store/tikv: Fix goroutine leak in tikv client (#20808) (#20863)

store/tikv/kv.go

@@ -305,6 +305,10 @@ func (s *tikvStore) Close() error {
 		s.txnLatches.Close()
 	}
 	s.regionCache.Close()
+
+	if err := s.kv.Close(); err != nil {
+		return errors.Trace(err)
+	}
 	return nil
 }
 

store/tikv/safepoint.go

@@ -43,6 +43,7 @@ const (
 type SafePointKV interface {
 	Put(k string, v string) error
 	Get(k string) (string, error)
+	Close() error
 }
 
 // MockSafePointKV implements SafePointKV at mock test
@@ -74,6 +75,11 @@ func (w *MockSafePointKV) Get(k string) (string, error) {
 	return elem, nil
 }
 
+// Close implements the Close method for SafePointKV
+func (w *MockSafePointKV) Close() error {
+	return nil
+}
+
 // EtcdSafePointKV implements SafePointKV at runtime
 type EtcdSafePointKV struct {
 	cli *clientv3.Client
@@ -113,6 +119,11 @@ func (w *EtcdSafePointKV) Get(k string) (string, error) {
 	return "", nil
 }
 
+// Close implements the Close for SafePointKV
+func (w *EtcdSafePointKV) Close() error {
+	return errors.Trace(w.cli.Close())
+}
+
 func saveSafePoint(kv SafePointKV, key string, t uint64) error {
 	s := strconv.FormatUint(t, 10)
 	err := kv.Put(GcSavedSafePoint, s)