Ensures API v2 router does not load plugin twice

Fixes bug 1020024

The router will simply use the QuantumManager which stores the instance
of the plugin being used by the Quantum server. Changes to unit tests
are for ensuring plugin instances are recycled across tests.

Change-Id: I339a40ee6fef74d938245e9c50c7ed695d866e3b

quantum/api/v2/router.py

@@ -125,9 +125,7 @@ class APIRouter(wsgi.Router):
 
     def __init__(self, **local_config):
         mapper = routes_mapper.Mapper()
-        plugin_provider = cfg.CONF.core_plugin
-        LOG.debug("Plugin location:%s", plugin_provider)
-        plugin = manager.get_plugin(plugin_provider)
+        plugin = manager.QuantumManager.get_plugin()
 
         col_kwargs = dict(collection_actions=COLLECTION_ACTIONS,
                           member_actions=MEMBER_ACTIONS)

quantum/manager.py

@@ -33,19 +33,6 @@ from quantum.openstack.common import importutils
 LOG = logging.getLogger(__name__)
 
 
-def get_plugin(plugin_provider):
-    # If the plugin can't be found let them know gracefully
-    try:
-        LOG.info("Loading Plugin: %s" % plugin_provider)
-        plugin_klass = importutils.import_class(plugin_provider)
-    except ClassNotFound:
-        LOG.exception("Error loading plugin")
-        raise Exception("Plugin not found.  You can install a "
-                        "plugin with: pip install <plugin-name>\n"
-                        "Example: pip install quantum-sample-plugin")
-    return plugin_klass()
-
-
 class QuantumManager(object):
 
     _instance = None
@@ -61,7 +48,16 @@ class QuantumManager(object):
         #                for performance metrics.
         plugin_provider = cfg.CONF.core_plugin
         LOG.debug("Plugin location:%s", plugin_provider)
-        self.plugin = get_plugin(plugin_provider)
+        # If the plugin can't be found let them know gracefully
+        try:
+            LOG.info("Loading Plugin: %s" % plugin_provider)
+            plugin_klass = importutils.import_class(plugin_provider)
+        except ClassNotFound:
+            LOG.exception("Error loading plugin")
+            raise Exception("Plugin not found.  You can install a "
+                            "plugin with: pip install <plugin-name>\n"
+                            "Example: pip install quantum-sample-plugin")
+        self.plugin = plugin_klass()
 
     @classmethod
     def get_plugin(cls):

quantum/tests/unit/test_api_v2.py

@@ -28,6 +28,7 @@ from quantum.api.v2 import views
 from quantum.common import config
 from quantum.common import exceptions as q_exc
 from quantum import context
+from quantum.manager import QuantumManager
 from quantum.openstack.common import cfg
 
 
@@ -133,6 +134,8 @@ class APIv2TestCase(unittest.TestCase):
     #                will get around this.
     def setUp(self):
         plugin = 'quantum.quantum_plugin_base_v2.QuantumPluginBaseV2'
+        # Ensure 'stale' patched copies of the plugin are never returned
+        QuantumManager._instance = None
         # Create the default configurations
         args = ['--config-file', etcdir('quantum.conf.test')]
         config.parse(args=args)

quantum/tests/unit/test_db_plugin.py

@@ -27,6 +27,7 @@ from quantum.common import config
 from quantum.common import exceptions as q_exc
 from quantum import context
 from quantum.db import api as db
+from quantum.manager import QuantumManager
 from quantum.openstack.common import cfg
 from quantum.tests.unit.testlib_api import create_request
 from quantum.wsgi import Serializer, JSONDeserializer
@@ -50,6 +51,8 @@ class QuantumDbPluginV2TestCase(unittest2.TestCase):
         #                doesn't like when the plugin changes ;)
         db._ENGINE = None
         db._MAKER = None
+        # Make sure at each test a new instance of the plugin is returned
+        QuantumManager._instance = None
 
         self._tenant_id = 'test-tenant'