lib/{fs,mergeset,storage}: substitute os.Open()+os.File.Readdir() with os.ReadDir()

This simplifies code a bit

lib/fs/fs.go

@@ -247,21 +247,16 @@ var atomicDirRemoveCounter = uint64(time.Now().UnixNano())
 //
 // Such directories may be left on unclean shutdown during MustRemoveDirAtomic call.
 func MustRemoveTemporaryDirs(dir string) {
-	d, err := os.Open(dir)
+	des, err := os.ReadDir(dir)
 	if err != nil {
-		logger.Panicf("FATAL: cannot open dir: %s", err)
+		logger.Panicf("FATAL: cannot read dir: %s", err)
 	}
-	defer MustClose(d)
+	for _, de := range des {
-	fis, err := d.Readdir(-1)
+		if !IsDirOrSymlink(de) {
-	if err != nil {
-		logger.Panicf("FATAL: cannot read dir %q: %s", dir, err)
-	}
-	for _, fi := range fis {
-		if !IsDirOrSymlink(fi) {
 			// Skip non-directories
 			continue
 		}
-		dirName := fi.Name()
+		dirName := de.Name()
 		if IsScheduledForRemoval(dirName) {
 			fullPath := dir + "/" + dirName
 			MustRemoveAll(fullPath)
@@ -276,26 +271,16 @@ func HardLinkFiles(srcDir, dstDir string) error {
 		return fmt.Errorf("cannot create dstDir=%q: %w", dstDir, err)
 	}
 
-	d, err := os.Open(srcDir)
+	des, err := os.ReadDir(srcDir)
 	if err != nil {
-		return fmt.Errorf("cannot open srcDir: %w", err)
+		return fmt.Errorf("cannot read files in scrDir: %w", err)
 	}
-	defer func() {
+	for _, de := range des {
-		if err := d.Close(); err != nil {
+		if IsDirOrSymlink(de) {
-			logger.Panicf("FATAL: cannot close %q: %s", srcDir, err)
-		}
-	}()
-
-	fis, err := d.Readdir(-1)
-	if err != nil {
-		return fmt.Errorf("cannot read files in scrDir=%q: %w", srcDir, err)
-	}
-	for _, fi := range fis {
-		if IsDirOrSymlink(fi) {
 			// Skip directories.
 			continue
 		}
-		fn := fi.Name()
+		fn := de.Name()
 		srcPath := srcDir + "/" + fn
 		dstPath := dstDir + "/" + fn
 		if err := os.Link(srcPath, dstPath); err != nil {
@@ -307,9 +292,9 @@ func HardLinkFiles(srcDir, dstDir string) error {
 	return nil
 }
 
-// IsDirOrSymlink returns true if fi is directory or symlink.
+// IsDirOrSymlink returns true if de is directory or symlink.
-func IsDirOrSymlink(fi os.FileInfo) bool {
+func IsDirOrSymlink(de os.DirEntry) bool {
-	return fi.IsDir() || (fi.Mode()&os.ModeSymlink == os.ModeSymlink)
+	return de.IsDir() || (de.Type()&os.ModeSymlink == os.ModeSymlink)
 }
 
 // SymlinkRelative creates relative symlink for srcPath in dstPath.

lib/mergeset/table.go

@@ -1426,11 +1426,6 @@ func openParts(path string) ([]*partWrapper, error) {
 		return nil, err
 	}
 	fs.MustRemoveTemporaryDirs(path)
-	d, err := os.Open(path)
-	if err != nil {
-		return nil, fmt.Errorf("cannot open difrectory: %w", err)
-	}
-	defer fs.MustClose(d)
 
 	// Run remaining transactions and cleanup /txn and /tmp directories.
 	// Snapshots cannot be created yet, so use fakeSnapshotLock.
@@ -1454,17 +1449,17 @@ func openParts(path string) ([]*partWrapper, error) {
 	fs.MustSyncPath(path)
 
 	// Open parts.
-	fis, err := d.Readdir(-1)
+	des, err := os.ReadDir(path)
 	if err != nil {
 		return nil, fmt.Errorf("cannot read directory: %w", err)
 	}
 	var pws []*partWrapper
-	for _, fi := range fis {
+	for _, de := range des {
-		if !fs.IsDirOrSymlink(fi) {
+		if !fs.IsDirOrSymlink(de) {
 			// Skip non-directories.
 			continue
 		}
-		fn := fi.Name()
+		fn := de.Name()
 		if isSpecialDir(fn) {
 			// Skip special dirs.
 			continue
@@ -1538,24 +1533,18 @@ func (tb *Table) CreateSnapshotAt(dstDir string, deadline uint64) error {
 		return fmt.Errorf("cannot create snapshot dir %q: %w", dstDir, err)
 	}
 
-	d, err := os.Open(srcDir)
+	des, err := os.ReadDir(srcDir)
-	if err != nil {
-		return fmt.Errorf("cannot open difrectory: %w", err)
-	}
-	defer fs.MustClose(d)
-
-	fis, err := d.Readdir(-1)
 	if err != nil {
 		return fmt.Errorf("cannot read directory: %w", err)
 	}
 
-	for _, fi := range fis {
+	for _, de := range des {
 		if deadline > 0 && fasttime.UnixTimestamp() > deadline {
 			return fmt.Errorf("cannot create snapshot for %q: timeout exceeded", tb.path)
 		}
 
-		fn := fi.Name()
+		fn := de.Name()
-		if !fs.IsDirOrSymlink(fi) {
+		if !fs.IsDirOrSymlink(de) {
 			// Skip non-directories.
 			continue
 		}
@@ -1586,27 +1575,21 @@ func runTransactions(txnLock *sync.RWMutex, path string) error {
 	defer pendingTxnDeletionsWG.Wait()
 
 	txnDir := path + "/txn"
-	d, err := os.Open(txnDir)
+	des, err := os.ReadDir(txnDir)
 	if err != nil {
 		if os.IsNotExist(err) {
 			return nil
 		}
-		return fmt.Errorf("cannot open transaction dir: %w", err)
+		return fmt.Errorf("cannot read transaction dir: %w", err)
-	}
-	defer fs.MustClose(d)
-
-	fis, err := d.Readdir(-1)
-	if err != nil {
-		return fmt.Errorf("cannot read directory %q: %w", d.Name(), err)
 	}
 
 	// Sort transaction files by id, since transactions must be ordered.
-	sort.Slice(fis, func(i, j int) bool {
+	sort.Slice(des, func(i, j int) bool {
-		return fis[i].Name() < fis[j].Name()
+		return des[i].Name() < des[j].Name()
 	})
 
-	for _, fi := range fis {
+	for _, de := range des {
-		fn := fi.Name()
+		fn := de.Name()
 		if fs.IsTemporaryFileName(fn) {
 			// Skip temporary files, which could be left after unclean shutdown.
 			continue

lib/storage/partition.go

@@ -1889,11 +1889,6 @@ func openParts(pathPrefix1, pathPrefix2, path string) ([]*partWrapper, error) {
 		return nil, err
 	}
 	fs.MustRemoveTemporaryDirs(path)
-	d, err := os.Open(path)
-	if err != nil {
-		return nil, fmt.Errorf("cannot open partition directory: %w", err)
-	}
-	defer fs.MustClose(d)
 
 	// Run remaining transactions and cleanup /txn and /tmp directories.
 	// Snapshots cannot be created yet, so use fakeSnapshotLock.
@@ -1911,17 +1906,17 @@ func openParts(pathPrefix1, pathPrefix2, path string) ([]*partWrapper, error) {
 	}
 
 	// Open parts.
-	fis, err := d.Readdir(-1)
+	des, err := os.ReadDir(path)
 	if err != nil {
-		return nil, fmt.Errorf("cannot read directory %q: %w", d.Name(), err)
+		return nil, fmt.Errorf("cannot read partition directory: %w", err)
 	}
 	var pws []*partWrapper
-	for _, fi := range fis {
+	for _, de := range des {
-		if !fs.IsDirOrSymlink(fi) {
+		if !fs.IsDirOrSymlink(de) {
 			// Skip non-directories.
 			continue
 		}
-		fn := fi.Name()
+		fn := de.Name()
 		if fn == "snapshots" {
 			// "snapshots" dir is skipped for backwards compatibility. Now it is unused.
 			continue
@@ -2000,19 +1995,13 @@ func (pt *partition) createSnapshot(srcDir, dstDir string) error {
 		return fmt.Errorf("cannot create snapshot dir %q: %w", dstDir, err)
 	}
 
-	d, err := os.Open(srcDir)
+	des, err := os.ReadDir(srcDir)
-	if err != nil {
-		return fmt.Errorf("cannot open partition difrectory: %w", err)
-	}
-	defer fs.MustClose(d)
-
-	fis, err := d.Readdir(-1)
 	if err != nil {
 		return fmt.Errorf("cannot read partition directory: %w", err)
 	}
-	for _, fi := range fis {
+	for _, de := range des {
-		fn := fi.Name()
+		fn := de.Name()
-		if !fs.IsDirOrSymlink(fi) {
+		if !fs.IsDirOrSymlink(de) {
 			if fn == "appliedRetention.txt" {
 				// Copy the appliedRetention.txt file to dstDir.
 				// This file can be created by VictoriaMetrics enterprise.
@@ -2052,27 +2041,21 @@ func runTransactions(txnLock *sync.RWMutex, pathPrefix1, pathPrefix2, path strin
 	defer pendingTxnDeletionsWG.Wait()
 
 	txnDir := path + "/txn"
-	d, err := os.Open(txnDir)
+	des, err := os.ReadDir(txnDir)
 	if err != nil {
 		if os.IsNotExist(err) {
 			return nil
 		}
-		return fmt.Errorf("cannot open transaction directory: %w", err)
+		return fmt.Errorf("cannot read transaction directory: %w", err)
-	}
-	defer fs.MustClose(d)
-
-	fis, err := d.Readdir(-1)
-	if err != nil {
-		return fmt.Errorf("cannot read directory %q: %w", d.Name(), err)
 	}
 
 	// Sort transaction files by id.
-	sort.Slice(fis, func(i, j int) bool {
+	sort.Slice(des, func(i, j int) bool {
-		return fis[i].Name() < fis[j].Name()
+		return des[i].Name() < des[j].Name()
 	})
 
-	for _, fi := range fis {
+	for _, de := range des {
-		fn := fi.Name()
+		fn := de.Name()
 		if fs.IsTemporaryFileName(fn) {
 			// Skip temporary files, which could be left after unclean shutdown.
 			continue

lib/storage/storage.go

@@ -2339,25 +2339,19 @@ func (s *Storage) openIndexDBTables(path string) (curr, prev *indexDB, err error
 	}
 	fs.MustRemoveTemporaryDirs(path)
 
-	d, err := os.Open(path)
-	if err != nil {
-		return nil, nil, fmt.Errorf("cannot open directory: %w", err)
-	}
-	defer fs.MustClose(d)
-
 	// Search for the two most recent tables - the last one is active,
 	// the previous one contains backup data.
-	fis, err := d.Readdir(-1)
+	des, err := os.ReadDir(path)
 	if err != nil {
 		return nil, nil, fmt.Errorf("cannot read directory: %w", err)
 	}
 	var tableNames []string
-	for _, fi := range fis {
+	for _, de := range des {
-		if !fs.IsDirOrSymlink(fi) {
+		if !fs.IsDirOrSymlink(de) {
 			// Skip non-directories.
 			continue
 		}
-		tableName := fi.Name()
+		tableName := de.Name()
 		if !indexDBTableNameRegexp.MatchString(tableName) {
 			// Skip invalid directories.
 			continue

lib/storage/table.go

@@ -535,22 +535,16 @@ func openPartitions(smallPartitionsPath, bigPartitionsPath string, s *Storage) (
 }
 
 func populatePartitionNames(partitionsPath string, ptNames map[string]bool) error {
-	d, err := os.Open(partitionsPath)
+	des, err := os.ReadDir(partitionsPath)
 	if err != nil {
-		return fmt.Errorf("cannot open directory with partitions: %w", err)
+		return fmt.Errorf("cannot read directory with partitions: %w", err)
 	}
-	defer fs.MustClose(d)
+	for _, de := range des {
-
+		if !fs.IsDirOrSymlink(de) {
-	fis, err := d.Readdir(-1)
-	if err != nil {
-		return fmt.Errorf("cannot read directory with partitions %q: %w", partitionsPath, err)
-	}
-	for _, fi := range fis {
-		if !fs.IsDirOrSymlink(fi) {
 			// Skip non-directories
 			continue
 		}
-		ptName := fi.Name()
+		ptName := de.Name()
 		if ptName == "snapshots" {
 			// Skip directory with snapshots
 			continue