Prevent Instance.refresh() from returning a new info cache

If an older node does a refresh() on an instance, conductor will
return a new copy of the InstanceInfoCache, which the client
will balk at. Instead, add a refresh() method to info_cache and
call it from Instance.refresh().

Closes-bug: #1265607
Change-Id: I6a4787a23cd851cf56958c61f8b0559a79847ca0

nova/objects/instance.py

@@ -474,8 +474,13 @@ class Instance(base.NovaPersistentObject, base.NovaObject):
         current._context = None
 
         for field in self.fields:
-            if self.obj_attr_is_set(field) and self[field] != current[field]:
-                self[field] = current[field]
+            if self.obj_attr_is_set(field):
+                if field == 'info_cache':
+                    self.info_cache.refresh()
+                    # NOTE(danms): Make sure this shows up as touched
+                    self.info_cache = self.info_cache
+                elif self[field] != current[field]:
+                    self[field] = current[field]
         self.obj_reset_changes()
 
     def obj_load_attr(self, attrname):

nova/objects/instance_info_cache.py

@@ -96,3 +96,15 @@ class InstanceInfoCache(base.NovaPersistentObject, base.NovaObject):
     @base.remotable
     def delete(self, context):
         db.instance_info_cache_delete(context, self.instance_uuid)
+
+    @base.remotable
+    def refresh(self, context):
+        current = self.__class__.get_by_instance_uuid(context,
+                                                      self.instance_uuid)
+        current._context = None
+
+        for field in self.fields:
+            if self.obj_attr_is_set(field) and self[field] != current[field]:
+                self[field] = current[field]
+
+        self.obj_reset_changes()

nova/tests/objects/test_instance.py

@@ -213,6 +213,9 @@ class _TestInstanceObject(object):
                                 use_slave=False
                                 ).AndReturn(dict(self.fake_instance,
                                                  host='new-host'))
+        self.mox.StubOutWithMock(instance_info_cache.InstanceInfoCache,
+                                 'refresh')
+        instance_info_cache.InstanceInfoCache.refresh()
         self.mox.ReplayAll()
         inst = instance.Instance.get_by_uuid(self.context, fake_uuid)
         self.assertEqual(inst.host, 'orig-host')

nova/tests/objects/test_instance_info_cache.py

@@ -96,6 +96,16 @@ class _TestInstanceInfoCacheObject(object):
     def test_save_without_update_cells(self):
         self._save_helper(None, False)
 
+    def test_refresh(self):
+        obj = instance_info_cache.InstanceInfoCache.new(self.context,
+                                                        'fake-uuid1')
+        self.mox.StubOutWithMock(db, 'instance_info_cache_get')
+        db.instance_info_cache_get(self.context, 'fake-uuid1').AndReturn(
+            fake_info_cache)
+        self.mox.ReplayAll()
+        obj.refresh()
+        self.assertEqual(fake_info_cache['instance_uuid'], obj.instance_uuid)
+
 
 class TestInstanceInfoCacheObject(test_objects._LocalTest,
                                   _TestInstanceInfoCacheObject):