backup: Write LATEST file for increments

There's no reason to distinguish between a full backup and an increment.
So let's just treat all steps an increments.

2 files changed, 36 insertions, 25 deletions

diff --git a/internal/backup/locator.go b/internal/backup/locator.go
index bb9b0eb68..5ef75f7d3 100644
--- a/internal/backup/locator.go
+++ b/internal/backup/locator.go
@@ -59,10 +59,11 @@ func (l LegacyLocator) newFull(repo *gitalypb.Repository) *Step {
 // file named LATEST.
 //
 // Structure:
-//   <repo relative path>/<backup id>/full.bundle
-//   <repo relative path>/<backup id>/full.refs
-//   <repo relative path>/<backup id>/custom_hooks.tar
 //   <repo relative path>/LATEST
+//   <repo relative path>/<backup id>/LATEST
+//   <repo relative path>/<backup id>/<nnn>.bundle
+//   <repo relative path>/<backup id>/<nnn>.refs
+//   <repo relative path>/<backup id>/<nnn>.custom_hooks.tar
 type PointerLocator struct {
 	Sink     Sink
 	Fallback Locator
@@ -73,9 +74,9 @@ func (l PointerLocator) BeginFull(ctx context.Context, repo *gitalypb.Repository
 	backupPath := strings.TrimSuffix(repo.RelativePath, ".git")
 
 	return &Step{
-		BundlePath:      filepath.Join(backupPath, backupID, "full.bundle"),
-		RefPath:         filepath.Join(backupPath, backupID, "full.refs"),
-		CustomHooksPath: filepath.Join(backupPath, backupID, "custom_hooks.tar"),
+		BundlePath:      filepath.Join(backupPath, backupID, "001.bundle"),
+		RefPath:         filepath.Join(backupPath, backupID, "001.refs"),
+		CustomHooksPath: filepath.Join(backupPath, backupID, "001.custom_hooks.tar"),
 	}
 }
 
@@ -84,7 +85,13 @@ func (l PointerLocator) CommitFull(ctx context.Context, full *Step) error {
 	bundleDir := filepath.Dir(full.BundlePath)
 	backupID := filepath.Base(bundleDir)
 	backupPath := filepath.Dir(bundleDir)
-	return l.commitLatestID(ctx, backupPath, backupID)
+	if err := l.writeLatest(ctx, bundleDir, "001"); err != nil {
+		return err
+	}
+	if err := l.writeLatest(ctx, backupPath, backupID); err != nil {
+		return err
+	}
+	return nil
 }
 
 // FindLatest returns the paths committed by the latest call to CommitFull.
@@ -104,9 +111,9 @@ func (l PointerLocator) FindLatest(ctx context.Context, repo *gitalypb.Repositor
 	return &Backup{
 		Steps: []Step{
 			{
-				BundlePath:      filepath.Join(backupPath, backupID, "full.bundle"),
-				RefPath:         filepath.Join(backupPath, backupID, "full.refs"),
-				CustomHooksPath: filepath.Join(backupPath, backupID, "custom_hooks.tar"),
+				BundlePath:      filepath.Join(backupPath, backupID, "001.bundle"),
+				RefPath:         filepath.Join(backupPath, backupID, "001.refs"),
+				CustomHooksPath: filepath.Join(backupPath, backupID, "001.custom_hooks.tar"),
 			},
 		},
 	}, nil
@@ -127,10 +134,10 @@ func (l PointerLocator) findLatestID(ctx context.Context, backupPath string) (st
 	return text.ChompBytes(latest), nil
 }
 
-func (l PointerLocator) commitLatestID(ctx context.Context, backupPath, backupID string) error {
-	latest := strings.NewReader(backupID)
-	if err := l.Sink.Write(ctx, filepath.Join(backupPath, "LATEST"), latest); err != nil {
-		return fmt.Errorf("commit latest ID: %w", err)
+func (l PointerLocator) writeLatest(ctx context.Context, path, target string) error {
+	latest := strings.NewReader(target)
+	if err := l.Sink.Write(ctx, filepath.Join(path, "LATEST"), latest); err != nil {
+		return fmt.Errorf("write latest: %w", err)
 	}
 	return nil
 }
diff --git a/internal/backup/locator_test.go b/internal/backup/locator_test.go
index c081e2584..cc39bf66f 100644
--- a/internal/backup/locator_test.go
+++ b/internal/backup/locator_test.go
@@ -68,10 +68,11 @@ func TestPointerLocator(t *testing.T) {
 		ctx, cancel := testhelper.Context()
 		defer cancel()
 
+		const expectedIncrement = "001"
 		expected := &Step{
-			BundlePath:      filepath.Join(repo.RelativePath, backupID, "full.bundle"),
-			RefPath:         filepath.Join(repo.RelativePath, backupID, "full.refs"),
-			CustomHooksPath: filepath.Join(repo.RelativePath, backupID, "custom_hooks.tar"),
+			BundlePath:      filepath.Join(repo.RelativePath, backupID, expectedIncrement+".bundle"),
+			RefPath:         filepath.Join(repo.RelativePath, backupID, expectedIncrement+".refs"),
+			CustomHooksPath: filepath.Join(repo.RelativePath, backupID, expectedIncrement+".custom_hooks.tar"),
 		}
 
 		full := l.BeginFull(ctx, repo, backupID)
@@ -79,8 +80,11 @@ func TestPointerLocator(t *testing.T) {
 
 		require.NoError(t, l.CommitFull(ctx, full))
 
-		pointer := testhelper.MustReadFile(t, filepath.Join(backupPath, repo.RelativePath, "LATEST"))
-		require.Equal(t, backupID, string(pointer))
+		backupPointer := testhelper.MustReadFile(t, filepath.Join(backupPath, repo.RelativePath, "LATEST"))
+		require.Equal(t, backupID, string(backupPointer))
+
+		incrementPointer := testhelper.MustReadFile(t, filepath.Join(backupPath, repo.RelativePath, backupID, "LATEST"))
+		require.Equal(t, expectedIncrement, string(incrementPointer))
 	})
 
 	t.Run("FindLatest", func(t *testing.T) {
@@ -101,9 +105,9 @@ func TestPointerLocator(t *testing.T) {
 			expected := &Backup{
 				Steps: []Step{
 					{
-						BundlePath:      filepath.Join(repo.RelativePath, backupID, "full.bundle"),
-						RefPath:         filepath.Join(repo.RelativePath, backupID, "full.refs"),
-						CustomHooksPath: filepath.Join(repo.RelativePath, backupID, "custom_hooks.tar"),
+						BundlePath:      filepath.Join(repo.RelativePath, backupID, "001.bundle"),
+						RefPath:         filepath.Join(repo.RelativePath, backupID, "001.refs"),
+						CustomHooksPath: filepath.Join(repo.RelativePath, backupID, "001.custom_hooks.tar"),
 					},
 				},
 			}
@@ -143,9 +147,9 @@ func TestPointerLocator(t *testing.T) {
 			expected := &Backup{
 				Steps: []Step{
 					{
-						BundlePath:      filepath.Join(repo.RelativePath, backupID, "full.bundle"),
-						RefPath:         filepath.Join(repo.RelativePath, backupID, "full.refs"),
-						CustomHooksPath: filepath.Join(repo.RelativePath, backupID, "custom_hooks.tar"),
+						BundlePath:      filepath.Join(repo.RelativePath, backupID, "001.bundle"),
+						RefPath:         filepath.Join(repo.RelativePath, backupID, "001.refs"),
+						CustomHooksPath: filepath.Join(repo.RelativePath, backupID, "001.custom_hooks.tar"),
 					},
 				},
 			}