Merge branch '2831-rpc-fail-to-disconnect-an-event-when-the-server-was-closed' into 'master'

Resolve "RPC: Fail to disconnect an event when the server was closed"

Closes #2831

See merge request !3818

bliss/comm/rpc.py

@@ -613,6 +613,9 @@ class RpcConnection:
     def _call__(self, code, args, kwargs, retry_on_disconnect=True):
         log_debug(self, f"rpc client ({self._address}): '{code}' args={args}")
 
+        if self._socket is None:
+            self.connect()
+
         # Check if already return a sub client
         method_name = args[0] if args else ""
         value = self._subclient.get((code, method_name))
@@ -719,7 +722,7 @@ class Client(proxy.Proxy):
         rpc_connection = RpcConnection(address, disconnect_callback, timeout)
         object.__setattr__(self, "_rpc_connection", rpc_connection)
         object.__setattr__(self, "_Client__class", None)
-        super().__init__(lambda: rpc_connection._proxy)
+        super().__init__(lambda: rpc_connection._proxy, init_once=True)
 
     @property
     def __class__(self):

tests/comm/test_rpc.py

@@ -435,3 +435,35 @@ def test_nonexisting_host(beacon):
                 raise CommunicationError(str(eee)) from eee
 
     client._rpc_connection.close()
+
+
+def test_disconnect_event_with_closed_server():
+
+    url = "tcp://127.0.0.1:12345"
+    results = gevent.queue.Queue()
+
+    def callback(*args):
+        results.put(args)
+
+    with rpc_server(url) as (server, car):
+        client_car = Client(url)
+        client_car._rpc_connection.connect()
+
+        event.connect(client_car, "test", callback)
+        event.send(car, "test", 3)
+        assert results.get() == (3,)
+
+    gevent.sleep(0.4)
+    event.disconnect(client_car, "test", callback)
+
+    with rpc_server(url) as (server, car):
+        # Synchronize
+        client_car.position
+
+        event.send(car, "test", 4)
+        # the previous event should not update 'results' since
+        # the event is disconnected
+        assert len(results) == 0
+
+    # close client
+    client_car._rpc_connection.close()