Explicitly cancel automatic discovery renewal (#326)

* Explicitly cancel automatic discovery renewal

* Update handle when rescheduling the callback

* Don't store the handle for the one-shot renewal callback
Co-authored-by: Kevin Perry <perry@coffee-break.at>

asyncua/server/server.py

@@ -87,6 +87,7 @@ class Server:
         self.bserver: Optional[BinaryServer] = None
         self._discovery_clients = {}
         self._discovery_period = 60
+        self._discovery_handle = None
         self._policies = []
         self.nodes = Shortcuts(self.iserver.isession)
         # enable all endpoints by default
@@ -223,16 +224,19 @@ class Server:
         if period:
             self.loop.call_soon(self._schedule_renew_registration)
 
-    def unregister_to_discovery(self, url: str = "opc.tcp://localhost:4840"):
+    async def unregister_to_discovery(self, url: str = "opc.tcp://localhost:4840"):
         """
         stop registration thread
         """
         # FIXME: is there really no way to deregister?
-        self._discovery_clients[url].disconnect()
+        await self._discovery_clients[url].disconnect()
+        del self._discovery_clients[url]
+        if not self._discovery_clients and self._discovery_handle:
+            self._discovery_handle.cancel()
 
     def _schedule_renew_registration(self):
         self.loop.create_task(self._renew_registration())
-        self.loop.call_later(self._discovery_period, self._schedule_renew_registration)
+        self._discovery_handle = self.loop.call_later(self._discovery_period, self._schedule_renew_registration)
 
     async def _renew_registration(self):
         for client in self._discovery_clients.values():
@@ -380,6 +384,8 @@ class Server:
         """
         Stop server
         """
+        if self._discovery_handle:
+            self._discovery_handle.cancel()
         if self._discovery_clients:
             await asyncio.wait([client.disconnect() for client in self._discovery_clients.values()])
         await self.bserver.stop()

tests/test_server.py

@@ -32,6 +32,22 @@ async def test_discovery(server, discovery_server):
         assert new_app_uri in [s.ApplicationUri for s in new_servers]
 
 
+async def test_unregister_discovery(server, discovery_server):
+    client = Client(discovery_server.endpoint.geturl())
+    async with client:
+        new_app_uri = 'urn:freeopcua:python:server:test_discovery2'
+        await server.set_application_uri(new_app_uri)
+        # register without automatic renewal
+        await server.register_to_discovery(discovery_server.endpoint.geturl(), period=0)
+        await asyncio.sleep(0.1)
+        # unregister, no automatic renewal to stop
+        await server.unregister_to_discovery(discovery_server.endpoint.geturl())
+        # reregister with automatic renewal
+        await server.register_to_discovery(discovery_server.endpoint.geturl(), period=60)
+        # unregister, cancel scheduled renewal
+        await server.unregister_to_discovery(discovery_server.endpoint.geturl())
+
+
 async def test_find_servers2(server, discovery_server):
     client = Client(discovery_server.endpoint.geturl())
     async with client: