smarm/tests/channel.rs

//! Channel tests. These run under the scheduler because `recv()` needs to
//! be able to park, which requires a live runtime.

use smarm::{channel, run, spawn};
use std::cell::Cell;

thread_local! {
    static OUT: Cell<i64> = const { Cell::new(0) };
}

#[test]
fn send_then_recv_same_actor() {
    OUT.with(|c| c.set(0));
    run(|| {
        let (tx, rx) = channel::<i64>();
        tx.send(42).unwrap();
        let v = rx.recv().unwrap();
        OUT.with(|c| c.set(v));
    });
    assert_eq!(OUT.with(|c| c.get()), 42);
}

#[test]
fn recv_parks_until_send_from_other_actor() {
    OUT.with(|c| c.set(0));
    run(|| {
        let (tx, rx) = channel::<i64>();
        let h = spawn(move || {
            // This actor blocks on an empty channel.
            let v = rx.recv().unwrap();
            OUT.with(|c| c.set(v));
        });
        // Parent runs, then yields to let the child block,
        // then sends, then joins.
        smarm::yield_now();
        tx.send(7).unwrap();
        h.join().unwrap();
    });
    assert_eq!(OUT.with(|c| c.get()), 7);
}

#[test]
fn multiple_messages_arrive_in_order() {
    let captured: std::sync::Arc<std::sync::Mutex<Vec<i64>>> =
        std::sync::Arc::new(std::sync::Mutex::new(Vec::new()));
    let cap2 = captured.clone();

    run(move || {
        let (tx, rx) = channel::<i64>();
        let h = spawn(move || {
            for _ in 0..3 {
                let v = rx.recv().unwrap();
                cap2.lock().unwrap().push(v);
            }
        });
        for v in 1..=3i64 {
            tx.send(v).unwrap();
        }
        h.join().unwrap();
    });

    assert_eq!(*captured.lock().unwrap(), vec![1, 2, 3]);
}

#[test]
fn cloned_senders_both_deliver() {
    let captured: std::sync::Arc<std::sync::Mutex<Vec<i64>>> =
        std::sync::Arc::new(std::sync::Mutex::new(Vec::new()));
    let cap2 = captured.clone();

    run(move || {
        let (tx, rx) = channel::<i64>();
        let tx2 = tx.clone();
        let h = spawn(move || {
            for _ in 0..2 {
                let v = rx.recv().unwrap();
                cap2.lock().unwrap().push(v);
            }
        });
        tx.send(10).unwrap();
        tx2.send(20).unwrap();
        h.join().unwrap();
    });

    let mut got = captured.lock().unwrap().clone();
    got.sort();
    assert_eq!(got, vec![10, 20]);
}

#[test]
fn recv_returns_err_when_all_senders_dropped() {
    let saw_err: std::sync::Arc<std::sync::atomic::AtomicBool> =
        std::sync::Arc::new(std::sync::atomic::AtomicBool::new(false));
    let saw_err2 = saw_err.clone();

    run(move || {
        let (tx, rx) = channel::<i64>();
        let h = spawn(move || {
            // Receiver waits; no message will ever come.
            if rx.recv().is_err() {
                saw_err2.store(true, std::sync::atomic::Ordering::SeqCst);
            }
        });
        smarm::yield_now();
        drop(tx); // last sender gone; rx.recv must return Err.
        h.join().unwrap();
    });

    assert!(saw_err.load(std::sync::atomic::Ordering::SeqCst));
}

#[test]
fn channel_ops_interleaved_with_monitor_churn_multi_thread() {
    // Regression for the RawMutex migration: monitor registration clones the
    // Down sender under the target's cold (Leaf) lock, which now nests a
    // Channel-class lock under it. Debug builds enforce the Leaf -> Channel
    // ordering on every acquisition, so driving channels, monitors, and actor
    // death concurrently across schedulers makes any ordering regression
    // panic here rather than deadlock in the field.
    use std::sync::atomic::{AtomicI64, Ordering};
    use std::sync::Arc;

    let total = Arc::new(AtomicI64::new(0));
    let total2 = total.clone();
    smarm::init(smarm::Config::exact(4)).run(move || {
        let (tx, rx) = channel::<i64>();
        let consumer = spawn(move || {
            let mut sum = 0;
            while let Ok(v) = rx.recv() {
                sum += v;
            }
            OUT.with(|c| c.set(sum)); // not asserted cross-thread; see total
            total2.fetch_add(sum, Ordering::Relaxed);
        });

        let mut handles = Vec::new();
        for i in 0..32i64 {
            let tx = tx.clone();
            handles.push(spawn(move || {
                // Short-lived target whose death fires the monitor below.
                let t = spawn(move || {
                    tx.send(i).unwrap();
                });
                let m = smarm::monitor(t.pid());
                t.join().unwrap();
                // Down delivery exercises send-from-finalize.
                let d = m.rx.recv().unwrap();
                assert_eq!(d.reason, smarm::DownReason::Exit);
            }));
        }
        drop(tx);
        for h in handles {
            h.join().unwrap();
        }
        consumer.join().unwrap();
    });
    assert_eq!(total.load(std::sync::atomic::Ordering::Relaxed), (0..32).sum::<i64>());
}