cloudstorage(ticdc): write meta file if not found and add ut for 10137 (

pingcap#10283)

* write meta file is not found and add ut for 10137

pkg/sink/cloudstorage/path.go

@@ -225,19 +225,19 @@ func (f *FilePathGenerator) CheckOrWriteSchema(
 	}
 
 	// Case 2: the table meta path is not empty.
-	if schemaFileCnt != 0 {
-		if lastVersion == 0 {
-			log.Warn("no table schema file found in an non-empty meta path",
-				zap.Any("versionedTableName", table),
-				zap.Uint32("checksum", checksum))
-		}
+	if schemaFileCnt != 0 && lastVersion != 0 {
 		f.versionMap[table] = lastVersion
 		return nil
 	}
 
 	// Case 3: the table meta path is empty, which happens when:
 	//  a. the table is existed before changefeed started. We need to write schema file to external storage.
 	//  b. the schema file is deleted by the consumer. We write schema file to external storage too.
+	if schemaFileCnt != 0 && lastVersion == 0 {
+		log.Warn("no table schema file found in an non-empty meta path",
+			zap.Any("versionedTableName", table),
+			zap.Uint32("checksum", checksum))
+	}
 	encodedDetail, err := def.MarshalWithQuery()
 	if err != nil {
 		return err

pkg/sink/cloudstorage/path_test.go

@@ -22,6 +22,7 @@ import (
 	"testing"
 	"time"
 
+	"github.com/google/uuid"
 	timodel "github.com/pingcap/tidb/parser/model"
 	"github.com/pingcap/tidb/parser/mysql"
 	"github.com/pingcap/tidb/parser/types"
@@ -325,9 +326,25 @@ func TestCheckOrWriteSchema(t *testing.T) {
 	require.Equal(t, tableInfo.Version, f.versionMap[table])
 
 	dir = filepath.Join(dir, "test/table1/meta")
-	cnt, err := os.ReadDir(dir)
+	files, err := os.ReadDir(dir)
 	require.NoError(t, err)
-	require.Equal(t, 1, len(cnt))
+	require.Equal(t, 1, len(files))
+
+	// test schema file is invalid
+	err = os.WriteFile(filepath.Join(dir,
+		fmt.Sprintf("%s.tmp.%s", files[0].Name(), uuid.NewString())),
+		[]byte("invalid"), 0o644)
+	require.NoError(t, err)
+	err = os.Remove(filepath.Join(dir, files[0].Name()))
+	require.NoError(t, err)
+	delete(f.versionMap, table)
+	err = f.CheckOrWriteSchema(ctx, table, tableInfo)
+	require.NoError(t, err)
+	require.Equal(t, table.TableInfoVersion, f.versionMap[table])
+
+	files, err = os.ReadDir(dir)
+	require.NoError(t, err)
+	require.Equal(t, 2, len(files))
 }
 
 func TestRemoveExpiredFilesWithoutPartition(t *testing.T) {