Move registration "ChassisBandwidthConfigEvent" to OvnSbIdl init

The "ChassisBandwidthConfigEvent" event registration is now done in the
"OvnSbIdl" class initialization. That ensures this event is registered
in a worker thread.

If the event is called before the "OVNMechanismDriver"'s "OVNClient"
has been instantiated, the event is skipped. When the OVN placement
extension is loaded, all chassis configurations are read and loaded,
thus any previous event is not relevant.

This patch also adds a "match_fn" check to
"ChassisBandwidthConfigEvent". If during an update event, the bandwidth
options are not modified, this class does not update the resource
provider inventories.

Closes-Bug: #1998108
Related-Bug: #1578989
Change-Id: I74883041c642b9498299ebf2b5bf885776e241e0

neutron/plugins/ml2/drivers/ovn/mech_driver/ovsdb/extensions/placement.py

@@ -110,8 +110,8 @@ def dict_chassis_config(state):
 class ChassisBandwidthConfigEvent(row_event.RowEvent):
     """Chassis create update event to track the bandwidth config changes."""
 
-    def __init__(self, placement_extension):
-        self._placement_extension = placement_extension
+    def __init__(self, driver):
+        self._driver = driver
         # NOTE(ralonsoh): BW resource provider information is stored in
         # "Chassis", not "Chassis_Private".
         table = 'Chassis'
@@ -119,9 +119,30 @@ class ChassisBandwidthConfigEvent(row_event.RowEvent):
         super().__init__(events, table, None)
         self.event_name = 'ChassisBandwidthConfigEvent'
 
+    @property
+    def placement_extension(self):
+        if self._driver._post_fork_event.is_set():
+            return self._driver._ovn_client.placement_extension
+
+    def match_fn(self, event, row, old=None):
+        # If the OVNMechanismDriver OVNClient has not been instantiated, the
+        # event is skipped. All chassis configurations are read during the
+        # OVN placement extension initialization.
+        if (not self.placement_extension or
+                not self.placement_extension.enabled):
+            return False
+        elif event == self.ROW_CREATE:
+            return True
+        elif event == self.ROW_UPDATE and old and hasattr(old, 'other_config'):
+            row_bw = _parse_ovn_cms_options(row)
+            old_bw = _parse_ovn_cms_options(old)
+            if row_bw != old_bw:
+                return True
+        return False
+
     def run(self, event, row, old):
-        name2uuid = self._placement_extension.name2uuid()
-        state = self._placement_extension.build_placement_state(row, name2uuid)
+        name2uuid = self.placement_extension.name2uuid()
+        state = self.placement_extension.build_placement_state(row, name2uuid)
         if not state:
             return
 
@@ -153,18 +174,6 @@ class OVNClientPlacementExtension(object):
         self._plugin = None
         self.uuid_ns = ovn_const.OVN_RP_UUID
         self.supported_vnic_types = ovn_const.OVN_SUPPORTED_VNIC_TYPES
-        if not self.enabled:
-            return
-
-        if not self._config_event:
-            self._config_event = ChassisBandwidthConfigEvent(self)
-            try:
-                self._driver._sb_idl.idl.notify_handler.watch_events(
-                    [self._config_event])
-            except AttributeError:
-                # "sb_idl.idl.notify_handler" is not present in the
-                # MaintenanceWorker.
-                pass
 
     @property
     def placement_plugin(self):

neutron/plugins/ml2/drivers/ovn/mech_driver/ovsdb/ovsdb_monitor.py

@@ -35,6 +35,8 @@ from neutron.common.ovn import utils
 from neutron.conf.plugins.ml2.drivers.ovn import ovn_conf
 from neutron.db import ovn_hash_ring_db
 from neutron.plugins.ml2.drivers.ovn.agent import neutron_agent as n_agent
+from neutron.plugins.ml2.drivers.ovn.mech_driver.ovsdb.extensions import \
+    placement
 
 
 CONF = cfg.CONF
@@ -808,6 +810,7 @@ class OvnSbIdl(OvnIdlDistributedLock):
             ChassisAgentTypeChangeEvent(self.driver),
             ChassisMetadataAgentWriteEvent(self.driver),
             PortBindingUpdateVirtualPortsEvent(driver),
+            placement.ChassisBandwidthConfigEvent(driver),
         ])
 
     @classmethod

neutron/tests/functional/plugins/ml2/drivers/ovn/mech_driver/ovsdb/extensions/test_placement.py

@@ -16,15 +16,18 @@ from unittest import mock
 
 from neutron_lib import constants as n_const
 from neutron_lib.plugins import constants as plugins_constants
+from oslo_utils import uuidutils
 
 from neutron.common.ovn import constants as ovn_const
 from neutron.common import utils as common_utils
 from neutron.plugins.ml2.drivers.ovn.mech_driver.ovsdb.extensions \
     import placement as placement_extension
 from neutron.tests.functional import base
+from neutron.tests.functional.plugins.ml2.drivers.ovn.mech_driver.ovsdb \
+    import test_ovsdb_monitor
 
 
-class TestOVNClientQosExtension(base.TestOVNFunctionalBase):
+class TestOVNClientPlacementExtension(base.TestOVNFunctionalBase):
 
     EMPTY_CHASSIS = {n_const.RP_BANDWIDTHS: {},
                      n_const.RP_INVENTORY_DEFAULTS: {},
@@ -186,3 +189,39 @@ class TestOVNClientQosExtension(base.TestOVNFunctionalBase):
             inventory_defaults='allocation_ratio:1.1;min_unit:1',
             hypervisors='br-provider0:host2')
         self._check_placement_config({**self.CHASSIS1, **self.CHASSIS2_B})
+
+    @mock.patch.object(placement_extension, '_send_deferred_batch')
+    def test_chassis_bandwidth_config_event(self, mock_send_placement):
+        ch_host = 'fake-chassis-host'
+        ch_name = uuidutils.generate_uuid()
+        ch_event = test_ovsdb_monitor.WaitForChassisPrivateCreateEvent(
+            ch_name, self.mech_driver.agent_chassis_table)
+        self.mech_driver.sb_ovn.idl.notify_handler.watch_event(ch_event)
+        self.chassis_name = self.add_fake_chassis(ch_host, name=ch_name)
+        self.assertTrue(ch_event.wait())
+        common_utils.wait_until_true(lambda: mock_send_placement.called,
+                                     timeout=2)
+        mock_send_placement.reset_mock()
+
+        # Once the chassis registger has been created, this new event will
+        # catch any chassis BW update.
+        self._update_chassis(
+            ch_name,
+            bandwidths='br-provider0:3000:4000',
+            inventory_defaults='allocation_ratio:3.0;min_unit:1',
+            hypervisors='br-provider0:host2')
+        common_utils.wait_until_true(lambda: mock_send_placement.called,
+                                     timeout=2)
+        mock_send_placement.reset_mock()
+
+        # The chassis BW information is written again without any change.
+        # That should not trigger the placement update.
+        self._update_chassis(
+            ch_name,
+            bandwidths='br-provider0:3000:4000',
+            inventory_defaults='allocation_ratio:3.0;min_unit:1',
+            hypervisors='br-provider0:host2')
+        self.assertRaises(common_utils.WaitTimeout,
+                          common_utils.wait_until_true,
+                          lambda: mock_send_placement.called,
+                          timeout=2)