From 5756bf81469232e405aaba6fc95e7d9bb910b4cd Mon Sep 17 00:00:00 2001
From: xhe <xw897002528@gmail.com>
Date: Wed, 30 Dec 2020 11:13:14 +0800
Subject: [PATCH] ddl: fix inconsistent rule cache (#22051)

Signed-off-by: xhe <xw897002528@gmail.com>
---
 infoschema/infoschema.go      | 11 +++++++----
 infoschema/infoschema_test.go | 14 +++++++++++++-
 2 files changed, 20 insertions(+), 5 deletions(-)

diff --git a/infoschema/infoschema.go b/infoschema/infoschema.go
index d01e42d768..4e2643ba3f 100644
--- a/infoschema/infoschema.go
+++ b/infoschema/infoschema.go
@@ -428,17 +428,20 @@ func GetBundle(h InfoSchema, ids []int64) *placement.Bundle {
 		}
 	}
 
+	newRules := []*placement.Rule{}
+
 	b, ok := h.BundleByName(placement.PDBundleID)
 	if ok {
-		newRules := b.Rules[:0]
 		for _, rule := range b.Rules {
 			if rule.StartKeyHex == "" && rule.EndKeyHex == "" {
 				newRules = append(newRules, rule.Clone())
 			}
 		}
-		b.Rules = newRules
-		return b
 	}
 
-	return &placement.Bundle{ID: placement.GroupID(ids[0])}
+	id := int64(-1)
+	if len(ids) > 0 {
+		id = ids[0]
+	}
+	return &placement.Bundle{ID: placement.GroupID(id), Rules: newRules}
 }
diff --git a/infoschema/infoschema_test.go b/infoschema/infoschema_test.go
index 38cb62a786..578d149e73 100644
--- a/infoschema/infoschema_test.go
+++ b/infoschema/infoschema_test.go
@@ -369,7 +369,11 @@ func (*testSuite) TestGetBundle(c *C) {
 	bundles[placement.PDBundleID] = bundle
 
 	b := infoschema.GetBundle(is, []int64{})
-	c.Assert(b, DeepEquals, bundle)
+	c.Assert(b.Rules, DeepEquals, bundle.Rules)
+
+	// bundle itself is cloned
+	b.ID = "test"
+	c.Assert(bundle.ID, Equals, placement.PDBundleID)
 
 	ptID := placement.GroupID(3)
 	bundle = &placement.Bundle{
@@ -388,6 +392,10 @@ func (*testSuite) TestGetBundle(c *C) {
 	b = infoschema.GetBundle(is, []int64{2, 3})
 	c.Assert(b, DeepEquals, bundle)
 
+	// bundle itself is cloned
+	b.ID = "test"
+	c.Assert(bundle.ID, Equals, ptID)
+
 	ptID = placement.GroupID(1)
 	bundle = &placement.Bundle{
 		ID: ptID,
@@ -404,4 +412,8 @@ func (*testSuite) TestGetBundle(c *C) {
 
 	b = infoschema.GetBundle(is, []int64{1, 2, 3})
 	c.Assert(b, DeepEquals, bundle)
+
+	// bundle itself is cloned
+	b.ID = "test"
+	c.Assert(bundle.ID, Equals, ptID)
 }