Appease the great mypy

tractor/_actor.py

@@ -168,8 +168,8 @@ class Actor:
     is_arbiter: bool = False
 
     # nursery placeholders filled in by `_async_main()` after fork
-    _root_n: trio.Nursery = None
-    _service_n: trio.Nursery = None
+    _root_n: Optional[trio.Nursery] = None
+    _service_n: Optional[trio.Nursery] = None
     _server_n: Optional[trio.Nursery] = None
 
     # Information about `__main__` from parent
@@ -497,6 +497,7 @@ class Actor:
 
                     # spin up a task for the requested function
                     log.debug(f"Spawning task for {func}")
+                    assert self._service_n
                     cs = await self._service_n.start(
                         partial(_invoke, self, cid, chan, func, kwargs),
                         name=funcname,
@@ -551,7 +552,7 @@ class Actor:
     async def _chan_to_parent(
         self,
         parent_addr: Optional[Tuple[str, int]],
-    ) -> Channel:
+    ) -> Tuple[Channel, Optional[Tuple[str, int]]]:
         try:
             # Connect back to the parent actor and conduct initial
             # handshake. From this point on if we error, we
@@ -564,6 +565,8 @@ class Actor:
             # Initial handshake: swap names.
             await self._do_handshake(chan)
 
+            accept_addr: Optional[Tuple[str, int]] = None
+
             if self._spawn_method == "trio":
                 # Receive runtime state from our parent
                 parent_data = await chan.recv()
@@ -578,9 +581,6 @@ class Actor:
                 for attr, value in parent_data.items():
                     setattr(self, attr, value)
 
-            else:  # mp
-                accept_addr = None
-
             return chan, accept_addr
 
         except OSError:  # failed to connect
@@ -636,6 +636,7 @@ class Actor:
             # a deterministic way.
             async with trio.open_nursery() as root_nursery:
                 self._root_n = root_nursery
+                assert self._root_n
 
                 async with trio.open_nursery() as service_nursery:
                     # This nursery is used to handle all inbound
@@ -643,6 +644,7 @@ class Actor:
                     # is killed, connections can continue to process
                     # in the background until this nursery is cancelled.
                     self._service_n = service_nursery
+                    assert self._service_n
 
                     # Startup up the channel server with,
                     # - subactor: the bind address sent to us by our parent
@@ -650,6 +652,7 @@ class Actor:
                     # - root actor: the ``accept_addr`` passed to this method
                     assert accept_addr
                     host, port = accept_addr
+
                     self._server_n = await service_nursery.start(
                         partial(
                             self._serve_forever,
@@ -765,7 +768,7 @@ class Actor:
         # (host, port) to bind for channel server
         accept_host: Tuple[str, int] = None,
         accept_port: int = 0,
-        task_status: TaskStatus[None] = trio.TASK_STATUS_IGNORED,
+        task_status: TaskStatus[trio.Nursery] = trio.TASK_STATUS_IGNORED,
     ) -> None:
         """Start the channel server, begin listening for new connections.
 
@@ -794,7 +797,7 @@ class Actor:
             # signal the server is down since nursery above terminated
             self._server_down.set()
 
-    async def cancel(self) -> None:
+    async def cancel(self) -> bool:
         """Cancel this actor.
 
         The "deterministic" teardown sequence in order is:
@@ -807,9 +810,15 @@ class Actor:
         """
         # cancel all ongoing rpc tasks
         with trio.CancelScope(shield=True):
+            # kill all ongoing tasks
             await self.cancel_rpc_tasks()
+
+            # stop channel server
             self.cancel_server()
             await self._server_down.wait()
+
+            # rekt all channel loops
+            if self._service_n:
                 self._service_n.cancel_scope.cancel()
 
         return True

tractor/_portal.py

@@ -338,9 +338,9 @@ async def open_portal(
         if channel.uid is None:
             await actor._do_handshake(channel)
 
-        msg_loop_cs = None
+        msg_loop_cs: Optional[trio.CancelScope] = None
         if start_msg_loop:
-            msg_loop_cs: trio.CancelScope = await nursery.start(
+            msg_loop_cs = await nursery.start(
                 partial(
                     actor._process_messages,
                     channel,