Move notifications before DB retry decorator

This patch moves the start notifications emitted in the API
layer ('network.create.start', etc) to before the DB retry
decorator. This prevents benign retry events from resending
notifications onto the message bus.

Change-Id: I8159692a107ede397a4abeff71310a99fffa4862
Closes-Bug: #1532051
(cherry picked from commit 447f4b1461)

neutron/api/v2/base.py

@@ -401,13 +401,16 @@ class Controller(object):
                 # We need a way for ensuring that if it has been created,
                 # it is then deleted
 
-    @db_api.retry_db_errors
     def create(self, request, body=None, **kwargs):
-        """Creates a new instance of the requested entity."""
-        parent_id = kwargs.get(self._parent_id_name)
         self._notifier.info(request.context,
                             self._resource + '.create.start',
                             body)
+        return self._create(request, body, **kwargs)
+
+    @db_api.retry_db_errors
+    def _create(self, request, body, **kwargs):
+        """Creates a new instance of the requested entity."""
+        parent_id = kwargs.get(self._parent_id_name)
         body = Controller.prepare_request_body(request.context,
                                                copy.deepcopy(body), True,
                                                self._resource, self._attr_info,
@@ -519,12 +522,15 @@ class Controller(object):
                 return notify({self._resource: self._view(request.context,
                                                           obj)})
 
-    @db_api.retry_db_errors
     def delete(self, request, id, **kwargs):
         """Deletes the specified entity."""
         self._notifier.info(request.context,
                             self._resource + '.delete.start',
                             {self._resource + '_id': id})
+        return self._delete(request, id, **kwargs)
+
+    @db_api.retry_db_errors
+    def _delete(self, request, id, **kwargs):
         action = self._plugin_handlers[self.DELETE]
 
         # Check authz
@@ -557,10 +563,8 @@ class Controller(object):
                                      result,
                                      notifier_method)
 
-    @db_api.retry_db_errors
     def update(self, request, id, body=None, **kwargs):
         """Updates the specified entity's attributes."""
-        parent_id = kwargs.get(self._parent_id_name)
         try:
             payload = body.copy()
         except AttributeError:
@@ -570,6 +574,10 @@ class Controller(object):
         self._notifier.info(request.context,
                             self._resource + '.update.start',
                             payload)
+        return self._update(request, id, body, **kwargs)
+
+    @db_api.retry_db_errors
+    def _update(self, request, id, body, **kwargs):
         body = Controller.prepare_request_body(request.context, body, False,
                                                self._resource, self._attr_info,
                                                allow_bulk=self._allow_bulk)
@@ -583,6 +591,7 @@ class Controller(object):
                           'default' not in value)]
         # Ensure policy engine is initialized
         policy.init()
+        parent_id = kwargs.get(self._parent_id_name)
         orig_obj = self._item(request, id, field_list=field_list,
                               parent_id=parent_id)
         orig_object_copy = copy.copy(orig_obj)