Delete segment RPs when network is deleted

When a network is deleted, only one Placement call per segment
is done to remove the associated (if existing) resource provider.

Before this patch, each time a subnet was deleted, the segment
resource provider was updated. When no subnets were present in the
related segment, the associated resource provider was deleted.

This optimization improves the network deletion time (see Launchpad
bug). E.g.: a network with two segments and ten subnets, the Neutron
server processing time dropped from 8.2 seconds to 4.4 seconds (note
that the poor performance was due to the modest testing environment).

Along with the segment RP optimization during the network deletion,
this patch also skips the router subnet update. Because all subnets
in the network are going to be deleted, there is no need to update
them during the network deletion process.

Conflicts:
    neutron/db/db_base_plugin_v2.py

Change-Id: Ifd50027911a9ca3508e80e0de9a6cc45b67006cf
Closes-Bug: #1878916
(cherry picked from commit 7f40e626d6)
(cherry picked from commit 2614637a69)

neutron/db/db_base_plugin_v2.py

@@ -495,6 +495,10 @@ class NeutronDbPluginV2(db_base_plugin_common.DbBasePluginCommon,
             # cleanup if a network-owned port snuck in without failing
             for subnet in subnets:
                 self._delete_subnet(context, subnet)
+                # TODO(ralonsoh): use payloads
+                registry.notify(resources.SUBNET, events.AFTER_DELETE,
+                                self, context=context, subnet=subnet.to_dict(),
+                                for_net_delete=True)
             with db_api.CONTEXT_WRITER.using(context):
                 network_db = self._get_network(context, id)
                 network = self._make_network_dict(network_db, context=context)

neutron/plugins/ml2/db.py

@@ -34,6 +34,7 @@ from neutron.db import models_v2
 from neutron.objects import base as objects_base
 from neutron.objects import ports as port_obj
 from neutron.plugins.ml2 import models
+from neutron.services.segments import db as seg_db
 from neutron.services.segments import exceptions as seg_exc
 
 LOG = log.getLogger(__name__)
@@ -336,7 +337,7 @@ def is_dhcp_active_on_any_subnet(context, subnet_ids):
 def _prevent_segment_delete_with_port_bound(resource, event, trigger,
                                             payload=None):
     """Raise exception if there are any ports bound with segment_id."""
-    if payload.metadata.get('for_net_delete'):
+    if payload.metadata.get(seg_db.FOR_NET_DELETE):
         # don't check for network deletes
         return
 

neutron/services/segments/db.py

@@ -38,6 +38,7 @@ from neutron.services.segments import exceptions
 
 
 _USER_CONFIGURED_SEGMENT_PLUGIN = None
+FOR_NET_DELETE = 'for_net_delete'
 
 
 def check_user_configured_segment_plugin():
@@ -189,7 +190,7 @@ class SegmentDbMixin(object):
                          self.delete_segment,
                          payload=events.DBEventPayload(
                              context, metadata={
-                                 'for_net_delete': for_net_delete},
+                                 FOR_NET_DELETE: for_net_delete},
                              states=(segment_dict,),
                              resource_id=uuid))
 

neutron/services/segments/plugin.py

@@ -121,7 +121,7 @@ class Plugin(db.SegmentDbMixin, segment.SegmentPluginBase):
     def _prevent_segment_delete_with_subnet_associated(
             self, resource, event, trigger, payload=None):
         """Raise exception if there are any subnets associated with segment."""
-        if payload.metadata.get('for_net_delete'):
+        if payload.metadata.get(db.FOR_NET_DELETE):
             # don't check if this is a part of a network delete operation
             return
         segment_id = payload.resource_id
@@ -343,6 +343,9 @@ class NovaSegmentNotifier(object):
     @registry.receives(resources.SUBNET, [events.AFTER_DELETE])
     def _notify_subnet_deleted(self, resource, event, trigger, context,
                                subnet, **kwargs):
+        if kwargs.get(db.FOR_NET_DELETE):
+            return  # skip segment RP update if it is going to be deleted
+
         segment_id = subnet.get('segment_id')
         if not segment_id or subnet['ip_version'] != constants.IP_VERSION_4:
             return
@@ -359,23 +362,32 @@ class NovaSegmentNotifier(object):
                     self._delete_nova_inventory, segment_id))
 
     def _get_aggregate_id(self, segment_id):
-        aggregate_uuid = self.p_client.list_aggregates(
-            segment_id)['aggregates'][0]
-        aggregates = self.n_client.aggregates.list()
-        for aggregate in aggregates:
+        try:
+            aggregate_uuid = self.p_client.list_aggregates(
+                segment_id)['aggregates'][0]
+        except placement_exc.PlacementAggregateNotFound:
+            LOG.info('Segment %s resource provider aggregate not found',
+                     segment_id)
+            return
+
+        for aggregate in self.n_client.aggregates.list():
             nc_aggregate_uuid = self._get_nova_aggregate_uuid(aggregate)
             if nc_aggregate_uuid == aggregate_uuid:
                 return aggregate.id
 
     def _delete_nova_inventory(self, event):
         aggregate_id = self._get_aggregate_id(event.segment_id)
-        aggregate = self.n_client.aggregates.get_details(
-            aggregate_id)
-        for host in aggregate.hosts:
-            self.n_client.aggregates.remove_host(aggregate_id,
-                                                 host)
-        self.n_client.aggregates.delete(aggregate_id)
-        self.p_client.delete_resource_provider(event.segment_id)
+        if aggregate_id:
+            aggregate = self.n_client.aggregates.get_details(aggregate_id)
+            for host in aggregate.hosts:
+                self.n_client.aggregates.remove_host(aggregate_id, host)
+            self.n_client.aggregates.delete(aggregate_id)
+
+        try:
+            self.p_client.delete_resource_provider(event.segment_id)
+        except placement_exc.PlacementClientError as exc:
+            LOG.info('Segment %s resource provider not found; error: %s',
+                     event.segment_id, str(exc))
 
     @registry.receives(resources.SEGMENT_HOST_MAPPING, [events.AFTER_CREATE])
     def _notify_host_addition_to_aggregate(self, resource, event, trigger,
@@ -390,9 +402,8 @@ class NovaSegmentNotifier(object):
 
     def _add_host_to_aggregate(self, event):
         for segment_id in event.segment_ids:
-            try:
-                aggregate_id = self._get_aggregate_id(segment_id)
-            except placement_exc.PlacementAggregateNotFound:
+            aggregate_id = self._get_aggregate_id(segment_id)
+            if not aggregate_id:
                 LOG.info('When adding host %(host)s, aggregate not found '
                          'for routed network segment %(segment_id)s',
                          {'host': event.host, 'segment_id': segment_id})
@@ -472,6 +483,13 @@ class NovaSegmentNotifier(object):
                 ipv4_subnet_ids.append(ip['subnet_id'])
         return ipv4_subnet_ids
 
+    @registry.receives(resources.SEGMENT, [events.AFTER_DELETE])
+    def _notify_segment_deleted(
+            self, resource, event, trigger, payload=None):
+        if payload:
+            self.batch_notifier.queue_event(Event(
+                self._delete_nova_inventory, payload.resource_id))
+
 
 @registry.has_registry_receivers
 class SegmentHostRoutes(object):
@@ -650,6 +668,9 @@ class SegmentHostRoutes(object):
                                  subnet, **kwargs):
         # If this is a routed network, remove any routes to this subnet on
         # this networks remaining subnets.
+        if kwargs.get(db.FOR_NET_DELETE):
+            return  # skip subnet update if the network is going to be deleted
+
         if subnet.get('segment_id'):
             self._update_routed_network_host_routes(
                 context, subnet['network_id'], deleted_cidr=subnet['cidr'])

neutron/tests/unit/extensions/test_segment.py

@@ -2478,6 +2478,33 @@ class TestNovaSegmentNotifier(SegmentAwareIpamTestCase):
             self.segments_plugin.nova_updater._send_notifications([event])
             self.assertTrue(log.called)
 
+    def _test_create_network_and_segment(self, phys_net):
+        with self.network() as net:
+            network = net['network']
+        segment = self._test_create_segment(
+            network_id=network['id'], physical_network=phys_net,
+            segmentation_id=200, network_type='vlan')
+        return network, segment['segment']
+
+    def test_delete_network_and_owned_segments(self):
+        db.subscribe()
+        aggregate = mock.MagicMock()
+        aggregate.uuid = uuidutils.generate_uuid()
+        aggregate.id = 1
+        aggregate.hosts = ['fakehost1']
+        self.mock_p_client.list_aggregates.return_value = {
+            'aggregates': [aggregate.uuid]}
+        self.mock_n_client.aggregates.list.return_value = [aggregate]
+        self.mock_n_client.aggregates.get_details.return_value = aggregate
+        network, segment = self._test_create_network_and_segment('physnet')
+        self._delete('networks', network['id'])
+        self.mock_n_client.aggregates.remove_host.assert_has_calls(
+            [mock.call(aggregate.id, 'fakehost1')])
+        self.mock_n_client.aggregates.delete.assert_has_calls(
+            [mock.call(aggregate.id)])
+        self.mock_p_client.delete_resource_provider.assert_has_calls(
+            [mock.call(segment['id'])])
+
 
 class TestDhcpAgentSegmentScheduling(HostSegmentMappingTestCase):