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104 lines
2.3 KiB
104 lines
2.3 KiB
3 years ago
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use std::sync::mpsc;
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use std::sync::Arc;
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use std::sync::Mutex;
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use std::thread;
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pub struct ThreadPool {
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workers: Vec<Worker>,
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sender: mpsc::Sender<Message>,
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}
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type Job = Box<dyn FnOnce() + Send + 'static>;
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enum Message {
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NewJob(Job),
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Terminate,
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}
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impl ThreadPool {
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/// Create a new ThreadPool.
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///
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/// The size is the number of threads in the pool.
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///
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/// # Panics
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///
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/// The `new` function will panic if the size is zero.
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pub fn new(size: usize) -> ThreadPool {
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assert!(size > 0);
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let (sender, receiver) = mpsc::channel();
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let receiver = Arc::new(Mutex::new(receiver));
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let mut workers = Vec::with_capacity(size);
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for id in 0..size {
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workers.push(Worker::new(id, Arc::clone(&receiver)));
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}
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ThreadPool { workers, sender }
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}
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pub fn execute<F>(&self, f: F)
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where
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F: FnOnce() + Send + 'static,
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{
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let job = Box::new(f);
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self.sender.send(Message::NewJob(job)).unwrap();
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}
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}
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// ANCHOR: here
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impl Drop for ThreadPool {
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fn drop(&mut self) {
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println!("Sending terminate message to all workers.");
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for _ in &self.workers {
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self.sender.send(Message::Terminate).unwrap();
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}
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println!("Shutting down all workers.");
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for worker in &mut self.workers {
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println!("Shutting down worker {}", worker.id);
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if let Some(thread) = worker.thread.take() {
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thread.join().unwrap();
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}
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}
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}
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}
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// ANCHOR_END: here
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struct Worker {
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id: usize,
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thread: Option<thread::JoinHandle<()>>,
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}
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impl Worker {
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fn new(id: usize, receiver: Arc<Mutex<mpsc::Receiver<Message>>>) -> Worker {
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let thread = thread::spawn(move || loop {
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let message = receiver.lock().unwrap().recv().unwrap();
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match message {
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Message::NewJob(job) => {
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println!("Worker {} got a job; executing.", id);
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job();
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}
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Message::Terminate => {
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println!("Worker {} was told to terminate.", id);
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break;
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}
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}
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});
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Worker {
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id,
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thread: Some(thread),
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}
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}
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}
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