Refactor RPC serialization: remove JsonPayloadSerializer class

* This class is not needed in Mistral, we can use the exact same
  class from oslo.messaging
* Changed RpcContextSerializer to use JsonPayloadSerializer by
  default so that we don't have to pass it as a parameter
  every time

Change-Id: Ic4ad92cb732c33e6d1971b50076afde219147536

mistral/context.py

@@ -19,6 +19,7 @@ from keystoneclient.v3 import client as keystone_client
 import logging
 from oslo_config import cfg
 import oslo_messaging as messaging
+from oslo_messaging import serializer as messaging_serializer
 from oslo_serialization import jsonutils
 from osprofiler import profiler
 import pecan
@@ -225,15 +226,9 @@ def context_from_config():
     )
 
 
-class JsonPayloadSerializer(messaging.NoOpSerializer):
-    @staticmethod
-    def serialize_entity(context, entity):
-        return jsonutils.to_primitive(entity, convert_instances=True)
-
-
 class RpcContextSerializer(messaging.Serializer):
     def __init__(self, base=None):
-        self._base = base or messaging.NoOpSerializer()
+        self._base = base or messaging_serializer.JsonPayloadSerializer()
 
     def serialize_entity(self, context, entity):
         if not self._base:

mistral/engine/rpc_backend/oslo/oslo_client.py

@@ -24,8 +24,7 @@ class OsloRPCClient(rpc_base.RPCClient):
         super(OsloRPCClient, self).__init__(conf)
         self.topic = conf.topic
 
-        serializer = auth_ctx.RpcContextSerializer(
-            auth_ctx.JsonPayloadSerializer())
+        serializer = auth_ctx.RpcContextSerializer()
 
         self._client = messaging.RPCClient(
             rpc.get_transport(),

mistral/engine/rpc_backend/oslo/oslo_server.py

@@ -52,7 +52,7 @@ class OsloRPCServer(rpc_base.RPCServer):
             target,
             self.endpoints,
             executor=executor,
-            serializer=ctx.RpcContextSerializer(ctx.JsonPayloadSerializer())
+            serializer=ctx.RpcContextSerializer()
         )
 
         self.oslo_server.start()

mistral/services/scheduler.py

@@ -58,9 +58,7 @@ def schedule_call(factory_method_path, target_method_name,
         delayed calls.
     :param method_args: Target method keyword arguments.
     """
-    ctx_serializer = context.RpcContextSerializer(
-        context.JsonPayloadSerializer()
-    )
+    ctx_serializer = context.RpcContextSerializer()
 
     ctx = (
         ctx_serializer.serialize_context(context.ctx())
@@ -167,9 +165,7 @@ class CallScheduler(periodic_task.PeriodicTasks):
                 (target_auth_context, target_method, method_args)
             )
 
-        ctx_serializer = context.RpcContextSerializer(
-            context.JsonPayloadSerializer()
-        )
+        ctx_serializer = context.RpcContextSerializer()
 
         for (target_auth_context, target_method, method_args) in delayed_calls:
             try:

mistral/tests/unit/engine/test_profiler.py

@@ -40,9 +40,7 @@ class EngineProfilerTest(base.EngineTestCase):
         self.mock_profiler_log_func = mock.Mock(return_value=None)
         osprofiler.notifier.set(self.mock_profiler_log_func)
 
-        self.ctx_serializer = context.RpcContextSerializer(
-            context.JsonPayloadSerializer()
-        )
+        self.ctx_serializer = context.RpcContextSerializer()
 
     def test_profile_trace(self):
         wf_def = """