Fix shutdown (#335)

Relates to #220 . This change is to enable blueapi to be shutdown with
crtl+c when the activemq drops and it can no longer connect to it.

---------

Co-authored-by: Callum Forrester <[email protected]>

src/blueapi/messaging/base.py

@@ -184,3 +184,12 @@ def disconnect(self) -> None:
         """
         Disconnect the app from transport
         """
+
+    @abstractmethod
+    def is_connected(self) -> bool:
+        """
+        Returns status of the connection between the app and the transport.
+
+        Returns:
+            status (bool): Returns True if connected, False otherwise
+        """

src/blueapi/messaging/stomptemplate.py

@@ -232,3 +232,6 @@ def _on_message(self, frame: Frame) -> None:
             sub.callback(frame)
         else:
             LOGGER.warn(f"No subscription active for id: {sub_id}")
+
+    def is_connected(self) -> bool:
+        return self._conn.is_connected()

src/blueapi/service/handler.py

@@ -80,7 +80,8 @@ def _publish_event_stream(self, stream: EventStream, destination: str) -> None:
 
     def stop(self) -> None:
         self.worker.stop()
-        self.messaging_template.disconnect()
+        if self.messaging_template.is_connected():
+            self.messaging_template.disconnect()
 
 
 HANDLER: Optional[Handler] = None

tests/messaging/test_stomptemplate.py

@@ -152,7 +152,9 @@ def test_reconnect(template: MessagingTemplate, test_queue: str) -> None:
     reply = template.send_and_receive(test_queue, "test", str).result(timeout=_TIMEOUT)
     assert reply == "ack"
     template.disconnect()
+    assert not template.is_connected()
     template.connect()
+    assert template.is_connected()
     reply = template.send_and_receive(test_queue, "test", str).result(timeout=_TIMEOUT)
     assert reply == "ack"