use payloads for SEGMENT BEFORE_DELETE callbacks

This patch switches over to the payload style of callbacks for SEGMENT
BEFORE_DELETE events. It does so by using the publish callback function
with DBEventPayload payloads. Corresponding listener callbacks are
updated where necessary.

NeutronLibImpact

Change-Id: I64031129ad458d4468a316a9385288ced091d333

neutron/plugins/ml2/db.py

@@ -333,23 +333,23 @@ def is_dhcp_active_on_any_subnet(context, subnet_ids):
 
 
 def _prevent_segment_delete_with_port_bound(resource, event, trigger,
-                                            context, segment,
-                                            for_net_delete=False):
+                                            payload=None):
     """Raise exception if there are any ports bound with segment_id."""
-    if for_net_delete:
+    if payload.metadata.get('for_net_delete'):
         # don't check for network deletes
         return
 
-    with db_api.CONTEXT_READER.using(context):
+    with db_api.CONTEXT_READER.using(payload.context):
         port_ids = port_obj.Port.get_port_ids_filter_by_segment_id(
-            context, segment_id=segment['id'])
+            payload.context, segment_id=payload.resource_id)
 
     # There are still some ports in the segment, segment should not be deleted
     # TODO(xiaohhui): Should we delete the dhcp port automatically here?
     if port_ids:
         reason = _("The segment is still bound with port(s) "
                    "%s") % ", ".join(port_ids)
-        raise seg_exc.SegmentInUse(segment_id=segment['id'], reason=reason)
+        raise seg_exc.SegmentInUse(segment_id=payload.resource_id,
+                                   reason=reason)
 
 
 def subscribe():

neutron/services/segments/db.py

@@ -165,9 +165,13 @@ class SegmentDbMixin(common_db_mixin.CommonDbMixin):
         """Delete an existing segment."""
         segment_dict = self.get_segment(context, uuid)
         # Do some preliminary operations before deleting the segment
-        registry.notify(resources.SEGMENT, events.BEFORE_DELETE,
-                        self.delete_segment, context=context,
-                        segment=segment_dict, for_net_delete=for_net_delete)
+        registry.publish(resources.SEGMENT, events.BEFORE_DELETE,
+                         self.delete_segment,
+                         payload=events.DBEventPayload(
+                             context, metadata={
+                                 'for_net_delete': for_net_delete},
+                             states=(segment_dict,),
+                             resource_id=uuid))
 
         # Delete segment in DB
         with db_api.CONTEXT_WRITER.using(context):

neutron/services/segments/plugin.py

@@ -110,14 +110,13 @@ class Plugin(db.SegmentDbMixin, segment.SegmentPluginBase):
 
     @registry.receives(resources.SEGMENT, [events.BEFORE_DELETE])
     def _prevent_segment_delete_with_subnet_associated(
-            self, resource, event, trigger, context, segment,
-            for_net_delete=False):
+            self, resource, event, trigger, payload=None):
         """Raise exception if there are any subnets associated with segment."""
-        if for_net_delete:
+        if payload.metadata.get('for_net_delete'):
             # don't check if this is a part of a network delete operation
             return
-        segment_id = segment['id']
-        subnets = subnet_obj.Subnet.get_objects(context,
+        segment_id = payload.resource_id
+        subnets = subnet_obj.Subnet.get_objects(payload.context,
                                                 segment_id=segment_id)
         subnet_ids = [s.id for s in subnets]
 

neutron/tests/unit/plugins/ml2/test_plugin.py

@@ -3092,9 +3092,10 @@ class TestML2Segments(Ml2PluginV2TestCase):
                 segment = segments_db.get_network_segments(
                     self.context, port['port']['network_id'])[0]
                 segment['network_id'] = port['port']['network_id']
-            self.assertRaises(c_exc.CallbackFailure, registry.notify,
+            self.assertRaises(c_exc.CallbackFailure, registry.publish,
                               resources.SEGMENT, events.BEFORE_DELETE,
-                              mock.ANY,
-                              context=self.context, segment=segment)
+                              mock.ANY, payload=events.DBEventPayload(
+                                  self.context, states=(segment,),
+                                  resource_id=segment['id']))
             exist_port = self._show('ports', port['port']['id'])
             self.assertEqual(port['port']['id'], exist_port['port']['id'])