graceful shutdown and clean up of server after 5 requests

src/lib.rs

@@ -5,7 +5,7 @@ use std::{
 
 pub struct ThreadPool {
     workers: Vec<Worker>,
-    sender: mpsc::Sender<Job>,
+    sender: Option<mpsc::Sender<Job>>,
 }
 type Job = Box<dyn FnOnce() + Send + 'static>;
 impl ThreadPool {
@@ -27,32 +27,59 @@ impl ThreadPool {
             workers.push(Worker::new(id, Arc::clone(&receiver)))
         }
 
-        ThreadPool { workers, sender }
+        ThreadPool {
+            workers,
+            sender: Some(sender),
+        }
     }
 
     pub fn execute<F>(&self, f: F)
     where
         F: FnOnce() + Send + 'static,
     {
         let job = Box::new(f);
-        self.sender.send(job).unwrap();
+        self.sender.as_ref().unwrap().send(job).unwrap();
+    }
+}
+
+impl Drop for ThreadPool {
+    fn drop(&mut self) {
+        drop(self.sender.take());
+        for worker in &mut self.workers {
+            println!("Shutting down worker {}", worker.id);
+
+            if let Some(thread) = worker.thread.take() {
+                thread.join().unwrap();
+            }
+        }
     }
 }
 
 struct Worker {
     id: usize,
-    thread: thread::JoinHandle<()>,
+    thread: Option<thread::JoinHandle<()>>,
 }
 
 impl Worker {
     pub fn new(id: usize, receiver: Arc<Mutex<mpsc::Receiver<Job>>>) -> Worker {
-        let thread = thread::spawn(move || {
-            let job = receiver.lock().unwrap().recv().unwrap();
+        let thread = thread::spawn(move || loop {
+            let message = receiver.lock().unwrap().recv();
 
-            println!("Worker {id} got a job; executing....");
+            match message {
+                Ok(job) => {
+                    println!("Worker {id} got a job; executing....");
 
-            job();
+                    job();
+                }
+                Err(_) => {
+                    println!("Worker {id} is shutting down....");
+                    break;
+                }
+            }
         });
-        Worker { id, thread }
+        Worker {
+            id,
+            thread: Some(thread),
+        }
     }
 }

src/main.rs

@@ -11,13 +11,15 @@ fn main() {
     let listener = TcpListener::bind("127.0.0.1:7878").unwrap();
     let pool = ThreadPool::new(4);
 
-    for stream in listener.incoming() {
+    for stream in listener.incoming().take(2) {
         let stream = stream.unwrap();
 
         pool.execute(|| {
             handle_connection(stream);
         });
     }
+
+    println!("Shutting down");
 }
 
 fn handle_connection(mut stream: TcpStream) {