From 80eddc40390e63c9c1102b827997054708f2618b Mon Sep 17 00:00:00 2001
From: Oleg Bondarev <obondarev@mirantis.com>
Date: Thu, 15 Apr 2021 11:31:01 +0300
Subject: [PATCH] Improve Network delete performance

- pass existing network dict to PRECOMMIT_DELETE ml2 handler;
- skip MTU and segment update handling in case network is
  about to be deleted.

Above gives up to 50% net delete speed-up

Change-Id: I07c70db027f2ae03ffb5a95072e019e8a5fdc411
---
 neutron/db/db_base_plugin_v2.py               |  3 ++-
 neutron/plugins/ml2/plugin.py                 | 12 +++++++++---
 neutron/services/segments/db.py               |  9 ++++++---
 neutron/tests/unit/extensions/test_segment.py |  3 ++-
 4 files changed, 19 insertions(+), 8 deletions(-)

diff --git a/neutron/db/db_base_plugin_v2.py b/neutron/db/db_base_plugin_v2.py
index f4738d85d82..37c9e2d39df 100644
--- a/neutron/db/db_base_plugin_v2.py
+++ b/neutron/db/db_base_plugin_v2.py
@@ -505,7 +505,8 @@ class NeutronDbPluginV2(db_base_plugin_common.DbBasePluginCommon,
                 network_db = self._get_network(context, id)
                 network = self._make_network_dict(network_db, context=context)
                 registry.notify(resources.NETWORK, events.PRECOMMIT_DELETE,
-                                self, context=context, network_id=id)
+                                self, context=context, network_id=id,
+                                network=network)
                 # We expire network_db here because precommit deletion
                 # might have left the relationship stale, for example,
                 # if we deleted a segment.
diff --git a/neutron/plugins/ml2/plugin.py b/neutron/plugins/ml2/plugin.py
index 889dae77fa2..4b92bfc7c67 100644
--- a/neutron/plugins/ml2/plugin.py
+++ b/neutron/plugins/ml2/plugin.py
@@ -1229,7 +1229,8 @@ class Ml2Plugin(db_base_plugin_v2.NeutronDbPluginV2,
                        priority=0)
     def _network_delete_precommit_handler(self, rtype, event, trigger,
                                           context, network_id, **kwargs):
-        network = self.get_network(context, network_id)
+        network = (kwargs.get('network') or
+                   self.get_network(context, network_id))
         mech_context = driver_context.NetworkContext(self,
                                                      context,
                                                      network)
@@ -2297,12 +2298,14 @@ class Ml2Plugin(db_base_plugin_v2.NeutronDbPluginV2,
         # TODO(boden); refactor into _handle_segment_change once all
         # event types use payloads
         return self._handle_segment_change(
-            rtype, event, trigger, payload.context, payload.latest_state)
+            rtype, event, trigger, payload.context, payload.latest_state,
+            for_net_delete=payload.metadata.get('for_net_delete'))
 
     @registry.receives(resources.SEGMENT, (events.PRECOMMIT_CREATE,
                                            events.PRECOMMIT_DELETE,
                                            events.AFTER_CREATE))
-    def _handle_segment_change(self, rtype, event, trigger, context, segment):
+    def _handle_segment_change(self, rtype, event, trigger, context, segment,
+                               for_net_delete=False):
         if (event == events.PRECOMMIT_CREATE and
                 not isinstance(trigger, segments_plugin.Plugin)):
             # TODO(xiaohhui): Now, when create network, ml2 will reserve
@@ -2323,6 +2326,9 @@ class Ml2Plugin(db_base_plugin_v2.NeutronDbPluginV2,
         elif event == events.PRECOMMIT_DELETE:
             self.type_manager.release_network_segment(context, segment)
 
+        if for_net_delete:
+            return
+
         # change in segments could affect resulting network mtu, so let's
         # recalculate it
         network_db = self._get_network(context, network_id)
diff --git a/neutron/services/segments/db.py b/neutron/services/segments/db.py
index 866bca33de3..db946f5f0f6 100644
--- a/neutron/services/segments/db.py
+++ b/neutron/services/segments/db.py
@@ -202,12 +202,15 @@ class SegmentDbMixin(object):
             # Do some preliminary operations before deleting segment in db
             registry.notify(resources.SEGMENT, events.PRECOMMIT_DELETE,
                             self.delete_segment, context=context,
-                            segment=segment_dict)
+                            segment=segment_dict,
+                            for_net_delete=for_net_delete)
 
         registry.publish(resources.SEGMENT, events.AFTER_DELETE,
                          self.delete_segment,
                          payload=events.DBEventPayload(
-                             context, states=(segment_dict,),
+                             context, metadata={
+                                 FOR_NET_DELETE: for_net_delete},
+                             states=(segment_dict,),
                              resource_id=uuid))
 
 
@@ -333,7 +336,7 @@ def _add_segment_host_mapping_for_segment(resource, event, trigger,
 
 
 def _delete_segments_for_network(resource, event, trigger,
-                                 context, network_id):
+                                 context, network_id, **kwargs):
     admin_ctx = common_utils.get_elevated_context(context)
     global segments_plugin
     if not segments_plugin:
diff --git a/neutron/tests/unit/extensions/test_segment.py b/neutron/tests/unit/extensions/test_segment.py
index ab14e7c4949..7614dca59c6 100644
--- a/neutron/tests/unit/extensions/test_segment.py
+++ b/neutron/tests/unit/extensions/test_segment.py
@@ -420,7 +420,8 @@ class TestSegment(SegmentTestCase):
                                events.PRECOMMIT_DELETE,
                                mock.ANY,
                                context=mock.ANY,
-                               network_id=mock.ANY)
+                               network_id=mock.ANY,
+                               network=mock.ANY)
 
 
 class TestSegmentML2(SegmentTestCase):