From a10bdc90159e351f0855c70e3236b7b785894d40 Mon Sep 17 00:00:00 2001
From: "Christoph J. Scherr" <Christoph.Scherr@newtec.de>
Date: Mon, 15 Jan 2024 18:06:32 +0100
Subject: [PATCH] holy fuck i implemented a threadpool

---
 members/socker/src/main.rs | 11 ++++--
 members/socker/src/pool.rs | 68 ++++++++++++++++++++++++++++++++++++++
 2 files changed, 77 insertions(+), 2 deletions(-)
 create mode 100644 members/socker/src/pool.rs

diff --git a/members/socker/src/main.rs b/members/socker/src/main.rs
index 7bad230..bcb3415 100644
--- a/members/socker/src/main.rs
+++ b/members/socker/src/main.rs
@@ -1,12 +1,17 @@
 use std::{
-    io::{BufRead, BufReader, Write},
+    io::{prelude::*, BufReader},
     net::{TcpListener, TcpStream},
     process::exit,
 };
 
+mod pool;
+use pool::ThreadPool;
+
+
 fn main() {
     println!("Starting the server");
     let target_address = "127.0.0.1:7878";
+    let pool = ThreadPool::build(4).unwrap();
     let listener = match TcpListener::bind(target_address) {
         Ok(listener) => listener,
         Err(err) => {
@@ -17,7 +22,9 @@ fn main() {
     for stream in listener.incoming() {
         let stream = stream.unwrap();
 
-        handle_connection(stream);
+        pool.execute(|| {
+            handle_connection(stream);
+        });
     }
 }
 
diff --git a/members/socker/src/pool.rs b/members/socker/src/pool.rs
new file mode 100644
index 0000000..b56f534
--- /dev/null
+++ b/members/socker/src/pool.rs
@@ -0,0 +1,68 @@
+use std::{
+    sync::{mpsc, Arc, Mutex},
+    thread,
+};
+
+struct WorkerThread {
+    handle: thread::JoinHandle<()>,
+    id: usize,
+}
+
+impl WorkerThread {
+    fn new(id: usize, receiver: Arc<Mutex<mpsc::Receiver<Job>>>) -> WorkerThread {
+        let handle = thread::spawn(move || loop {
+            let job = receiver.lock().unwrap().recv().unwrap();
+
+            println!("Worker {id} got a job; executing.");
+
+            job();
+        });
+        WorkerThread { handle, id }
+    }
+}
+
+/// Shares tasks over multiple worker threads
+pub struct ThreadPool {
+    /// executes tasks assigned by the instructor
+    workers: Vec<WorkerThread>,
+    /// sends instructions to the workers
+    sender: mpsc::Sender<Job>,
+}
+
+/// Something for the workers to do
+type Job = Box<dyn FnOnce() + Send + 'static>;
+
+impl ThreadPool {
+    /// Create a new ThreadPool.
+    ///
+    /// The size is the number of threads in the pool.
+    ///
+    /// # Panics
+    ///
+    /// The `new` function will panic if the size is zero.
+    pub fn build(size: usize) -> Result<ThreadPool, String> {
+        if !(size > 0) {
+            return Err(format!("cannot build a thread pool with 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 threads and store them in the vector
+            workers.push(WorkerThread::new(id, Arc::clone(&receiver)));
+        }
+
+        Ok(ThreadPool { workers, sender })
+    }
+
+    /// schedules the given job for execution
+    pub fn execute<F>(&self, f: F)
+    where
+        F: FnOnce() + Send + 'static,
+    {
+        // now it's getting crazy
+        let job = Box::new(f);
+        self.sender.send(job).unwrap();
+    }
+}