Merge pull request #443 from ahrtr/surgery_abandon_freelist_20230330

cmd: add `surgery abandon-freelist` command

Author: ahrtr

cmd/bbolt/command_surgery_cobra.go

@@ -19,14 +19,15 @@ var (
 )
 
 func newSurgeryCobraCommand() *cobra.Command {
-	cmd := &cobra.Command{
+	surgeryCmd := &cobra.Command{
 		Use:   "surgery <subcommand>",
 		Short: "surgery related commands",
 	}
 
-	cmd.AddCommand(newSurgeryClearPageElementsCommand())
+	surgeryCmd.AddCommand(newSurgeryClearPageElementsCommand())
+	surgeryCmd.AddCommand(newSurgeryFreelistCommand())
 
-	return cmd
+	return surgeryCmd
 }
 
 func newSurgeryClearPageElementsCommand() *cobra.Command {
@@ -42,7 +43,6 @@ func newSurgeryClearPageElementsCommand() *cobra.Command {
 			}
 			return nil
 		},
-
 		RunE: surgeryClearPageElementFunc,
 	}
 
@@ -78,3 +78,53 @@ func surgeryClearPageElementFunc(cmd *cobra.Command, args []string) error {
 	fmt.Fprintf(os.Stdout, "All elements in [%d, %d) in page %d were cleared\n", surgeryStartElementIdx, surgeryEndElementIdx, surgeryPageId)
 	return nil
 }
+
+// TODO(ahrtr): add `bbolt surgery freelist rebuild/check ...` commands,
+// and move all `surgery freelist` commands into a separate file,
+// e.g command_surgery_freelist.go.
+func newSurgeryFreelistCommand() *cobra.Command {
+	cmd := &cobra.Command{
+		Use:   "freelist <subcommand>",
+		Short: "freelist related surgery commands",
+	}
+
+	cmd.AddCommand(newSurgeryFreelistAbandonCommand())
+
+	return cmd
+}
+
+func newSurgeryFreelistAbandonCommand() *cobra.Command {
+	abandonFreelistCmd := &cobra.Command{
+		Use:   "abandon <bbolt-file> [options]",
+		Short: "Abandon the freelist from both meta pages",
+		Args: func(cmd *cobra.Command, args []string) error {
+			if len(args) == 0 {
+				return errors.New("db file path not provided")
+			}
+			if len(args) > 1 {
+				return errors.New("too many arguments")
+			}
+			return nil
+		},
+		RunE: surgeryFreelistAbandonFunc,
+	}
+
+	abandonFreelistCmd.Flags().StringVar(&surgeryTargetDBFilePath, "output", "", "path to the target db file")
+
+	return abandonFreelistCmd
+}
+
+func surgeryFreelistAbandonFunc(cmd *cobra.Command, args []string) error {
+	srcDBPath := args[0]
+
+	if err := copyFile(srcDBPath, surgeryTargetDBFilePath); err != nil {
+		return fmt.Errorf("[abandon-freelist] copy file failed: %w", err)
+	}
+
+	if err := surgeon.ClearFreelist(surgeryTargetDBFilePath); err != nil {
+		return fmt.Errorf("abandom-freelist command failed: %w", err)
+	}
+
+	fmt.Fprintf(os.Stdout, "The freelist was abandoned in both meta pages.\nIt may cause some delay on next startup because bbolt needs to scan the whole db to reconstruct the free list.\n")
+	return nil
+}

cmd/bbolt/command_surgery_cobra_test.go

@@ -11,6 +11,7 @@ import (
 	bolt "go.etcd.io/bbolt"
 	main "go.etcd.io/bbolt/cmd/bbolt"
 	"go.etcd.io/bbolt/internal/btesting"
+	"go.etcd.io/bbolt/internal/common"
 	"go.etcd.io/bbolt/internal/guts_cli"
 )
 
@@ -428,3 +429,31 @@ func testSurgeryClearPageElementsWithOverflow(t *testing.T, startIdx, endIdx int
 
 	compareDataAfterClearingElement(t, srcPath, output, pageId, false, startIdx, endIdx)
 }
+
+func TestSurgery_Freelist_Abandon(t *testing.T) {
+	pageSize := 4096
+	db := btesting.MustCreateDBWithOption(t, &bolt.Options{PageSize: pageSize})
+	srcPath := db.Path()
+
+	defer requireDBNoChange(t, dbData(t, srcPath), srcPath)
+
+	rootCmd := main.NewRootCommand()
+	output := filepath.Join(t.TempDir(), "db")
+	rootCmd.SetArgs([]string{
+		"surgery", "freelist", "abandon", srcPath,
+		"--output", output,
+	})
+	err := rootCmd.Execute()
+	require.NoError(t, err)
+
+	meta0 := loadMetaPage(t, output, 0)
+	assert.Equal(t, common.PgidNoFreelist, meta0.Freelist())
+	meta1 := loadMetaPage(t, output, 1)
+	assert.Equal(t, common.PgidNoFreelist, meta1.Freelist())
+}
+
+func loadMetaPage(t *testing.T, dbPath string, pageID uint64) *common.Meta {
+	_, buf, err := guts_cli.ReadPage(dbPath, 0)
+	require.NoError(t, err)
+	return common.LoadPageMeta(buf)
+}

internal/surgeon/surgeon.go

@@ -104,15 +104,15 @@ func ClearPageElements(path string, pgId common.Pgid, start, end int, abandonFre
 
 	if preOverflow != p.Overflow() || p.IsBranchPage() {
 		if abandonFreelist {
-			return false, clearFreelist(path)
+			return false, ClearFreelist(path)
 		}
 		return true, nil
 	}
 
 	return false, nil
 }
 
-func clearFreelist(path string) error {
+func ClearFreelist(path string) error {
 	if err := clearFreelistInMetaPage(path, 0); err != nil {
 		return fmt.Errorf("clearFreelist on meta page 0 failed: %w", err)
 	}