dumpling: fix consistency lock table when tables to dump is empty

dumpling/export/consistency.go

@@ -42,8 +42,9 @@ func NewConsistencyController(ctx context.Context, conf *Config, session *sql.DB
 		}, nil
 	case ConsistencyTypeLock:
 		return &ConsistencyLockDumpingTables{
-			conn: conn,
-			conf: conf,
+			conn:         conn,
+			conf:         conf,
+			emptyLockSQL: false,
 		}, nil
 	case ConsistencyTypeSnapshot:
 		if conf.ServerInfo.ServerType != version.ServerTypeTiDB {
@@ -118,8 +119,9 @@ func (c *ConsistencyFlushTableWithReadLock) PingContext(ctx context.Context) err
 
 // ConsistencyLockDumpingTables execute lock tables read on all tables before dump
 type ConsistencyLockDumpingTables struct {
-	conn *sql.Conn
-	conf *Config
+	conn         *sql.Conn
+	conf         *Config
+	emptyLockSQL bool
 }
 
 // Setup implements ConsistencyController.Setup
@@ -135,7 +137,15 @@ func (c *ConsistencyLockDumpingTables) Setup(tctx *tcontext.Context) error {
 	blockList := make(map[string]map[string]interface{})
 	return utils.WithRetry(tctx, func() error {
 		lockTablesSQL := buildLockTablesSQL(c.conf.Tables, blockList)
-		_, err := c.conn.ExecContext(tctx, lockTablesSQL)
+		var err error
+		if len(lockTablesSQL) == 0 {
+			c.emptyLockSQL = true
+			// transfer to ConsistencyNone
+			_ = c.conn.Close()
+			c.conn = nil
+		} else {
+			_, err = c.conn.ExecContext(tctx, lockTablesSQL)
+		}
 		if err == nil {
 			if len(blockList) > 0 {
 				filterTablesFunc(tctx, c.conf, func(db string, tbl string) bool {
@@ -166,6 +176,9 @@ func (c *ConsistencyLockDumpingTables) TearDown(ctx context.Context) error {
 
 // PingContext implements ConsistencyController.PingContext
 func (c *ConsistencyLockDumpingTables) PingContext(ctx context.Context) error {
+	if c.emptyLockSQL {
+		return nil
+	}
 	if c.conn == nil {
 		return errors.New("consistency connection has already been closed")
 	}

dumpling/export/consistency_test.go

@@ -107,6 +107,39 @@ func TestConsistencyLockControllerRetry(t *testing.T) {
 	require.NoError(t, mock.ExpectationsWereMet())
 }
 
+func TestConsistencyLockControllerEmpty(t *testing.T) {
+	db, mock, err := sqlmock.New()
+	require.NoError(t, err)
+	defer func() {
+		_ = db.Close()
+	}()
+
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+	tctx := tcontext.Background().WithContext(ctx)
+	conf := defaultConfigForTest(t)
+
+	conf.ServerInfo.ServerType = version.ServerTypeMySQL
+	conf.Consistency = ConsistencyTypeLock
+	conf.Tables = NewDatabaseTables().
+		AppendTables("db1", []string{"t1"}, []uint64{1}).
+		AppendViews("db2", "t4")
+	mock.ExpectExec("LOCK TABLES `db1`.`t1` READ").
+		WillReturnError(&mysql.MySQLError{Number: ErrNoSuchTable, Message: "Table 'db1.t1' doesn't exist"})
+	ctrl, _ := NewConsistencyController(ctx, conf, db)
+	_, ok := ctrl.(*ConsistencyLockDumpingTables)
+	require.True(t, ok)
+	require.NoError(t, ctrl.Setup(tctx))
+	require.NoError(t, ctrl.TearDown(tctx))
+
+	// should remove table db1.t1 in tables to dump
+	expectedDumpTables := NewDatabaseTables().
+		AppendViews("db2", "t4")
+	expectedDumpTables["db1"] = make([]*TableInfo, 0)
+	require.Equal(t, expectedDumpTables, conf.Tables)
+	require.NoError(t, mock.ExpectationsWereMet())
+}
+
 func TestResolveAutoConsistency(t *testing.T) {
 	conf := defaultConfigForTest(t)
 	cases := []struct {

dumpling/tests/_utils/run_services

@@ -36,6 +36,7 @@ start_services() {
 
     cat > "$DUMPLING_TEST_DIR/tidb.toml" <<EOF
 port = 4000
+enable-table-lock = true
 [status]
 status-port = 10080
 [log.file]

dumpling/tests/basic/run.sh

@@ -117,3 +117,14 @@ echo "expected panic 0, actual ${actual}"
 actual=$(grep -w "Error 1064: You have an error in your SQL syntax" ${DUMPLING_OUTPUT_DIR}/dumpling.log|wc -l)
 echo "expect contain Error 1064, actual ${actual}"
 [ "$actual" -ge 1 ]
+
+# Test for consistency lock with empty database.
+export DUMPLING_TEST_PORT=3306
+run_sql "drop database if exists \`$DB_NAME\`;"
+run_sql "create database \`$DB_NAME\` DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin;"
+
+run_dumpling --consistency lock -B "$DB_NAME" -L ${DUMPLING_OUTPUT_DIR}/dumpling.log
+
+cnt=$(grep -w "$DB_NAME" ${DUMPLING_OUTPUT_DIR}/${DB_NAME}-schema-create.sql|wc -l)
+echo "records count is ${cnt}"
+[ "$cnt" = 1 ]