gen_server: tick_every periodic sugar — loop-driven re-arm via factory + Sys::Tick (RFC 015 §4.3)

tests/gen_server.rs

@@ -453,6 +453,7 @@ use smarm::TimerId;
 
 enum TkCast {
     Arm(Duration),
+    Tick(Duration),
     CancelLast,
 }
 
@@ -482,6 +483,7 @@ impl GenServer for Timed {
         let t = self.timer.as_ref().expect("init ran first");
         match c {
             TkCast::Arm(d) => self.last = Some(t.arm_after(d, 7)),
+            TkCast::Tick(d) => self.last = Some(t.tick_every(d, 9)),
             TkCast::CancelLast => {
                 let id = self.last.take().expect("a timer was armed");
                 *self.cancel_won.lock().unwrap() = Some(t.cancel(id));
@@ -535,3 +537,46 @@ fn cancel_before_fire_suppresses_it() {
     assert_eq!(*cancel_won.lock().unwrap(), Some(true), "cancel beat the fire");
     assert!(fired.lock().unwrap().is_empty());
 }
+
+// tick_every re-arms: a periodic fires repeatedly off one arm, each tick
+// carrying a fresh payload. (Timer fires outrank the inbox by arm position, so
+// a periodic cannot be starved by userspace traffic — the same property the
+// info_outranks_inbox test pins for infos.)
+#[test]
+fn tick_every_rearms_repeatedly() {
+    let fired = Arc::new(Mutex::new(Vec::new()));
+    let f2 = fired.clone();
+    run(move || {
+        let cw = Arc::new(Mutex::new(None));
+        let server = start(timed(f2, cw));
+        server.cast(TkCast::Tick(Duration::from_millis(20))).unwrap();
+        let _ = server.call(()).unwrap(); // sync: periodic armed
+        smarm::sleep(Duration::from_millis(130)); // ~6 periods
+        let count = server.call(()).unwrap();
+        assert!(count >= 3, "periodic should have re-armed several times, got {count}");
+    });
+    // Every tick delivered the same payload.
+    assert!(fired.lock().unwrap().iter().all(|&v| v == 9));
+}
+
+// Cancelling a periodic stops the re-arm: no further ticks land after cancel.
+#[test]
+fn cancel_stops_a_periodic() {
+    let fired = Arc::new(Mutex::new(Vec::new()));
+    let cancel_won = Arc::new(Mutex::new(None));
+    let f2 = fired.clone();
+    let c2 = cancel_won.clone();
+    run(move || {
+        let server = start(timed(f2, c2));
+        server.cast(TkCast::Tick(Duration::from_millis(20))).unwrap();
+        let _ = server.call(()).unwrap();
+        smarm::sleep(Duration::from_millis(70)); // a few ticks
+        server.cast(TkCast::CancelLast).unwrap();
+        let after_cancel = server.call(()).unwrap(); // sync: cancel handled
+        smarm::sleep(Duration::from_millis(80)); // would be several more ticks
+        let later = server.call(()).unwrap();
+        assert_eq!(later, after_cancel, "no ticks may land after cancel");
+    });
+    // The periodic had fired at least once before being cancelled.
+    assert!(!fired.lock().unwrap().is_empty());
+}