From 1c66a4b029cc9f939f596cd08ae4c20894d3550e Mon Sep 17 00:00:00 2001
From: Yikun Jiang <yikunkero@gmail.com>
Date: Tue, 31 Jul 2018 18:27:39 +0800
Subject: [PATCH] Remove redundant join in _anchors_for_sharing_providers

There is a redundant join when we want to get id from
_anchors_for_sharing_providers. The last outerjoin is used to get the
rp.UUID according rp.id, if we set get_id=True, we no longer need this
outer join.

So, we remove the redundant join in this patch.

Change-Id: Ib5fc6e4efae29dd88ce92df834700d2121ed8076
Closes-bug: #1784604
---
 .../openstack/placement/objects/resource_provider.py  | 11 ++++++-----
 .../openstack/placement/db/test_resource_provider.py  |  6 ++++++
 2 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/nova/api/openstack/placement/objects/resource_provider.py b/nova/api/openstack/placement/objects/resource_provider.py
index d5eb8436e90b..a31ec76eff42 100644
--- a/nova/api/openstack/placement/objects/resource_provider.py
+++ b/nova/api/openstack/placement/objects/resource_provider.py
@@ -471,13 +471,14 @@ def _anchors_for_sharing_providers(context, rp_ids, get_id=False):
     join_chain = sa.join(
         join_chain, shr_with_sps,
         shr_with_sps_aggs.c.resource_provider_id == shr_with_sps.c.id)
-    # TODO(efried): Change this to an inner join when we are sure all
-    # root_provider_id values are NOT NULL
-    join_chain = sa.outerjoin(
-        join_chain, rps, shr_with_sps.c.root_provider_id == rps.c.id)
     if get_id:
-        sel = sa.select([sps.c.id, func.coalesce(rps.c.id, shr_with_sps.c.id)])
+        sel = sa.select([sps.c.id, func.coalesce(
+            shr_with_sps.c.root_provider_id, shr_with_sps.c.id)])
     else:
+        # TODO(efried): Change this to an inner join when we are sure all
+        # root_provider_id values are NOT NULL
+        join_chain = sa.outerjoin(
+            join_chain, rps, shr_with_sps.c.root_provider_id == rps.c.id)
         sel = sa.select([sps.c.uuid, func.coalesce(rps.c.uuid,
                                                    shr_with_sps.c.uuid)])
     sel = sel.select_from(join_chain)
diff --git a/nova/tests/functional/api/openstack/placement/db/test_resource_provider.py b/nova/tests/functional/api/openstack/placement/db/test_resource_provider.py
index 7b69235bfb28..a93c3f2e13c7 100644
--- a/nova/tests/functional/api/openstack/placement/db/test_resource_provider.py
+++ b/nova/tests/functional/api/openstack/placement/db/test_resource_provider.py
@@ -1046,6 +1046,12 @@ class TestResourceProviderAggregates(tb.PlacementDbBaseTestCase):
         self.assertItemsEqual(
             expected, rp_obj._anchors_for_sharing_providers(self.ctx, [s1.id]))
 
+        # Get same result (id format) when we set get_id=True
+        expected = set([(s1.id, rp.id) for rp in (s1, r1, r2, r3, s5)])
+        self.assertItemsEqual(
+            expected, rp_obj._anchors_for_sharing_providers(self.ctx, [s1.id],
+                                                            get_id=True))
+
         # s2 gets s2 (self) and r3 via agg4
         expected = set([(s2.uuid, rp.uuid) for rp in (s2, r3)])
         self.assertItemsEqual(