: &mut Vec<u8>) {
    unsafe {
        dst.set_len(SIZE);
        ptr::copy_nonoverlapping(src.as_ptr(), (&mut dst[..]).as_mut_ptr(), SIZE);
    }
}

fn main() {
    let args: Vec<_> = env::args().collect();
    if args.len() < 2 {
        panic!("Provide method")
    }

    let src = vec![1; SIZE];
    let mut dst = Vec::with_capacity(SIZE);

    println!("{}", Duration::span(|| {
        match &(args[1])[..] {
            "iter" => copy_iter(&src[..], &mut dst),
            "index" => copy_index(&src[..], &mut dst),
            "push_all" => copy_push_all(&src[..], &mut dst),
            "ptr" => copy_ptr(&src[..], &mut dst),
            _ => println!("Wrong method"),
        }
    }));

    println!("{:?}", &dst[..10]);

}