store the thread's handle with arbiter (#60)

actix-rt/CHANGES.md

@@ -6,6 +6,10 @@
 
 * Fix arbiter's thread panic message.
 
+### Added
+
+* Allow to join arbiter's thread. #60
+
 
 ## [0.2.5] - 2019-09-02
 

actix-rt/src/arbiter.rs

@@ -39,11 +39,20 @@ impl fmt::Debug for ArbiterCommand {
     }
 }
 
-#[derive(Debug, Clone)]
+#[derive(Debug)]
 /// Arbiters provide an asynchronous execution environment for actors, functions
 /// and futures. When an Arbiter is created, they spawn a new OS thread, and
 /// host an event loop. Some Arbiter functions execute on the current thread.
-pub struct Arbiter(UnboundedSender<ArbiterCommand>);
+pub struct Arbiter {
+    sender: UnboundedSender<ArbiterCommand>,
+    thread_handle: Option<thread::JoinHandle<()>>,
+}
+
+impl Clone for Arbiter {
+    fn clone(&self) -> Self {
+        Self::with_sender(self.sender.clone())
+    }
+}
 
 impl Default for Arbiter {
     fn default() -> Self {
@@ -55,7 +64,7 @@ impl Arbiter {
     pub(crate) fn new_system() -> Self {
         let (tx, rx) = unbounded();
 
-        let arb = Arbiter(tx);
+        let arb = Arbiter::with_sender(tx);
         ADDR.with(|cell| *cell.borrow_mut() = Some(arb.clone()));
         RUNNING.with(|cell| cell.set(false));
         STORAGE.with(|cell| cell.borrow_mut().clear());
@@ -75,7 +84,7 @@ impl Arbiter {
 
     /// Stop arbiter from continuing it's event loop.
     pub fn stop(&self) {
-        let _ = self.0.unbounded_send(ArbiterCommand::Stop);
+        let _ = self.sender.unbounded_send(ArbiterCommand::Stop);
     }
 
     /// Spawn new thread and run event loop in spawned thread.
@@ -87,9 +96,9 @@ impl Arbiter {
         let (arb_tx, arb_rx) = unbounded();
         let arb_tx2 = arb_tx.clone();
 
-        let _ = thread::Builder::new().name(name.clone()).spawn(move || {
+        let handle = thread::Builder::new().name(name.clone()).spawn(move || {
             let mut rt = Builder::new().build_rt().expect("Can not create Runtime");
-            let arb = Arbiter(arb_tx);
+            let arb = Arbiter::with_sender(arb_tx);
 
             let (stop, stop_rx) = channel();
             RUNNING.with(|cell| cell.set(true));
@@ -119,9 +128,9 @@ impl Arbiter {
             let _ = System::current()
                 .sys()
                 .unbounded_send(SystemCommand::UnregisterArbiter(id));
-        });
+        }).unwrap_or_else(|err| panic!("Cannot spawn an arbiter's thread {:?}: {:?}", &name, err));
 
-        Arbiter(arb_tx2)
+        Arbiter{sender: arb_tx2, thread_handle: Some(handle)}
     }
 
     pub(crate) fn run_system() {
@@ -171,7 +180,7 @@ impl Arbiter {
         F: Future<Item = (), Error = ()> + Send + 'static,
     {
         let _ = self
-            .0
+            .sender
             .unbounded_send(ArbiterCommand::Execute(Box::new(future)));
     }
 
@@ -182,7 +191,7 @@ impl Arbiter {
         F: FnOnce() + Send + 'static,
     {
         let _ = self
-            .0
+            .sender
             .unbounded_send(ArbiterCommand::ExecuteFn(Box::new(move || {
                 f();
             })));
@@ -198,7 +207,7 @@ impl Arbiter {
     {
         let (tx, rx) = channel();
         let _ = self
-            .0
+            .sender
             .unbounded_send(ArbiterCommand::ExecuteFn(Box::new(move || {
                 if !tx.is_canceled() {
                     let _ = tx.send(f());
@@ -250,6 +259,20 @@ impl Arbiter {
             f(item)
         })
     }
+
+    fn with_sender(sender: UnboundedSender<ArbiterCommand>) -> Self {
+        Self{sender, thread_handle: None}
+    }
+
+    /// Wait for the event loop to stop by joining the underlying thread (if have Some).
+    pub fn join(&mut self) -> thread::Result<()>{
+        if let Some(thread_handle) = self.thread_handle.take() {
+            thread_handle.join()
+        }
+        else {
+            Ok(())
+        }
+    }
 }
 
 struct ArbiterController {