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|
use std::sync::Arc;
use std::sync::Mutex;
use std::sync::mpsc;
use std::thread;
enum Message {
NewJob(Job),
Terminate,
}
trait FnBox {
fn call_box(self: Box<Self>);
}
impl <F: FnOnce()> FnBox for F {
fn call_box(self: Box<F>) {
(*self)()
}
}
type Job = Box<FnBox + Send + 'static>;
pub struct ThreadPool {
workers: Vec<Worker>,
sender: mpsc::Sender<Message>,
}
impl ThreadPool {
pub fn new(size: usize) -> Result<ThreadPool, &'static str> {
if size <= 0 {
return Err("failed to create pool");
}
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))?);
}
Ok(ThreadPool {
workers,
sender,
})
}
pub fn spawn<F, T>(f: F) -> thread::JoinHandle<T>
where
F: FnOnce() -> T + Send + 'static,
T: Send + 'static
{
thread::spawn(f)
}
pub fn execute<F>(&self, f: F)
where
F: FnOnce() + Send + 'static
{
let job = Box::new(f);
self.sender.send(Message::NewJob(job)).unwrap();
}
}
impl Drop for ThreadPool {
fn drop(&mut self) {
for _ in &mut self.workers {
self.sender.send(Message::Terminate).unwrap();
}
println!("shutting down all workers...");
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: Option<thread::JoinHandle<()>>,
}
impl Worker {
pub fn new(id: usize, receiver: Arc<Mutex<mpsc::Receiver<Message>>>)
-> Result<Worker, &'static str>
{
let thread = thread::spawn(move || {
loop {
let message = receiver.lock().unwrap().recv().unwrap();
match message {
Message::NewJob(job) => {
println!("worker {} got job, executing...", id);
job.call_box();
},
Message::Terminate => {
println!("worker {} was told to terminate...", id);
break;
},
}
}
});
Ok(Worker {
id,
thread: Some(thread),
})
}
}
|
