Make the saving cfn-signaling more reliable

1) The metadata saved in manager.py was not always showing up
   in the db (from wait_condition.py)
2) Reuse a little method in parser.py to retrieve the parsed_template
   db entry (and store the parsed_template_id).

Change-Id: Ib5b5474b81c0b7439eb1fa4aec5a0f1f21bbde1c
Signed-off-by: Angus Salkeld <asalkeld@redhat.com>

heat/engine/manager.py

@@ -509,8 +509,7 @@ class EngineManager(manager.Manager):
         # There's probably an idiomatic way I'm missing right now.
         t = deepcopy(pt.template)
         t['Resources'][resource_id]['Metadata'] = metadata
-        pt.template = t
-        pt.save()
+        pt.update_and_save({'template': t})
         return [None, metadata]
 
     @manager.periodic_task

heat/engine/parser.py

@@ -147,19 +147,27 @@ class Stack(object):
             response['ValidateTemplateResult']['Parameters'].append(res)
         return response
 
+    def parsed_template_get(self):
+        stack = None
+        if self.parsed_template_id == 0:
+            if self.id == 0:
+                stack = db_api.stack_get(self.context, self.id)
+            else:
+                stack = db_api.stack_get_by_name(self.context, self.name)
+
+            if stack is None:
+                return None
+
+            self.parsed_template_id = stack.raw_template.parsed_template.id
+        return db_api.parsed_template_get(self.context,
+                                          self.parsed_template_id)
+
     def update_parsed_template(self):
         '''
         Update the parsed template after each resource has been
         created, so commands like describe will work.
         '''
-        if self.parsed_template_id == 0:
-            stack = db_api.stack_get(self.context, self.id)
-            if stack:
-                self.parsed_template_id = stack.raw_template.parsed_template.id
-            else:
-                return
-
-        pt = db_api.parsed_template_get(self.context, self.parsed_template_id)
+        pt = self.parsed_template_get()
         if pt:
             template = self.t.copy()
             template['Resources'] = dict((k, r.parsed_template())

heat/engine/wait_condition.py

@@ -78,16 +78,14 @@ class WaitCondition(Resource):
         try:
             while status == 'WAITING':
                 pt = None
-                if self.stack.parsed_template_id:
-                    try:
-                        pt = db_api.parsed_template_get(self.stack.context,
-                                             self.stack.parsed_template_id)
-                    except Exception as ex:
-                        if 'not found' in ex:
-                            # it has been deleted
-                            status = 'DELETED'
-                        else:
-                            pass
+                try:
+                    pt = self.stack.parsed_template_get()
+                except Exception as ex:
+                    if 'not found' in ex:
+                        # it has been deleted
+                        status = 'DELETED'
+                    else:
+                        pass
 
                 if pt:
                     res = pt.template['Resources'][self.resource_id]