Reduce db access in prep_resize in the compute manager.

This patch changes the arguments passed to prep_resize in the compute
manager.  Previously it took instance and instance_type IDs.  It now
receives a full dict for both of these.  This cuts down on database
access needed on the compute node.

This method was not previously in the compute rpcapi module, so it has
been added there.  The scheduler had a bit of work done ot get it to use
the rpcapi module for prep_resize, as well.

Part of blueprint no-db-messaging.

Change-Id: Idadbf4fc624d5d1b128f758a46c61b3c840b9898

2 files changed, 38 insertions, 16 deletions

diff --git a/nova/tests/compute/test_compute.py b/nova/tests/compute/test_compute.py
index efb241b75..5d41cd7c6 100644
--- a/nova/tests/compute/test_compute.py
+++ b/nova/tests/compute/test_compute.py
@@ -1146,7 +1146,8 @@ class ComputeTestCase(BaseTestCase):
 
         context = self.context.elevated()
         instance = jsonutils.to_primitive(self._create_fake_instance())
-        self.compute.prep_resize(context, instance['uuid'], 1, {})
+        self.compute.prep_resize(context, instance=instance, instance_type={},
+                                 image={})
         migration_ref = db.migration_get_by_instance_and_status(context,
                 instance['uuid'], 'pre-migrating')
         self.compute.finish_resize(context,
@@ -1167,7 +1168,8 @@ class ComputeTestCase(BaseTestCase):
 
         context = self.context.elevated()
         instance = jsonutils.to_primitive(self._create_fake_instance())
-        self.compute.prep_resize(context, instance['uuid'], 1, {})
+        self.compute.prep_resize(context, instance=instance, instance_type={},
+                                 image={})
         migration_ref = db.migration_get_by_instance_and_status(context,
                 instance['uuid'], 'pre-migrating')
 
@@ -1250,12 +1252,14 @@ class ComputeTestCase(BaseTestCase):
         context = self.context.elevated()
         old_type_id = instance_types.get_instance_type_by_name(
                                                 'm1.tiny')['id']
-        new_type_id = instance_types.get_instance_type_by_name(
-                                                'm1.small')['id']
+        new_type = instance_types.get_instance_type_by_name('m1.small')
+        new_type = jsonutils.to_primitive(new_type)
+        new_type_id = new_type['id']
         self.compute.run_instance(self.context, instance['uuid'])
 
         db.instance_update(self.context, instance['uuid'], {'host': 'foo'})
-        self.compute.prep_resize(context, instance['uuid'], new_type_id, {})
+        self.compute.prep_resize(context, instance=instance,
+                instance_type=new_type, image={})
         migration_ref = db.migration_get_by_instance_and_status(context,
                                                 instance['uuid'],
                                                 'pre-migrating')
@@ -1304,7 +1308,9 @@ class ComputeTestCase(BaseTestCase):
         test_notifier.NOTIFICATIONS = []
 
         db.instance_update(self.context, instance['uuid'], {'host': 'foo'})
-        self.compute.prep_resize(context, instance['uuid'], 1, {})
+        self.compute.prep_resize(context,
+                instance=jsonutils.to_primitive(instance),
+                instance_type={}, image={})
         db.migration_get_by_instance_and_status(context,
                                                 instance['uuid'],
                                                 'pre-migrating')
@@ -1343,12 +1349,15 @@ class ComputeTestCase(BaseTestCase):
         context = self.context.elevated()
 
         self.compute.run_instance(self.context, instance['uuid'])
-        db.instance_update(self.context, instance['uuid'], {'host': 'foo'})
+        new_instance = db.instance_update(self.context, instance['uuid'],
+                                          {'host': 'foo'})
 
         self.assertRaises(exception.MigrationError, self.compute.prep_resize,
-                          context, instance['uuid'], 1, {})
+                          context,
+                          instance=jsonutils.to_primitive(new_instance),
+                          instance_type={}, image={})
         self.compute.terminate_instance(context,
-            instance=jsonutils.to_primitive(instance))
+            instance=jsonutils.to_primitive(new_instance))
 
     def test_resize_instance_driver_error(self):
         """Ensure instance status set to Error on resize error"""
@@ -1364,7 +1373,8 @@ class ComputeTestCase(BaseTestCase):
 
         self.compute.run_instance(self.context, instance['uuid'])
         db.instance_update(self.context, instance['uuid'], {'host': 'foo'})
-        self.compute.prep_resize(context, instance['uuid'], 1, {})
+        self.compute.prep_resize(context, instance=instance,
+                                 instance_type={}, image={})
         migration_ref = db.migration_get_by_instance_and_status(context,
                 instance['uuid'], 'pre-migrating')
 
@@ -1385,7 +1395,8 @@ class ComputeTestCase(BaseTestCase):
         self.compute.run_instance(self.context, instance['uuid'])
         db.instance_update(self.context, instance['uuid'],
                            {'host': 'foo'})
-        self.compute.prep_resize(context, instance['uuid'], 1, {})
+        self.compute.prep_resize(context, instance=instance,
+                instance_type={}, image={})
         migration_ref = db.migration_get_by_instance_and_status(context,
                 instance['uuid'], 'pre-migrating')
         self.compute.resize_instance(context, migration_ref['id'], {},
@@ -1413,11 +1424,14 @@ class ComputeTestCase(BaseTestCase):
                 inst_ref['instance_type_id'])
         self.assertEqual(instance_type_ref['flavorid'], '1')
 
-        db.instance_update(self.context, instance['uuid'], {'host': 'foo'})
+        new_inst_ref = db.instance_update(self.context, instance['uuid'],
+                                          {'host': 'foo'})
 
         new_instance_type_ref = db.instance_type_get_by_flavor_id(context, 3)
-        self.compute.prep_resize(context, inst_ref['uuid'],
-                                 new_instance_type_ref['id'], {})
+        self.compute.prep_resize(context,
+                instance=jsonutils.to_primitive(new_inst_ref),
+                instance_type=jsonutils.to_primitive(new_instance_type_ref),
+                image={})
 
         migration_ref = db.migration_get_by_instance_and_status(context,
                 inst_ref['uuid'], 'pre-migrating')
@@ -1465,7 +1479,9 @@ class ComputeTestCase(BaseTestCase):
         self.compute.run_instance(self.context, instance['uuid'])
         instance = db.instance_get_by_uuid(self.context, instance['uuid'])
         self.assertRaises(exception.MigrationError, self.compute.prep_resize,
-                self.context, instance['uuid'], 1, {})
+                self.context,
+                instance=jsonutils.to_primitive(instance),
+                instance_type={}, image={})
         self.compute.terminate_instance(self.context,
                 instance=jsonutils.to_primitive(instance))
 
@@ -1482,7 +1498,8 @@ class ComputeTestCase(BaseTestCase):
 
         self.compute.run_instance(self.context, inst_ref['uuid'])
         db.instance_update(self.context, inst_ref['uuid'], {'host': 'foo'})
-        self.compute.prep_resize(context, inst_ref['uuid'], 1, {})
+        self.compute.prep_resize(context, instance=inst_ref, instance_type={},
+                                 image={})
         migration_ref = db.migration_get_by_instance_and_status(context,
                 inst_ref['uuid'], 'pre-migrating')
         self.assertRaises(test.TestingException, self.compute.resize_instance,
diff --git a/nova/tests/compute/test_rpcapi.py b/nova/tests/compute/test_rpcapi.py
index a1062ea57..94b44b345 100644
--- a/nova/tests/compute/test_rpcapi.py
+++ b/nova/tests/compute/test_rpcapi.py
@@ -210,6 +210,11 @@ class ComputeRpcAPITestCase(test.TestCase):
                 instance=self.fake_instance, block_migration='block_migration',
                 disk='disk', host='host', version='1.23')
 
+    def test_prep_resize(self):
+        self._test_compute_api('prep_resize', 'cast',
+                instance=self.fake_instance, instance_type='fake_type',
+                image='fake_image', host='host', version='1.38')
+
     def test_reboot_instance(self):
         self._test_compute_api('reboot_instance', 'cast',
                 instance=self.fake_instance, reboot_type='type', version='1.4')