rusthash_time_prealloc.rs

use std::collections::hash_set::HashSet;
use std::vec::Vec;
use std::time::{Instant,Duration};
use std::env;

const SAMPLE_INTERVAL : usize = 1000;

fn duration_ns(d : Duration) -> i64 {
    return (d.as_secs() as i64) * 1000000000 + (d.subsec_nanos() as i64);
}

struct DataPoint {
    i : u64,
    ns : i64,
}

fn main() {
    let limit = env::args().nth(1).unwrap().parse::<u32>().unwrap();

    let mut one = HashSet::new();
    for i in 1..limit {
        one.insert(i);
    }

    let mid = Instant::now();

    let mut two = HashSet::with_capacity(one.capacity() / 2);
    let mut ts = Vec::with_capacity(one.len() / SAMPLE_INTERVAL);
    let mut i = 0;
    for v in one {
        i += 1;
        if i % SAMPLE_INTERVAL == 0 {
            ts.push(DataPoint{
                i: i as u64,
                ns: duration_ns(Instant::now().duration_since(mid))
            });
        }

        two.insert(v);
    }

    println!("n,ns");
    for d in ts {
        println!("{},{}", d.i, d.ns);
    }
}