Example of threapool usage

tp.rs

#[macro_use]
extern crate error_chain;
extern crate walkdir;
extern crate ring;
extern crate num_cpus;
extern crate threadpool;

// error_chain! {
//     foreign_links {
//         Io(std::io::Error);
//     }
// }

use walkdir::{WalkDir, DirEntry};
use std::fs::File;
use std::io::BufReader;
use std::io::prelude::*;
use threadpool::ThreadPool;
use std::sync::mpsc::channel;
use ring::digest;

// Verify the iso extension
fn is_iso(entry: &DirEntry) -> bool {
    entry.file_name()
        .to_str()
        .map(|s| s.ends_with(".iso"))
        .unwrap_or(false)
}

fn run() -> Result<()> {
    let cpus = num_cpus::get();
    let pool = ThreadPool::new(cpus);
    let mut file_counter: usize = 0;

    let (tx, rx) = channel();

    for entry in WalkDir::new(".")
        .follow_links(true)
        .into_iter()
        .filter_map(|e| e.ok())
        .filter(|e| !e.file_type().is_dir() && is_iso(e)) {
            // Need to know how many entry were sent to the pool.
            file_counter = file_counter + 1;
            let entry = entry.clone();
            let tx = tx.clone();
            pool.execute(move || {
                let file = match File::open(entry.path()) {
                    Ok(file) => file,
                    Err(err) => {
                        tx.send(Err(err)).expect("Could not send data!");
                        return;
                    },
                };
                let mut buf_reader = BufReader::new(file);
                let mut content: Vec<u8> = Vec::new();
                buf_reader.read_to_end(&mut content);
                // Compute the SHA1
                let digest = digest::digest(&digest::SHA1, &content);
                let file_path = String::from(entry.path().to_string_lossy());
                // Send as a Result
                tx.send(Ok((digest, file_path))).expect("Could not send data!");
            });
        }

    for t in rx.iter().take(file_counter) {
        let (sha, path) = t?;
        println!("{:?} {}", sha, path);
    }
    Ok(())
}

quick_main!(run);