pc_rpc: raise AttributeError immediately for nonexistent RPC methods. Closes #534

RELEASE_NOTES.rst

@@ -10,6 +10,9 @@ Release notes
   ARTIQ_APPLET_EMBED. The GUI sets this enviroment variable itself and the
   user simply needs to remove the --embed argument.
 * EnvExperiment's prepare calls prepare for all its children.
+* Dynamic __getattr__'s returning RPC target methods are not supported anymore.
+  Controller driver classes must define all their methods intended for RPC as
+  members.
 
 
 2.0rc1

artiq/devices/ctlmgr.py

@@ -41,7 +41,7 @@ class Controller:
         await remote.connect_rpc(self.host, self.port, None)
         try:
             targets, _ = remote.get_rpc_id()
-            remote.select_rpc_target(targets[0])
+            await remote.select_rpc_target(targets[0])
             r = await getattr(remote, method)(*args, **kwargs)
         finally:
             remote.close_rpc()

artiq/protocols/fire_and_forget.py

@@ -1,5 +1,6 @@
 import threading
 import logging
+import inspect
 
 
 logger = logging.getLogger(__name__)
@@ -20,6 +21,9 @@ class FFProxy:
     """
     def __init__(self, target):
         self.target = target
+
+        valid_methods = inspect.getmembers(target, inspect.ismethod)
+        self._valid_methods = {m[0] for m in valid_methods}
         self._thread = None
 
     def ff_join(self):
@@ -28,6 +32,8 @@ class FFProxy:
             self._thread.join()
 
     def __getattr__(self, k):
+        if k not in self._valid_methods:
+            raise AttributeError
         def run_in_thread(*args, **kwargs):
             if self._thread is not None and self._thread.is_alive():
                 logger.warning("skipping fire-and-forget call to %r.%s as "

artiq/protocols/pc_rpc.py

@@ -94,8 +94,6 @@ class Client:
         in the middle of a RPC can break subsequent RPCs (from the same
         client).
     """
-    kernel_invariants = set()
-
     def __init__(self, host, port, target_name=AutoTarget, timeout=None):
         self.__socket = socket.create_connection((host, port), timeout)
 
@@ -106,6 +104,7 @@ class Client:
             self.__target_names = server_identification["targets"]
             self.__description = server_identification["description"]
             self.__selected_target = None
+            self.__valid_methods = set()
             if target_name is not None:
                 self.select_rpc_target(target_name)
         except:
@@ -118,6 +117,7 @@ class Client:
         target_name = _validate_target_name(target_name, self.__target_names)
         self.__socket.sendall((target_name + "\n").encode())
         self.__selected_target = target_name
+        self.__valid_methods = self.__recv()
 
     def get_selected_target(self):
         """Returns the selected target, or ``None`` if no target has been
@@ -173,6 +173,8 @@ class Client:
         return self.__do_action(obj)
 
     def __getattr__(self, name):
+        if name not in self.__valid_methods:
+            raise AttributeError
         def proxy(*args, **kwargs):
             return self.__do_rpc(name, args, kwargs)
         return proxy
@@ -187,8 +189,6 @@ class AsyncioClient:
     Concurrent access from different asyncio tasks is supported; all calls
     use a single lock.
     """
-    kernel_invariants = set()
-
     def __init__(self):
         self.__lock = asyncio.Lock()
         self.__reader = None
@@ -208,19 +208,21 @@ class AsyncioClient:
             self.__target_names = server_identification["targets"]
             self.__description = server_identification["description"]
             self.__selected_target = None
+            self.__valid_methods = set()
             if target_name is not None:
-                self.select_rpc_target(target_name)
+                await self.select_rpc_target(target_name)
         except:
             self.close_rpc()
             raise
 
-    def select_rpc_target(self, target_name):
+    async def select_rpc_target(self, target_name):
         """Selects a RPC target by name. This function should be called
         exactly once if the connection was created with ``target_name=None``.
         """
         target_name = _validate_target_name(target_name, self.__target_names)
         self.__writer.write((target_name + "\n").encode())
         self.__selected_target = target_name
+        self.__valid_methods = await self.__recv()
 
     def get_selected_target(self):
         """Returns the selected target, or ``None`` if no target has been
@@ -273,6 +275,8 @@ class AsyncioClient:
             self.__lock.release()
 
     def __getattr__(self, name):
+        if name not in self.__valid_methods:
+            raise AttributeError
         async def proxy(*args, **kwargs):
             res = await self.__do_rpc(name, args, kwargs)
             return res
@@ -292,8 +296,6 @@ class BestEffortClient:
     :param retry: Amount of time to wait between retries when reconnecting
         in the background.
     """
-    kernel_invariants = set()
-
     def __init__(self, host, port, target_name,
                  firstcon_timeout=1.0, retry=5.0):
         self.__host = host
@@ -303,6 +305,7 @@ class BestEffortClient:
 
         self.__conretry_terminate = False
         self.__socket = None
+        self.__valid_methods = set()
         try:
             self.__coninit(firstcon_timeout)
         except:
@@ -327,6 +330,7 @@ class BestEffortClient:
         target_name = _validate_target_name(self.__target_name,
                                             server_identification["targets"])
         self.__socket.sendall((target_name + "\n").encode())
+        self.__valid_methods = self.__recv()
 
     def __start_conretry(self):
         self.__conretry_thread = threading.Thread(target=self.__conretry)
@@ -401,6 +405,8 @@ class BestEffortClient:
                 raise ValueError
 
     def __getattr__(self, name):
+        if name not in self.__valid_methods:
+            raise AttributeError
         def proxy(*args, **kwargs):
             return self.__do_rpc(name, args, kwargs)
         return proxy
@@ -558,6 +564,12 @@ class Server(_AsyncioServer):
             if callable(target):
                 target = target()
 
+            valid_methods = inspect.getmembers(target, inspect.ismethod)
+            valid_methods = {m[0] for m in valid_methods}
+            if self.builtin_terminate:
+                valid_methods.add("terminate")
+            writer.write((pyon.encode(valid_methods) + "\n").encode())
+
             while True:
                 line = await reader.readline()
                 if not line:

artiq/test/test_ctlmgr.py

@@ -33,7 +33,7 @@ class ControllerCase(unittest.TestCase):
         remote = AsyncioClient()
         await remote.connect_rpc(host, port, None)
         targets, _ = remote.get_rpc_id()
-        remote.select_rpc_target(targets[0])
+        await remote.select_rpc_target(targets[0])
         self.addCleanup(remote.close_rpc)
         return remote
 

artiq/test/test_pc_rpc.py

@@ -46,7 +46,7 @@ class RPCCase(unittest.TestCase):
             test_object_back = remote.async_echo(test_object)
             self.assertEqual(test_object, test_object_back)
             with self.assertRaises(AttributeError):
-                remote.non_existing_method()
+                remote.non_existing_method
             remote.terminate()
         finally:
             remote.close_rpc()
@@ -73,7 +73,7 @@ class RPCCase(unittest.TestCase):
             test_object_back = await remote.async_echo(test_object)
             self.assertEqual(test_object, test_object_back)
             with self.assertRaises(AttributeError):
-                await remote.non_existing_method()
+                await remote.non_existing_method
             await remote.terminate()
         finally:
             remote.close_rpc()
@@ -101,6 +101,8 @@ class FireAndForgetCase(unittest.TestCase):
         self.ok = False
         p = fire_and_forget.FFProxy(self)
         p._set_ok()
+        with self.assertRaises(AttributeError):
+            p.non_existing_method
         p.ff_join()
         self.assertTrue(self.ok)