actix-rt: Add Arbiter::is_running helper and fix System::is_set doc

`Arbiter::is_running` can be used to check if the current even-loop is currently
running; which should also work after the system has stopped. `System::is_set`
was updated to reflect what it actually does, it tells if the event loop has
started, which alone can't tell if it has stopped.

Signed-off-by: Jonathas-Conceicao <jadoliveira@inf.ufpel.edu.br>

actix-rt/CHANGES.md

@@ -2,7 +2,11 @@
 
 ## [TBD] - [TBD]
 
-- Expose `System::is_set` to check if current system is running
+Added
+
+- Expose `System::is_set` to check if current system has ben started
+
+- Add `Arbiter::is_running` to check if event loop is running
 
 - Add `Arbiter::local_join` associated function to get be able to `await` for spawned futures
 

actix-rt/src/arbiter.rs

@@ -89,6 +89,11 @@ impl Arbiter {
         })
     }
 
+    /// Check if current arbiter is running.
+    pub fn is_running() -> bool {
+        RUNNING.with(|cell| cell.get())
+    }
+
     /// Stop arbiter from continuing it's event loop.
     pub fn stop(&self) {
         let _ = self.sender.unbounded_send(ArbiterCommand::Stop);

actix-rt/src/system.rs

@@ -79,7 +79,7 @@ impl System {
         })
     }
 
-    /// Check if current system is running.
+    /// Check if current system is set, i.e., as already been started.
     pub fn is_set() -> bool {
         CURRENT.with(|cell| cell.borrow().is_some())
     }

actix-rt/tests/integration_tests.rs

@@ -1,5 +1,19 @@
 use std::time::{Duration, Instant};
 
+#[test]
+fn start_and_stop() {
+    actix_rt::System::new("start_and_stop").block_on(async move {
+        assert!(
+            actix_rt::Arbiter::is_running(),
+            "System doesn't seem to have started"
+        );
+    });
+    assert!(
+        !actix_rt::Arbiter::is_running(),
+        "System doesn't seem to have stopped"
+    );
+}
+
 #[test]
 fn await_for_timer() {
     let time = Duration::from_secs(2);