From fc6d71284086e0f78ef89ed15d187afe363becca Mon Sep 17 00:00:00 2001
From: Nikolay Mahotkin <nmakhotkin@mirantis.com>
Date: Thu, 25 Jun 2015 17:28:36 +0300
Subject: [PATCH] Make RPC implementation configurable

Partially implements blueprint mistral-alternative-rpc

Co-Authored-By: Dawid Deja <dawid.deja@intel.com>
Change-Id: I7308e75625e108b5b1395b6cfa6dc1d6321fe253
---
 mistral/cmd/launch.py     |  1 -
 mistral/config.py         |  9 +++++++++
 mistral/engine/rpc/rpc.py | 29 +++++++++++++++++++++++++++++
 setup.cfg                 |  6 ++++++
 4 files changed, 44 insertions(+), 1 deletion(-)

diff --git a/mistral/cmd/launch.py b/mistral/cmd/launch.py
index 7b5198e80..204f6c833 100644
--- a/mistral/cmd/launch.py
+++ b/mistral/cmd/launch.py
@@ -231,7 +231,6 @@ def get_properly_ordered_parameters():
 def main():
     try:
         config.parse_args(get_properly_ordered_parameters())
-
         print_server_info()
 
         logging.setup(CONF, 'Mistral')
diff --git a/mistral/config.py b/mistral/config.py
index d9125054e..b945d74fa 100644
--- a/mistral/config.py
+++ b/mistral/config.py
@@ -46,6 +46,13 @@ api_opts = [
     )
 ]
 
+rpc_impl_opt = cfg.StrOpt(
+    'rpc_implementation',
+    default='oslo',
+    choices=['oslo', 'kombu'],
+    help='Specifies RPC implementation for RPC client and server.'
+)
+
 pecan_opts = [
     cfg.StrOpt(
         'root',
@@ -188,6 +195,7 @@ CONF.register_opts(execution_expiration_policy_opts,
 CONF.register_opt(wf_trace_log_name_opt)
 CONF.register_opts(coordination_opts, group=COORDINATION_GROUP)
 CONF.register_opts(profiler_opts, group=PROFILER_GROUP)
+CONF.register_opt(rpc_impl_opt)
 
 
 CLI_OPTS = [
@@ -224,6 +232,7 @@ def list_opts():
             CLI_OPTS,
             [
                 wf_trace_log_name_opt,
+                rpc_impl_opt
             ]
         ))
     ]
diff --git a/mistral/engine/rpc/rpc.py b/mistral/engine/rpc/rpc.py
index a154ec571..1dbf55adc 100644
--- a/mistral/engine/rpc/rpc.py
+++ b/mistral/engine/rpc/rpc.py
@@ -19,6 +19,7 @@ import oslo_messaging as messaging
 from oslo_messaging.rpc import client
 from oslo_messaging.rpc import dispatcher
 from oslo_messaging.rpc import server
+from stevedore import driver
 
 from mistral import context as auth_ctx
 from mistral.engine import base
@@ -29,6 +30,8 @@ from mistral.workflow import utils as wf_utils
 LOG = logging.getLogger(__name__)
 
 
+_IMPL_CLIENT = None
+_IMPL_SERVER = None
 _TRANSPORT = None
 
 _ENGINE_CLIENT = None
@@ -84,6 +87,32 @@ def get_executor_client():
     return _EXECUTOR_CLIENT
 
 
+def get_rpc_server_driver():
+    rpc_impl = cfg.CONF.rpc_implementation
+
+    global _IMPL_SERVER
+    if not _IMPL_SERVER:
+        _IMPL_SERVER = driver.DriverManager(
+            'mistral.engine.rpc',
+            '%s_server' % rpc_impl
+        ).driver
+
+    return _IMPL_SERVER
+
+
+def get_rpc_client_driver():
+    rpc_impl = cfg.CONF.rpc_implementation
+
+    global _IMPL_CLIENT
+    if not _IMPL_CLIENT:
+        _IMPL_CLIENT = driver.DriverManager(
+            'mistral.engine.rpc',
+            '%s_client' % rpc_impl
+        ).driver
+
+    return _IMPL_CLIENT
+
+
 class EngineServer(object):
     """RPC Engine server."""
 
diff --git a/setup.cfg b/setup.cfg
index 5ce69d80e..9840eb9b2 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -40,6 +40,12 @@ console_scripts =
     mistral-server = mistral.cmd.launch:main
     mistral-db-manage = mistral.db.sqlalchemy.migration.cli:main
 
+mistral.engine.rpc =
+    oslo_client = mistral.engine.rpc.oslo.oslo_client:OsloRPCClient
+    oslo_server = mistral.engine.rpc.oslo.oslo_server:OsloRPCServer
+    kombu_client = mistral.engine.rpc.kombu.kombu_client:KombuRPCClient
+    kombu_server = mistral.engine.rpc.kombu.kombu_server:KombuRPCServer
+
 oslo.config.opts =
     mistral.config = mistral.config:list_opts