smarm/tests/registry.rs

//! Mailbox-registry tests (RFC 014). Run under the scheduler: registration
//! captures a live actor's channel, resolution checks liveness.
//!
//! Workers register their *own* inbox (`register` claims the current actor);
//! the root closure resolves and sends by name. A `ready` handshake closes the
//! register-then-send race without busy-waiting on `whereis`.

use smarm::{
    channel, install, register, run, send, send_to, spawn, unregister, whereis, Addressable, Name,
    Pid, RegisterError, SendError,
};

const SVC: Name<u64> = Name::new("svc");

#[test]
fn register_then_send_by_name_delivers() {
    run(|| {
        let (ready_tx, ready_rx) = channel::<()>();
        let (tx, rx) = channel::<u64>();
        let h = spawn(move || {
            register(SVC, tx).unwrap();
            ready_tx.send(()).unwrap();
            assert_eq!(rx.recv().unwrap(), 42);
        });
        ready_rx.recv().unwrap(); // worker has registered
        assert_eq!(whereis("svc"), Some(h.pid()));
        send(SVC, 42).unwrap();
        h.join().unwrap();
    });
}

#[test]
fn one_actor_many_typed_channels_route_by_type() {
    // Same name, two message types: capability separation falls out of the
    // type parameter — `Name<u64>` and `Name<&str>` hit different channels of
    // the one actor (RFC 014 §4.7).
    run(|| {
        let (ready_tx, ready_rx) = channel::<()>();
        let (cmd_tx, cmd_rx) = channel::<u64>();
        let (adm_tx, adm_rx) = channel::<&'static str>();
        let h = spawn(move || {
            register(Name::<u64>::new("port"), cmd_tx).unwrap();
            register(Name::<&'static str>::new("port"), adm_tx).unwrap();
            ready_tx.send(()).unwrap();
            assert_eq!(cmd_rx.recv().unwrap(), 7);
            assert_eq!(adm_rx.recv().unwrap(), "halt");
        });
        ready_rx.recv().unwrap();
        send(Name::<u64>::new("port"), 7u64).unwrap();
        send(Name::<&'static str>::new("port"), "halt").unwrap();
        h.join().unwrap();
    });
}

#[test]
fn name_held_by_live_actor_is_taken() {
    run(|| {
        let (ready_tx, ready_rx) = channel::<()>();
        let (tx_a, rx_a) = channel::<u64>();
        let a = spawn(move || {
            register(SVC, tx_a).unwrap();
            ready_tx.send(()).unwrap();
            assert_eq!(rx_a.recv().unwrap(), 0); // wait to be released
        });
        ready_rx.recv().unwrap();
        // Root tries to claim a live actor's name for itself -> NameTaken.
        let (tx_b, _rx_b) = channel::<u64>();
        assert_eq!(register(SVC, tx_b), Err(RegisterError::NameTaken { holder: a.pid() }));
        send(SVC, 0).unwrap(); // release a (delivers to the holder, a)
        a.join().unwrap();
    });
}

#[test]
fn dead_holder_is_pruned_and_name_taken_over() {
    // a registers, signals, then dies. Its slot index is typically reused by b;
    // b's registration must prune the stale binding and take the name over.
    run(|| {
        let (rt1, rr1) = channel::<()>();
        let (tx1, _rx1) = channel::<u64>();
        let a = spawn(move || {
            register(SVC, tx1).unwrap();
            rt1.send(()).unwrap(); // then return -> die, _rx1 dropped
        });
        rr1.recv().unwrap();
        let a_pid = a.pid();
        a.join().unwrap(); // a is dead; "svc" now points at a stale pid

        let (rt2, rr2) = channel::<()>();
        let (tx2, rx2) = channel::<u64>();
        let b = spawn(move || {
            register(SVC, tx2).unwrap(); // takes over the freed name
            rt2.send(()).unwrap();
            assert_eq!(rx2.recv().unwrap(), 9);
        });
        rr2.recv().unwrap();
        assert_ne!(b.pid(), a_pid); // distinct incarnation even if slot reused
        assert_eq!(whereis("svc"), Some(b.pid()));
        send(SVC, 9).unwrap();
        b.join().unwrap();
    });
}

#[test]
fn send_errors_unresolved_and_no_channel() {
    run(|| {
        // No actor at all.
        assert!(matches!(send(Name::<u64>::new("ghost"), 1u64), Err(SendError::Unresolved(_))));

        let (ready_tx, ready_rx) = channel::<()>();
        let (tx, rx) = channel::<u64>();
        let h = spawn(move || {
            register(Name::<u64>::new("svc2"), tx).unwrap();
            ready_tx.send(()).unwrap();
            assert_eq!(rx.recv().unwrap(), 0);
        });
        ready_rx.recv().unwrap();
        // Right actor, wrong message type: it has a u64 channel, not a String.
        let e = send(Name::<String>::new("svc2"), "x".to_string());
        assert!(matches!(e, Err(SendError::NoChannel(_))));
        assert_eq!(e.unwrap_err().into_inner(), "x"); // message handed back
        send(Name::<u64>::new("svc2"), 0u64).unwrap();
        h.join().unwrap();
    });
}

#[test]
fn unregister_frees_the_name_only() {
    run(|| {
        let (ready_tx, ready_rx) = channel::<()>();
        let (done_tx, done_rx) = channel::<()>();
        let (tx, _rx) = channel::<u64>(); // _rx moves into the actor, kept open
        let h = spawn(move || {
            register(SVC, tx).unwrap();
            let _keep_open = _rx;
            ready_tx.send(()).unwrap();
            done_rx.recv().unwrap(); // released over a separate channel
        });
        ready_rx.recv().unwrap();
        assert_eq!(whereis("svc"), Some(h.pid()));
        assert_eq!(unregister("svc"), Some(h.pid()));
        assert_eq!(whereis("svc"), None);
        assert!(matches!(send(SVC, 1u64), Err(SendError::Unresolved(_))));
        done_tx.send(()).unwrap();
        h.join().unwrap();
    });
}

// --- RFC 014 §4.2: direct, identity-bound addressing via `Pid<A>` ----------

// A stand-in single-message actor. `install::<Worker>` publishes its inbox and
// returns a `Pid<Worker>` that delivers `u64` to exactly that incarnation.
struct Worker;
impl Addressable for Worker {
    type Msg = u64;
}

#[test]
fn install_then_send_to_pid_delivers() {
    run(|| {
        let (addr_tx, addr_rx) = channel::<Pid<Worker>>();
        let h = spawn(move || {
            let (tx, rx) = channel::<u64>();
            let me = install::<Worker>(tx); // nameless publish, typed pid back
            addr_tx.send(me).unwrap();
            assert_eq!(rx.recv().unwrap(), 42);
        });
        let addr = addr_rx.recv().unwrap(); // worker installed, handed its Pid<Worker>
        assert_eq!(addr.erase(), h.pid()); // same identity, just re-typed
        send_to(addr, 42u64).unwrap();
        h.join().unwrap();
    });
}

#[test]
fn send_to_does_not_redirect_after_takeover() {
    // The load-bearing §4.2 property: a `Pid<A>` is identity-bound. When the
    // actor dies and a new incarnation reuses the slot, sending to the *old*
    // address fails `Dead` — it must never silently reach the new occupant
    // (that redirect is the re-resolving `Name`'s job, not a pid's).
    run(|| {
        let (addr_a_tx, addr_a_rx) = channel::<Pid<Worker>>();
        let (rt1, rr1) = channel::<()>();
        let a = spawn(move || {
            let (tx, _rx) = channel::<u64>();
            let me = install::<Worker>(tx);
            addr_a_tx.send(me).unwrap();
            rt1.send(()).unwrap(); // then return -> die
        });
        let a_addr = addr_a_rx.recv().unwrap();
        rr1.recv().unwrap();
        a.join().unwrap(); // a dead; a_addr names a dead incarnation

        let (addr_b_tx, addr_b_rx) = channel::<Pid<Worker>>();
        let (rt2, rr2) = channel::<()>();
        let b = spawn(move || {
            let (tx, rx) = channel::<u64>();
            let me = install::<Worker>(tx); // reuses a's slot index, new generation
            addr_b_tx.send(me).unwrap();
            rt2.send(()).unwrap();
            // Only b's own message ever arrives; the stale send never redirects.
            assert_eq!(rx.recv().unwrap(), 7);
        });
        let b_addr = addr_b_rx.recv().unwrap();
        rr2.recv().unwrap();
        assert_ne!(b_addr.erase(), a_addr.erase()); // distinct incarnation
        assert!(matches!(send_to(a_addr, 99u64), Err(SendError::Dead(_)))); // no redirect
        send_to(b_addr, 7u64).unwrap(); // b's real message
        b.join().unwrap();
    });
}