maintain list of positional arguments as tuple

Signed-off-by: fenn-cs <fenn25.fn@gmail.com>

src/allmydata/test/test_eliotutil.py

@@ -297,7 +297,7 @@ class LogCallDeferredTests(TestCase):
         self.assertThat(
             f(4), succeeded(Equals(16)))
         msg = logger.messages[0]
-        assertContainsFields(self, msg, {"args": {'arg_0': 4}})
+        assertContainsFields(self, msg, {"args": (4,)})
 
     @capture_logging(
         lambda self, logger:
@@ -328,5 +328,5 @@ class LogCallDeferredTests(TestCase):
             return base ** exp
         self.assertThat(f(10, 2, message="an exponential function"), succeeded(Equals(100)))
         msg = logger.messages[0]
-        assertContainsFields(self, msg, {"args": {'arg_0': 10, 'arg_1': 2}})
+        assertContainsFields(self, msg, {"args": (10, 2)})
         assertContainsFields(self, msg, {"kwargs": {"message": "an exponential function"}})

src/allmydata/util/eliotutil.py

@@ -335,11 +335,7 @@ def log_call_deferred(action_type):
             kwargs = {k: bytes_to_unicode(True, kw[k]) for k in kw}
             # Remove complex (unserializable) objects from positional args to
             # prevent eliot from throwing errors when it attempts serialization
-            args = {
-                "arg_" + str(pos): bytes_to_unicode(True, a[pos])
-                for pos in range(len(a))
-                if is_json_serializable(a[pos])
-            }
+            args = tuple([a[pos] for pos in range(len(a)) if is_json_serializable(a[pos])])
             with start_action(action_type=action_type, args=args, kwargs=kwargs).context():
                 # Use addActionFinish so that the action finishes when the
                 # Deferred fires.