pc_rpc: fix handling of type annotations

artiq/protocols/pc_rpc.py

@@ -11,12 +11,12 @@ client passes a list as a parameter of an RPC method, and that method
 client's list.
 """
 
-import socket
 import asyncio
+import inspect
+import logging
+import socket
 import threading
 import time
-import logging
-import inspect
 from operator import itemgetter
 
 from artiq.monkey_patches import *
@@ -24,7 +24,6 @@ from artiq.protocols import pyon
 from artiq.protocols.asyncio_server import AsyncioServer as _AsyncioServer
 from artiq.protocols.packed_exceptions import *
 
-
 logger = logging.getLogger(__name__)
 
 
@@ -487,6 +486,27 @@ class Server(_AsyncioServer):
         else:
             self._noparallel = asyncio.Lock()
 
+    @staticmethod
+    def _document_function(function):
+        """
+        Turn a function into a tuple of its arguments and documentation.
+        
+        Allows remote inspection of what methods are available on a local device.
+        
+        Args:
+            function (Callable): a Python function to be documented.
+        
+        Returns:
+            Tuple[dict, str]: tuple of (argument specifications, 
+            function documentation).
+            Any type annotations are converted to strings (for PYON serialization).
+        """
+        argspec_dict = dict(inspect.getfullargspec(function)._asdict())
+        # Fix issue #1186: PYON can't serialize type annotations.
+        if any(argspec_dict.get("annotations", {})):
+            argspec_dict["annotations"] = str(argspec_dict["annotations"])
+        return argspec_dict, inspect.getdoc(function)
+
     async def _process_action(self, target, obj):
         if self._noparallel is not None:
             await self._noparallel.acquire()
@@ -501,9 +521,7 @@ class Server(_AsyncioServer):
                     if name.startswith("_"):
                         continue
                     method = getattr(target, name)
-                    argspec = inspect.getfullargspec(method)
-                    doc["methods"][name] = (dict(argspec._asdict()),
-                                            inspect.getdoc(method))
+                    doc["methods"][name] = self._document_function(method)
                 if self.builtin_terminate:
                     doc["methods"]["terminate"] = (
                         {
@@ -515,6 +533,7 @@ class Server(_AsyncioServer):
                             "kwonlydefaults": [],
                         },
                         "Terminate the server.")
+                logger.debug("RPC docs for %s: %s", target, doc)
                 return {"status": "ok", "ret": doc}
             elif obj["action"] == "call":
                 logger.debug("calling %s", _PrettyPrintCall(obj))

artiq/test/test_pc_rpc.py

@@ -1,13 +1,13 @@
-import unittest
-import sys
-import subprocess
 import asyncio
+import inspect
+import subprocess
+import sys
 import time
+import unittest
 
 import numpy as np
 
-from artiq.protocols import pc_rpc, fire_and_forget
-
+from artiq.protocols import fire_and_forget, pc_rpc, pyon
 
 test_address = "::1"
 test_port = 7777
@@ -92,6 +92,38 @@ class RPCCase(unittest.TestCase):
     def test_asyncio_echo_autotarget(self):
         self._run_server_and_test(self._loop_asyncio_echo, pc_rpc.AutoTarget)
 
+    def test_rpc_encode_function(self):
+        """Test that `pc_rpc` can encode a function properly.
+
+        Used in `get_rpc_method_list` part of
+        :meth:`artiq.protocols.pc_rpc.Server._process_action`
+        """
+
+        def _annotated_function(
+            arg1: str, arg2: np.ndarray = np.array([1, 2])
+        ) -> np.ndarray:
+            """Sample docstring."""
+            return arg1
+
+        argspec_documented, docstring = pc_rpc.Server._document_function(
+            _annotated_function
+        )
+        print(argspec_documented)
+        self.assertEqual(docstring, "Sample docstring.")
+
+        # purposefully ignore how argspec["annotations"] is treated.
+        # allows option to change PYON later to encode annotations.
+        argspec_master = dict(inspect.getfullargspec(_annotated_function)._asdict())
+        argspec_without_annotation = argspec_master.copy()
+        del argspec_without_annotation["annotations"]
+        # check if all items (excluding annotations) are same in both dictionaries
+        self.assertLessEqual(
+            argspec_without_annotation.items(), argspec_documented.items()
+        )
+        self.assertDictEqual(
+            argspec_documented, pyon.decode(pyon.encode(argspec_documented))
+        )
+
 
 class FireAndForgetCase(unittest.TestCase):
     def _set_ok(self):
@@ -130,5 +162,6 @@ def run_server():
     finally:
         loop.close()
 
+
 if __name__ == "__main__":
     run_server()