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| #![feature(trait_alias)] | |
| #![feature(box_syntax)] | |
| use std::thread; | |
| use std::sync::{ | |
| Arc, | |
| Mutex, | |
| Condvar, | |
| }; | |
| use std::sync::atomic::{ AtomicBool, Ordering }; | |
| use std::collections::VecDeque; | |
| pub trait Job = FnOnce() + Send + Sync + 'static; | |
| struct ThreadPoolInner { | |
| queue: Mutex<VecDeque<Box<dyn Job>>>, | |
| on_change: Condvar, | |
| is_running: AtomicBool, | |
| } | |
| #[derive(Clone)] | |
| pub struct ThreadPool(Arc<ThreadPoolInner>); | |
| impl ThreadPool { | |
| pub fn new(num_threads: usize) -> Self { | |
| let state = Arc::new(ThreadPoolInner { | |
| queue: Mutex::new(VecDeque::new()), | |
| on_change: Condvar::new(), | |
| is_running: AtomicBool::new(true), | |
| }); | |
| for _ in 0..num_threads { | |
| let pool = state.clone(); | |
| thread::spawn(move || { | |
| while pool.is_running.load(Ordering::Relaxed) { | |
| let mut queue = pool.queue.lock().unwrap(); | |
| let job = queue.pop_front(); | |
| match job { | |
| Some(job) => job(), | |
| None => {} | |
| } | |
| } | |
| }); | |
| } | |
| Self(state) | |
| } | |
| pub fn enqueue<F, T>(&self, f: F) -> Future<T> | |
| where | |
| F: FnOnce() -> T, | |
| F: Send + Sync + 'static, | |
| T: Send + Sync + 'static | |
| { | |
| let mut queue = self.0.queue.lock().unwrap(); | |
| let result: Future<T> = Future::new(); | |
| let their_future = result.clone(); | |
| queue.push_back(box move || { | |
| let (inner, on_change) = &*their_future.0; | |
| { | |
| let mut guard = inner.lock().unwrap(); | |
| *guard = Some(f()); | |
| } | |
| on_change.notify_all(); | |
| }); | |
| self.0.on_change.notify_one(); | |
| result | |
| } | |
| pub fn shutdown(&self) { | |
| self.0.is_running.store(false, Ordering::Relaxed); | |
| } | |
| } | |
| pub struct Future<T>(Arc<(Mutex<Option<T>>, Condvar)>); | |
| impl<T> Clone for Future<T> { | |
| fn clone(&self) -> Self { | |
| Self(self.0.clone()) | |
| } | |
| } | |
| impl<T> Future<T> { | |
| pub fn new() -> Self { | |
| Self(Arc::new((Mutex::new(None), Condvar::new()))) | |
| } | |
| pub fn get(&self) -> T { | |
| let (inner, on_change) = &*self.0; | |
| let mut guard = inner.lock().unwrap(); | |
| if guard.is_some() { | |
| return guard.take().unwrap(); | |
| } | |
| let mut guard = on_change.wait(guard).unwrap(); | |
| guard.take().unwrap() | |
| } | |
| } |
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