Merge "placement: Perform build list of standard classes once"

nova/db/sqlalchemy/resource_class_cache.py

@@ -57,6 +57,11 @@ def _refresh_from_db(ctx, cache):
 class ResourceClassCache(object):
     """A cache of integer and string lookup values for resource classes."""
 
+    # List of dict of all standard resource classes, where every list item
+    # have a form {'id': <ID>, 'name': <NAME>}
+    STANDARDS = [{'id': fields.ResourceClass.STANDARD.index(s), 'name': s}
+                 for s in fields.ResourceClass.STANDARD]
+
     def __init__(self, ctx):
         """Initialize the cache of resource class identifiers.
 
@@ -72,13 +77,6 @@ class ResourceClassCache(object):
             self.id_cache = {}
             self.str_cache = {}
 
-    def get_standards(self):
-        """Return a list of {'id': <ID>, 'name': <NAME> for all standard
-        resource classes.
-        """
-        return [{'id': fields.ResourceClass.STANDARD.index(s), 'name': s}
-                for s in fields.ResourceClass.STANDARD]
-
     def id_from_string(self, rc_str):
         """Given a string representation of a resource class -- e.g. "DISK_GB"
         or "IRON_SILVER" -- return the integer code for the resource class. For

nova/objects/resource_provider.py

@@ -1222,8 +1222,7 @@ class ResourceClass(base.NovaObject):
         # Never delete any standard resource class, since the standard resource
         # classes don't even exist in the database table anyway.
         _ensure_rc_cache(self._context)
-        standards = _RC_CACHE.get_standards()
+        if self.id in (rc['id'] for rc in _RC_CACHE.STANDARDS):
-        if self.id in (rc['id'] for rc in standards):
             raise exception.ResourceClassCannotDeleteStandard(
                     resource_class=self.name)
 
@@ -1253,8 +1252,7 @@ class ResourceClass(base.NovaObject):
         # Never update any standard resource class, since the standard resource
         # classes don't even exist in the database table anyway.
         _ensure_rc_cache(self._context)
-        standards = _RC_CACHE.get_standards()
+        if self.id in (rc['id'] for rc in _RC_CACHE.STANDARDS):
-        if self.id in (rc['id'] for rc in standards):
             raise exception.ResourceClassCannotUpdateStandard(
                     resource_class=self.name)
         self._save(self._context, self.id, self.name, updates)
@@ -1285,9 +1283,8 @@ class ResourceClassList(base.ObjectListBase, base.NovaObject):
     @db_api.api_context_manager.reader
     def _get_all(context):
         _ensure_rc_cache(context)
-        standards = _RC_CACHE.get_standards()
         customs = list(context.session.query(models.ResourceClass).all())
-        return standards + customs
+        return _RC_CACHE.STANDARDS + customs
 
     @base.remotable_classmethod
     def get_all(cls, context):

nova/tests/functional/db/test_resource_class_cache.py

@@ -44,14 +44,19 @@ class TestResourceClassCache(test.TestCase):
 
         self.assertFalse(sel_mock.called)
 
-    def test_get_standards(self):
+    def test_standards(self):
         cache = rc_cache.ResourceClassCache(self.context)
-        standards = cache.get_standards()
+        standards = cache.STANDARDS
+
         self.assertEqual(len(standards), len(fields.ResourceClass.STANDARD))
         names = (rc['name'] for rc in standards)
         for name in fields.ResourceClass.STANDARD:
             self.assertIn(name, names)
 
+        cache = rc_cache.ResourceClassCache(self.context)
+        standards2 = cache.STANDARDS
+        self.assertEqual(id(standards), id(standards2))
+
     def test_rc_cache_custom(self):
         """Test that non-standard, custom resource classes hit the database and
         return appropriate results, caching the results after a single