fix: bring back delayed leaf detection in listing (#10346)

cmd/api-response.go

@@ -36,7 +36,7 @@ import (
 const (
 	// RFC3339 a subset of the ISO8601 timestamp format. e.g 2014-04-29T18:30:38Z
 	iso8601TimeFormat = "2006-01-02T15:04:05.000Z" // Reply date format with nanosecond precision.
-	maxObjectList     = 10000                      // Limit number of objects in a listObjectsResponse/listObjectsVersionsResponse.
+	maxObjectList     = 1000                       // Limit number of objects in a listObjectsResponse/listObjectsVersionsResponse.
 	maxDeleteList     = 10000                      // Limit number of objects deleted in a delete call.
 	maxUploadsList    = 10000                      // Limit number of uploads in a listUploadsResponse.
 	maxPartsList      = 10000                      // Limit number of parts in a listPartsResponse.

cmd/erasure-sets.go

@@ -838,9 +838,17 @@ func (f *FileInfoCh) Push(fi FileInfo) {
 // if the caller wishes to list N entries to call lexicallySortedEntry
 // N times until this boolean is 'false'.
 func lexicallySortedEntry(entryChs []FileInfoCh, entries []FileInfo, entriesValid []bool) (FileInfo, int, bool) {
-	for i := range entryChs {
-		entries[i], entriesValid[i] = entryChs[i].Pop()
+	var wg sync.WaitGroup
+	for j := range entryChs {
+		j := j
+		wg.Add(1)
+		// Pop() entries in parallel for large drive setups.
+		go func() {
+			defer wg.Done()
+			entries[j], entriesValid[j] = entryChs[j].Pop()
+		}()
 	}
+	wg.Wait()
 
 	var isTruncated = false
 	for _, valid := range entriesValid {
@@ -902,9 +910,17 @@ func lexicallySortedEntry(entryChs []FileInfoCh, entries []FileInfo, entriesVali
 // if the caller wishes to list N entries to call lexicallySortedEntry
 // N times until this boolean is 'false'.
 func lexicallySortedEntryVersions(entryChs []FileInfoVersionsCh, entries []FileInfoVersions, entriesValid []bool) (FileInfoVersions, int, bool) {
-	for i := range entryChs {
-		entries[i], entriesValid[i] = entryChs[i].Pop()
+	var wg sync.WaitGroup
+	for j := range entryChs {
+		j := j
+		wg.Add(1)
+		// Pop() entries in parallel for large drive setups.
+		go func() {
+			defer wg.Done()
+			entries[j], entriesValid[j] = entryChs[j].Pop()
+		}()
 	}
+	wg.Wait()
 
 	var isTruncated = false
 	for _, valid := range entriesValid {

cmd/fs-v1.go

@@ -1334,23 +1334,31 @@ func (fs *FSObjects) DeleteObject(ctx context.Context, bucket, object string, op
 	return ObjectInfo{Bucket: bucket, Name: object}, nil
 }
 
+func (fs *FSObjects) isLeafDir(bucket string, leafPath string) bool {
+	return fs.isObjectDir(bucket, leafPath)
+}
+
+func (fs *FSObjects) isLeaf(bucket string, leafPath string) bool {
+	return !strings.HasSuffix(leafPath, slashSeparator)
+}
+
 // Returns function "listDir" of the type listDirFunc.
 // isLeaf - is used by listDir function to check if an entry
 // is a leaf or non-leaf entry.
 func (fs *FSObjects) listDirFactory() ListDirFunc {
 	// listDir - lists all the entries at a given prefix and given entry in the prefix.
-	listDir := func(bucket, prefixDir, prefixEntry string) (emptyDir bool, entries []string) {
+	listDir := func(bucket, prefixDir, prefixEntry string) (emptyDir bool, entries []string, delayIsLeaf bool) {
 		var err error
 		entries, err = readDir(pathJoin(fs.fsPath, bucket, prefixDir))
 		if err != nil && err != errFileNotFound {
 			logger.LogIf(GlobalContext, err)
-			return false, nil
+			return false, nil, false
 		}
 		if len(entries) == 0 {
-			return true, nil
+			return true, nil, false
 		}
-		sort.Strings(entries)
-		return false, filterMatchingPrefix(entries, prefixEntry)
+		entries, delayIsLeaf = filterListEntries(bucket, prefixDir, entries, prefixEntry, fs.isLeaf)
+		return false, entries, delayIsLeaf
 	}
 
 	// Return list factory instance.
@@ -1453,7 +1461,7 @@ func (fs *FSObjects) ListObjects(ctx context.Context, bucket, prefix, marker, de
 	}()
 
 	return listObjects(ctx, fs, bucket, prefix, marker, delimiter, maxKeys, fs.listPool,
-		fs.listDirFactory(), fs.getObjectInfoNoFSLock, fs.getObjectInfoNoFSLock)
+		fs.listDirFactory(), fs.isLeaf, fs.isLeafDir, fs.getObjectInfoNoFSLock, fs.getObjectInfoNoFSLock)
 }
 
 // GetObjectTags - get object tags from an existing object
@@ -1550,7 +1558,7 @@ func (fs *FSObjects) HealBucket(ctx context.Context, bucket string, dryRun, remo
 // error walker returns error. Optionally if context.Done() is received
 // then Walk() stops the walker.
 func (fs *FSObjects) Walk(ctx context.Context, bucket, prefix string, results chan<- ObjectInfo, opts ObjectOptions) error {
-	return fsWalk(ctx, fs, bucket, prefix, fs.listDirFactory(), results, fs.getObjectInfoNoFSLock, fs.getObjectInfoNoFSLock)
+	return fsWalk(ctx, fs, bucket, prefix, fs.listDirFactory(), fs.isLeaf, fs.isLeafDir, results, fs.getObjectInfoNoFSLock, fs.getObjectInfoNoFSLock)
 }
 
 // HealObjects - no-op for fs. Valid only for Erasure.

cmd/gateway-common.go

@@ -48,8 +48,8 @@ var (
 	// ListObjects function alias.
 	ListObjects = listObjects
 
-	// FilterMatchingPrefix function alias.
-	FilterMatchingPrefix = filterMatchingPrefix
+	// FilterListEntries function alias.
+	FilterListEntries = filterListEntries
 
 	// IsStringEqual is string equal.
 	IsStringEqual = isStringEqual

cmd/gateway/hdfs/gateway-hdfs.go

@@ -348,9 +348,17 @@ func (n *hdfsObjects) ListBuckets(ctx context.Context) (buckets []minio.BucketIn
 	return buckets, nil
 }
 
+func (n *hdfsObjects) isLeafDir(bucket, leafPath string) bool {
+	return n.isObjectDir(context.Background(), bucket, leafPath)
+}
+
+func (n *hdfsObjects) isLeaf(bucket, leafPath string) bool {
+	return !strings.HasSuffix(leafPath, hdfsSeparator)
+}
+
 func (n *hdfsObjects) listDirFactory() minio.ListDirFunc {
 	// listDir - lists all the entries at a given prefix and given entry in the prefix.
-	listDir := func(bucket, prefixDir, prefixEntry string) (emptyDir bool, entries []string) {
+	listDir := func(bucket, prefixDir, prefixEntry string) (emptyDir bool, entries []string, delayIsLeaf bool) {
 		f, err := n.clnt.Open(n.hdfsPathJoin(bucket, prefixDir))
 		if err != nil {
 			if os.IsNotExist(err) {
@@ -366,7 +374,7 @@ func (n *hdfsObjects) listDirFactory() minio.ListDirFunc {
 			return
 		}
 		if len(fis) == 0 {
-			return true, nil
+			return true, nil, false
 		}
 		for _, fi := range fis {
 			if fi.IsDir() {
@@ -375,7 +383,8 @@ func (n *hdfsObjects) listDirFactory() minio.ListDirFunc {
 				entries = append(entries, fi.Name())
 			}
 		}
-		return false, minio.FilterMatchingPrefix(entries, prefixEntry)
+		entries, delayIsLeaf = minio.FilterListEntries(bucket, prefixDir, entries, prefixEntry, n.isLeaf)
+		return false, entries, delayIsLeaf
 	}
 
 	// Return list factory instance.
@@ -426,7 +435,7 @@ func (n *hdfsObjects) ListObjects(ctx context.Context, bucket, prefix, marker, d
 		return objectInfo, nil
 	}
 
-	return minio.ListObjects(ctx, n, bucket, prefix, marker, delimiter, maxKeys, n.listPool, n.listDirFactory(), getObjectInfo, getObjectInfo)
+	return minio.ListObjects(ctx, n, bucket, prefix, marker, delimiter, maxKeys, n.listPool, n.listDirFactory(), n.isLeaf, n.isLeafDir, getObjectInfo, getObjectInfo)
 }
 
 // Lists a path's direct, first-level entries and populates them in the `fileInfos` cache which maps

cmd/object-api-common.go

@@ -139,11 +139,11 @@ func cleanupDir(ctx context.Context, storage StorageAPI, volume, dirPath string)
 	return err
 }
 
-func listObjectsNonSlash(ctx context.Context, bucket, prefix, marker, delimiter string, maxKeys int, tpool *TreeWalkPool, listDir ListDirFunc, getObjInfo func(context.Context, string, string) (ObjectInfo, error), getObjectInfoDirs ...func(context.Context, string, string) (ObjectInfo, error)) (loi ListObjectsInfo, err error) {
+func listObjectsNonSlash(ctx context.Context, bucket, prefix, marker, delimiter string, maxKeys int, tpool *TreeWalkPool, listDir ListDirFunc, isLeaf IsLeafFunc, isLeafDir IsLeafDirFunc, getObjInfo func(context.Context, string, string) (ObjectInfo, error), getObjectInfoDirs ...func(context.Context, string, string) (ObjectInfo, error)) (loi ListObjectsInfo, err error) {
 	endWalkCh := make(chan struct{})
 	defer close(endWalkCh)
 	recursive := true
-	walkResultCh := startTreeWalk(ctx, bucket, prefix, "", recursive, listDir, endWalkCh)
+	walkResultCh := startTreeWalk(ctx, bucket, prefix, "", recursive, listDir, isLeaf, isLeafDir, endWalkCh)
 
 	var objInfos []ObjectInfo
 	var eof bool
@@ -227,14 +227,14 @@ func listObjectsNonSlash(ctx context.Context, bucket, prefix, marker, delimiter
 // to allocate a receive channel for ObjectInfo, upon any unhandled
 // error walker returns error. Optionally if context.Done() is received
 // then Walk() stops the walker.
-func fsWalk(ctx context.Context, obj ObjectLayer, bucket, prefix string, listDir ListDirFunc, results chan<- ObjectInfo, getObjInfo func(context.Context, string, string) (ObjectInfo, error), getObjectInfoDirs ...func(context.Context, string, string) (ObjectInfo, error)) error {
+func fsWalk(ctx context.Context, obj ObjectLayer, bucket, prefix string, listDir ListDirFunc, isLeaf IsLeafFunc, isLeafDir IsLeafDirFunc, results chan<- ObjectInfo, getObjInfo func(context.Context, string, string) (ObjectInfo, error), getObjectInfoDirs ...func(context.Context, string, string) (ObjectInfo, error)) error {
 	if err := checkListObjsArgs(ctx, bucket, prefix, "", obj); err != nil {
 		// Upon error close the channel.
 		close(results)
 		return err
 	}
 
-	walkResultCh := startTreeWalk(ctx, bucket, prefix, "", true, listDir, ctx.Done())
+	walkResultCh := startTreeWalk(ctx, bucket, prefix, "", true, listDir, isLeaf, isLeafDir, ctx.Done())
 
 	go func() {
 		defer close(results)
@@ -277,9 +277,9 @@ func fsWalk(ctx context.Context, obj ObjectLayer, bucket, prefix string, listDir
 	return nil
 }
 
-func listObjects(ctx context.Context, obj ObjectLayer, bucket, prefix, marker, delimiter string, maxKeys int, tpool *TreeWalkPool, listDir ListDirFunc, getObjInfo func(context.Context, string, string) (ObjectInfo, error), getObjectInfoDirs ...func(context.Context, string, string) (ObjectInfo, error)) (loi ListObjectsInfo, err error) {
+func listObjects(ctx context.Context, obj ObjectLayer, bucket, prefix, marker, delimiter string, maxKeys int, tpool *TreeWalkPool, listDir ListDirFunc, isLeaf IsLeafFunc, isLeafDir IsLeafDirFunc, getObjInfo func(context.Context, string, string) (ObjectInfo, error), getObjectInfoDirs ...func(context.Context, string, string) (ObjectInfo, error)) (loi ListObjectsInfo, err error) {
 	if delimiter != SlashSeparator && delimiter != "" {
-		return listObjectsNonSlash(ctx, bucket, prefix, marker, delimiter, maxKeys, tpool, listDir, getObjInfo, getObjectInfoDirs...)
+		return listObjectsNonSlash(ctx, bucket, prefix, marker, delimiter, maxKeys, tpool, listDir, isLeaf, isLeafDir, getObjInfo, getObjectInfoDirs...)
 	}
 
 	if err := checkListObjsArgs(ctx, bucket, prefix, marker, obj); err != nil {
@@ -322,7 +322,7 @@ func listObjects(ctx context.Context, obj ObjectLayer, bucket, prefix, marker, d
 	walkResultCh, endWalkCh := tpool.Release(listParams{bucket, recursive, marker, prefix})
 	if walkResultCh == nil {
 		endWalkCh = make(chan struct{})
-		walkResultCh = startTreeWalk(ctx, bucket, prefix, marker, recursive, listDir, endWalkCh)
+		walkResultCh = startTreeWalk(ctx, bucket, prefix, marker, recursive, listDir, isLeaf, isLeafDir, endWalkCh)
 	}
 
 	var objInfos []ObjectInfo

cmd/os-readdir_unix.go

@@ -30,10 +30,10 @@ import (
 // refer https://github.com/golang/go/issues/24015
 const blockSize = 8 << 10 // 8192
 
-// By default atleast 1000 entries in single getdents call
+// By default atleast 20 entries in single getdents call
 var direntPool = sync.Pool{
 	New: func() interface{} {
-		buf := make([]byte, blockSize*1000)
+		buf := make([]byte, blockSize*20)
 		return &buf
 	},
 }

cmd/tree-walk.go

@@ -51,15 +51,84 @@ func filterMatchingPrefix(entries []string, prefixEntry string) []string {
 		}
 		end--
 	}
-	sort.Strings(entries[start:end])
 	return entries[start:end]
 }
 
+// xl.ListDir returns entries with trailing "/" for directories. At the object layer
+// we need to remove this trailing "/" for objects and retain "/" for prefixes before
+// sorting because the trailing "/" can affect the sorting results for certain cases.
+// Ex. lets say entries = ["a-b/", "a/"] and both are objects.
+//     sorting with out trailing "/" = ["a", "a-b"]
+//     sorting with trailing "/"     = ["a-b/", "a/"]
+// Hence if entries[] does not have a case like the above example then isLeaf() check
+// can be delayed till the entry is pushed into the TreeWalkResult channel.
+// delayIsLeafCheck() returns true if isLeaf can be delayed or false if
+// isLeaf should be done in listDir()
+func delayIsLeafCheck(entries []string) bool {
+	for i, entry := range entries {
+		if i == len(entries)-1 {
+			break
+		}
+		// If any byte in the "entry" string is less than '/' then the
+		// next "entry" should not contain '/' at the same same byte position.
+		for j := 0; j < len(entry); j++ {
+			if entry[j] < '/' {
+				if len(entries[i+1]) > j {
+					if entries[i+1][j] == '/' {
+						return false
+					}
+				}
+			}
+		}
+	}
+	return true
+}
+
 // ListDirFunc - "listDir" function of type listDirFunc returned by listDirFactory() - explained below.
-type ListDirFunc func(bucket, prefixDir, prefixEntry string) (emptyDir bool, entries []string)
+type ListDirFunc func(bucket, prefixDir, prefixEntry string) (emptyDir bool, entries []string, delayIsLeaf bool)
+
+// IsLeafFunc - A function isLeaf of type isLeafFunc is used to detect if an
+// entry is a leaf entry. There are 2 scenarios where isLeaf should behave
+// differently depending on the backend:
+// 1. FS backend object listing - isLeaf is true if the entry
+//    has no trailing "/"
+// 2. Erasure backend object listing - isLeaf is true if the entry
+//    is a directory and contains xl.meta
+type IsLeafFunc func(string, string) bool
+
+// IsLeafDirFunc - A function isLeafDir of type isLeafDirFunc is used to detect
+// if an entry is empty directory.
+type IsLeafDirFunc func(string, string) bool
+
+func filterListEntries(bucket, prefixDir string, entries []string, prefixEntry string, isLeaf IsLeafFunc) ([]string, bool) {
+	// Listing needs to be sorted.
+	sort.Strings(entries)
+
+	// Filter entries that have the prefix prefixEntry.
+	entries = filterMatchingPrefix(entries, prefixEntry)
+
+	// Can isLeaf() check be delayed till when it has to be sent down the
+	// TreeWalkResult channel?
+	delayIsLeaf := delayIsLeafCheck(entries)
+	if delayIsLeaf {
+		return entries, true
+	}
+
+	// isLeaf() check has to happen here so that trailing "/" for objects can be removed.
+	for i, entry := range entries {
+		if isLeaf(bucket, pathJoin(prefixDir, entry)) {
+			entries[i] = strings.TrimSuffix(entry, slashSeparator)
+		}
+	}
+
+	// Sort again after removing trailing "/" for objects as the previous sort
+	// does not hold good anymore.
+	sort.Strings(entries)
+	return entries, false
+}
 
 // treeWalk walks directory tree recursively pushing TreeWalkResult into the channel as and when it encounters files.
-func doTreeWalk(ctx context.Context, bucket, prefixDir, entryPrefixMatch, marker string, recursive bool, listDir ListDirFunc, resultCh chan TreeWalkResult, endWalkCh <-chan struct{}, isEnd bool) (emptyDir bool, treeErr error) {
+func doTreeWalk(ctx context.Context, bucket, prefixDir, entryPrefixMatch, marker string, recursive bool, listDir ListDirFunc, isLeaf IsLeafFunc, isLeafDir IsLeafDirFunc, resultCh chan TreeWalkResult, endWalkCh <-chan struct{}, isEnd bool) (emptyDir bool, treeErr error) {
 	// Example:
 	// if prefixDir="one/two/three/" and marker="four/five.txt" treeWalk is recursively
 	// called with prefixDir="one/two/three/four/" and marker="five.txt"
@@ -75,7 +144,12 @@ func doTreeWalk(ctx context.Context, bucket, prefixDir, entryPrefixMatch, marker
 		}
 	}
 
-	emptyDir, entries := listDir(bucket, prefixDir, entryPrefixMatch)
+	emptyDir, entries, delayIsLeaf := listDir(bucket, prefixDir, entryPrefixMatch)
+	// When isleaf check is delayed, make sure that it is set correctly here.
+	if delayIsLeaf && isLeaf == nil || isLeafDir == nil {
+		return false, errInvalidArgument
+	}
+
 	// For an empty list return right here.
 	if emptyDir {
 		return true, nil
@@ -94,8 +168,23 @@ func doTreeWalk(ctx context.Context, bucket, prefixDir, entryPrefixMatch, marker
 	}
 
 	for i, entry := range entries {
-		pentry := pathJoin(prefixDir, entry)
-		isDir := HasSuffix(pentry, SlashSeparator)
+		var leaf, leafDir bool
+
+		// Decision to do isLeaf check was pushed from listDir() to here.
+		if delayIsLeaf {
+			leaf = isLeaf(bucket, pathJoin(prefixDir, entry))
+			if leaf {
+				entry = strings.TrimSuffix(entry, slashSeparator)
+			}
+		} else {
+			leaf = !strings.HasSuffix(entry, slashSeparator)
+		}
+
+		if strings.HasSuffix(entry, slashSeparator) {
+			leafDir = isLeafDir(bucket, pathJoin(prefixDir, entry))
+		}
+
+		isDir := !leafDir && !leaf
 
 		if i == 0 && markerDir == entry {
 			if !recursive {
@@ -123,8 +212,8 @@ func doTreeWalk(ctx context.Context, bucket, prefixDir, entryPrefixMatch, marker
 			// markIsEnd is passed to this entry's treeWalk() so that treeWalker.end can be marked
 			// true at the end of the treeWalk stream.
 			markIsEnd := i == len(entries)-1 && isEnd
-			emptyDir, err := doTreeWalk(ctx, bucket, pentry, prefixMatch, markerArg, recursive,
-				listDir, resultCh, endWalkCh, markIsEnd)
+			emptyDir, err := doTreeWalk(ctx, bucket, pathJoin(prefixDir, entry), prefixMatch, markerArg, recursive,
+				listDir, isLeaf, isLeafDir, resultCh, endWalkCh, markIsEnd)
 			if err != nil {
 				return false, err
 			}
@@ -142,7 +231,7 @@ func doTreeWalk(ctx context.Context, bucket, prefixDir, entryPrefixMatch, marker
 		select {
 		case <-endWalkCh:
 			return false, errWalkAbort
-		case resultCh <- TreeWalkResult{entry: pentry, end: isEOF}:
+		case resultCh <- TreeWalkResult{entry: pathJoin(prefixDir, entry), end: isEOF}:
 		}
 	}
 
@@ -151,7 +240,7 @@ func doTreeWalk(ctx context.Context, bucket, prefixDir, entryPrefixMatch, marker
 }
 
 // Initiate a new treeWalk in a goroutine.
-func startTreeWalk(ctx context.Context, bucket, prefix, marker string, recursive bool, listDir ListDirFunc, endWalkCh <-chan struct{}) chan TreeWalkResult {
+func startTreeWalk(ctx context.Context, bucket, prefix, marker string, recursive bool, listDir ListDirFunc, isLeaf IsLeafFunc, isLeafDir IsLeafDirFunc, endWalkCh <-chan struct{}) chan TreeWalkResult {
 	// Example 1
 	// If prefix is "one/two/three/" and marker is "one/two/three/four/five.txt"
 	// treeWalk is called with prefixDir="one/two/three/" and marker="four/five.txt"
@@ -173,7 +262,7 @@ func startTreeWalk(ctx context.Context, bucket, prefix, marker string, recursive
 	marker = strings.TrimPrefix(marker, prefixDir)
 	go func() {
 		isEnd := true // Indication to start walking the tree with end as true.
-		doTreeWalk(ctx, bucket, prefixDir, entryPrefixMatch, marker, recursive, listDir, resultCh, endWalkCh, isEnd)
+		doTreeWalk(ctx, bucket, prefixDir, entryPrefixMatch, marker, recursive, listDir, isLeaf, isLeafDir, resultCh, endWalkCh, isEnd)
 		close(resultCh)
 	}()
 	return resultCh

cmd/tree-walk_test.go

@@ -23,6 +23,7 @@ import (
 	"os"
 	"reflect"
 	"sort"
+	"strings"
 	"testing"
 	"time"
 )
@@ -85,27 +86,27 @@ func createNamespace(disk StorageAPI, volume string, files []string) error {
 
 // Returns function "listDir" of the type listDirFunc.
 // disks - used for doing disk.ListDir()
-func listDirFactory(ctx context.Context, disk StorageAPI) ListDirFunc {
-	return func(volume, dirPath, dirEntry string) (emptyDir bool, entries []string) {
+func listDirFactory(ctx context.Context, disk StorageAPI, isLeaf IsLeafFunc) ListDirFunc {
+	return func(volume, dirPath, dirEntry string) (emptyDir bool, entries []string, delayIsLeaf bool) {
 		entries, err := disk.ListDir(volume, dirPath, -1)
 		if err != nil {
-			return false, nil
+			return false, nil, false
 		}
 		if len(entries) == 0 {
-			return true, nil
+			return true, nil, false
 		}
-		sort.Strings(entries)
-		return false, filterMatchingPrefix(entries, dirEntry)
+		entries, delayIsLeaf = filterListEntries(volume, dirPath, entries, dirEntry, isLeaf)
+		return false, entries, delayIsLeaf
 	}
 }
 
 // Test if tree walker returns entries matching prefix alone are received
 // when a non empty prefix is supplied.
-func testTreeWalkPrefix(t *testing.T, listDir ListDirFunc) {
+func testTreeWalkPrefix(t *testing.T, listDir ListDirFunc, isLeaf IsLeafFunc, isLeafDir IsLeafDirFunc) {
 	// Start the tree walk go-routine.
 	prefix := "d/"
 	endWalkCh := make(chan struct{})
-	twResultCh := startTreeWalk(context.Background(), volume, prefix, "", true, listDir, endWalkCh)
+	twResultCh := startTreeWalk(context.Background(), volume, prefix, "", true, listDir, isLeaf, isLeafDir, endWalkCh)
 
 	// Check if all entries received on the channel match the prefix.
 	for res := range twResultCh {
@@ -116,11 +117,11 @@ func testTreeWalkPrefix(t *testing.T, listDir ListDirFunc) {
 }
 
 // Test if entries received on tree walk's channel appear after the supplied marker.
-func testTreeWalkMarker(t *testing.T, listDir ListDirFunc) {
+func testTreeWalkMarker(t *testing.T, listDir ListDirFunc, isLeaf IsLeafFunc, isLeafDir IsLeafDirFunc) {
 	// Start the tree walk go-routine.
 	prefix := ""
 	endWalkCh := make(chan struct{})
-	twResultCh := startTreeWalk(context.Background(), volume, prefix, "d/g", true, listDir, endWalkCh)
+	twResultCh := startTreeWalk(context.Background(), volume, prefix, "d/g", true, listDir, isLeaf, isLeafDir, endWalkCh)
 
 	// Check if only 3 entries, namely d/g/h, i/j/k, lmn are received on the channel.
 	expectedCount := 3
@@ -157,12 +158,22 @@ func TestTreeWalk(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	listDir := listDirFactory(context.Background(), disk)
+	isLeaf := func(bucket, leafPath string) bool {
+		return !strings.HasSuffix(leafPath, slashSeparator)
+	}
+
+	isLeafDir := func(bucket, leafPath string) bool {
+		entries, _ := disk.ListDir(bucket, leafPath, 1)
+		return len(entries) == 0
+	}
+
+	listDir := listDirFactory(context.Background(), disk, isLeaf)
 
 	// Simple test for prefix based walk.
-	testTreeWalkPrefix(t, listDir)
+	testTreeWalkPrefix(t, listDir, isLeaf, isLeafDir)
+
 	// Simple test when marker is set.
-	testTreeWalkMarker(t, listDir)
+	testTreeWalkMarker(t, listDir, isLeaf, isLeafDir)
 
 	err = os.RemoveAll(fsDir)
 	if err != nil {
@@ -191,7 +202,16 @@ func TestTreeWalkTimeout(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	listDir := listDirFactory(context.Background(), disk)
+	isLeaf := func(bucket, leafPath string) bool {
+		return !strings.HasSuffix(leafPath, slashSeparator)
+	}
+
+	isLeafDir := func(bucket, leafPath string) bool {
+		entries, _ := disk.ListDir(bucket, leafPath, 1)
+		return len(entries) == 0
+	}
+
+	listDir := listDirFactory(context.Background(), disk, isLeaf)
 
 	// TreeWalk pool with 2 seconds timeout for tree-walk go routines.
 	pool := NewTreeWalkPool(2 * time.Second)
@@ -200,7 +220,7 @@ func TestTreeWalkTimeout(t *testing.T) {
 	prefix := ""
 	marker := ""
 	recursive := true
-	resultCh := startTreeWalk(context.Background(), volume, prefix, marker, recursive, listDir, endWalkCh)
+	resultCh := startTreeWalk(context.Background(), volume, prefix, marker, recursive, listDir, isLeaf, isLeafDir, endWalkCh)
 
 	params := listParams{
 		bucket:    volume,
@@ -250,8 +270,17 @@ func TestRecursiveTreeWalk(t *testing.T) {
 		t.Fatalf("Unable to create StorageAPI: %s", err)
 	}
 
+	isLeaf := func(bucket, leafPath string) bool {
+		return !strings.HasSuffix(leafPath, slashSeparator)
+	}
+
+	isLeafDir := func(bucket, leafPath string) bool {
+		entries, _ := disk1.ListDir(bucket, leafPath, 1)
+		return len(entries) == 0
+	}
+
 	// Create listDir function.
-	listDir := listDirFactory(context.Background(), disk1)
+	listDir := listDirFactory(context.Background(), disk1, isLeaf)
 
 	// Create the namespace.
 	var files = []string{
@@ -329,7 +358,7 @@ func TestRecursiveTreeWalk(t *testing.T) {
 		t.Run(fmt.Sprintf("Test%d", i+1), func(t *testing.T) {
 			for entry := range startTreeWalk(context.Background(), volume,
 				testCase.prefix, testCase.marker, testCase.recursive,
-				listDir, endWalkCh) {
+				listDir, isLeaf, isLeafDir, endWalkCh) {
 				if _, found := testCase.expected[entry.entry]; !found {
 					t.Errorf("Expected %s, but couldn't find", entry.entry)
 				}
@@ -355,8 +384,17 @@ func TestSortedness(t *testing.T) {
 		t.Fatalf("Unable to create StorageAPI: %s", err)
 	}
 
+	isLeaf := func(bucket, leafPath string) bool {
+		return !strings.HasSuffix(leafPath, slashSeparator)
+	}
+
+	isLeafDir := func(bucket, leafPath string) bool {
+		entries, _ := disk1.ListDir(bucket, leafPath, 1)
+		return len(entries) == 0
+	}
+
 	// Create listDir function.
-	listDir := listDirFactory(context.Background(), disk1)
+	listDir := listDirFactory(context.Background(), disk1, isLeaf)
 
 	// Create the namespace.
 	var files = []string{
@@ -398,7 +436,7 @@ func TestSortedness(t *testing.T) {
 		var actualEntries []string
 		for entry := range startTreeWalk(context.Background(), volume,
 			test.prefix, test.marker, test.recursive,
-			listDir, endWalkCh) {
+			listDir, isLeaf, isLeafDir, endWalkCh) {
 			actualEntries = append(actualEntries, entry.entry)
 		}
 		if !sort.IsSorted(sort.StringSlice(actualEntries)) {
@@ -426,8 +464,17 @@ func TestTreeWalkIsEnd(t *testing.T) {
 		t.Fatalf("Unable to create StorageAPI: %s", err)
 	}
 
+	isLeaf := func(bucket, leafPath string) bool {
+		return !strings.HasSuffix(leafPath, slashSeparator)
+	}
+
+	isLeafDir := func(bucket, leafPath string) bool {
+		entries, _ := disk1.ListDir(bucket, leafPath, 1)
+		return len(entries) == 0
+	}
+
 	// Create listDir function.
-	listDir := listDirFactory(context.Background(), disk1)
+	listDir := listDirFactory(context.Background(), disk1, isLeaf)
 
 	// Create the namespace.
 	var files = []string{
@@ -469,7 +516,7 @@ func TestTreeWalkIsEnd(t *testing.T) {
 	for i, test := range testCases {
 		var entry TreeWalkResult
 		for entry = range startTreeWalk(context.Background(), volume, test.prefix,
-			test.marker, test.recursive, listDir, endWalkCh) {
+			test.marker, test.recursive, listDir, isLeaf, isLeafDir, endWalkCh) {
 		}
 		if entry.entry != test.expectedEntry {
 			t.Errorf("Test %d: Expected entry %s, but received %s with the EOF marker", i, test.expectedEntry, entry.entry)

cmd/xl-storage.go

@@ -28,10 +28,10 @@ import (
 	"io/ioutil"
 	"net/url"
 	"os"
+	"path"
 	slashpath "path"
 	"path/filepath"
 	"runtime"
-	"sort"
 	"strings"
 	"sync"
 	"sync/atomic"
@@ -733,8 +733,6 @@ func (s *xlStorage) ListDirSplunk(volume, dirPath string, count int) (entries []
 		return nil, nil
 	}
 
-	const receiptJSON = "receipt.json"
-
 	atomic.AddInt32(&s.activeIOCount, 1)
 	defer func() {
 		atomic.AddInt32(&s.activeIOCount, -1)
@@ -765,24 +763,45 @@ func (s *xlStorage) ListDirSplunk(volume, dirPath string, count int) (entries []
 		return nil, err
 	}
 
-	for i, entry := range entries {
-		if entry != receiptJSON {
-			continue
-		}
-		_, err = os.Stat(pathJoin(dirPathAbs, entry, xlStorageFormatFile))
-		if err == nil {
-			entries[i] = strings.TrimSuffix(entry, SlashSeparator)
-			continue
-		}
-		if os.IsNotExist(err) {
-			if err = s.renameLegacyMetadata(volume, pathJoin(dirPath, entry)); err == nil {
-				// Rename was successful means we found old `xl.json`
-				entries[i] = strings.TrimSuffix(entry, SlashSeparator)
-			}
-		}
+	return entries, nil
+}
+
+func (s *xlStorage) isLeafSplunk(volume string, leafPath string) bool {
+	const receiptJSON = "receipt.json"
+
+	if path.Base(leafPath) != receiptJSON {
+		return false
 	}
+	return s.isLeaf(volume, leafPath)
+}
 
-	return entries, nil
+func (s *xlStorage) isLeaf(volume string, leafPath string) bool {
+	volumeDir, err := s.getVolDir(volume)
+	if err != nil {
+		return false
+	}
+
+	_, err = os.Stat(pathJoin(volumeDir, leafPath, xlStorageFormatFile))
+	if err == nil {
+		return true
+	}
+	if os.IsNotExist(err) {
+		// We need a fallback code where directory might contain
+		// legacy `xl.json`, in such situation we just rename
+		// and proceed if rename is successful we know that it
+		// is the leaf since `xl.json` was present.
+		return s.renameLegacyMetadata(volume, leafPath) == nil
+	}
+	return false
+}
+
+func (s *xlStorage) isLeafDir(volume, leafPath string) bool {
+	volumeDir, err := s.getVolDir(volume)
+	if err != nil {
+		return false
+	}
+
+	return isDirEmpty(pathJoin(volumeDir, leafPath))
 }
 
 // WalkSplunk - is a sorted walker which returns file entries in lexically
@@ -810,19 +829,19 @@ func (s *xlStorage) WalkSplunk(volume, dirPath, marker string, endWalkCh <-chan
 	ch = make(chan FileInfo)
 	go func() {
 		defer close(ch)
-		listDir := func(volume, dirPath, dirEntry string) (bool, []string) {
+		listDir := func(volume, dirPath, dirEntry string) (emptyDir bool, entries []string, delayIsLeaf bool) {
 			entries, err := s.ListDirSplunk(volume, dirPath, -1)
 			if err != nil {
-				return false, nil
+				return false, nil, false
 			}
 			if len(entries) == 0 {
-				return true, nil
+				return true, nil, false
 			}
-			sort.Strings(entries)
-			return false, filterMatchingPrefix(entries, dirEntry)
+			entries, delayIsLeaf = filterListEntries(volume, dirPath, entries, dirEntry, s.isLeafSplunk)
+			return false, entries, delayIsLeaf
 		}
 
-		walkResultCh := startTreeWalk(GlobalContext, volume, dirPath, marker, true, listDir, endWalkCh)
+		walkResultCh := startTreeWalk(GlobalContext, volume, dirPath, marker, true, listDir, s.isLeafSplunk, s.isLeafDir, endWalkCh)
 		for {
 			walkResult, ok := <-walkResultCh
 			if !ok {
@@ -895,23 +914,22 @@ func (s *xlStorage) WalkVersions(volume, dirPath, marker string, recursive bool,
 		}
 	}
 
-	// buffer channel matches the S3 ListObjects implementation
-	ch = make(chan FileInfoVersions, maxObjectList)
+	ch = make(chan FileInfoVersions)
 	go func() {
 		defer close(ch)
-		listDir := func(volume, dirPath, dirEntry string) (emptyDir bool, entries []string) {
+		listDir := func(volume, dirPath, dirEntry string) (emptyDir bool, entries []string, delayIsLeaf bool) {
 			entries, err := s.ListDir(volume, dirPath, -1)
 			if err != nil {
-				return false, nil
+				return false, nil, false
 			}
 			if len(entries) == 0 {
-				return true, nil
+				return true, nil, false
 			}
-			sort.Strings(entries)
-			return false, filterMatchingPrefix(entries, dirEntry)
+			entries, delayIsLeaf = filterListEntries(volume, dirPath, entries, dirEntry, s.isLeaf)
+			return false, entries, delayIsLeaf
 		}
 
-		walkResultCh := startTreeWalk(GlobalContext, volume, dirPath, marker, recursive, listDir, endWalkCh)
+		walkResultCh := startTreeWalk(GlobalContext, volume, dirPath, marker, recursive, listDir, s.isLeaf, s.isLeafDir, endWalkCh)
 		for walkResult := range walkResultCh {
 			var fiv FileInfoVersions
 			if HasSuffix(walkResult.entry, SlashSeparator) {
@@ -981,23 +999,22 @@ func (s *xlStorage) Walk(volume, dirPath, marker string, recursive bool, endWalk
 		}
 	}
 
-	// buffer channel matches the S3 ListObjects implementation
-	ch = make(chan FileInfo, maxObjectList)
+	ch = make(chan FileInfo)
 	go func() {
 		defer close(ch)
-		listDir := func(volume, dirPath, dirEntry string) (emptyDir bool, entries []string) {
+		listDir := func(volume, dirPath, dirEntry string) (emptyDir bool, entries []string, delayIsLeaf bool) {
 			entries, err := s.ListDir(volume, dirPath, -1)
 			if err != nil {
-				return false, nil
+				return false, nil, false
 			}
 			if len(entries) == 0 {
-				return true, nil
+				return true, nil, false
 			}
-			sort.Strings(entries)
-			return false, filterMatchingPrefix(entries, dirEntry)
+			entries, delayIsLeaf = filterListEntries(volume, dirPath, entries, dirEntry, s.isLeaf)
+			return false, entries, delayIsLeaf
 		}
 
-		walkResultCh := startTreeWalk(GlobalContext, volume, dirPath, marker, recursive, listDir, endWalkCh)
+		walkResultCh := startTreeWalk(GlobalContext, volume, dirPath, marker, recursive, listDir, s.isLeaf, s.isLeafDir, endWalkCh)
 		for walkResult := range walkResultCh {
 			var fi FileInfo
 			if HasSuffix(walkResult.entry, SlashSeparator) {
@@ -1066,20 +1083,6 @@ func (s *xlStorage) ListDir(volume, dirPath string, count int) (entries []string
 		return nil, err
 	}
 
-	for i, entry := range entries {
-		_, err = os.Stat(pathJoin(dirPathAbs, entry, xlStorageFormatFile))
-		if err == nil {
-			entries[i] = strings.TrimSuffix(entry, SlashSeparator)
-			continue
-		}
-		if os.IsNotExist(err) {
-			if err = s.renameLegacyMetadata(volume, pathJoin(dirPath, entry)); err == nil {
-				// if rename was successful, means we did find old `xl.json`
-				entries[i] = strings.TrimSuffix(entry, SlashSeparator)
-			}
-		}
-	}
-
 	return entries, nil
 }