Send compute usage via in the compute.updated notification

Ref https://github.com/GNS3/gns3-gui/issues/1261

gns3server/controller/compute.py

@@ -89,6 +89,8 @@ class Compute:
         self._set_auth(user, password)
         self._session = aiohttp.ClientSession()
         self._version = None
+        self._cpu_usage_percent = None
+        self._memory_usage_percent = None
         self.name = name
         # Websocket for notifications
         self._ws = None
@@ -228,6 +230,14 @@ class Compute:
     def password(self, value):
         self._set_auth(self._user, value)
 
+    @property
+    def cpu_usage_percent(self):
+        return self._cpu_usage_percent
+
+    @property
+    def memory_usage_percent(self):
+        return self._memory_usage_percent
+
     def __json__(self, topology_dump=False):
         """
         :param topology_dump: Filter to keep only properties require for saving on disk
@@ -247,7 +257,9 @@ class Compute:
             "host": self._host,
             "port": self._port,
             "user": self._user,
-            "connected": self._connected
+            "connected": self._connected,
+            "cpu_usage_percent": self._cpu_usage_percent,
+            "memory_usage_percent": self._memory_usage_percent
         }
 
     @asyncio.coroutine
@@ -307,7 +319,13 @@ class Compute:
             msg = json.loads(response.data)
             action = msg.pop("action")
             event = msg.pop("event")
-            self._controller.notification.dispatch(action, event, compute_id=self.id)
+
+            if action == "ping":
+                self._cpu_usage_percent = event["cpu_usage_percent"]
+                self._memory_usage_percent = event["memory_usage_percent"]
+                self._controller.notification.emit("compute.updated", self.__json__())
+            else:
+                self._controller.notification.dispatch(action, event, compute_id=self.id)
         yield from self._ws.close()
         self._ws = None