sim_lib_server/
pool.rs

1use std::sync::{Arc, Mutex, OnceLock, mpsc};
2use std::thread::JoinHandle;
3
4type Job = Box<dyn FnOnce() + Send + 'static>;
5
6/// A fixed-size pool for dispatching thread-independent work.
7pub struct WorkerPool {
8    sender: Option<mpsc::Sender<Job>>,
9    workers: Vec<JoinHandle<()>>,
10}
11
12impl WorkerPool {
13    /// Starts a pool with at least one worker.
14    pub fn new(size: usize) -> Self {
15        let (sender, receiver) = mpsc::channel::<Job>();
16        let receiver = Arc::new(Mutex::new(receiver));
17        let mut workers = Vec::with_capacity(size.max(1));
18        for _ in 0..size.max(1) {
19            let rx = receiver.clone();
20            workers.push(std::thread::spawn(move || {
21                loop {
22                    let job = match rx.lock() {
23                        Ok(receiver) => receiver.recv(),
24                        Err(_) => break,
25                    };
26                    match job {
27                        Ok(job) => job(),
28                        Err(_) => break,
29                    }
30                }
31            }));
32        }
33        Self {
34            sender: Some(sender),
35            workers,
36        }
37    }
38
39    /// Queues one owned job for execution.
40    pub fn execute<F: FnOnce() + Send + 'static>(&self, f: F) {
41        if let Some(sender) = &self.sender {
42            let _ = sender.send(Box::new(f));
43        }
44    }
45}
46
47impl Drop for WorkerPool {
48    fn drop(&mut self) {
49        self.sender.take();
50        for worker in self.workers.drain(..) {
51            let _ = worker.join();
52        }
53    }
54}
55
56/// Returns the process-wide worker pool sized to available parallelism.
57pub fn default_worker_pool() -> &'static WorkerPool {
58    static POOL: OnceLock<WorkerPool> = OnceLock::new();
59    POOL.get_or_init(|| {
60        let size = std::thread::available_parallelism()
61            .map(|parallelism| parallelism.get())
62            .unwrap_or(1);
63        WorkerPool::new(size)
64    })
65}
66
67#[cfg(test)]
68mod tests {
69    use std::sync::mpsc;
70
71    use super::WorkerPool;
72
73    #[test]
74    fn worker_pool_executes_jobs_and_joins_on_drop() {
75        let (tx, rx) = mpsc::channel();
76        {
77            let pool = WorkerPool::new(2);
78            pool.execute(move || {
79                let _ = tx.send("done");
80            });
81            assert_eq!(rx.recv().unwrap(), "done");
82        }
83    }
84}
sim_lib_server/pool.rs

sim_lib_server/
pool.rs
