Revert "Load resources using Resource.load_all_from_stack()"

This reverts commit 570e69b7ab.

We are seeing issues with missing heat data obtained from
the Heat CFN API in TripleO.

Change-Id: Ideea039e51ae7fb3350ee1f35706adce8847de64
Closes-bug: #1331720

heat/engine/parser.py

@@ -89,6 +89,7 @@ class Stack(collections.Mapping):
         self._resources = None
         self._dependencies = None
         self._access_allowed_handlers = {}
+        self._db_resources = None
         self.adopt_stack_data = adopt_stack_data
         self.stack_user_project_id = stack_user_project_id
         self.created_time = created_time
@@ -131,13 +132,25 @@ class Stack(collections.Mapping):
     @property
     def resources(self):
         if self._resources is None:
-            definitions = self.t.resource_definitions(self)
-            rsrcs = resource.Resource.load_all_from_stack(self.context,
-                                                          self,
-                                                          definitions)
-            self._resources = dict((res.name, res) for res in rsrcs)
+            self._resources = dict((name, resource.Resource(name, data, self))
+                                   for (name, data) in
+                                   self.t.resource_definitions(self).items())
+            # There is no need to continue storing the db resources
+            # after resource creation
+            self._db_resources = None
         return self._resources
 
+    def db_resource_get(self, name):
+        if not self.id:
+            return None
+        if self._db_resources is None:
+            try:
+                self._db_resources = db_api.resource_get_all_by_stack(
+                    self.context, self.id)
+            except exception.NotFound:
+                return None
+        return self._db_resources.get(name)
+
     @property
     def dependencies(self):
         if self._dependencies is None:

heat/engine/resource.py

@@ -133,45 +133,6 @@ class Resource(object):
 
         return super(Resource, cls).__new__(ResourceClass)
 
-    @classmethod
-    def load(cls, context, name, definition, stack):
-        '''
-        Create a resource and load any associated state from the DB.
-
-        Note that this is really inefficient if you have to do it for a group
-        of resources. Use Resource.load_all_from_stack() where possible
-        instead.
-        '''
-        resource = cls(name, definition, stack)
-        if stack.id is not None:
-            db_res = db_api.resource_get_by_name_and_stack(context, name,
-                                                           stack.id)
-            if db_res is not None:
-                resource._load_data(db_res)
-        return resource
-
-    @staticmethod
-    def load_all_from_stack(context, stack, definitions):
-        '''
-        Return an iterator over all Resources in a stack.
-
-        Resources are created from the provided definitions, and any associated
-        state loaded from the DB.
-        '''
-        db_resources = {}
-        if stack.id is not None:
-            try:
-                db_resources = db_api.resource_get_all_by_stack(context,
-                                                                stack.id)
-            except exception.NotFound:
-                pass
-
-        for name, definition in definitions.items():
-            resource = Resource(name, definition, stack)
-            if name in db_resources:
-                resource._load_data(db_resources[name])
-            yield resource
-
     def __init__(self, name, definition, stack):
         if '/' in name:
             raise ValueError(_('Resource name may not contain "/"'))
@@ -201,6 +162,10 @@ class Resource(object):
         self.created_time = None
         self.updated_time = None
 
+        resource = stack.db_resource_get(name)
+        if resource:
+            self._load_data(resource)
+
     def _load_data(self, resource):
         '''Load the resource state from its DB representation.'''
         self.resource_id = resource.nova_instance

heat/tests/test_server.py

@@ -599,9 +599,8 @@ class ServersTest(HeatTestCase):
         }, server.metadata_get())
 
         resource_defns = tmpl.resource_definitions(stack)
-        created_server = servers.Server.load(stack.context, 'WebServer',
-                                             resource_defns['WebServer'],
-                                             stack)
+        created_server = servers.Server('WebServer',
+                                        resource_defns['WebServer'], stack)
         self.assertEqual('4567', created_server.access_key)
         self.assertTrue(stack.access_allowed('4567', 'WebServer'))
 
@@ -667,9 +666,8 @@ class ServersTest(HeatTestCase):
         }, server.metadata_get())
 
         resource_defns = tmpl.resource_definitions(stack)
-        created_server = servers.Server.load(stack.context, 'WebServer',
-                                             resource_defns['WebServer'],
-                                             stack)
+        created_server = servers.Server('WebServer',
+                                        resource_defns['WebServer'], stack)
         self.assertEqual('1234', created_server._get_user_id())
         self.assertTrue(stack.access_allowed('1234', 'WebServer'))