Option for auto close project when no client listen

And fix websocket not correctly detected has closed.

Ref https://github.com/GNS3/gns3-gui/issues/1331

gns3server/controller/notification.py

@@ -44,6 +44,13 @@ class Notification:
         yield queue
         self._listeners[project.id].remove(queue)
 
+    def project_has_listeners(self, project):
+        """
+        :param project_id: Project object
+        :returns: True if client listen this project
+        """
+        return project.id in self._listeners and len(self._listeners[project.id]) > 0
+
     def dispatch(self, action, event, compute_id):
         """
         Notification received from compute node. Send it directly

gns3server/handlers/api/compute/notification_handler.py

@@ -32,11 +32,16 @@ class NotificationHandler:
         ws = WebSocketResponse()
         yield from ws.prepare(request)
 
+        # Process ping / pong and close message
+        asyncio.async(ws.receive())
+
         with notifications.queue() as queue:
             while True:
                 try:
                     notification = yield from queue.get_json(5)
                 except asyncio.futures.CancelledError:
                     break
+                if ws.closed:
+                    break
                 ws.send_str(notification)
         return ws

gns3server/handlers/api/controller/project_handler.py

@@ -213,6 +213,9 @@ class ProjectHandler:
                 except asyncio.futures.CancelledError as e:
                     break
 
+        if project.auto_close and not controller.notification.project_has_listeners(project):
+            yield from project.close()
+
     @Route.get(
         r"/projects/{project_id}/notifications/ws",
         description="Receive notifications about projects from a Websocket",
@@ -231,13 +234,22 @@ class ProjectHandler:
         ws = aiohttp.web.WebSocketResponse()
         yield from ws.prepare(request)
 
+        # Process ping / pong and close message
+        asyncio.async(ws.receive())
+
         with controller.notification.queue(project) as queue:
             while True:
                 try:
                     notification = yield from queue.get_json(5)
                 except asyncio.futures.CancelledError as e:
                     break
+                if ws.closed:
+                    break
                 ws.send_str(notification)
+
+        if project.auto_close and not controller.notification.project_has_listeners(project):
+            yield from project.close()
+
         return ws
 
     @Route.get(