rust-webserver/src/lib.rs

use std::thread;
use std::sync::{mpsc, Mutex, Arc};

pub struct ThreadPool{
    workers: Vec<Worker>,
    sender: mpsc::Sender<Job>,
}

type Job = Box<dyn FnOnce() + Send + 'static>;

impl ThreadPool {
    pub fn new(size: usize) -> ThreadPool {
        assert!(size > 0);

        let (sender, receiver) = mpsc::channel();

        let receiver = Arc::new(Mutex::new(receiver));

        let mut workers = Vec::with_capacity(size);

        for id in 0..size {
            workers.push(Worker::new(id, Arc::clone(&receiver)));
        }

        ThreadPool {
            workers,
            sender,
        }

    }

    pub fn execute<F>(&self, f: F)
        where F: FnOnce() + Send + 'static 
    {
        let job = Box::new(f);
        self.sender.send(job).unwrap();
    }

    // pub fn spawn<F, T>(f: F) -> JoinHandle<T> 
    //     where 
    //         F: FnOnce() -> T + Send + 'static,
    //         T: Send + 'static
    // {

    // }

}

impl Drop for ThreadPool {
    fn drop(&mut self) {
        for worker in &mut self.workers {
            println!("Shutting down worker {}", worker.id);

            worker.thread.join().unwrap();
        }
    }
}

struct Worker {
    id: usize,
    thread: thread::JoinHandle<()>,
}

impl Worker {
    fn new(id: usize, receiver: Arc<Mutex<mpsc::Receiver<Job>>>) -> Worker {
        let thread = thread::spawn(move || {
            loop {
                let job = receiver.lock().unwrap().recv().unwrap();

                println!("Worker {} got a job, executing.", id);

                job();
            }
        });

        Worker {
            id,
            thread,
        }
    }
}