Merge "Allow resource_provider_association_refresh=0"

nova/conf/compute.py

@@ -650,7 +650,8 @@ Related options:
 """),
     cfg.IntOpt('resource_provider_association_refresh',
         default=300,
-        min=1,
+        min=0,
+        mutable=True,
         help="""
 Interval for updating nova-compute-side cache of the compute node resource
 provider's aggregates and traits info.
@@ -659,9 +660,11 @@ This option specifies the number of seconds between attempts to update a
 provider's aggregates and traits information in the local cache of the compute
 node.
 
+A value of zero disables cache refresh completely.
+
 Possible values:
 
-* Any positive integer in seconds.
+* Any positive integer in seconds, or zero to disable refresh.
 """),
    cfg.StrOpt('cpu_shared_set',
         help="""

nova/scheduler/client/report.py

@@ -847,10 +847,20 @@ class SchedulerReportClient(object):
         Associations are stale if association_refresh_time for this uuid is not
         set or is more than CONF.compute.resource_provider_association_refresh
         seconds ago.
+
+        Always False if CONF.compute.resource_provider_association_refresh is
+        zero.
         """
+        rpar = CONF.compute.resource_provider_association_refresh
         refresh_time = self._association_refresh_time.get(uuid, 0)
-        return ((time.time() - refresh_time) >
-                CONF.compute.resource_provider_association_refresh)
+        # If refresh is disabled, associations are "never" stale. (But still
+        # load them if we haven't yet done so.)
+        if rpar == 0 and refresh_time != 0:
+            # TODO(efried): If refresh is disabled, we could avoid touching the
+            # _association_refresh_time dict anywhere, but that would take some
+            # nontrivial refactoring.
+            return False
+        return (time.time() - refresh_time) > rpar
 
     def _update_inventory_attempt(self, context, rp_uuid, inv_data):
         """Update the inventory for this resource provider if needed.

nova/tests/unit/scheduler/client/test_report.py

@@ -2934,6 +2934,62 @@ class TestAssociations(SchedulerReportClientTestCase):
             mock_trait_get.assert_called_once_with(self.context, uuid)
             mock_shr_get.assert_called_once_with(self.context, set())
 
+    @mock.patch('nova.scheduler.client.report.SchedulerReportClient.'
+                '_get_provider_aggregates')
+    @mock.patch('nova.scheduler.client.report.SchedulerReportClient.'
+                '_get_provider_traits')
+    @mock.patch('nova.scheduler.client.report.SchedulerReportClient.'
+                '_get_sharing_providers')
+    def test_refresh_associations_disabled(self, mock_shr_get, mock_trait_get,
+                                           mock_agg_get):
+        """Test that refresh associations can be disabled."""
+        self.flags(resource_provider_association_refresh=0, group='compute')
+        uuid = uuids.compute_node
+        # Seed the provider tree so _refresh_associations finds the provider
+        self.client._provider_tree.new_root('compute', uuid, generation=1)
+        mock_agg_get.return_value = report.AggInfo(aggregates=set([]),
+                                                   generation=42)
+        mock_trait_get.return_value = report.TraitInfo(traits=set([]),
+                                                       generation=43)
+        mock_shr_get.return_value = []
+
+        # Called a first time because association_refresh_time is empty.
+        now = time.time()
+        self.client._refresh_associations(self.context, uuid)
+        mock_agg_get.assert_called_once_with(self.context, uuid)
+        mock_trait_get.assert_called_once_with(self.context, uuid)
+        mock_shr_get.assert_called_once_with(self.context, set())
+        self.assertIn(uuid, self.client._association_refresh_time)
+
+        # Clear call count.
+        mock_agg_get.reset_mock()
+        mock_trait_get.reset_mock()
+        mock_shr_get.reset_mock()
+
+        with mock.patch('time.time') as mock_future:
+            # A lot of time passes
+            mock_future.return_value = now + 10000000000000
+            self.client._refresh_associations(self.context, uuid)
+            mock_agg_get.assert_not_called()
+            mock_trait_get.assert_not_called()
+            mock_shr_get.assert_not_called()
+
+            # Forever passes
+            mock_future.return_value = float('inf')
+            self.client._refresh_associations(self.context, uuid)
+            mock_agg_get.assert_not_called()
+            mock_trait_get.assert_not_called()
+            mock_shr_get.assert_not_called()
+
+            # Even if no time passes, clearing the counter triggers refresh
+            mock_future.return_value = now
+            del self.client._association_refresh_time[uuid]
+            self.client._refresh_associations(self.context, uuid)
+            mock_agg_get.assert_called_once_with(self.context, uuid)
+            mock_trait_get.assert_called_once_with(self.context, uuid)
+            mock_shr_get.assert_called_once_with(self.context, set())
+            self.assertIn(uuid, self.client._association_refresh_time)
+
 
 class TestComputeNodeToInventoryDict(test.NoDBTestCase):
     def test_compute_node_inventory(self):

releasenotes/notes/disable-rt-cache-refresh-9f6633e585516760.yaml

@@ -0,0 +1,10 @@
+---
+features:
+  - |
+    The configuration option
+    ``[compute]resource_provider_association_refresh`` can now
+    be set to zero to disable refresh entirely. This follows on from `bug
+    1767309`_ allowing more aggressive reduction in the amount of traffic to
+    the placement service.
+
+    .. _`bug 1767309`: https://bugs.launchpad.net/nova/+bug/1767309