add: execute connections asynchronously

src/bin/main.rs

@@ -2,14 +2,20 @@ use httparse;
 use std::io::prelude::*;
 use std::net::{TcpListener, TcpStream};
 
+use myip::ThreadPool;
+
 fn main() {
     println!("Replying with most probable peer's ip on port 7878");
     let listener = TcpListener::bind("127.0.0.1:7878").unwrap();
 
+    let pool = ThreadPool::new(4);
+
     for stream in listener.incoming() {
         let stream = stream.unwrap();
 
-        handle_connection(stream);
+        pool.execute(|| {
+            handle_connection(stream);
+        });
     }
 }
 

src/lib.rs

@@ -0,0 +1,67 @@
+use std::{
+    sync::{mpsc, Arc, Mutex},
+    thread,
+};
+
+pub struct ThreadPool {
+    workers: Vec<Worker>,
+    sender: mpsc::Sender<Job>,
+}
+
+impl ThreadPool {
+    /// Create a new ThreadPool.
+    ///
+    /// The size is the number of workers in the pool.
+    ///
+    /// # Panics
+    ///
+    /// The `new` function will panic if the size is zero.
+    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 {
+            // create some workers and store them in the vector
+            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();
+    }
+}
+
+type Job = Box<dyn FnOnce() + Send + 'static>;
+
+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()
+                .expect("Mutex poisoned; bailing out.")
+                .recv()
+                .expect("Failed to receive job.");
+
+            println!("Worker {} got a job; executing.", id);
+
+            job();
+        });
+
+        Worker { id, thread }
+    }
+}