Pull resource extensions into APIRouter

First step in refactoring extensions to do away with the extensions
middleware, which is needed to get rid of the lazy serialization
middleware.  Converts ExtensionManager into a singleton to inhibit
double-loading of extensions.

Change-Id: Ia561d601df1a8c72c734c9426270268c1be13c3e

nova/api/openstack/v2/__init__.py

@@ -26,6 +26,7 @@
 
 from nova.api.openstack.v2 import accounts
 from nova.api.openstack.v2 import consoles
+from nova.api.openstack.v2 import extensions
 from nova.api.openstack.v2 import flavors
 from nova.api.openstack.v2 import images
 from nova.api.openstack.v2 import image_metadata
@@ -101,11 +102,36 @@ def factory(cls, global_config, **local_config):
         return cls()
 
     def __init__(self, ext_mgr=None):
+        if ext_mgr is None:
+            ext_mgr = extensions.ExtensionManager()
+
         self.server_members = {}
         mapper = ProjectMapper()
         self._setup_routes(mapper)
+        self._setup_ext_routes(mapper, ext_mgr)
         super(APIRouter, self).__init__(mapper)
 
+    def _setup_ext_routes(self, mapper, ext_mgr):
+        serializer = wsgi.ResponseSerializer(
+            {'application/xml': wsgi.XMLDictSerializer()})
+        for resource in ext_mgr.get_resources():
+            LOG.debug(_('Extended resource: %s'),
+                      resource.collection)
+            if resource.serializer is None:
+                resource.serializer = serializer
+
+            kargs = dict(
+                controller=wsgi.Resource(
+                    resource.controller, resource.deserializer,
+                    resource.serializer),
+                collection=resource.collection_actions,
+                member=resource.member_actions)
+
+            if resource.parent:
+                kargs['parent_resource'] = resource.parent
+
+            mapper.resource(resource.collection, resource.collection, **kargs)
+
     def _setup_routes(self, mapper):
         server_members = self.server_members
         server_members['action'] = 'POST'

nova/api/openstack/v2/extensions.py

@@ -293,27 +293,6 @@ def __init__(self, application, ext_mgr=None):
 
         mapper = nova.api.openstack.v2.ProjectMapper()
 
-        serializer = wsgi.ResponseSerializer(
-            {'application/xml': wsgi.XMLDictSerializer()})
-        # extended resources
-        for resource in ext_mgr.get_resources():
-            LOG.debug(_('Extended resource: %s'),
-                        resource.collection)
-            if resource.serializer is None:
-                resource.serializer = serializer
-
-            kargs = dict(
-                controller=wsgi.Resource(
-                    resource.controller, resource.deserializer,
-                    resource.serializer),
-                collection=resource.collection_actions,
-                member=resource.member_actions)
-
-            if resource.parent:
-                kargs['parent_resource'] = resource.parent
-
-            mapper.resource(resource.collection, resource.collection, **kargs)
-
         # extended actions
         action_resources = self._action_ext_resources(application, ext_mgr,
                                                         mapper)
@@ -368,11 +347,22 @@ class ExtensionManager(object):
 
     """
 
-    def __init__(self):
-        LOG.audit(_('Initializing extension manager.'))
+    _ext_mgr = None
+
+    @classmethod
+    def reset(cls):
+        cls._ext_mgr = None
+
+    def __new__(cls):
+        if cls._ext_mgr is None:
+            LOG.audit(_('Initializing extension manager.'))
+
+            cls._ext_mgr = super(ExtensionManager, cls).__new__(cls)
+
+            cls._ext_mgr.extensions = {}
+            cls._ext_mgr._load_extensions()
 
-        self.extensions = {}
-        self._load_extensions()
+        return cls._ext_mgr
 
     def register(self, ext):
         # Do nothing if the extension doesn't check out

nova/tests/api/openstack/v2/test_extensions.py

@@ -89,6 +89,7 @@ def setUp(self):
         ext_list.append('nova.tests.api.openstack.v2.extensions.'
                         'foxinsocks.Foxinsocks')
         self.flags(osapi_extension=ext_list)
+        extensions.ExtensionManager.reset()
 
 
 class ExtensionControllerTest(ExtensionTestCase):
@@ -227,7 +228,7 @@ class ResourceExtensionTest(ExtensionTestCase):
 
     def test_no_extension_present(self):
         manager = StubExtensionManager(None)
-        app = v2.APIRouter()
+        app = v2.APIRouter(manager)
         ext_midware = extensions.ExtensionMiddleware(app, manager)
         ser_midware = wsgi.LazySerializationMiddleware(ext_midware)
         request = webob.Request.blank("/blah")
@@ -238,7 +239,7 @@ def test_get_resources(self):
         res_ext = extensions.ResourceExtension('tweedles',
                                                StubController(response_body))
         manager = StubExtensionManager(res_ext)
-        app = v2.APIRouter()
+        app = v2.APIRouter(manager)
         ext_midware = extensions.ExtensionMiddleware(app, manager)
         ser_midware = wsgi.LazySerializationMiddleware(ext_midware)
         request = webob.Request.blank("/123/tweedles")
@@ -250,7 +251,7 @@ def test_get_resources_with_controller(self):
         res_ext = extensions.ResourceExtension('tweedles',
                                                StubController(response_body))
         manager = StubExtensionManager(res_ext)
-        app = v2.APIRouter()
+        app = v2.APIRouter(manager)
         ext_midware = extensions.ExtensionMiddleware(app, manager)
         ser_midware = wsgi.LazySerializationMiddleware(ext_midware)
         request = webob.Request.blank("/123/tweedles")
@@ -262,7 +263,7 @@ def test_bad_request(self):
         res_ext = extensions.ResourceExtension('tweedles',
                                                StubController(response_body))
         manager = StubExtensionManager(res_ext)
-        app = v2.APIRouter()
+        app = v2.APIRouter(manager)
         ext_midware = extensions.ExtensionMiddleware(app, manager)
         ser_midware = wsgi.LazySerializationMiddleware(ext_midware)
         request = webob.Request.blank("/123/tweedles")
@@ -283,7 +284,7 @@ def test_non_exist_resource(self):
         res_ext = extensions.ResourceExtension('tweedles',
                                                StubController(response_body))
         manager = StubExtensionManager(res_ext)
-        app = v2.APIRouter()
+        app = v2.APIRouter(manager)
         ext_midware = extensions.ExtensionMiddleware(app, manager)
         ser_midware = wsgi.LazySerializationMiddleware(ext_midware)
         request = webob.Request.blank("/123/tweedles/1")

nova/tests/integrated/test_extensions.py

@@ -17,6 +17,7 @@
 
 import os
 
+from nova.api.openstack.v2 import extensions
 from nova import flags
 from nova.log import logging
 from nova.tests.integrated import integrated_helpers
@@ -28,6 +29,8 @@
 
 class ExtensionsTest(integrated_helpers._IntegratedTestBase):
     def _get_flags(self):
+        extensions.ExtensionManager.reset()
+
         f = super(ExtensionsTest, self)._get_flags()
         f['osapi_extension'] = FLAGS.osapi_extension[:]
         f['osapi_extension'].append('nova.tests.api.openstack.v2.extensions.'