Remove the need for locking memory w/ rayon

xordirs_lockless.rs

extern crate rayon;

use rayon::prelude::*;
use std::{collections::HashSet, env, error::Error, fs};

fn main() -> Result<(), Box<dyn Error>> {
    let args: Vec<String> = env::args().collect();

    let final_diff: HashSet<String> = args[1..]
        .par_iter()
        .map(|file| match get_set(&file[..]) {
            Ok(s) => Some(s),
            Err(e) => {
                eprintln!("error encountered collecting files: {} \n {}", file, e);
                return None;
            }
        }).filter_map(|x| x)
        .reduce(|| HashSet::new(), |acc, set| &acc ^ &set);

    println!("{:?}", final_diff);

    Ok(())
}

fn get_set<S>(file: S) -> Result<HashSet<String>, Box<dyn Error>>
where
    S: AsRef<str>,
{
    let mut set = HashSet::new();
    let contents = fs::read_dir(file.as_ref())?;
    for entry in contents {
        let dir = entry?;
        if let Some(name) = dir.path().file_name() {
            set.insert(name.to_str().unwrap().to_string());
        }
    }
    Ok(set)
}