From 52102a1a79a2afc5f71e5e5ba8998d7cb4d52828 Mon Sep 17 00:00:00 2001
From: whitequark <whitequark@whitequark.org>
Date: Fri, 18 Dec 2015 18:03:07 +0800
Subject: [PATCH] Fix handling of default values for RPC arguments (fixes
 #190).

---
 artiq/coredevice/comm_generic.py   | 28 +++++++++++++++++-----------
 artiq/test/coredevice/embedding.py | 20 +++++++++++++++++++-
 2 files changed, 36 insertions(+), 12 deletions(-)

diff --git a/artiq/coredevice/comm_generic.py b/artiq/coredevice/comm_generic.py
index c5ecd4309..1d3d69f2a 100644
--- a/artiq/coredevice/comm_generic.py
+++ b/artiq/coredevice/comm_generic.py
@@ -294,6 +294,7 @@ class CommGeneric:
         logger.debug("running kernel")
 
     _rpc_sentinel = object()
+    _rpc_undefined = object()
 
     # See session.c:{send,receive}_rpc_value and llvm_ir_generator.py:_rpc_tag.
     def _receive_rpc_value(self, object_map):
@@ -331,18 +332,23 @@ class CommGeneric:
             present = self._read_int8()
             if present:
                 return self._receive_rpc_value(object_map)
+            else:
+                return self._rpc_undefined
         elif tag == "O":
             return object_map.retrieve(self._read_int32())
         else:
             raise IOError("Unknown RPC value tag: {}".format(repr(tag)))
 
-    def _receive_rpc_args(self, object_map):
+    def _receive_rpc_args(self, object_map, defaults):
         args = []
         while True:
             value = self._receive_rpc_value(object_map)
             if value is self._rpc_sentinel:
                 return args
-            args.append(value)
+            elif value is self._rpc_undefined:
+                args.append(defaults[len(args)])
+            else:
+                args.append(value)
 
     def _skip_rpc_value(self, tags):
         tag = tags.pop(0)
@@ -425,22 +431,22 @@ class CommGeneric:
             raise IOError("Unknown RPC value tag: {}".format(repr(tag)))
 
     def _serve_rpc(self, object_map):
-        service = self._read_int32()
-        args = self._receive_rpc_args(object_map)
+        service_id  = self._read_int32()
+        service     = object_map.retrieve(service_id)
+        arguments   = self._receive_rpc_args(object_map, service.__defaults__)
         return_tags = self._read_bytes()
-        logger.debug("rpc service: %d %r -> %s", service, args, return_tags)
+        logger.debug("rpc service: [%d]%r %r -> %s", service_id, service, arguments, return_tags)
 
         try:
-            result = object_map.retrieve(service)(*args)
-            logger.debug("rpc service: %d %r == %r", service, args, result)
+            result = service(*arguments)
+            logger.debug("rpc service: %d %r == %r", service_id, arguments, result)
 
             self._write_header(_H2DMsgType.RPC_REPLY)
             self._write_bytes(return_tags)
-            self._send_rpc_value(bytearray(return_tags), result, result,
-                                 object_map.retrieve(service))
+            self._send_rpc_value(bytearray(return_tags), result, result, service)
             self._write_flush()
         except core_language.ARTIQException as exn:
-            logger.debug("rpc service: %d %r ! %r", service, args, exn)
+            logger.debug("rpc service: %d %r ! %r", service_id, arguments, exn)
 
             self._write_header(_H2DMsgType.RPC_EXCEPTION)
             self._write_string(exn.name)
@@ -455,7 +461,7 @@ class CommGeneric:
 
             self._write_flush()
         except Exception as exn:
-            logger.debug("rpc service: %d %r ! %r", service, args, exn)
+            logger.debug("rpc service: %d %r ! %r", service_id, arguments, exn)
 
             self._write_header(_H2DMsgType.RPC_EXCEPTION)
             self._write_string(type(exn).__name__)
diff --git a/artiq/test/coredevice/embedding.py b/artiq/test/coredevice/embedding.py
index b80abe0c2..a5a7095ad 100644
--- a/artiq/test/coredevice/embedding.py
+++ b/artiq/test/coredevice/embedding.py
@@ -10,7 +10,6 @@ class Roundtrip(EnvExperiment):
     def roundtrip(self, obj, fn):
         fn(obj)
 
-
 class RoundtripTest(ExperimentCase):
     def assertRoundtrip(self, obj):
         exp = self.create(Roundtrip)
@@ -41,3 +40,22 @@ class RoundtripTest(ExperimentCase):
     def test_object(self):
         obj = object()
         self.assertRoundtrip(obj)
+
+
+class DefaultArg(EnvExperiment):
+    def build(self):
+        self.setattr_device("core")
+
+    def test(self, foo=42) -> TInt32:
+        return foo
+
+    @kernel
+    def run(self, callback):
+        callback(self.test())
+
+class DefaultArgTest(ExperimentCase):
+    def test_default_arg(self):
+        exp = self.create(DefaultArg)
+        def callback(value):
+            self.assertEqual(value, 42)
+        exp.run(callback)