From e2b4e3346e20615473328e7ae90b5083500961ca Mon Sep 17 00:00:00 2001
From: Matt Riedemann <mriedem.os@gmail.com>
Date: Mon, 21 Oct 2019 13:00:59 -0400
Subject: [PATCH] Join migration_context and flavor in Migration.instance

This builds on Ifc7dcde8a659710acecb1967da15c632c69d675c
by joining the Migration.instance migration_context and
flavor to avoid lazy-loading those later.

When tracking an incoming migration, the ResourceTracker
_pair_instances_to_migrations can hit a KeyError since it's
not yet tracking the instance on that dest host yet. Then
_update_usage_from_migrations will lazy-load the Migration.instance
field and access the migration_context and flavor fields on the
instance, which get lazy-loaded, which kind of defeats part of
the purpose of that optimization.

Change-Id: I613ad054f77b1a0a9d2e7718c0c531d11525283c
Related-Bug: #1540526
(cherry picked from commit c15e36e5849b6baddebb4b39475a6bf03ec5908b)
---
 nova/objects/migration.py                        | 3 ++-
 nova/tests/unit/compute/test_resource_tracker.py | 5 ++++-
 nova/tests/unit/objects/test_migration.py        | 9 +++++----
 3 files changed, 11 insertions(+), 6 deletions(-)

diff --git a/nova/objects/migration.py b/nova/objects/migration.py
index 032615b0122c..4489f5c0bc6c 100644
--- a/nova/objects/migration.py
+++ b/nova/objects/migration.py
@@ -194,7 +194,8 @@ class Migration(base.NovaPersistentObject, base.NovaObject,
     def instance(self):
         if not hasattr(self, '_cached_instance'):
             self._cached_instance = objects.Instance.get_by_uuid(
-                self._context, self.instance_uuid)
+                self._context, self.instance_uuid,
+                expected_attrs=['migration_context', 'flavor'])
         return self._cached_instance
 
     @instance.setter
diff --git a/nova/tests/unit/compute/test_resource_tracker.py b/nova/tests/unit/compute/test_resource_tracker.py
index 0b401b5f3598..9bae648efe9a 100644
--- a/nova/tests/unit/compute/test_resource_tracker.py
+++ b/nova/tests/unit/compute/test_resource_tracker.py
@@ -3233,7 +3233,10 @@ class TestUpdateUsageFromMigrations(BaseTestCase):
         self.rt._update_usage_from_migrations(mock.sentinel.ctx, [migration],
                                               _NODENAME)
         mock_get_instance.assert_called_once_with(mock.sentinel.ctx,
-                                                  'some_uuid')
+                                                  'some_uuid',
+                                                  expected_attrs=[
+                                                      'migration_context',
+                                                      'flavor'])
         self.assertFalse(mock_update_usage.called)
 
     @mock.patch('nova.compute.resource_tracker.ResourceTracker.'
diff --git a/nova/tests/unit/objects/test_migration.py b/nova/tests/unit/objects/test_migration.py
index 71c8ec8d0822..fd9b9b5fcad5 100644
--- a/nova/tests/unit/objects/test_migration.py
+++ b/nova/tests/unit/objects/test_migration.py
@@ -200,10 +200,11 @@ class _TestMigrationObject(object):
                                                   fake_migration)
         mig._context = ctxt
         self.assertEqual(mig.instance.host, fake_inst['host'])
-        mock_get.assert_called_once_with(ctxt,
-                                         fake_migration['instance_uuid'],
-                                         columns_to_join=['info_cache',
-                                                          'security_groups'])
+        mock_get.assert_called_once_with(
+            ctxt, fake_migration['instance_uuid'],
+            columns_to_join=['extra',
+                             'extra.flavor',
+                             'extra.migration_context'])
 
     def test_instance_setter(self):
         migration = objects.Migration(instance_uuid=uuidsentinel.instance)