prevent arbiter leaks by waiting for registration

actix-rt/CHANGES.md

@@ -14,8 +14,8 @@
 * Add `System::with_init` as replacement for `Builder::run`. [#257]
 * Rename `System::{is_set => is_registered}`. [#257]
 * Add `ArbiterHandle` for sending messages to non-current-thread arbiters. [#257].
-* `System::arbiter` now returns a `&ArbiterHandle`. [#257]
-* Rename `Arbiter::{current => handle}` and return a `ArbiterHandle` instead. [#257]
+* `System::arbiter` now returns an `&ArbiterHandle`. [#257]
+* `Arbiter::current` now returns an `ArbiterHandle` instead. [#257]
 * `Arbiter::join` now takes self by value. [#257]
 
 [#253]: https://github.com/actix/actix-net/pull/253

actix-rt/src/arbiter.rs

@@ -42,12 +42,12 @@ impl fmt::Debug for ArbiterCommand {
 /// A handle for sending spawn and stop messages to an [Arbiter].
 #[derive(Debug, Clone)]
 pub struct ArbiterHandle {
-    sender: mpsc::UnboundedSender<ArbiterCommand>,
+    tx: mpsc::UnboundedSender<ArbiterCommand>,
 }
 
 impl ArbiterHandle {
-    pub(crate) fn new(sender: mpsc::UnboundedSender<ArbiterCommand>) -> Self {
-        Self { sender }
+    pub(crate) fn new(tx: mpsc::UnboundedSender<ArbiterCommand>) -> Self {
+        Self { tx }
     }
 
     /// Send a future to the [Arbiter]'s thread and spawn it.
@@ -59,7 +59,7 @@ impl ArbiterHandle {
     where
         Fut: Future<Output = ()> + Send + 'static,
     {
-        self.sender
+        self.tx
             .send(ArbiterCommand::Execute(Box::pin(future)))
             .is_ok()
     }
@@ -82,7 +82,7 @@ impl ArbiterHandle {
     /// Returns true if stop message was sent successfully and false if the [Arbiter] has
     /// been dropped.
     pub fn stop(&self) -> bool {
-        self.sender.send(ArbiterCommand::Stop).is_ok()
+        self.tx.send(ArbiterCommand::Stop).is_ok()
     }
 }
 
@@ -92,7 +92,7 @@ impl ArbiterHandle {
 /// When an arbiter is created, it spawns a new [OS thread](thread), and hosts an event loop.
 #[derive(Debug)]
 pub struct Arbiter {
-    sender: mpsc::UnboundedSender<ArbiterCommand>,
+    tx: mpsc::UnboundedSender<ArbiterCommand>,
     thread_handle: thread::JoinHandle<()>,
 }
 
@@ -109,12 +109,14 @@ impl Arbiter {
         let sys = System::current();
         let (tx, rx) = mpsc::unbounded_channel();
 
+        let (ready_tx, ready_rx) = std::sync::mpsc::channel::<()>();
+
         let thread_handle = thread::Builder::new()
             .name(name.clone())
             .spawn({
                 let tx = tx.clone();
                 move || {
-                    let rt = Runtime::new().expect("Can not create Runtime");
+                    let rt = Runtime::new().expect("Cannot create new Arbiter's Runtime.");
                     let hnd = ArbiterHandle::new(tx);
 
                     System::set_current(sys);
@@ -127,6 +129,8 @@ impl Arbiter {
                         .tx()
                         .send(SystemCommand::RegisterArbiter(id, hnd));
 
+                    ready_tx.send(()).unwrap();
+
                     // run arbiter event processing loop
                     rt.block_on(ArbiterRunner { rx });
 
@@ -140,13 +144,12 @@ impl Arbiter {
                 panic!("Cannot spawn Arbiter's thread: {:?}. {:?}", &name, err)
             });
 
-        Arbiter {
-            sender: tx,
-            thread_handle,
-        }
+        ready_rx.recv().unwrap();
+
+        Arbiter { tx, thread_handle }
     }
 
-    /// Sets up an Arbiter runner on the current thread using the provided runtime local task set.
+    /// Sets up an Arbiter runner in a new System using the provided runtime local task set.
     pub(crate) fn in_new_system(local: &LocalSet) -> ArbiterHandle {
         let (tx, rx) = mpsc::unbounded_channel();
 
@@ -160,11 +163,11 @@ impl Arbiter {
         hnd
     }
 
-    /// Return a handle to the Arbiter's message sender.
+    /// Return a handle to the current thread's Arbiter's message sender.
     ///
     /// # Panics
     /// Panics if no Arbiter is running on the current thread.
-    pub fn handle() -> ArbiterHandle {
+    pub fn current() -> ArbiterHandle {
         HANDLE.with(|cell| match *cell.borrow() {
             Some(ref addr) => addr.clone(),
             None => panic!("Arbiter is not running."),
@@ -175,7 +178,7 @@ impl Arbiter {
     ///
     /// Returns true if stop message was sent successfully and false if the Arbiter has been dropped.
     pub fn stop(&self) -> bool {
-        self.sender.send(ArbiterCommand::Stop).is_ok()
+        self.tx.send(ArbiterCommand::Stop).is_ok()
     }
 
     /// Send a future to the Arbiter's thread and spawn it.
@@ -187,7 +190,7 @@ impl Arbiter {
     where
         Fut: Future<Output = ()> + Send + 'static,
     {
-        self.sender
+        self.tx
             .send(ArbiterCommand::Execute(Box::pin(future)))
             .is_ok()
     }

actix-rt/src/system.rs

@@ -40,7 +40,13 @@ impl System {
         let (sys_tx, sys_rx) = mpsc::unbounded_channel();
 
         let rt = Runtime::new().expect("Actix (Tokio) runtime could not be created.");
-        let system = System::construct(sys_tx, Arbiter::in_new_system(rt.local_set()));
+        let sys_arbiter = Arbiter::in_new_system(rt.local_set());
+        let system = System::construct(sys_tx, sys_arbiter.clone());
+
+        system
+            .tx()
+            .send(SystemCommand::RegisterArbiter(usize::MAX, sys_arbiter))
+            .unwrap();
 
         // init background system arbiter
         let sys_ctrl = SystemController::new(sys_rx, stop_tx);
@@ -201,8 +207,8 @@ impl Future for SystemController {
                 Some(cmd) => match cmd {
                     SystemCommand::Exit(code) => {
                         // stop all arbiters
-                        for wkr in self.arbiters.values() {
-                            wkr.stop();
+                        for arb in self.arbiters.values() {
+                            arb.stop();
                         }
 
                         // stop event loop
@@ -212,12 +218,12 @@ impl Future for SystemController {
                         }
                     }
 
-                    SystemCommand::RegisterArbiter(name, hnd) => {
-                        self.arbiters.insert(name, hnd);
+                    SystemCommand::RegisterArbiter(id, arb) => {
+                        self.arbiters.insert(id, arb);
                     }
 
-                    SystemCommand::DeregisterArbiter(name) => {
-                        self.arbiters.remove(&name);
+                    SystemCommand::DeregisterArbiter(id) => {
+                        self.arbiters.remove(&id);
                     }
                 },
             }

actix-rt/tests/tests.rs

@@ -28,7 +28,7 @@ fn join_another_arbiter() {
         let arbiter = Arbiter::new();
         arbiter.spawn(Box::pin(async move {
             tokio::time::sleep(time).await;
-            Arbiter::handle().stop();
+            Arbiter::current().stop();
         }));
         arbiter.join().unwrap();
     });
@@ -43,7 +43,7 @@ fn join_another_arbiter() {
         arbiter.spawn_fn(move || {
             actix_rt::spawn(async move {
                 tokio::time::sleep(time).await;
-                Arbiter::handle().stop();
+                Arbiter::current().stop();
             });
         });
         arbiter.join().unwrap();
@@ -58,7 +58,7 @@ fn join_another_arbiter() {
         let arbiter = Arbiter::new();
         arbiter.spawn(Box::pin(async move {
             tokio::time::sleep(time).await;
-            Arbiter::handle().stop();
+            Arbiter::current().stop();
         }));
         arbiter.stop();
         arbiter.join().unwrap();
@@ -190,7 +190,7 @@ fn system_arbiter_spawn() {
 
     thread::spawn(|| {
         // this thread will have no arbiter in it's thread local so call will panic
-        Arbiter::handle();
+        Arbiter::current();
     })
     .join()
     .unwrap_err();
@@ -200,8 +200,8 @@ fn system_arbiter_spawn() {
         System::set_current(sys);
         let sys = System::current();
 
-        let wrk = sys.arbiter();
-        wrk.spawn(async move {
+        let arb = sys.arbiter();
+        arb.spawn(async move {
             tx.send(42u32).unwrap();
             System::current().stop();
         });
@@ -210,3 +210,22 @@ fn system_arbiter_spawn() {
     assert_eq!(runner.block_on(rx).unwrap(), 42);
     thread.join().unwrap();
 }
+
+#[test]
+fn system_stop_stops_arbiters() {
+    let sys = System::new();
+    let arb = Arbiter::new();
+
+    // arbiter should be alive to receive spawn msg
+    assert!(Arbiter::current().spawn_fn(|| {}));
+    assert!(arb.spawn_fn(|| {}));
+
+    System::current().stop();
+    sys.run().unwrap();
+
+    // arbiter should be dead and return false
+    assert!(!Arbiter::current().spawn_fn(|| {}));
+    assert!(!arb.spawn_fn(|| {}));
+
+    arb.join().unwrap();
+}

actix-server/src/worker.rs

@@ -215,7 +215,7 @@ impl ServerWorker {
                     }
                     Err(e) => {
                         error!("Can not start worker: {:?}", e);
-                        Arbiter::handle().stop();
+                        Arbiter::current().stop();
                     }
                 }
                 wrk.await
@@ -386,7 +386,7 @@ impl Future for ServerWorker {
                 let num = num_connections();
                 if num == 0 {
                     let _ = tx.take().unwrap().send(true);
-                    Arbiter::handle().stop();
+                    Arbiter::current().stop();
                     return Poll::Ready(());
                 }
 
@@ -394,7 +394,7 @@ impl Future for ServerWorker {
                 if Pin::new(t2).poll(cx).is_ready() {
                     let _ = tx.take().unwrap().send(false);
                     self.shutdown(true);
-                    Arbiter::handle().stop();
+                    Arbiter::current().stop();
                     return Poll::Ready(());
                 }