feat: introduce threadpool

src/utils/mod.rs

@@ -1,4 +1,5 @@
 pub mod md5;
+pub mod thread_pool;
 pub mod zlib;
 
 pub use md5::*;

src/utils/thread_pool.rs

@@ -0,0 +1,69 @@
+use std::sync::{mpsc, Arc, Mutex};
+use std::thread;
+
+type Job = Box<dyn FnOnce() + Send + 'static>;
+
+pub struct ThreadPool {
+    workers: Vec<Worker>,
+    sender: mpsc::Sender<Job>,
+}
+
+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();
+    }
+}
+
+impl Drop for ThreadPool {
+    fn drop(&mut self) {
+        for worker in &mut self.workers {
+            if let Some(thread) = worker.thread.take() {
+                thread.join().unwrap();
+            }
+        }
+    }
+}
+
+struct Worker {
+    _id: usize,
+    thread: Option<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();
+            match job {
+                Ok(job) => {
+                    job();
+                }
+                Err(_) => {
+                    break;
+                }
+            }
+        });
+
+        Worker {
+            _id: id,
+            thread: Some(thread),
+        }
+    }
+}