more solid weed mount (#4089)

* compare chunks by timestamp * fix slab clearing error * fix test compilation * move oldest chunk to sealed, instead of by fullness * lock on fh.entryViewCache * remove verbose logs * revert slat clearing * less logs * less logs * track write and read by timestamp * remove useless logic * add entry lock on file handle release * use mem chunk only, swap file chunk has problems * comment out code that maybe used later * add debug mode to compare data read and write * more efficient readResolvedChunks with linked list * small optimization * fix test compilation * minor fix on writer * add SeparateGarbageChunks * group chunks into sections * turn off debug mode * fix tests * fix tests * tmp enable swap file chunk * Revert "tmp enable swap file chunk" This reverts commit 985137ec472924e4815f258189f6ca9f2168a0a7. * simple refactoring * simple refactoring * do not re-use swap file chunk. Sealed chunks should not be re-used. * comment out debugging facilities * either mem chunk or swap file chunk is fine now * remove orderedMutex as *semaphore.Weighted not found impactful * optimize size calculation for changing large files * optimize performance to avoid going through the long list of chunks * still problems with swap file chunk * rename * tiny optimization * swap file chunk save only successfully read data * fix * enable both mem and swap file chunk * resolve chunks with range * rename * fix chunk interval list * also change file handle chunk group when adding chunks * pick in-active chunk with time-decayed counter * fix compilation * avoid nil with empty fh.entry * refactoring * rename * rename * refactor visible intervals to *list.List * refactor chunkViews to *list.List * add IntervalList for generic interval list * change visible interval to use IntervalList in generics * cahnge chunkViews to *IntervalList[*ChunkView] * use NewFileChunkSection to create * rename variables * refactor * fix renaming leftover * renaming * renaming * add insert interval * interval list adds lock * incrementally add chunks to readers Fixes: 1. set start and stop offset for the value object 2. clone the value object 3. use pointer instead of copy-by-value when passing to interval.Value 4. use insert interval since adding chunk could be out of order * fix tests compilation * fix tests compilation
author: Chris Lu <chrislusf@users.noreply.github.com> 2023-01-02 23:20:45 -0800
committer: GitHub <noreply@github.com> 2023-01-02 23:20:45 -0800
commit: d4566d4aaa426b33015780c7cc18f887fc07cca4 (patch)
tree: 7c3b5cb3d9e54297b9d4213b67408f86149013f7
parent: 367353b936c450906e88e850c7d1e804f97c3560 (diff)
download: seaweedfs-d4566d4aaa426b33015780c7cc18f887fc07cca4.tar.xz
seaweedfs-d4566d4aaa426b33015780c7cc18f887fc07cca4.zip
45 files changed, 1835 insertions, 806 deletions
diff --git a/weed/command/filer_copy.go b/weed/command/filer_copy.go
index 667b089ed..0c4626317 100644
--- a/weed/command/filer_copy.go
+++ b/weed/command/filer_copy.go
@@ -365,7 +365,7 @@ func (worker *FileCopyWorker) uploadFileAsOne(task FileCopyTask, f *os.File) err
 		if flushErr != nil {
 			return flushErr
 		}
-		chunks = append(chunks, uploadResult.ToPbFileChunk(finalFileId, 0))
+		chunks = append(chunks, uploadResult.ToPbFileChunk(finalFileId, 0, time.Now().UnixNano()))
 	}
 
 	if err := pb.WithGrpcFilerClient(false, worker.filerAddress, worker.options.grpcDialOption, func(client filer_pb.SeaweedFilerClient) error {
@@ -450,7 +450,7 @@ func (worker *FileCopyWorker) uploadFileInChunks(task FileCopyTask, f *os.File,
 				uploadError = fmt.Errorf("upload %v result: %v\n", fileName, uploadResult.Error)
 				return
 			}
-			chunksChan <- uploadResult.ToPbFileChunk(fileId, i*chunkSize)
+			chunksChan <- uploadResult.ToPbFileChunk(fileId, i*chunkSize, time.Now().UnixNano())
 
 			fmt.Printf("uploaded %s-%d [%d,%d)\n", fileName, i+1, i*chunkSize, i*chunkSize+int64(uploadResult.Size))
 		}(i)
@@ -530,7 +530,7 @@ func detectMimeType(f *os.File) string {
 	return mimeType
 }
 
-func (worker *FileCopyWorker) saveDataAsChunk(reader io.Reader, name string, offset int64) (chunk *filer_pb.FileChunk, err error) {
+func (worker *FileCopyWorker) saveDataAsChunk(reader io.Reader, name string, offset int64, tsNs int64) (chunk *filer_pb.FileChunk, err error) {
 
 	finalFileId, uploadResult, flushErr, _ := operation.UploadWithRetry(
 		worker,
@@ -561,7 +561,7 @@ func (worker *FileCopyWorker) saveDataAsChunk(reader io.Reader, name string, off
 	if uploadResult.Error != "" {
 		return nil, fmt.Errorf("upload result: %v", uploadResult.Error)
 	}
-	return uploadResult.ToPbFileChunk(finalFileId, offset), nil
+	return uploadResult.ToPbFileChunk(finalFileId, offset, tsNs), nil
 }
 
 var _ = filer_pb.FilerClient(&FileCopyWorker{})
diff --git a/weed/filer/filechunk_group.go b/weed/filer/filechunk_group.go
new file mode 100644
index 000000000..5dbf16a5c
--- /dev/null
+++ b/weed/filer/filechunk_group.go
@@ -0,0 +1,148 @@
+package filer
+
+import (
+	"github.com/seaweedfs/seaweedfs/weed/pb/filer_pb"
+	"github.com/seaweedfs/seaweedfs/weed/util/chunk_cache"
+	"github.com/seaweedfs/seaweedfs/weed/wdclient"
+	"sync"
+)
+
+type ChunkGroup struct {
+	lookupFn       wdclient.LookupFileIdFunctionType
+	chunkCache     chunk_cache.ChunkCache
+	manifestChunks []*filer_pb.FileChunk
+	sections       map[SectionIndex]*FileChunkSection
+	sectionsLock   sync.RWMutex
+}
+
+func NewChunkGroup(lookupFn wdclient.LookupFileIdFunctionType, chunkCache chunk_cache.ChunkCache, chunks []*filer_pb.FileChunk) (*ChunkGroup, error) {
+	group := &ChunkGroup{
+		lookupFn:   lookupFn,
+		chunkCache: chunkCache,
+		sections:   make(map[SectionIndex]*FileChunkSection),
+	}
+
+	err := group.SetChunks(chunks)
+	return group, err
+}
+
+func (group *ChunkGroup) AddChunk(chunk *filer_pb.FileChunk) error {
+
+	group.sectionsLock.Lock()
+	defer group.sectionsLock.Unlock()
+
+	sectionIndexStart, sectionIndexStop := SectionIndex(chunk.Offset/SectionSize), SectionIndex((chunk.Offset+int64(chunk.Size))/SectionSize)
+	for si := sectionIndexStart; si < sectionIndexStop+1; si++ {
+		section, found := group.sections[si]
+		if !found {
+			section = NewFileChunkSection(si)
+			group.sections[si] = section
+		}
+		section.addChunk(chunk)
+	}
+	return nil
+}
+
+func (group *ChunkGroup) ReadDataAt(fileSize int64, buff []byte, offset int64) (n int, tsNs int64, err error) {
+
+	group.sectionsLock.RLock()
+	defer group.sectionsLock.RUnlock()
+
+	sectionIndexStart, sectionIndexStop := SectionIndex(offset/SectionSize), SectionIndex((offset+int64(len(buff)))/SectionSize)
+	for si := sectionIndexStart; si < sectionIndexStop+1; si++ {
+		section, found := group.sections[si]
+		rangeStart, rangeStop := max(offset, int64(si*SectionSize)), min(offset+int64(len(buff)), int64((si+1)*SectionSize))
+		if !found {
+			for i := rangeStart; i < rangeStop; i++ {
+				buff[i-offset] = 0
+			}
+			continue
+		}
+		xn, xTsNs, xErr := section.readDataAt(group, fileSize, buff[rangeStart-offset:rangeStop-offset], rangeStart)
+		if xErr != nil {
+			err = xErr
+		}
+		n += xn
+		tsNs = max(tsNs, xTsNs)
+	}
+	return
+}
+
+func (group *ChunkGroup) SetChunks(chunks []*filer_pb.FileChunk) error {
+	var dataChunks []*filer_pb.FileChunk
+	for _, chunk := range chunks {
+
+		if !chunk.IsChunkManifest {
+			dataChunks = append(dataChunks, chunk)
+			continue
+		}
+
+		resolvedChunks, err := ResolveOneChunkManifest(group.lookupFn, chunk)
+		if err != nil {
+			return err
+		}
+
+		group.manifestChunks = append(group.manifestChunks, chunk)
+		dataChunks = append(dataChunks, resolvedChunks...)
+	}
+
+	for _, chunk := range dataChunks {
+		sectionIndexStart, sectionIndexStop := SectionIndex(chunk.Offset/SectionSize), SectionIndex((chunk.Offset+int64(chunk.Size))/SectionSize)
+		for si := sectionIndexStart; si < sectionIndexStop+1; si++ {
+			section, found := group.sections[si]
+			if !found {
+				section = NewFileChunkSection(si)
+				group.sections[si] = section
+			}
+			section.chunks = append(section.chunks, chunk)
+		}
+	}
+	return nil
+}
+
+const (
+	// see weedfs_file_lseek.go
+	SEEK_DATA uint32 = 3 // seek to next data after the offset
+	// SEEK_HOLE uint32 = 4 // seek to next hole after the offset
+)
+
+// FIXME: needa tests
+func (group *ChunkGroup) SearchChunks(offset, fileSize int64, whence uint32) (found bool, out int64) {
+	group.sectionsLock.RLock()
+	defer group.sectionsLock.RUnlock()
+
+	return group.doSearchChunks(offset, fileSize, whence)
+}
+
+func (group *ChunkGroup) doSearchChunks(offset, fileSize int64, whence uint32) (found bool, out int64) {
+
+	sectionIndex, maxSectionIndex := SectionIndex(offset/SectionSize), SectionIndex(fileSize/SectionSize)
+	if whence == SEEK_DATA {
+		for si := sectionIndex; si < maxSectionIndex+1; si++ {
+			section, foundSection := group.sections[si]
+			if !foundSection {
+				continue
+			}
+			sectionStart := section.DataStartOffset(group, offset, fileSize)
+			if sectionStart == -1 {
+				continue
+			}
+			return true, sectionStart
+		}
+		return false, 0
+	} else {
+		// whence == SEEK_HOLE
+		for si := sectionIndex; si < maxSectionIndex; si++ {
+			section, foundSection := group.sections[si]
+			if !foundSection {
+				return true, offset
+			}
+			holeStart := section.NextStopOffset(group, offset, fileSize)
+			if holeStart%SectionSize == 0 {
+				continue
+			}
+			return true, holeStart
+		}
+		return true, fileSize
+	}
+}
diff --git a/weed/filer/filechunk_group_test.go b/weed/filer/filechunk_group_test.go
new file mode 100644
index 000000000..d24d66a49
--- /dev/null
+++ b/weed/filer/filechunk_group_test.go
@@ -0,0 +1,36 @@
+package filer
+
+import (
+	"github.com/stretchr/testify/assert"
+	"testing"
+)
+
+func TestChunkGroup_doSearchChunks(t *testing.T) {
+	type fields struct {
+		sections map[SectionIndex]*FileChunkSection
+	}
+	type args struct {
+		offset   int64
+		fileSize int64
+		whence   uint32
+	}
+	tests := []struct {
+		name      string
+		fields    fields
+		args      args
+		wantFound bool
+		wantOut   int64
+	}{
+		// TODO: Add test cases.
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			group := &ChunkGroup{
+				sections: tt.fields.sections,
+			}
+			gotFound, gotOut := group.doSearchChunks(tt.args.offset, tt.args.fileSize, tt.args.whence)
+			assert.Equalf(t, tt.wantFound, gotFound, "doSearchChunks(%v, %v, %v)", tt.args.offset, tt.args.fileSize, tt.args.whence)
+			assert.Equalf(t, tt.wantOut, gotOut, "doSearchChunks(%v, %v, %v)", tt.args.offset, tt.args.fileSize, tt.args.whence)
+		})
+	}
+}
diff --git a/weed/filer/filechunk_manifest.go b/weed/filer/filechunk_manifest.go
index 221a11ffe..d9d0331be 100644
--- a/weed/filer/filechunk_manifest.go
+++ b/weed/filer/filechunk_manifest.go
@@ -264,7 +264,7 @@ func mergeIntoManifest(saveFunc SaveDataAsChunkFunctionType, dataChunks []*filer
 		}
 	}
 
-	manifestChunk, err = saveFunc(bytes.NewReader(data), "", 0)
+	manifestChunk, err = saveFunc(bytes.NewReader(data), "", 0, 0)
 	if err != nil {
 		return nil, err
 	}
@@ -275,4 +275,4 @@ func mergeIntoManifest(saveFunc SaveDataAsChunkFunctionType, dataChunks []*filer
 	return
 }
 
-type SaveDataAsChunkFunctionType func(reader io.Reader, name string, offset int64) (chunk *filer_pb.FileChunk, err error)
+type SaveDataAsChunkFunctionType func(reader io.Reader, name string, offset int64, tsNs int64) (chunk *filer_pb.FileChunk, err error)
diff --git a/weed/filer/filechunk_section.go b/weed/filer/filechunk_section.go
new file mode 100644
index 000000000..60c919569
--- /dev/null
+++ b/weed/filer/filechunk_section.go
@@ -0,0 +1,119 @@
+package filer
+
+import (
+	"github.com/seaweedfs/seaweedfs/weed/pb/filer_pb"
+	"sync"
+)
+
+const SectionSize = 2 * 1024 * 1024 * 128 // 256MiB
+type SectionIndex int64
+type FileChunkSection struct {
+	sectionIndex     SectionIndex
+	chunks           []*filer_pb.FileChunk
+	visibleIntervals *IntervalList[*VisibleInterval]
+	chunkViews       *IntervalList[*ChunkView]
+	reader           *ChunkReadAt
+	lock             sync.Mutex
+}
+
+func NewFileChunkSection(si SectionIndex) *FileChunkSection {
+	return &FileChunkSection{
+		sectionIndex: si,
+	}
+}
+
+func (section *FileChunkSection) addChunk(chunk *filer_pb.FileChunk) error {
+	section.lock.Lock()
+	defer section.lock.Unlock()
+
+	start, stop := max(int64(section.sectionIndex)*SectionSize, chunk.Offset), min(((int64(section.sectionIndex)+1)*SectionSize), chunk.Offset+int64(chunk.Size))
+
+	section.chunks = append(section.chunks, chunk)
+
+	if section.visibleIntervals != nil {
+		MergeIntoVisibles(section.visibleIntervals, start, stop, chunk)
+	}
+
+	if section.visibleIntervals != nil {
+		section.chunks, _ = SeparateGarbageChunks(section.visibleIntervals, section.chunks)
+	}
+
+	if section.chunkViews != nil {
+		MergeIntoChunkViews(section.chunkViews, start, stop, chunk)
+	}
+
+	return nil
+}
+
+func (section *FileChunkSection) setupForRead(group *ChunkGroup, fileSize int64) {
+	if section.visibleIntervals == nil {
+		section.visibleIntervals = readResolvedChunks(section.chunks, int64(section.sectionIndex)*SectionSize, (int64(section.sectionIndex)+1)*SectionSize)
+		section.chunks, _ = SeparateGarbageChunks(section.visibleIntervals, section.chunks)
+		if section.reader != nil {
+			_ = section.reader.Close()
+			section.reader = nil
+		}
+	}
+	if section.chunkViews == nil {
+		section.chunkViews = ViewFromVisibleIntervals(section.visibleIntervals, int64(section.sectionIndex)*SectionSize, (int64(section.sectionIndex)+1)*SectionSize)
+	}
+
+	if section.reader == nil {
+		section.reader = NewChunkReaderAtFromClient(group.lookupFn, section.chunkViews, group.chunkCache, min(int64(section.sectionIndex+1)*SectionSize, fileSize))
+	}
+	section.reader.fileSize = fileSize
+}
+
+func (section *FileChunkSection) readDataAt(group *ChunkGroup, fileSize int64, buff []byte, offset int64) (n int, tsNs int64, err error) {
+	section.lock.Lock()
+	defer section.lock.Unlock()
+
+	section.setupForRead(group, fileSize)
+
+	return section.reader.ReadAtWithTime(buff, offset)
+}
+
+func (section *FileChunkSection) DataStartOffset(group *ChunkGroup, offset int64, fileSize int64) int64 {
+	section.lock.Lock()
+	defer section.lock.Unlock()
+
+	section.setupForRead(group, fileSize)
+
+	for x := section.visibleIntervals.Front(); x != nil; x = x.Next {
+		visible := x.Value
+		if visible.stop <= offset {
+			continue
+		}
+		if offset < visible.start {
+			return offset
+		}
+		return offset
+	}
+	return -1
+}
+
+func (section *FileChunkSection) NextStopOffset(group *ChunkGroup, offset int64, fileSize int64) int64 {
+	section.lock.Lock()
+	defer section.lock.Unlock()
+
+	section.setupForRead(group, fileSize)
+
+	isAfterOffset := false
+	for x := section.visibleIntervals.Front(); x != nil; x = x.Next {
+		visible := x.Value
+		if !isAfterOffset {
+			if visible.stop <= offset {
+				continue
+			}
+			isAfterOffset = true
+		}
+		if offset < visible.start {
+			return offset
+		}
+		// now visible.start <= offset
+		if offset < visible.stop {
+			offset = visible.stop
+		}
+	}
+	return offset
+}
diff --git a/weed/filer/filechunks.go b/weed/filer/filechunks.go
index 061e0757a..d872bd22d 100644
--- a/weed/filer/filechunks.go
+++ b/weed/filer/filechunks.go
@@ -4,7 +4,6 @@ import (
 	"bytes"
 	"fmt"
 	"github.com/seaweedfs/seaweedfs/weed/wdclient"
-	"golang.org/x/exp/slices"
 	"math"
 
 	"github.com/seaweedfs/seaweedfs/weed/pb/filer_pb"
@@ -42,7 +41,7 @@ func ETag(entry *filer_pb.Entry) (etag string) {
 }
 
 func ETagEntry(entry *Entry) (etag string) {
-        if entry.IsInRemoteOnly() {
+	if entry.IsInRemoteOnly() {
 		return entry.Remote.RemoteETag
 	}
 	if entry.Attr.Md5 == nil {
@@ -66,8 +65,15 @@ func CompactFileChunks(lookupFileIdFn wdclient.LookupFileIdFunctionType, chunks
 
 	visibles, _ := NonOverlappingVisibleIntervals(lookupFileIdFn, chunks, 0, math.MaxInt64)
 
+	compacted, garbage = SeparateGarbageChunks(visibles, chunks)
+
+	return
+}
+
+func SeparateGarbageChunks(visibles *IntervalList[*VisibleInterval], chunks []*filer_pb.FileChunk) (compacted []*filer_pb.FileChunk, garbage []*filer_pb.FileChunk) {
 	fileIds := make(map[string]bool)
-	for _, interval := range visibles {
+	for x := visibles.Front(); x != nil; x = x.Next {
+		interval := x.Value
 		fileIds[interval.fileId] = true
 	}
 	for _, chunk := range chunks {
@@ -77,8 +83,7 @@ func CompactFileChunks(lookupFileIdFn wdclient.LookupFileIdFunctionType, chunks
 			garbage = append(garbage, chunk)
 		}
 	}
-
-	return
+	return compacted, garbage
 }
 
 func MinusChunks(lookupFileIdFn wdclient.LookupFileIdFunctionType, as, bs []*filer_pb.FileChunk) (delta []*filer_pb.FileChunk, err error) {
@@ -131,20 +136,39 @@ func DoMinusChunksBySourceFileId(as, bs []*filer_pb.FileChunk) (delta []*filer_p
 }
 
 type ChunkView struct {
-	FileId      string
-	Offset      int64
-	Size        uint64
-	LogicOffset int64 // actual offset in the file, for the data specified via [offset, offset+size) in current chunk
-	ChunkSize   uint64
-	CipherKey   []byte
-	IsGzipped   bool
+	FileId        string
+	OffsetInChunk int64 // offset within the chunk
+	ViewSize      uint64
+	ViewOffset    int64 // actual offset in the file, for the data specified via [offset, offset+size) in current chunk
+	ChunkSize     uint64
+	CipherKey     []byte
+	IsGzipped     bool
+	ModifiedTsNs  int64
+}
+
+func (cv *ChunkView) SetStartStop(start, stop int64) {
+	cv.OffsetInChunk += start - cv.ViewOffset
+	cv.ViewOffset = start
+	cv.ViewSize = uint64(stop - start)
+}
+func (cv *ChunkView) Clone() IntervalValue {
+	return &ChunkView{
+		FileId:        cv.FileId,
+		OffsetInChunk: cv.OffsetInChunk,
+		ViewSize:      cv.ViewSize,
+		ViewOffset:    cv.ViewOffset,
+		ChunkSize:     cv.ChunkSize,
+		CipherKey:     cv.CipherKey,
+		IsGzipped:     cv.IsGzipped,
+		ModifiedTsNs:  cv.ModifiedTsNs,
+	}
 }
 
 func (cv *ChunkView) IsFullChunk() bool {
-	return cv.Size == cv.ChunkSize
+	return cv.ViewSize == cv.ChunkSize
 }
 
-func ViewFromChunks(lookupFileIdFn wdclient.LookupFileIdFunctionType, chunks []*filer_pb.FileChunk, offset int64, size int64) (views []*ChunkView) {
+func ViewFromChunks(lookupFileIdFn wdclient.LookupFileIdFunctionType, chunks []*filer_pb.FileChunk, offset int64, size int64) (chunkViews *IntervalList[*ChunkView]) {
 
 	visibles, _ := NonOverlappingVisibleIntervals(lookupFileIdFn, chunks, offset, offset+size)
 
@@ -152,7 +176,7 @@ func ViewFromChunks(lookupFileIdFn wdclient.LookupFileIdFunctionType, chunks []*
 
 }
 
-func ViewFromVisibleIntervals(visibles []VisibleInterval, offset int64, size int64) (views []*ChunkView) {
+func ViewFromVisibleIntervals(visibles *IntervalList[*VisibleInterval], offset int64, size int64) (chunkViews *IntervalList[*ChunkView]) {
 
 	stop := offset + size
 	if size == math.MaxInt64 {
@@ -162,164 +186,112 @@ func ViewFromVisibleIntervals(visibles []VisibleInterval, offset int64, size int
 		stop = math.MaxInt64
 	}
 
-	for _, chunk := range visibles {
+	chunkViews = NewIntervalList[*ChunkView]()
+	for x := visibles.Front(); x != nil; x = x.Next {
+		chunk := x.Value
 
 		chunkStart, chunkStop := max(offset, chunk.start), min(stop, chunk.stop)
 
 		if chunkStart < chunkStop {
-			views = append(views, &ChunkView{
-				FileId:      chunk.fileId,
-				Offset:      chunkStart - chunk.start + chunk.chunkOffset,
-				Size:        uint64(chunkStop - chunkStart),
-				LogicOffset: chunkStart,
-				ChunkSize:   chunk.chunkSize,
-				CipherKey:   chunk.cipherKey,
-				IsGzipped:   chunk.isGzipped,
+			chunkView := &ChunkView{
+				FileId:        chunk.fileId,
+				OffsetInChunk: chunkStart - chunk.start + chunk.offsetInChunk,
+				ViewSize:      uint64(chunkStop - chunkStart),
+				ViewOffset:    chunkStart,
+				ChunkSize:     chunk.chunkSize,
+				CipherKey:     chunk.cipherKey,
+				IsGzipped:     chunk.isGzipped,
+				ModifiedTsNs:  chunk.modifiedTsNs,
+			}
+			chunkViews.AppendInterval(&Interval[*ChunkView]{
+				StartOffset: chunkStart,
+				StopOffset:  chunkStop,
+				TsNs:        chunk.modifiedTsNs,
+				Value:       chunkView,
+				Prev:        nil,
+				Next:        nil,
 			})
 		}
 	}
 
-	return views
+	return chunkViews
 
 }
 
-func logPrintf(name string, visibles []VisibleInterval) {
-
-	/*
-		glog.V(0).Infof("%s len %d", name, len(visibles))
-		for _, v := range visibles {
-			glog.V(0).Infof("%s:  [%d,%d) %s %d", name, v.start, v.stop, v.fileId, v.chunkOffset)
-		}
-	*/
-}
-
-func MergeIntoVisibles(visibles []VisibleInterval, chunk *filer_pb.FileChunk) (newVisibles []VisibleInterval) {
-
-	newV := newVisibleInterval(chunk.Offset, chunk.Offset+int64(chunk.Size), chunk.GetFileIdString(), chunk.ModifiedTsNs, 0, chunk.Size, chunk.CipherKey, chunk.IsCompressed)
-
-	length := len(visibles)
-	if length == 0 {
-		return append(visibles, newV)
-	}
-	last := visibles[length-1]
-	if last.stop <= chunk.Offset {
-		return append(visibles, newV)
+func MergeIntoVisibles(visibles *IntervalList[*VisibleInterval], start int64, stop int64, chunk *filer_pb.FileChunk) {
+
+	newV := &VisibleInterval{
+		start:         start,
+		stop:          stop,
+		fileId:        chunk.GetFileIdString(),
+		modifiedTsNs:  chunk.ModifiedTsNs,
+		offsetInChunk: start - chunk.Offset, // the starting position in the chunk
+		chunkSize:     chunk.Size,           // size of the chunk
+		cipherKey:     chunk.CipherKey,
+		isGzipped:     chunk.IsCompressed,
 	}
 
-	logPrintf("  before", visibles)
-	// glog.V(0).Infof("newVisibles %d adding chunk [%d,%d) %s size:%d", len(newVisibles), chunk.Offset, chunk.Offset+int64(chunk.Size), chunk.GetFileIdString(), chunk.Size)
-	chunkStop := chunk.Offset + int64(chunk.Size)
-	for _, v := range visibles {
-		if v.start < chunk.Offset && chunk.Offset < v.stop {
-			t := newVisibleInterval(v.start, chunk.Offset, v.fileId, v.modifiedTsNs, v.chunkOffset, v.chunkSize, v.cipherKey, v.isGzipped)
-			newVisibles = append(newVisibles, t)
-			// glog.V(0).Infof("visible %d [%d,%d) =1> [%d,%d)", i, v.start, v.stop, t.start, t.stop)
-		}
-		if v.start < chunkStop && chunkStop < v.stop {
-			t := newVisibleInterval(chunkStop, v.stop, v.fileId, v.modifiedTsNs, v.chunkOffset+(chunkStop-v.start), v.chunkSize, v.cipherKey, v.isGzipped)
-			newVisibles = append(newVisibles, t)
-			// glog.V(0).Infof("visible %d [%d,%d) =2> [%d,%d)", i, v.start, v.stop, t.start, t.stop)
-		}
-		if chunkStop <= v.start || v.stop <= chunk.Offset {
-			newVisibles = append(newVisibles, v)
-			// glog.V(0).Infof("visible %d [%d,%d) =3> [%d,%d)", i, v.start, v.stop, v.start, v.stop)
-		}
-	}
-	newVisibles = append(newVisibles, newV)
-
-	logPrintf("  append", newVisibles)
+	visibles.InsertInterval(start, stop, chunk.ModifiedTsNs, newV)
+}
 
-	for i := len(newVisibles) - 1; i >= 0; i-- {
-		if i > 0 && newV.start < newVisibles[i-1].start {
-			newVisibles[i] = newVisibles[i-1]
-		} else {
-			newVisibles[i] = newV
-			break
-		}
+func MergeIntoChunkViews(chunkViews *IntervalList[*ChunkView], start int64, stop int64, chunk *filer_pb.FileChunk) {
+
+	chunkView := &ChunkView{
+		FileId:        chunk.GetFileIdString(),
+		OffsetInChunk: start - chunk.Offset,
+		ViewSize:      uint64(stop - start),
+		ViewOffset:    start,
+		ChunkSize:     chunk.Size,
+		CipherKey:     chunk.CipherKey,
+		IsGzipped:     chunk.IsCompressed,
+		ModifiedTsNs:  chunk.ModifiedTsNs,
 	}
-	logPrintf("  sorted", newVisibles)
 
-	return newVisibles
+	chunkViews.InsertInterval(start, stop, chunk.ModifiedTsNs, chunkView)
 }
 
 // NonOverlappingVisibleIntervals translates the file chunk into VisibleInterval in memory
 // If the file chunk content is a chunk manifest
-func NonOverlappingVisibleIntervals(lookupFileIdFn wdclient.LookupFileIdFunctionType, chunks []*filer_pb.FileChunk, startOffset int64, stopOffset int64) (visibles []VisibleInterval, err error) {
+func NonOverlappingVisibleIntervals(lookupFileIdFn wdclient.LookupFileIdFunctionType, chunks []*filer_pb.FileChunk, startOffset int64, stopOffset int64) (visibles *IntervalList[*VisibleInterval], err error) {
 
 	chunks, _, err = ResolveChunkManifest(lookupFileIdFn, chunks, startOffset, stopOffset)
 	if err != nil {
 		return
 	}
 
-	visibles2 := readResolvedChunks(chunks)
-
-	if true {
-		return visibles2, err
-	}
-	slices.SortFunc(chunks, func(a, b *filer_pb.FileChunk) bool {
-		if a.ModifiedTsNs == b.ModifiedTsNs {
-			filer_pb.EnsureFid(a)
-			filer_pb.EnsureFid(b)
-			if a.Fid == nil || b.Fid == nil {
-				return true
-			}
-			return a.Fid.FileKey < b.Fid.FileKey
-		}
-		return a.ModifiedTsNs < b.ModifiedTsNs
-	})
-	for _, chunk := range chunks {
-
-		// glog.V(0).Infof("merge [%d,%d)", chunk.Offset, chunk.Offset+int64(chunk.Size))
-		visibles = MergeIntoVisibles(visibles, chunk)
-
-		logPrintf("add", visibles)
+	visibles2 := readResolvedChunks(chunks, 0, math.MaxInt64)
 
-	}
-
-	if len(visibles) != len(visibles2) {
-		fmt.Printf("different visibles size %d : %d\n", len(visibles), len(visibles2))
-	} else {
-		for i := 0; i < len(visibles); i++ {
-			checkDifference(visibles[i], visibles2[i])
-		}
-	}
-
-	return
-}
-
-func checkDifference(x, y VisibleInterval) {
-	if x.start != y.start ||
-		x.stop != y.stop ||
-		x.fileId != y.fileId ||
-		x.modifiedTsNs != y.modifiedTsNs {
-		fmt.Printf("different visible %+v : %+v\n", x, y)
-	}
+	return visibles2, err
 }
 
 // find non-overlapping visible intervals
 // visible interval map to one file chunk
 
 type VisibleInterval struct {
-	start        int64
-	stop         int64
-	modifiedTsNs int64
-	fileId       string
-	chunkOffset  int64
-	chunkSize    uint64
-	cipherKey    []byte
-	isGzipped    bool
+	start         int64
+	stop          int64
+	modifiedTsNs  int64
+	fileId        string
+	offsetInChunk int64
+	chunkSize     uint64
+	cipherKey     []byte
+	isGzipped     bool
 }
 
-func newVisibleInterval(start, stop int64, fileId string, modifiedTime int64, chunkOffset int64, chunkSize uint64, cipherKey []byte, isGzipped bool) VisibleInterval {
-	return VisibleInterval{
-		start:        start,
-		stop:         stop,
-		fileId:       fileId,
-		modifiedTsNs: modifiedTime,
-		chunkOffset:  chunkOffset, // the starting position in the chunk
-		chunkSize:    chunkSize,
-		cipherKey:    cipherKey,
-		isGzipped:    isGzipped,
+func (v *VisibleInterval) SetStartStop(start, stop int64) {
+	v.offsetInChunk += start - v.start
+	v.start, v.stop = start, stop
+}
+func (v *VisibleInterval) Clone() IntervalValue {
+	return &VisibleInterval{
+		start:         v.start,
+		stop:          v.stop,
+		modifiedTsNs:  v.modifiedTsNs,
+		fileId:        v.fileId,
+		offsetInChunk: v.offsetInChunk,
+		chunkSize:     v.chunkSize,
+		cipherKey:     v.cipherKey,
+		isGzipped:     v.isGzipped,
 	}
 }
 
diff --git a/weed/filer/filechunks_read.go b/weed/filer/filechunks_read.go
index 8a15f6e7a..8b2d36e12 100644
--- a/weed/filer/filechunks_read.go
+++ b/weed/filer/filechunks_read.go
@@ -1,14 +1,22 @@
 package filer
 
 import (
+	"container/list"
 	"github.com/seaweedfs/seaweedfs/weed/pb/filer_pb"
 	"golang.org/x/exp/slices"
 )
 
-func readResolvedChunks(chunks []*filer_pb.FileChunk) (visibles []VisibleInterval) {
+func readResolvedChunks(chunks []*filer_pb.FileChunk, startOffset int64, stopOffset int64) (visibles *IntervalList[*VisibleInterval]) {
 
 	var points []*Point
 	for _, chunk := range chunks {
+		if chunk.IsChunkManifest {
+			println("This should not happen! A manifest chunk found:", chunk.GetFileIdString())
+		}
+		start, stop := max(chunk.Offset, startOffset), min(chunk.Offset+int64(chunk.Size), stopOffset)
+		if start >= stop {
+			continue
+		}
 		points = append(points, &Point{
 			x:       chunk.Offset,
 			ts:      chunk.ModifiedTsNs,
@@ -33,40 +41,45 @@ func readResolvedChunks(chunks []*filer_pb.FileChunk) (visibles []VisibleInterva
 	})
 
 	var prevX int64
-	var queue []*Point
+	queue := list.New() // points with higher ts are at the tail
+	visibles = NewIntervalList[*VisibleInterval]()
+	var prevPoint *Point
 	for _, point := range points {
+		if queue.Len() > 0 {
+			prevPoint = queue.Back().Value.(*Point)
+		} else {
+			prevPoint = nil
+		}
 		if point.isStart {
-			if len(queue) > 0 {
-				lastIndex := len(queue) - 1
-				lastPoint := queue[lastIndex]
-				if point.x != prevX && lastPoint.ts < point.ts {
-					visibles = addToVisibles(visibles, prevX, lastPoint, point)
+			if prevPoint != nil {
+				if point.x != prevX && prevPoint.ts < point.ts {
+					addToVisibles(visibles, prevX, prevPoint, point)
 					prevX = point.x
 				}
 			}
 			// insert into queue
-			for i := len(queue); i >= 0; i-- {
-				if i == 0 || queue[i-1].ts <= point.ts {
-					if i == len(queue) {
-						prevX = point.x
+			if prevPoint == nil || prevPoint.ts < point.ts {
+				queue.PushBack(point)
+				prevX = point.x
+			} else {
+				for e := queue.Front(); e != nil; e = e.Next() {
+					if e.Value.(*Point).ts > point.ts {
+						queue.InsertBefore(point, e)
+						break
 					}
-					queue = addToQueue(queue, i, point)
-					break
 				}
 			}
 		} else {
-			lastIndex := len(queue) - 1
-			index := lastIndex
-			var startPoint *Point
-			for ; index >= 0; index-- {
-				startPoint = queue[index]
-				if startPoint.ts == point.ts {
-					queue = removeFromQueue(queue, index)
+			isLast := true
+			for e := queue.Back(); e != nil; e = e.Prev() {
+				if e.Value.(*Point).ts == point.ts {
+					queue.Remove(e)
 					break
 				}
+				isLast = false
 			}
-			if index == lastIndex && startPoint != nil {
-				visibles = addToVisibles(visibles, prevX, startPoint, point)
+			if isLast && prevPoint != nil {
+				addToVisibles(visibles, prevX, prevPoint, point)
 				prevX = point.x
 			}
 		}
@@ -75,37 +88,30 @@ func readResolvedChunks(chunks []*filer_pb.FileChunk) (visibles []VisibleInterva
 	return
 }
 
-func removeFromQueue(queue []*Point, index int) []*Point {
-	for i := index; i < len(queue)-1; i++ {
-		queue[i] = queue[i+1]
-	}
-	queue = queue[:len(queue)-1]
-	return queue
-}
-
-func addToQueue(queue []*Point, index int, point *Point) []*Point {
-	queue = append(queue, point)
-	for i := len(queue) - 1; i > index; i-- {
-		queue[i], queue[i-1] = queue[i-1], queue[i]
-	}
-	return queue
-}
-
-func addToVisibles(visibles []VisibleInterval, prevX int64, startPoint *Point, point *Point) []VisibleInterval {
+func addToVisibles(visibles *IntervalList[*VisibleInterval], prevX int64, startPoint *Point, point *Point) {
 	if prevX < point.x {
 		chunk := startPoint.chunk
-		visibles = append(visibles, VisibleInterval{
-			start:        prevX,
-			stop:         point.x,
-			fileId:       chunk.GetFileIdString(),
-			modifiedTsNs: chunk.ModifiedTsNs,
-			chunkOffset:  prevX - chunk.Offset,
-			chunkSize:    chunk.Size,
-			cipherKey:    chunk.CipherKey,
-			isGzipped:    chunk.IsCompressed,
-		})
+		visible := &VisibleInterval{
+			start:         prevX,
+			stop:          point.x,
+			fileId:        chunk.GetFileIdString(),
+			modifiedTsNs:  chunk.ModifiedTsNs,
+			offsetInChunk: prevX - chunk.Offset,
+			chunkSize:     chunk.Size,
+			cipherKey:     chunk.CipherKey,
+			isGzipped:     chunk.IsCompressed,
+		}
+		appendVisibleInterfal(visibles, visible)
 	}
-	return visibles
+}
+
+func appendVisibleInterfal(visibles *IntervalList[*VisibleInterval], visible *VisibleInterval) {
+	visibles.AppendInterval(&Interval[*VisibleInterval]{
+		StartOffset: visible.start,
+		StopOffset:  visible.stop,
+		TsNs:        visible.modifiedTsNs,
+		Value:       visible,
+	})
 }
 
 type Point struct {
diff --git a/weed/filer/filechunks_read_test.go b/weed/filer/filechunks_read_test.go
index d4bfca72e..c66a874bc 100644
--- a/weed/filer/filechunks_read_test.go
+++ b/weed/filer/filechunks_read_test.go
@@ -3,6 +3,7 @@ package filer
 import (
 	"fmt"
 	"github.com/seaweedfs/seaweedfs/weed/pb/filer_pb"
+	"math"
 	"math/rand"
 	"testing"
 )
@@ -42,9 +43,38 @@ func TestReadResolvedChunks(t *testing.T) {
 		},
 	}
 
-	visibles := readResolvedChunks(chunks)
+	visibles := readResolvedChunks(chunks, 0, math.MaxInt64)
 
-	for _, visible := range visibles {
+	fmt.Printf("resolved to %d visible intervales\n", visibles.Len())
+	for x := visibles.Front(); x != nil; x = x.Next {
+		visible := x.Value
+		fmt.Printf("[%d,%d) %s %d\n", visible.start, visible.stop, visible.fileId, visible.modifiedTsNs)
+	}
+
+}
+
+func TestReadResolvedChunks2(t *testing.T) {
+
+	chunks := []*filer_pb.FileChunk{
+		{
+			FileId:       "c",
+			Offset:       200,
+			Size:         50,
+			ModifiedTsNs: 3,
+		},
+		{
+			FileId:       "e",
+			Offset:       200,
+			Size:         25,
+			ModifiedTsNs: 5,
+		},
+	}
+
+	visibles := readResolvedChunks(chunks, 0, math.MaxInt64)
+
+	fmt.Printf("resolved to %d visible intervales\n", visibles.Len())
+	for x := visibles.Front(); x != nil; x = x.Next {
+		visible := x.Value
 		fmt.Printf("[%d,%d) %s %d\n", visible.start, visible.stop, visible.fileId, visible.modifiedTsNs)
 	}
 
@@ -72,9 +102,10 @@ func TestRandomizedReadResolvedChunks(t *testing.T) {
 		chunks = append(chunks, randomWrite(array, start, size, ts))
 	}
 
-	visibles := readResolvedChunks(chunks)
+	visibles := readResolvedChunks(chunks, 0, math.MaxInt64)
 
-	for _, visible := range visibles {
+	for x := visibles.Front(); x != nil; x = x.Next {
+		visible := x.Value
 		for i := visible.start; i < visible.stop; i++ {
 			if array[i] != visible.modifiedTsNs {
 				t.Errorf("position %d expected ts %d actual ts %d", i, array[i], visible.modifiedTsNs)
@@ -112,9 +143,9 @@ func TestSequentialReadResolvedChunks(t *testing.T) {
 		})
 	}
 
-	visibles := readResolvedChunks(chunks)
+	visibles := readResolvedChunks(chunks, 0, math.MaxInt64)
 
-	fmt.Printf("visibles %d", len(visibles))
+	fmt.Printf("visibles %d", visibles.Len())
 
 }
 
@@ -201,9 +232,48 @@ func TestActualReadResolvedChunks(t *testing.T) {
 		},
 	}
 
-	visibles := readResolvedChunks(chunks)
+	visibles := readResolvedChunks(chunks, 0, math.MaxInt64)
+
+	for x := visibles.Front(); x != nil; x = x.Next {
+		visible := x.Value
+		fmt.Printf("[%d,%d) %s %d\n", visible.start, visible.stop, visible.fileId, visible.modifiedTsNs)
+	}
+
+}
+
+func TestActualReadResolvedChunks2(t *testing.T) {
+
+	chunks := []*filer_pb.FileChunk{
+		{
+			FileId:       "1,e7b96fef48",
+			Offset:       0,
+			Size:         184320,
+			ModifiedTsNs: 1,
+		},
+		{
+			FileId:       "2,22562640b9",
+			Offset:       184320,
+			Size:         4096,
+			ModifiedTsNs: 2,
+		},
+		{
+			FileId:       "2,33562640b9",
+			Offset:       184320,
+			Size:         4096,
+			ModifiedTsNs: 4,
+		},
+		{
+			FileId:       "4,df033e0fe4",
+			Offset:       188416,
+			Size:         2097152,
+			ModifiedTsNs: 3,
+		},
+	}
+
+	visibles := readResolvedChunks(chunks, 0, math.MaxInt64)
 
-	for _, visible := range visibles {
+	for x := visibles.Front(); x != nil; x = x.Next {
+		visible := x.Value
 		fmt.Printf("[%d,%d) %s %d\n", visible.start, visible.stop, visible.fileId, visible.modifiedTsNs)
 	}
 
diff --git a/weed/filer/filechunks_test.go b/weed/filer/filechunks_test.go
index d29e0a600..b448950a9 100644
--- a/weed/filer/filechunks_test.go
+++ b/weed/filer/filechunks_test.go
@@ -92,7 +92,8 @@ func TestRandomFileChunksCompact(t *testing.T) {
 
 	visibles, _ := NonOverlappingVisibleIntervals(nil, chunks, 0, math.MaxInt64)
 
-	for _, v := range visibles {
+	for visible := visibles.Front(); visible != nil; visible = visible.Next {
+		v := visible.Value
 		for x := v.start; x < v.stop; x++ {
 			assert.Equal(t, strconv.Itoa(int(data[x])), v.fileId)
 		}
@@ -137,7 +138,7 @@ func TestIntervalMerging(t *testing.T) {
 			},
 			Expected: []*VisibleInterval{
 				{start: 0, stop: 70, fileId: "b"},
-				{start: 70, stop: 100, fileId: "a", chunkOffset: 70},
+				{start: 70, stop: 100, fileId: "a", offsetInChunk: 70},
 			},
 		},
 		// case 3: updates overwrite full chunks
@@ -174,15 +175,15 @@ func TestIntervalMerging(t *testing.T) {
 			},
 			Expected: []*VisibleInterval{
 				{start: 0, stop: 200, fileId: "d"},
-				{start: 200, stop: 220, fileId: "c", chunkOffset: 130},
+				{start: 200, stop: 220, fileId: "c", offsetInChunk: 130},
 			},
 		},
 		// case 6: same updates
 		{
 			Chunks: []*filer_pb.FileChunk{
 				{Offset: 0, Size: 100, FileId: "abc", Fid: &filer_pb.FileId{FileKey: 1}, ModifiedTsNs: 123},
-				{Offset: 0, Size: 100, FileId: "axf", Fid: &filer_pb.FileId{FileKey: 2}, ModifiedTsNs: 123},
-				{Offset: 0, Size: 100, FileId: "xyz", Fid: &filer_pb.FileId{FileKey: 3}, ModifiedTsNs: 123},
+				{Offset: 0, Size: 100, FileId: "axf", Fid: &filer_pb.FileId{FileKey: 2}, ModifiedTsNs: 124},
+				{Offset: 0, Size: 100, FileId: "xyz", Fid: &filer_pb.FileId{FileKey: 3}, ModifiedTsNs: 125},
 			},
 			Expected: []*VisibleInterval{
 				{start: 0, stop: 100, fileId: "xyz"},
@@ -228,11 +229,17 @@ func TestIntervalMerging(t *testing.T) {
 	for i, testcase := range testcases {
 		log.Printf("++++++++++ merged test case %d ++++++++++++++++++++", i)
 		intervals, _ := NonOverlappingVisibleIntervals(nil, testcase.Chunks, 0, math.MaxInt64)
-		for x, interval := range intervals {
-			log.Printf("test case %d, interval %d, start=%d, stop=%d, fileId=%s",
-				i, x, interval.start, interval.stop, interval.fileId)
+		x := -1
+		for visible := intervals.Front(); visible != nil; visible = visible.Next {
+			x++
+			interval := visible.Value
+			log.Printf("test case %d, interval start=%d, stop=%d, fileId=%s",
+				i, interval.start, interval.stop, interval.fileId)
 		}
-		for x, interval := range intervals {
+		x = -1
+		for visible := intervals.Front(); visible != nil; visible = visible.Next {
+			x++
+			interval := visible.Value
 			if interval.start != testcase.Expected[x].start {
 				t.Fatalf("failed on test case %d, interval %d, start %d, expect %d",
 					i, x, interval.start, testcase.Expected[x].start)
@@ -245,13 +252,13 @@ func TestIntervalMerging(t *testing.T) {
 				t.Fatalf("failed on test case %d, interval %d, chunkId %s, expect %s",
 					i, x, interval.fileId, testcase.Expected[x].fileId)
 			}
-			if interval.chunkOffset != testcase.Expected[x].chunkOffset {
-				t.Fatalf("failed on test case %d, interval %d, chunkOffset %d, expect %d",
-					i, x, interval.chunkOffset, testcase.Expected[x].chunkOffset)
+			if interval.offsetInChunk != testcase.Expected[x].offsetInChunk {
+				t.Fatalf("failed on test case %d, interval %d, offsetInChunk %d, expect %d",
+					i, x, interval.offsetInChunk, testcase.Expected[x].offsetInChunk)
 			}
 		}
-		if len(intervals) != len(testcase.Expected) {
-			t.Fatalf("failed to compact test case %d, len %d expected %d", i, len(intervals), len(testcase.Expected))
+		if intervals.Len() != len(testcase.Expected) {
+			t.Fatalf("failed to compact test case %d, len %d expected %d", i, intervals.Len(), len(testcase.Expected))
 		}
 
 	}
@@ -276,9 +283,9 @@ func TestChunksReading(t *testing.T) {
 			Offset: 0,
 			Size:   250,
 			Expected: []*ChunkView{
-				{Offset: 0, Size: 100, FileId: "abc", LogicOffset: 0},
-				{Offset: 0, Size: 100, FileId: "asdf", LogicOffset: 100},
-				{Offset: 0, Size: 50, FileId: "fsad", LogicOffset: 200},
+				{OffsetInChunk: 0, ViewSize: 100, FileId: "abc", ViewOffset: 0},
+				{OffsetInChunk: 0, ViewSize: 100, FileId: "asdf", ViewOffset: 100},
+				{OffsetInChunk: 0, ViewSize: 50, FileId: "fsad", ViewOffset: 200},
 			},
 		},
 		// case 1: updates overwrite full chunks
@@ -290,7 +297,7 @@ func TestChunksReading(t *testing.T) {
 			Offset: 50,
 			Size:   100,
 			Expected: []*ChunkView{
-				{Offset: 50, Size: 100, FileId: "asdf", LogicOffset: 50},
+				{OffsetInChunk: 50, ViewSize: 100, FileId: "asdf", ViewOffset: 50},
 			},
 		},
 		// case 2: updates overwrite part of previous chunks
@@ -302,8 +309,8 @@ func TestChunksReading(t *testing.T) {
 			Offset: 30,
 			Size:   40,
 			Expected: []*ChunkView{
-				{Offset: 20, Size: 30, FileId: "b", LogicOffset: 30},
-				{Offset: 57, Size: 10, FileId: "a", LogicOffset: 60},
+				{OffsetInChunk: 20, ViewSize: 30, FileId: "b", ViewOffset: 30},
+				{OffsetInChunk: 57, ViewSize: 10, FileId: "a", ViewOffset: 60},
 			},
 		},
 		// case 3: updates overwrite full chunks
@@ -316,8 +323,8 @@ func TestChunksReading(t *testing.T) {
 			Offset: 0,
 			Size:   200,
 			Expected: []*ChunkView{
-				{Offset: 0, Size: 50, FileId: "asdf", LogicOffset: 0},
-				{Offset: 0, Size: 150, FileId: "xxxx", LogicOffset: 50},
+				{OffsetInChunk: 0, ViewSize: 50, FileId: "asdf", ViewOffset: 0},
+				{OffsetInChunk: 0, ViewSize: 150, FileId: "xxxx", ViewOffset: 50},
 			},
 		},
 		// case 4: updates far away from prev chunks
@@ -330,8 +337,8 @@ func TestChunksReading(t *testing.T) {
 			Offset: 0,
 			Size:   400,
 			Expected: []*ChunkView{
-				{Offset: 0, Size: 200, FileId: "asdf", LogicOffset: 0},
-				{Offset: 0, Size: 150, FileId: "xxxx", LogicOffset: 250},
+				{OffsetInChunk: 0, ViewSize: 200, FileId: "asdf", ViewOffset: 0},
+				{OffsetInChunk: 0, ViewSize: 150, FileId: "xxxx", ViewOffset: 250},
 			},
 		},
 		// case 5: updates overwrite full chunks
@@ -345,21 +352,21 @@ func TestChunksReading(t *testing.T) {
 			Offset: 0,
 			Size:   220,
 			Expected: []*ChunkView{
-				{Offset: 0, Size: 200, FileId: "c", LogicOffset: 0},
-				{Offset: 130, Size: 20, FileId: "b", LogicOffset: 200},
+				{OffsetInChunk: 0, ViewSize: 200, FileId: "c", ViewOffset: 0},
+				{OffsetInChunk: 130, ViewSize: 20, FileId: "b", ViewOffset: 200},
 			},
 		},
 		// case 6: same updates
 		{
 			Chunks: []*filer_pb.FileChunk{
 				{Offset: 0, Size: 100, FileId: "abc", Fid: &filer_pb.FileId{FileKey: 1}, ModifiedTsNs: 123},
-				{Offset: 0, Size: 100, FileId: "def", Fid: &filer_pb.FileId{FileKey: 2}, ModifiedTsNs: 123},
-				{Offset: 0, Size: 100, FileId: "xyz", Fid: &filer_pb.FileId{FileKey: 3}, ModifiedTsNs: 123},
+				{Offset: 0, Size: 100, FileId: "def", Fid: &filer_pb.FileId{FileKey: 2}, ModifiedTsNs: 124},
+				{Offset: 0, Size: 100, FileId: "xyz", Fid: &filer_pb.FileId{FileKey: 3}, ModifiedTsNs: 125},
 			},
 			Offset: 0,
 			Size:   100,
 			Expected: []*ChunkView{
-				{Offset: 0, Size: 100, FileId: "xyz", LogicOffset: 0},
+				{OffsetInChunk: 0, ViewSize: 100, FileId: "xyz", ViewOffset: 0},
 			},
 		},
 		// case 7: edge cases
@@ -372,8 +379,8 @@ func TestChunksReading(t *testing.T) {
 			Offset: 0,
 			Size:   200,
 			Expected: []*ChunkView{
-				{Offset: 0, Size: 100, FileId: "abc", LogicOffset: 0},
-				{Offset: 0, Size: 100, FileId: "asdf", LogicOffset: 100},
+				{OffsetInChunk: 0, ViewSize: 100, FileId: "abc", ViewOffset: 0},
+				{OffsetInChunk: 0, ViewSize: 100, FileId: "asdf", ViewOffset: 100},
 			},
 		},
 		// case 8: edge cases
@@ -386,9 +393,9 @@ func TestChunksReading(t *testing.T) {
 			Offset: 0,
 			Size:   300,
 			Expected: []*ChunkView{
-				{Offset: 0, Size: 90, FileId: "abc", LogicOffset: 0},
-				{Offset: 0, Size: 100, FileId: "asdf", LogicOffset: 90},
-				{Offset: 0, Size: 110, FileId: "fsad", LogicOffset: 190},
+				{OffsetInChunk: 0, ViewSize: 90, FileId: "abc", ViewOffset: 0},
+				{OffsetInChunk: 0, ViewSize: 100, FileId: "asdf", ViewOffset: 90},
+				{OffsetInChunk: 0, ViewSize: 110, FileId: "fsad", ViewOffset: 190},
 			},
 		},
 		// case 9: edge cases
@@ -404,12 +411,12 @@ func TestChunksReading(t *testing.T) {
 			Offset: 0,
 			Size:   153578836,
 			Expected: []*ChunkView{
-				{Offset: 0, Size: 43175936, FileId: "2,111fc2cbfac1", LogicOffset: 0},
-				{Offset: 0, Size: 52981760 - 43175936, FileId: "2,112a36ea7f85", LogicOffset: 43175936},
-				{Offset: 0, Size: 72564736 - 52981760, FileId: "4,112d5f31c5e7", LogicOffset: 52981760},
-				{Offset: 0, Size: 133255168 - 72564736, FileId: "1,113245f0cdb6", LogicOffset: 72564736},
-				{Offset: 0, Size: 137269248 - 133255168, FileId: "3,1141a70733b5", LogicOffset: 133255168},
-				{Offset: 0, Size: 153578836 - 137269248, FileId: "1,114201d5bbdb", LogicOffset: 137269248},
+				{OffsetInChunk: 0, ViewSize: 43175936, FileId: "2,111fc2cbfac1", ViewOffset: 0},
+				{OffsetInChunk: 0, ViewSize: 52981760 - 43175936, FileId: "2,112a36ea7f85", ViewOffset: 43175936},
+				{OffsetInChunk: 0, ViewSize: 72564736 - 52981760, FileId: "4,112d5f31c5e7", ViewOffset: 52981760},
+				{OffsetInChunk: 0, ViewSize: 133255168 - 72564736, FileId: "1,113245f0cdb6", ViewOffset: 72564736},
+				{OffsetInChunk: 0, ViewSize: 137269248 - 133255168, FileId: "3,1141a70733b5", ViewOffset: 133255168},
+				{OffsetInChunk: 0, ViewSize: 153578836 - 137269248, FileId: "1,114201d5bbdb", ViewOffset: 137269248},
 			},
 		},
 	}
@@ -420,28 +427,31 @@ func TestChunksReading(t *testing.T) {
 		}
 		log.Printf("++++++++++ read test case %d ++++++++++++++++++++", i)
 		chunks := ViewFromChunks(nil, testcase.Chunks, testcase.Offset, testcase.Size)
-		for x, chunk := range chunks {
+		x := -1
+		for c := chunks.Front(); c != nil; c = c.Next {
+			x++
+			chunk := c.Value
 			log.Printf("read case %d, chunk %d, offset=%d, size=%d, fileId=%s",
-				i, x, chunk.Offset, chunk.Size, chunk.FileId)
-			if chunk.Offset != testcase.Expected[x].Offset {
+				i, x, chunk.OffsetInChunk, chunk.ViewSize, chunk.FileId)
+			if chunk.OffsetInChunk != testcase.Expected[x].OffsetInChunk {
 				t.Fatalf("failed on read case %d, chunk %s, Offset %d, expect %d",
-					i, chunk.FileId, chunk.Offset, testcase.Expected[x].Offset)
+					i, chunk.FileId, chunk.OffsetInChunk, testcase.Expected[x].OffsetInChunk)
 			}
-			if chunk.Size != testcase.Expected[x].Size {
-				t.Fatalf("failed on read case %d, chunk %s, Size %d, expect %d",
-					i, chunk.FileId, chunk.Size, testcase.Expected[x].Size)
+			if chunk.ViewSize != testcase.Expected[x].ViewSize {
+				t.Fatalf("failed on read case %d, chunk %s, ViewSize %d, expect %d",
+					i, chunk.FileId, chunk.ViewSize, testcase.Expected[x].ViewSize)
 			}
 			if chunk.FileId != testcase.Expected[x].FileId {
 				t.Fatalf("failed on read case %d, chunk %d, FileId %s, expect %s",
 					i, x, chunk.FileId, testcase.Expected[x].FileId)
 			}
-			if chunk.LogicOffset != testcase.Expected[x].LogicOffset {
-				t.Fatalf("failed on read case %d, chunk %d, LogicOffset %d, expect %d",
-					i, x, chunk.LogicOffset, testcase.Expected[x].LogicOffset)
+			if chunk.ViewOffset != testcase.Expected[x].ViewOffset {
+				t.Fatalf("failed on read case %d, chunk %d, ViewOffset %d, expect %d",
+					i, x, chunk.ViewOffset, testcase.Expected[x].ViewOffset)
 			}
 		}
-		if len(chunks) != len(testcase.Expected) {
-			t.Fatalf("failed to read test case %d, len %d expected %d", i, len(chunks), len(testcase.Expected))
+		if chunks.Len() != len(testcase.Expected) {
+			t.Fatalf("failed to read test case %d, len %d expected %d", i, chunks.Len(), len(testcase.Expected))
 		}
 	}
 
@@ -467,73 +477,79 @@ func BenchmarkCompactFileChunks(b *testing.B) {
 	}
 }
 
+func addVisibleInterval(visibles *IntervalList[*VisibleInterval], x *VisibleInterval) {
+	visibles.AppendInterval(&Interval[*VisibleInterval]{
+		StartOffset: x.start,
+		StopOffset:  x.stop,
+		TsNs:        x.modifiedTsNs,
+		Value:       x,
+	})
+}
+
 func TestViewFromVisibleIntervals(t *testing.T) {
-	visibles := []VisibleInterval{
-		{
-			start:  0,
-			stop:   25,
-			fileId: "fid1",
-		},
-		{
-			start:  4096,
-			stop:   8192,
-			fileId: "fid2",
-		},
-		{
-			start:  16384,
-			stop:   18551,
-			fileId: "fid3",
-		},
-	}
+	visibles := NewIntervalList[*VisibleInterval]()
+	addVisibleInterval(visibles, &VisibleInterval{
+		start:  0,
+		stop:   25,
+		fileId: "fid1",
+	})
+	addVisibleInterval(visibles, &VisibleInterval{
+		start:  4096,
+		stop:   8192,
+		fileId: "fid2",
+	})
+	addVisibleInterval(visibles, &VisibleInterval{
+		start:  16384,
+		stop:   18551,
+		fileId: "fid3",
+	})
 
 	views := ViewFromVisibleIntervals(visibles, 0, math.MaxInt32)
 
-	if len(views) != len(visibles) {
-		assert.Equal(t, len(visibles), len(views), "ViewFromVisibleIntervals error")
+	if views.Len() != visibles.Len() {
+		assert.Equal(t, visibles.Len(), views.Len(), "ViewFromVisibleIntervals error")
 	}
 
 }
 
 func TestViewFromVisibleIntervals2(t *testing.T) {
-	visibles := []VisibleInterval{
-		{
-			start:  344064,
-			stop:   348160,
-			fileId: "fid1",
-		},
-		{
-			start:  348160,
-			stop:   356352,
-			fileId: "fid2",
-		},
-	}
+	visibles := NewIntervalList[*VisibleInterval]()
+	addVisibleInterval(visibles, &VisibleInterval{
+		start:  344064,
+		stop:   348160,
+		fileId: "fid1",
+	})
+	addVisibleInterval(visibles, &VisibleInterval{
+		start:  348160,
+		stop:   356352,
+		fileId: "fid2",
+	})
 
 	views := ViewFromVisibleIntervals(visibles, 0, math.MaxInt32)
 
-	if len(views) != len(visibles) {
-		assert.Equal(t, len(visibles), len(views), "ViewFromVisibleIntervals error")
+	if views.Len() != visibles.Len() {
+		assert.Equal(t, visibles.Len(), views.Len(), "ViewFromVisibleIntervals error")
 	}
 
 }
 
 func TestViewFromVisibleIntervals3(t *testing.T) {
-	visibles := []VisibleInterval{
-		{
-			start:  1000,
-			stop:   2000,
-			fileId: "fid1",
-		},
-		{
-			start:  3000,
-			stop:   4000,
-			fileId: "fid2",
-		},
-	}
+	visibles := NewIntervalList[*VisibleInterval]()
+	addVisibleInterval(visibles, &VisibleInterval{
+		start:  1000,
+		stop:   2000,
+		fileId: "fid1",
+	})
+	addVisibleInterval(visibles, &VisibleInterval{
+		start:  3000,
+		stop:   4000,
+		fileId: "fid2",
+	})
 
 	views := ViewFromVisibleIntervals(visibles, 1700, 1500)
 
-	if len(views) != len(visibles) {
-		assert.Equal(t, len(visibles), len(views), "ViewFromVisibleIntervals error")
+	if views.Len() != visibles.Len() {
+		assert.Equal(t, visibles.Len(), views.Len(), "ViewFromVisibleIntervals error")
 	}
 
 }
diff --git a/weed/filer/filer_notify_append.go b/weed/filer/filer_notify_append.go
index 5c03d4f16..55278c492 100644
--- a/weed/filer/filer_notify_append.go
+++ b/weed/filer/filer_notify_append.go
@@ -40,7 +40,7 @@ func (f *Filer) appendToFile(targetFile string, data []byte) error {
 	}
 
 	// append to existing chunks
-	entry.Chunks = append(entry.GetChunks(), uploadResult.ToPbFileChunk(assignResult.Fid, offset))
+	entry.Chunks = append(entry.GetChunks(), uploadResult.ToPbFileChunk(assignResult.Fid, offset, time.Now().UnixNano()))
 
 	// update the entry
 	err = f.CreateEntry(context.Background(), entry, false, false, nil, false)
diff --git a/weed/filer/interval_list.go b/weed/filer/interval_list.go
new file mode 100644
index 000000000..b3d2a76b9
--- /dev/null
+++ b/weed/filer/interval_list.go
@@ -0,0 +1,259 @@
+package filer
+
+import (
+	"math"
+	"sync"
+)
+
+type IntervalValue interface {
+	SetStartStop(start, stop int64)
+	Clone() IntervalValue
+}
+
+type Interval[T IntervalValue] struct {
+	StartOffset int64
+	StopOffset  int64
+	TsNs        int64
+	Value       T
+	Prev        *Interval[T]
+	Next        *Interval[T]
+}
+
+func (interval *Interval[T]) Size() int64 {
+	return interval.StopOffset - interval.StartOffset
+}
+
+// IntervalList mark written intervals within one page chunk
+type IntervalList[T IntervalValue] struct {
+	head *Interval[T]
+	tail *Interval[T]
+	Lock sync.Mutex
+}
+
+func NewIntervalList[T IntervalValue]() *IntervalList[T] {
+	list := &IntervalList[T]{
+		head: &Interval[T]{
+			StartOffset: -1,
+			StopOffset:  -1,
+		},
+		tail: &Interval[T]{
+			StartOffset: math.MaxInt64,
+			StopOffset:  math.MaxInt64,
+		},
+	}
+	return list
+}
+
+func (list *IntervalList[T]) Front() (interval *Interval[T]) {
+	return list.head.Next
+}
+
+func (list *IntervalList[T]) AppendInterval(interval *Interval[T]) {
+	list.Lock.Lock()
+	defer list.Lock.Unlock()
+
+	if list.head.Next == nil {
+		list.head.Next = interval
+	}
+	interval.Prev = list.tail.Prev
+	if list.tail.Prev != nil {
+		list.tail.Prev.Next = interval
+	}
+	list.tail.Prev = interval
+}
+
+func (list *IntervalList[T]) Overlay(startOffset, stopOffset, tsNs int64, value T) {
+	if startOffset >= stopOffset {
+		return
+	}
+	interval := &Interval[T]{
+		StartOffset: startOffset,
+		StopOffset:  stopOffset,
+		TsNs:        tsNs,
+		Value:       value,
+	}
+
+	list.Lock.Lock()
+	defer list.Lock.Unlock()
+
+	list.overlayInterval(interval)
+}
+
+func (list *IntervalList[T]) InsertInterval(startOffset, stopOffset, tsNs int64, value T) {
+	interval := &Interval[T]{
+		StartOffset: startOffset,
+		StopOffset:  stopOffset,
+		TsNs:        tsNs,
+		Value:       value,
+	}
+
+	list.Lock.Lock()
+	defer list.Lock.Unlock()
+
+	value.SetStartStop(startOffset, stopOffset)
+	list.insertInterval(interval)
+}
+
+func (list *IntervalList[T]) insertInterval(interval *Interval[T]) {
+	prev := list.head
+	next := prev.Next
+
+	for interval.StartOffset < interval.StopOffset {
+		if next == nil {
+			// add to the end
+			list.insertBetween(prev, interval, list.tail)
+			break
+		}
+
+		// interval is ahead of the next
+		if interval.StopOffset <= next.StartOffset {
+			list.insertBetween(prev, interval, next)
+			break
+		}
+
+		// interval is after the next
+		if next.StopOffset <= interval.StartOffset {
+			prev = next
+			next = next.Next
+			continue
+		}
+
+		// intersecting next and interval
+		if interval.TsNs >= next.TsNs {
+			// interval is newer
+			if next.StartOffset < interval.StartOffset {
+				// left side of next is ahead of interval
+				t := &Interval[T]{
+					StartOffset: next.StartOffset,
+					StopOffset:  interval.StartOffset,
+					TsNs:        next.TsNs,
+					Value:       next.Value.Clone().(T),
+				}
+				t.Value.SetStartStop(t.StartOffset, t.StopOffset)
+				list.insertBetween(prev, t, interval)
+				next.StartOffset = interval.StartOffset
+				next.Value.SetStartStop(next.StartOffset, next.StopOffset)
+				prev = t
+			}
+			if interval.StopOffset < next.StopOffset {
+				// right side of next is after interval
+				next.StartOffset = interval.StopOffset
+				next.Value.SetStartStop(next.StartOffset, next.StopOffset)
+				list.insertBetween(prev, interval, next)
+				break
+			} else {
+				// next is covered
+				prev.Next = interval
+				next = next.Next
+			}
+		} else {
+			// next is newer
+			if interval.StartOffset < next.StartOffset {
+				// left side of interval is ahead of next
+				t := &Interval[T]{
+					StartOffset: interval.StartOffset,
+					StopOffset:  next.StartOffset,
+					TsNs:        interval.TsNs,
+					Value:       interval.Value.Clone().(T),
+				}
+				t.Value.SetStartStop(t.StartOffset, t.StopOffset)
+				list.insertBetween(prev, t, next)
+				interval.StartOffset = next.StartOffset
+				interval.Value.SetStartStop(interval.StartOffset, interval.StopOffset)
+			}
+			if next.StopOffset < interval.StopOffset {
+				// right side of interval is after next
+				interval.StartOffset = next.StopOffset
+				interval.Value.SetStartStop(interval.StartOffset, interval.StopOffset)
+			} else {
+				// interval is covered
+				break
+			}
+		}
+
+	}
+}
+
+func (list *IntervalList[T]) insertBetween(a, interval, b *Interval[T]) {
+	a.Next = interval
+	b.Prev = interval
+	if a != list.head {
+		interval.Prev = a
+	}
+	if b != list.tail {
+		interval.Next = b
+	}
+}
+
+func (list *IntervalList[T]) overlayInterval(interval *Interval[T]) {
+
+	//t := list.head
+	//for ; t.Next != nil; t = t.Next {
+	//	if t.TsNs > interval.TsNs {
+	//		println("writes is out of order", t.TsNs-interval.TsNs, "ns")
+	//	}
+	//}
+
+	p := list.head
+	for ; p.Next != nil && p.Next.StopOffset <= interval.StartOffset; p = p.Next {
+	}
+	q := list.tail
+	for ; q.Prev != nil && q.Prev.StartOffset >= interval.StopOffset; q = q.Prev {
+	}
+
+	// left side
+	// interval after p.Next start
+	if p.Next != nil && p.Next.StartOffset < interval.StartOffset {
+		t := &Interval[T]{
+			StartOffset: p.Next.StartOffset,
+			StopOffset:  interval.StartOffset,
+			TsNs:        p.Next.TsNs,
+			Value:       p.Next.Value,
+		}
+		p.Next = t
+		if p != list.head {
+			t.Prev = p
+		}
+		t.Next = interval
+		interval.Prev = t
+	} else {
+		p.Next = interval
+		if p != list.head {
+			interval.Prev = p
+		}
+	}
+
+	// right side
+	// interval ends before p.Prev
+	if q.Prev != nil && interval.StopOffset < q.Prev.StopOffset {
+		t := &Interval[T]{
+			StartOffset: interval.StopOffset,
+			StopOffset:  q.Prev.StopOffset,
+			TsNs:        q.Prev.TsNs,
+			Value:       q.Prev.Value,
+		}
+		q.Prev = t
+		if q != list.tail {
+			t.Next = q
+		}
+		interval.Next = t
+		t.Prev = interval
+	} else {
+		q.Prev = interval
+		if q != list.tail {
+			interval.Next = q
+		}
+	}
+
+}
+
+func (list *IntervalList[T]) Len() int {
+	list.Lock.Lock()
+	defer list.Lock.Unlock()
+
+	var count int
+	for t := list.head; t != nil; t = t.Next {
+		count++
+	}
+	return count - 1
+}
diff --git a/weed/filer/interval_list_test.go b/weed/filer/interval_list_test.go
new file mode 100644
index 000000000..dea510fed
--- /dev/null
+++ b/weed/filer/interval_list_test.go
@@ -0,0 +1,327 @@
+package filer
+
+import (
+	"fmt"
+	"github.com/stretchr/testify/assert"
+	"testing"
+)
+
+type IntervalInt int
+
+func (i IntervalInt) SetStartStop(start, stop int64) {
+}
+func (i IntervalInt) Clone() IntervalValue {
+	return i
+}
+
+func TestIntervalList_Overlay(t *testing.T) {
+	list := NewIntervalList[IntervalInt]()
+	list.Overlay(0, 100, 1, 1)
+	list.Overlay(50, 150, 2, 2)
+	list.Overlay(200, 250, 3, 3)
+	list.Overlay(225, 250, 4, 4)
+	list.Overlay(175, 210, 5, 5)
+	list.Overlay(0, 25, 6, 6)
+	for p := list.Front(); p != nil; p = p.Next {
+		fmt.Printf("[%d,%d) %d %d\n", p.StartOffset, p.StopOffset, p.TsNs, p.Value)
+	}
+	assert.Equal(t, 6, list.Len())
+	println()
+	list.Overlay(50, 150, 7, 7)
+	for p := list.Front(); p != nil; p = p.Next {
+		fmt.Printf("[%d,%d) %d %d\n", p.StartOffset, p.StopOffset, p.TsNs, p.Value)
+	}
+	assert.Equal(t, 6, list.Len())
+}
+
+func TestIntervalList_Overlay2(t *testing.T) {
+	list := NewIntervalList[IntervalInt]()
+	list.Overlay(50, 100, 1, 1)
+	list.Overlay(0, 50, 2, 2)
+	for p := list.Front(); p != nil; p = p.Next {
+		fmt.Printf("[%d,%d) %d %d\n", p.StartOffset, p.StopOffset, p.TsNs, p.Value)
+	}
+}
+
+func TestIntervalList_Overlay3(t *testing.T) {
+	list := NewIntervalList[IntervalInt]()
+	list.Overlay(50, 100, 1, 1)
+	assert.Equal(t, 1, list.Len())
+
+	list.Overlay(0, 60, 2, 2)
+	for p := list.Front(); p != nil; p = p.Next {
+		fmt.Printf("[%d,%d) %d %d\n", p.StartOffset, p.StopOffset, p.TsNs, p.Value)
+	}
+	assert.Equal(t, 2, list.Len())
+}
+
+func TestIntervalList_Overlay4(t *testing.T) {
+	list := NewIntervalList[IntervalInt]()
+	list.Overlay(50, 100, 1, 1)
+	list.Overlay(0, 100, 2, 2)
+	for p := list.Front(); p != nil; p = p.Next {
+		fmt.Printf("[%d,%d) %d %d\n", p.StartOffset, p.StopOffset, p.TsNs, p.Value)
+	}
+	assert.Equal(t, 1, list.Len())
+}
+
+func TestIntervalList_Overlay5(t *testing.T) {
+	list := NewIntervalList[IntervalInt]()
+	list.Overlay(50, 100, 1, 1)
+	list.Overlay(0, 110, 2, 2)
+	for p := list.Front(); p != nil; p = p.Next {
+		fmt.Printf("[%d,%d) %d %d\n", p.StartOffset, p.StopOffset, p.TsNs, p.Value)
+	}
+	assert.Equal(t, 1, list.Len())
+}
+
+func TestIntervalList_Overlay6(t *testing.T) {
+	list := NewIntervalList[IntervalInt]()
+	list.Overlay(50, 100, 1, 1)
+	list.Overlay(50, 110, 2, 2)
+	for p := list.Front(); p != nil; p = p.Next {
+		fmt.Printf("[%d,%d) %d %d\n", p.StartOffset, p.StopOffset, p.TsNs, p.Value)
+	}
+	assert.Equal(t, 1, list.Len())
+}
+
+func TestIntervalList_Overlay7(t *testing.T) {
+	list := NewIntervalList[IntervalInt]()
+	list.Overlay(50, 100, 1, 1)
+	list.Overlay(50, 90, 2, 2)
+	for p := list.Front(); p != nil; p = p.Next {
+		fmt.Printf("[%d,%d) %d %d\n", p.StartOffset, p.StopOffset, p.TsNs, p.Value)
+	}
+	assert.Equal(t, 2, list.Len())
+}
+
+func TestIntervalList_Overlay8(t *testing.T) {
+	list := NewIntervalList[IntervalInt]()
+	list.Overlay(50, 100, 1, 1)
+	list.Overlay(60, 90, 2, 2)
+	for p := list.Front(); p != nil; p = p.Next {
+		fmt.Printf("[%d,%d) %d %d\n", p.StartOffset, p.StopOffset, p.TsNs, p.Value)
+	}
+	assert.Equal(t, 3, list.Len())
+}
+
+func TestIntervalList_Overlay9(t *testing.T) {
+	list := NewIntervalList[IntervalInt]()
+	list.Overlay(50, 100, 1, 1)
+	list.Overlay(60, 100, 2, 2)
+	for p := list.Front(); p != nil; p = p.Next {
+		fmt.Printf("[%d,%d) %d %d\n", p.StartOffset, p.StopOffset, p.TsNs, p.Value)
+	}
+	assert.Equal(t, 2, list.Len())
+}
+
+func TestIntervalList_Overlay10(t *testing.T) {
+	list := NewIntervalList[IntervalInt]()
+	list.Overlay(50, 100, 1, 1)
+	list.Overlay(60, 110, 2, 2)
+	for p := list.Front(); p != nil; p = p.Next {
+		fmt.Printf("[%d,%d) %d %d\n", p.StartOffset, p.StopOffset, p.TsNs, p.Value)
+	}
+	assert.Equal(t, 2, list.Len())
+}
+
+func TestIntervalList_Overlay11(t *testing.T) {
+	list := NewIntervalList[IntervalInt]()
+	list.Overlay(0, 100, 1, 1)
+	list.Overlay(100, 110, 2, 2)
+	list.Overlay(0, 90, 3, 3)
+	list.Overlay(0, 80, 4, 4)
+	list.Overlay(0, 90, 5, 5)
+	list.Overlay(90, 90, 6, 6)
+	for p := list.Front(); p != nil; p = p.Next {
+		fmt.Printf("[%d,%d) %d %d\n", p.StartOffset, p.StopOffset, p.TsNs, p.Value)
+	}
+	assert.Equal(t, 3, list.Len())
+}
+
+func TestIntervalList_insertInterval1(t *testing.T) {
+	list := NewIntervalList[IntervalInt]()
+	list.InsertInterval(50, 150, 2, 2)
+	list.InsertInterval(200, 250, 3, 3)
+
+	for p := list.Front(); p != nil; p = p.Next {
+		fmt.Printf("[%d,%d) %d %d\n", p.StartOffset, p.StopOffset, p.TsNs, p.Value)
+	}
+	assert.Equal(t, 2, list.Len())
+}
+
+func TestIntervalList_insertInterval2(t *testing.T) {
+	list := NewIntervalList[IntervalInt]()
+	list.InsertInterval(50, 150, 2, 2)
+	list.InsertInterval(0, 25, 3, 3)
+
+	for p := list.Front(); p != nil; p = p.Next {
+		fmt.Printf("[%d,%d) %d %d\n", p.StartOffset, p.StopOffset, p.TsNs, p.Value)
+	}
+	assert.Equal(t, 2, list.Len())
+}
+
+func TestIntervalList_insertInterval3(t *testing.T) {
+	list := NewIntervalList[IntervalInt]()
+	list.InsertInterval(50, 150, 2, 2)
+	list.InsertInterval(200, 250, 4, 4)
+
+	list.InsertInterval(0, 75, 3, 3)
+
+	for p := list.Front(); p != nil; p = p.Next {
+		fmt.Printf("[%d,%d) %d %d\n", p.StartOffset, p.StopOffset, p.TsNs, p.Value)
+	}
+	assert.Equal(t, 3, list.Len())
+}
+
+func TestIntervalList_insertInterval4(t *testing.T) {
+	list := NewIntervalList[IntervalInt]()
+	list.InsertInterval(200, 250, 4, 4)
+
+	list.InsertInterval(0, 225, 3, 3)
+
+	for p := list.Front(); p != nil; p = p.Next {
+		fmt.Printf("[%d,%d) %d %d\n", p.StartOffset, p.StopOffset, p.TsNs, p.Value)
+	}
+	assert.Equal(t, 2, list.Len())
+}
+
+func TestIntervalList_insertInterval5(t *testing.T) {
+	list := NewIntervalList[IntervalInt]()
+	list.InsertInterval(200, 250, 4, 4)
+
+	list.InsertInterval(0, 225, 5, 5)
+
+	for p := list.Front(); p != nil; p = p.Next {
+		fmt.Printf("[%d,%d) %d %d\n", p.StartOffset, p.StopOffset, p.TsNs, p.Value)
+	}
+	assert.Equal(t, 2, list.Len())
+}
+
+func TestIntervalList_insertInterval6(t *testing.T) {
+	list := NewIntervalList[IntervalInt]()
+
+	list.InsertInterval(50, 150, 2, 2)
+	list.InsertInterval(200, 250, 4, 4)
+
+	list.InsertInterval(0, 275, 1, 1)
+
+	for p := list.Front(); p != nil; p = p.Next {
+		fmt.Printf("[%d,%d) %d %d\n", p.StartOffset, p.StopOffset, p.TsNs, p.Value)
+	}
+	assert.Equal(t, 5, list.Len())
+}
+
+func TestIntervalList_insertInterval7(t *testing.T) {
+	list := NewIntervalList[IntervalInt]()
+
+	list.InsertInterval(50, 150, 2, 2)
+	list.InsertInterval(200, 250, 4, 4)
+
+	list.InsertInterval(75, 275, 1, 1)
+
+	for p := list.Front(); p != nil; p = p.Next {
+		fmt.Printf("[%d,%d) %d %d\n", p.StartOffset, p.StopOffset, p.TsNs, p.Value)
+	}
+	assert.Equal(t, 4, list.Len())
+}
+
+func TestIntervalList_insertInterval8(t *testing.T) {
+	list := NewIntervalList[IntervalInt]()
+
+	list.InsertInterval(50, 150, 2, 2)
+	list.InsertInterval(200, 250, 4, 4)
+
+	list.InsertInterval(75, 275, 3, 3)
+
+	for p := list.Front(); p != nil; p = p.Next {
+		fmt.Printf("[%d,%d) %d %d\n", p.StartOffset, p.StopOffset, p.TsNs, p.Value)
+	}
+	assert.Equal(t, 4, list.Len())
+}
+
+func TestIntervalList_insertInterval9(t *testing.T) {
+	list := NewIntervalList[IntervalInt]()
+
+	list.InsertInterval(50, 150, 2, 2)
+	list.InsertInterval(200, 250, 4, 4)
+
+	list.InsertInterval(50, 150, 3, 3)
+
+	for p := list.Front(); p != nil; p = p.Next {
+		fmt.Printf("[%d,%d) %d %d\n", p.StartOffset, p.StopOffset, p.TsNs, p.Value)
+	}
+	assert.Equal(t, 2, list.Len())
+}
+
+func TestIntervalList_insertInterval10(t *testing.T) {
+	list := NewIntervalList[IntervalInt]()
+
+	list.InsertInterval(50, 100, 2, 2)
+
+	list.InsertInterval(200, 300, 4, 4)
+
+	list.InsertInterval(100, 200, 5, 5)
+
+	for p := list.Front(); p != nil; p = p.Next {
+		fmt.Printf("[%d,%d) %d %d\n", p.StartOffset, p.StopOffset, p.TsNs, p.Value)
+	}
+	assert.Equal(t, 3, list.Len())
+}
+
+func TestIntervalList_insertInterval11(t *testing.T) {
+	list := NewIntervalList[IntervalInt]()
+
+	list.InsertInterval(0, 64, 1, 1)
+
+	list.InsertInterval(72, 136, 3, 3)
+
+	list.InsertInterval(64, 128, 2, 2)
+
+	list.InsertInterval(68, 72, 4, 4)
+
+	for p := list.Front(); p != nil; p = p.Next {
+		fmt.Printf("[%d,%d) %d %d\n", p.StartOffset, p.StopOffset, p.TsNs, p.Value)
+	}
+	assert.Equal(t, 4, list.Len())
+}
+
+type IntervalStruct struct {
+	x     int
+	start int64
+	stop  int64
+}
+
+func newIntervalStruct(i int) IntervalStruct {
+	return IntervalStruct{
+		x: i,
+	}
+}
+
+func (i IntervalStruct) SetStartStop(start, stop int64) {
+	i.start, i.stop = start, stop
+}
+func (i IntervalStruct) Clone() IntervalValue {
+	return &IntervalStruct{
+		x:     i.x,
+		start: i.start,
+		stop:  i.stop,
+	}
+}
+
+func TestIntervalList_insertIntervalStruct(t *testing.T) {
+	list := NewIntervalList[IntervalStruct]()
+
+	list.InsertInterval(0, 64, 1, newIntervalStruct(1))
+
+	list.InsertInterval(64, 72, 2, newIntervalStruct(2))
+
+	list.InsertInterval(72, 136, 3, newIntervalStruct(3))
+
+	list.InsertInterval(64, 68, 4, newIntervalStruct(4))
+
+	for p := list.Front(); p != nil; p = p.Next {
+		fmt.Printf("[%d,%d) %d %d\n", p.StartOffset, p.StopOffset, p.TsNs, p.Value)
+	}
+	assert.Equal(t, 4, list.Len())
+}
diff --git a/weed/filer/reader_at.go b/weed/filer/reader_at.go
index 9d1fab20a..27e8f79a6 100644
--- a/weed/filer/reader_at.go
+++ b/weed/filer/reader_at.go
@@ -16,8 +16,7 @@ import (
 
 type ChunkReadAt struct {
 	masterClient  *wdclient.MasterClient
-	chunkViews    []*ChunkView
-	readerLock    sync.Mutex
+	chunkViews    *IntervalList[*ChunkView]
 	fileSize      int64
 	readerCache   *ReaderCache
 	readerPattern *ReaderPattern
@@ -89,7 +88,7 @@ func LookupFn(filerClient filer_pb.FilerClient) wdclient.LookupFileIdFunctionTyp
 	}
 }
 
-func NewChunkReaderAtFromClient(lookupFn wdclient.LookupFileIdFunctionType, chunkViews []*ChunkView, chunkCache chunk_cache.ChunkCache, fileSize int64) *ChunkReadAt {
+func NewChunkReaderAtFromClient(lookupFn wdclient.LookupFileIdFunctionType, chunkViews *IntervalList[*ChunkView], chunkCache chunk_cache.ChunkCache, fileSize int64) *ChunkReadAt {
 
 	return &ChunkReadAt{
 		chunkViews:    chunkViews,
@@ -108,44 +107,58 @@ func (c *ChunkReadAt) ReadAt(p []byte, offset int64) (n int, err error) {
 
 	c.readerPattern.MonitorReadAt(offset, len(p))
 
-	c.readerLock.Lock()
-	defer c.readerLock.Unlock()
+	c.chunkViews.Lock.Lock()
+	defer c.chunkViews.Lock.Unlock()
+
+	// glog.V(4).Infof("ReadAt [%d,%d) of total file size %d bytes %d chunk views", offset, offset+int64(len(p)), c.fileSize, len(c.chunkViews))
+	n, _, err = c.doReadAt(p, offset)
+	return
+}
+
+func (c *ChunkReadAt) ReadAtWithTime(p []byte, offset int64) (n int, ts int64, err error) {
+
+	c.readerPattern.MonitorReadAt(offset, len(p))
+
+	c.chunkViews.Lock.Lock()
+	defer c.chunkViews.Lock.Unlock()
 
 	// glog.V(4).Infof("ReadAt [%d,%d) of total file size %d bytes %d chunk views", offset, offset+int64(len(p)), c.fileSize, len(c.chunkViews))
 	return c.doReadAt(p, offset)
 }
 
-func (c *ChunkReadAt) doReadAt(p []byte, offset int64) (n int, err error) {
+func (c *ChunkReadAt) doReadAt(p []byte, offset int64) (n int, ts int64, err error) {
 
 	startOffset, remaining := offset, int64(len(p))
-	var nextChunks []*ChunkView
-	for i, chunk := range c.chunkViews {
+	var nextChunks *Interval[*ChunkView]
+	for x := c.chunkViews.Front(); x != nil; x = x.Next {
+		chunk := x.Value
 		if remaining <= 0 {
 			break
 		}
-		if i+1 < len(c.chunkViews) {
-			nextChunks = c.chunkViews[i+1:]
+		if x.Next != nil {
+			nextChunks = x.Next
 		}
-		if startOffset < chunk.LogicOffset {
-			gap := chunk.LogicOffset - startOffset
-			glog.V(4).Infof("zero [%d,%d)", startOffset, chunk.LogicOffset)
+		if startOffset < chunk.ViewOffset {
+			gap := chunk.ViewOffset - startOffset
+			glog.V(4).Infof("zero [%d,%d)", startOffset, chunk.ViewOffset)
 			n += zero(p, startOffset-offset, gap)
-			startOffset, remaining = chunk.LogicOffset, remaining-gap
+			startOffset, remaining = chunk.ViewOffset, remaining-gap
 			if remaining <= 0 {
 				break
 			}
 		}
-		// fmt.Printf(">>> doReadAt [%d,%d), chunk[%d,%d)\n", offset, offset+int64(len(p)), chunk.LogicOffset, chunk.LogicOffset+int64(chunk.Size))
-		chunkStart, chunkStop := max(chunk.LogicOffset, startOffset), min(chunk.LogicOffset+int64(chunk.Size), startOffset+remaining)
+		// fmt.Printf(">>> doReadAt [%d,%d), chunk[%d,%d)\n", offset, offset+int64(len(p)), chunk.ViewOffset, chunk.ViewOffset+int64(chunk.ViewSize))
+		chunkStart, chunkStop := max(chunk.ViewOffset, startOffset), min(chunk.ViewOffset+int64(chunk.ViewSize), startOffset+remaining)
 		if chunkStart >= chunkStop {
 			continue
 		}
-		// glog.V(4).Infof("read [%d,%d), %d/%d chunk %s [%d,%d)", chunkStart, chunkStop, i, len(c.chunkViews), chunk.FileId, chunk.LogicOffset-chunk.Offset, chunk.LogicOffset-chunk.Offset+int64(chunk.Size))
-		bufferOffset := chunkStart - chunk.LogicOffset + chunk.Offset
+		// glog.V(4).Infof("read [%d,%d), %d/%d chunk %s [%d,%d)", chunkStart, chunkStop, i, len(c.chunkViews), chunk.FileId, chunk.ViewOffset-chunk.Offset, chunk.ViewOffset-chunk.Offset+int64(chunk.ViewSize))
+		bufferOffset := chunkStart - chunk.ViewOffset + chunk.OffsetInChunk
+		ts = chunk.ModifiedTsNs
 		copied, err := c.readChunkSliceAt(p[startOffset-offset:chunkStop-chunkStart+startOffset-offset], chunk, nextChunks, uint64(bufferOffset))
 		if err != nil {
 			glog.Errorf("fetching chunk %+v: %v\n", chunk, err)
-			return copied, err
+			return copied, ts, err
 		}
 
 		n += copied
@@ -177,7 +190,7 @@ func (c *ChunkReadAt) doReadAt(p []byte, offset int64) (n int, err error) {
 
 }
 
-func (c *ChunkReadAt) readChunkSliceAt(buffer []byte, chunkView *ChunkView, nextChunkViews []*ChunkView, offset uint64) (n int, err error) {
+func (c *ChunkReadAt) readChunkSliceAt(buffer []byte, chunkView *ChunkView, nextChunkViews *Interval[*ChunkView], offset uint64) (n int, err error) {
 
 	if c.readerPattern.IsRandomMode() {
 		n, err := c.readerCache.chunkCache.ReadChunkAt(buffer, chunkView.FileId, offset)
@@ -187,16 +200,14 @@ func (c *ChunkReadAt) readChunkSliceAt(buffer []byte, chunkView *ChunkView, next
 		return fetchChunkRange(buffer, c.readerCache.lookupFileIdFn, chunkView.FileId, chunkView.CipherKey, chunkView.IsGzipped, int64(offset))
 	}
 
-	n, err = c.readerCache.ReadChunkAt(buffer, chunkView.FileId, chunkView.CipherKey, chunkView.IsGzipped, int64(offset), int(chunkView.ChunkSize), chunkView.LogicOffset == 0)
+	n, err = c.readerCache.ReadChunkAt(buffer, chunkView.FileId, chunkView.CipherKey, chunkView.IsGzipped, int64(offset), int(chunkView.ChunkSize), chunkView.ViewOffset == 0)
 	if c.lastChunkFid != chunkView.FileId {
-		if chunkView.Offset == 0 { // start of a new chunk
+		if chunkView.OffsetInChunk == 0 { // start of a new chunk
 			if c.lastChunkFid != "" {
 				c.readerCache.UnCache(c.lastChunkFid)
-				c.readerCache.MaybeCache(nextChunkViews)
-			} else {
-				if len(nextChunkViews) >= 1 {
-					c.readerCache.MaybeCache(nextChunkViews[:1]) // just read the next chunk if at the very beginning
-				}
+			}
+			if nextChunkViews != nil {
+				c.readerCache.MaybeCache(nextChunkViews) // just read the next chunk if at the very beginning
 			}
 		}
 	}
diff --git a/weed/filer/reader_at_test.go b/weed/filer/reader_at_test.go
index 29bd47ea4..f61d68a6d 100644
--- a/weed/filer/reader_at_test.go
+++ b/weed/filer/reader_at_test.go
@@ -5,7 +5,6 @@ import (
 	"io"
 	"math"
 	"strconv"
-	"sync"
 	"testing"
 )
 
@@ -34,42 +33,40 @@ func (m *mockChunkCache) SetChunk(fileId string, data []byte) {
 
 func TestReaderAt(t *testing.T) {
 
-	visibles := []VisibleInterval{
-		{
-			start:     1,
-			stop:      2,
-			fileId:    "1",
-			chunkSize: 9,
-		},
-		{
-			start:     3,
-			stop:      4,
-			fileId:    "3",
-			chunkSize: 1,
-		},
-		{
-			start:     5,
-			stop:      6,
-			fileId:    "5",
-			chunkSize: 2,
-		},
-		{
-			start:     7,
-			stop:      9,
-			fileId:    "7",
-			chunkSize: 2,
-		},
-		{
-			start:     9,
-			stop:      10,
-			fileId:    "9",
-			chunkSize: 2,
-		},
-	}
+	visibles := NewIntervalList[*VisibleInterval]()
+	addVisibleInterval(visibles, &VisibleInterval{
+		start:     1,
+		stop:      2,
+		fileId:    "1",
+		chunkSize: 9,
+	})
+	addVisibleInterval(visibles, &VisibleInterval{
+		start:     3,
+		stop:      4,
+		fileId:    "3",
+		chunkSize: 1,
+	})
+	addVisibleInterval(visibles, &VisibleInterval{
+		start:     5,
+		stop:      6,
+		fileId:    "5",
+		chunkSize: 2,
+	})
+	addVisibleInterval(visibles, &VisibleInterval{
+		start:     7,
+		stop:      9,
+		fileId:    "7",
+		chunkSize: 2,
+	})
+	addVisibleInterval(visibles, &VisibleInterval{
+		start:     9,
+		stop:      10,
+		fileId:    "9",
+		chunkSize: 2,
+	})
 
 	readerAt := &ChunkReadAt{
 		chunkViews:    ViewFromVisibleIntervals(visibles, 0, math.MaxInt64),
-		readerLock:    sync.Mutex{},
 		fileSize:      10,
 		readerCache:   newReaderCache(3, &mockChunkCache{}, nil),
 		readerPattern: NewReaderPattern(),
@@ -86,7 +83,7 @@ func testReadAt(t *testing.T, readerAt *ChunkReadAt, offset int64, size int, exp
 	if data == nil {
 		data = make([]byte, size)
 	}
-	n, err := readerAt.doReadAt(data, offset)
+	n, _, err := readerAt.doReadAt(data, offset)
 
 	if expectedN != n {
 		t.Errorf("unexpected read size: %d, expect: %d", n, expectedN)
@@ -101,24 +98,22 @@ func testReadAt(t *testing.T, readerAt *ChunkReadAt, offset int64, size int, exp
 
 func TestReaderAt0(t *testing.T) {
 
-	visibles := []VisibleInterval{
-		{
-			start:     2,
-			stop:      5,
-			fileId:    "1",
-			chunkSize: 9,
-		},
-		{
-			start:     7,
-			stop:      9,
-			fileId:    "2",
-			chunkSize: 9,
-		},
-	}
+	visibles := NewIntervalList[*VisibleInterval]()
+	addVisibleInterval(visibles, &VisibleInterval{
+		start:     2,
+		stop:      5,
+		fileId:    "1",
+		chunkSize: 9,
+	})
+	addVisibleInterval(visibles, &VisibleInterval{
+		start:     7,
+		stop:      9,
+		fileId:    "2",
+		chunkSize: 9,
+	})
 
 	readerAt := &ChunkReadAt{
 		chunkViews:    ViewFromVisibleIntervals(visibles, 0, math.MaxInt64),
-		readerLock:    sync.Mutex{},
 		fileSize:      10,
 		readerCache:   newReaderCache(3, &mockChunkCache{}, nil),
 		readerPattern: NewReaderPattern(),
@@ -135,18 +130,16 @@ func TestReaderAt0(t *testing.T) {
 
 func TestReaderAt1(t *testing.T) {
 
-	visibles := []VisibleInterval{
-		{
-			start:     2,
-			stop:      5,
-			fileId:    "1",
-			chunkSize: 9,
-		},
-	}
+	visibles := NewIntervalList[*VisibleInterval]()
+	addVisibleInterval(visibles, &VisibleInterval{
+		start:     2,
+		stop:      5,
+		fileId:    "1",
+		chunkSize: 9,
+	})
 
 	readerAt := &ChunkReadAt{
 		chunkViews:    ViewFromVisibleIntervals(visibles, 0, math.MaxInt64),
-		readerLock:    sync.Mutex{},
 		fileSize:      20,
 		readerCache:   newReaderCache(3, &mockChunkCache{}, nil),
 		readerPattern: NewReaderPattern(),
@@ -164,24 +157,22 @@ func TestReaderAt1(t *testing.T) {
 }
 
 func TestReaderAtGappedChunksDoNotLeak(t *testing.T) {
-	visibles := []VisibleInterval{
-		{
-			start:     2,
-			stop:      3,
-			fileId:    "1",
-			chunkSize: 5,
-		},
-		{
-			start:     7,
-			stop:      9,
-			fileId:    "1",
-			chunkSize: 4,
-		},
-	}
+	visibles := NewIntervalList[*VisibleInterval]()
+	addVisibleInterval(visibles, &VisibleInterval{
+		start:     2,
+		stop:      3,
+		fileId:    "1",
+		chunkSize: 5,
+	})
+	addVisibleInterval(visibles, &VisibleInterval{
+		start:     7,
+		stop:      9,
+		fileId:    "1",
+		chunkSize: 4,
+	})
 
 	readerAt := &ChunkReadAt{
 		chunkViews:    ViewFromVisibleIntervals(visibles, 0, math.MaxInt64),
-		readerLock:    sync.Mutex{},
 		fileSize:      9,
 		readerCache:   newReaderCache(3, &mockChunkCache{}, nil),
 		readerPattern: NewReaderPattern(),
@@ -193,8 +184,7 @@ func TestReaderAtGappedChunksDoNotLeak(t *testing.T) {
 
 func TestReaderAtSparseFileDoesNotLeak(t *testing.T) {
 	readerAt := &ChunkReadAt{
-		chunkViews:    ViewFromVisibleIntervals([]VisibleInterval{}, 0, math.MaxInt64),
-		readerLock:    sync.Mutex{},
+		chunkViews:    ViewFromVisibleIntervals(NewIntervalList[*VisibleInterval](), 0, math.MaxInt64),
 		fileSize:      3,
 		readerCache:   newReaderCache(3, &mockChunkCache{}, nil),
 		readerPattern: NewReaderPattern(),
diff --git a/weed/filer/reader_cache.go b/weed/filer/reader_cache.go
index cb89c03c5..0a7c83de7 100644
--- a/weed/filer/reader_cache.go
+++ b/weed/filer/reader_cache.go
@@ -43,7 +43,7 @@ func newReaderCache(limit int, chunkCache chunk_cache.ChunkCache, lookupFileIdFn
 	}
 }
 
-func (rc *ReaderCache) MaybeCache(chunkViews []*ChunkView) {
+func (rc *ReaderCache) MaybeCache(chunkViews *Interval[*ChunkView]) {
 	if rc.lookupFileIdFn == nil {
 		return
 	}
@@ -55,7 +55,8 @@ func (rc *ReaderCache) MaybeCache(chunkViews []*ChunkView) {
 		return
 	}
 
-	for _, chunkView := range chunkViews {
+	for x := chunkViews; x != nil; x = x.Next {
+		chunkView := x.Value
 		if _, found := rc.downloaders[chunkView.FileId]; found {
 			continue
 		}
@@ -65,7 +66,7 @@ func (rc *ReaderCache) MaybeCache(chunkViews []*ChunkView) {
 			return
 		}
 
-		// glog.V(4).Infof("prefetch %s offset %d", chunkView.FileId, chunkView.LogicOffset)
+		// glog.V(4).Infof("prefetch %s offset %d", chunkView.FileId, chunkView.ViewOffset)
 		// cache this chunk if not yet
 		cacher := newSingleChunkCacher(rc, chunkView.FileId, chunkView.CipherKey, chunkView.IsGzipped, int(chunkView.ChunkSize), false)
 		go cacher.startCaching()
diff --git a/weed/filer/stream.go b/weed/filer/stream.go
index f28341be4..d49784686 100644
--- a/weed/filer/stream.go
+++ b/weed/filer/stream.go
@@ -6,7 +6,6 @@ import (
 	"golang.org/x/exp/slices"
 	"io"
 	"math"
-	"sort"
 	"strings"
 	"sync"
 	"time"
@@ -78,7 +77,8 @@ func StreamContentWithThrottler(masterClient wdclient.HasLookupFileIdFunction, w
 
 	fileId2Url := make(map[string][]string)
 
-	for _, chunkView := range chunkViews {
+	for x := chunkViews.Front(); x != nil; x = x.Next {
+		chunkView := x.Value
 		var urlStrings []string
 		var err error
 		for _, backoff := range getLookupFileIdBackoffSchedule {
@@ -102,29 +102,30 @@ func StreamContentWithThrottler(masterClient wdclient.HasLookupFileIdFunction, w
 
 	downloadThrottler := util.NewWriteThrottler(downloadMaxBytesPs)
 	remaining := size
-	for _, chunkView := range chunkViews {
-		if offset < chunkView.LogicOffset {
-			gap := chunkView.LogicOffset - offset
+	for x := chunkViews.Front(); x != nil; x = x.Next {
+		chunkView := x.Value
+		if offset < chunkView.ViewOffset {
+			gap := chunkView.ViewOffset - offset
 			remaining -= gap
-			glog.V(4).Infof("zero [%d,%d)", offset, chunkView.LogicOffset)
+			glog.V(4).Infof("zero [%d,%d)", offset, chunkView.ViewOffset)
 			err := writeZero(writer, gap)
 			if err != nil {
-				return fmt.Errorf("write zero [%d,%d)", offset, chunkView.LogicOffset)
+				return fmt.Errorf("write zero [%d,%d)", offset, chunkView.ViewOffset)
 			}
-			offset = chunkView.LogicOffset
+			offset = chunkView.ViewOffset
 		}
 		urlStrings := fileId2Url[chunkView.FileId]
 		start := time.Now()
-		err := retriedStreamFetchChunkData(writer, urlStrings, chunkView.CipherKey, chunkView.IsGzipped, chunkView.IsFullChunk(), chunkView.Offset, int(chunkView.Size))
-		offset += int64(chunkView.Size)
-		remaining -= int64(chunkView.Size)
+		err := retriedStreamFetchChunkData(writer, urlStrings, chunkView.CipherKey, chunkView.IsGzipped, chunkView.IsFullChunk(), chunkView.OffsetInChunk, int(chunkView.ViewSize))
+		offset += int64(chunkView.ViewSize)
+		remaining -= int64(chunkView.ViewSize)
 		stats.FilerRequestHistogram.WithLabelValues("chunkDownload").Observe(time.Since(start).Seconds())
 		if err != nil {
 			stats.FilerRequestCounter.WithLabelValues("chunkDownloadError").Inc()
 			return fmt.Errorf("read chunk: %v", err)
 		}
 		stats.FilerRequestCounter.WithLabelValues("chunkDownload").Inc()
-		downloadThrottler.MaybeSlowdown(int64(chunkView.Size))
+		downloadThrottler.MaybeSlowdown(int64(chunkView.ViewSize))
 	}
 	if remaining > 0 {
 		glog.V(4).Infof("zero [%d,%d)", offset, offset+remaining)
@@ -167,14 +168,15 @@ func ReadAll(buffer []byte, masterClient *wdclient.MasterClient, chunks []*filer
 
 	idx := 0
 
-	for _, chunkView := range chunkViews {
+	for x := chunkViews.Front(); x != nil; x = x.Next {
+		chunkView := x.Value
 		urlStrings, err := lookupFileIdFn(chunkView.FileId)
 		if err != nil {
 			glog.V(1).Infof("operation LookupFileId %s failed, err: %v", chunkView.FileId, err)
 			return err
 		}
 
-		n, err := retriedFetchChunkData(buffer[idx:idx+int(chunkView.Size)], urlStrings, chunkView.CipherKey, chunkView.IsGzipped, chunkView.IsFullChunk(), chunkView.Offset)
+		n, err := retriedFetchChunkData(buffer[idx:idx+int(chunkView.ViewSize)], urlStrings, chunkView.CipherKey, chunkView.IsGzipped, chunkView.IsFullChunk(), chunkView.OffsetInChunk)
 		if err != nil {
 			return err
 		}
@@ -185,7 +187,7 @@ func ReadAll(buffer []byte, masterClient *wdclient.MasterClient, chunks []*filer
 
 // ----------------  ChunkStreamReader ----------------------------------
 type ChunkStreamReader struct {
-	chunkViews   []*ChunkView
+	chunkView    *Interval[*ChunkView]
 	totalSize    int64
 	logicOffset  int64
 	buffer       []byte
@@ -201,17 +203,15 @@ var _ = io.ReaderAt(&ChunkStreamReader{})
 func doNewChunkStreamReader(lookupFileIdFn wdclient.LookupFileIdFunctionType, chunks []*filer_pb.FileChunk) *ChunkStreamReader {
 
 	chunkViews := ViewFromChunks(lookupFileIdFn, chunks, 0, math.MaxInt64)
-	slices.SortFunc(chunkViews, func(a, b *ChunkView) bool {
-		return a.LogicOffset < b.LogicOffset
-	})
 
 	var totalSize int64
-	for _, chunk := range chunkViews {
-		totalSize += int64(chunk.Size)
+	for x := chunkViews.Front(); x != nil; x = x.Next {
+		chunk := x.Value
+		totalSize += int64(chunk.ViewSize)
 	}
 
 	return &ChunkStreamReader{
-		chunkViews:   chunkViews,
+		chunkView:    chunkViews.Front(),
 		lookupFileId: lookupFileIdFn,
 		totalSize:    totalSize,
 	}
@@ -290,7 +290,7 @@ func (c *ChunkStreamReader) Seek(offset int64, whence int) (int64, error) {
 }
 
 func insideChunk(offset int64, chunk *ChunkView) bool {
-	return chunk.LogicOffset <= offset && offset < chunk.LogicOffset+int64(chunk.Size)
+	return chunk.ViewOffset <= offset && offset < chunk.ViewOffset+int64(chunk.ViewSize)
 }
 
 func (c *ChunkStreamReader) prepareBufferFor(offset int64) (err error) {
@@ -300,48 +300,22 @@ func (c *ChunkStreamReader) prepareBufferFor(offset int64) (err error) {
 	}
 
 	// fmt.Printf("fetch for offset %d\n", offset)
-
-	// need to seek to a different chunk
-	currentChunkIndex := sort.Search(len(c.chunkViews), func(i int) bool {
-		return offset < c.chunkViews[i].LogicOffset
-	})
-	if currentChunkIndex == len(c.chunkViews) {
-		// not found
-		if insideChunk(offset, c.chunkViews[0]) {
-			// fmt.Printf("select0 chunk %d %s\n", currentChunkIndex, c.chunkViews[currentChunkIndex].FileId)
-			currentChunkIndex = 0
-		} else if insideChunk(offset, c.chunkViews[len(c.chunkViews)-1]) {
-			currentChunkIndex = len(c.chunkViews) - 1
-			// fmt.Printf("select last chunk %d %s\n", currentChunkIndex, c.chunkViews[currentChunkIndex].FileId)
-		} else {
-			return io.EOF
-		}
-	} else if currentChunkIndex > 0 {
-		if insideChunk(offset, c.chunkViews[currentChunkIndex]) {
-			// good hit
-		} else if insideChunk(offset, c.chunkViews[currentChunkIndex-1]) {
-			currentChunkIndex -= 1
-			// fmt.Printf("select -1 chunk %d %s\n", currentChunkIndex, c.chunkViews[currentChunkIndex].FileId)
-		} else {
-			// glog.Fatalf("unexpected1 offset %d", offset)
-			return fmt.Errorf("unexpected1 offset %d", offset)
-		}
-	} else {
-		// glog.Fatalf("unexpected2 offset %d", offset)
-		return fmt.Errorf("unexpected2 offset %d", offset)
+	c.chunkView = c.chunkView.Next
+	if c.chunkView == nil {
+		return io.EOF
 	}
 
 	// positioning within the new chunk
-	chunk := c.chunkViews[currentChunkIndex]
+	chunk := c.chunkView.Value
 	if insideChunk(offset, chunk) {
-		if c.isBufferEmpty() || c.bufferOffset != chunk.LogicOffset {
+		if c.isBufferEmpty() || c.bufferOffset != chunk.ViewOffset {
 			if err = c.fetchChunkToBuffer(chunk); err != nil {
 				return
 			}
 		}
 	} else {
-		// glog.Fatalf("unexpected3 offset %d in %s [%d,%d)", offset, chunk.FileId, chunk.LogicOffset, chunk.LogicOffset+int64(chunk.Size))
-		return fmt.Errorf("unexpected3 offset %d in %s [%d,%d)", offset, chunk.FileId, chunk.LogicOffset, chunk.LogicOffset+int64(chunk.Size))
+		// glog.Fatalf("unexpected3 offset %d in %s [%d,%d)", offset, chunk.FileId, chunk.ViewOffset, chunk.ViewOffset+int64(chunk.ViewSize))
+		return fmt.Errorf("unexpected3 offset %d in %s [%d,%d)", offset, chunk.FileId, chunk.ViewOffset, chunk.ViewOffset+int64(chunk.ViewSize))
 	}
 	return
 }
@@ -355,7 +329,7 @@ func (c *ChunkStreamReader) fetchChunkToBuffer(chunkView *ChunkView) error {
 	var buffer bytes.Buffer
 	var shouldRetry bool
 	for _, urlString := range urlStrings {
-		shouldRetry, err = util.ReadUrlAsStream(urlString+"?readDeleted=true", chunkView.CipherKey, chunkView.IsGzipped, chunkView.IsFullChunk(), chunkView.Offset, int(chunkView.Size), func(data []byte) {
+		shouldRetry, err = util.ReadUrlAsStream(urlString+"?readDeleted=true", chunkView.CipherKey, chunkView.IsGzipped, chunkView.IsFullChunk(), chunkView.OffsetInChunk, int(chunkView.ViewSize), func(data []byte) {
 			buffer.Write(data)
 		})
 		if !shouldRetry {
@@ -372,10 +346,10 @@ func (c *ChunkStreamReader) fetchChunkToBuffer(chunkView *ChunkView) error {
 		return err
 	}
 	c.buffer = buffer.Bytes()
-	c.bufferOffset = chunkView.LogicOffset
+	c.bufferOffset = chunkView.ViewOffset
 	c.chunk = chunkView.FileId
 
-	// glog.V(0).Infof("fetched %s [%d,%d)", chunkView.FileId, chunkView.LogicOffset, chunkView.LogicOffset+int64(chunkView.Size))
+	// glog.V(0).Infof("fetched %s [%d,%d)", chunkView.FileId, chunkView.ViewOffset, chunkView.ViewOffset+int64(chunkView.ViewSize))
 
 	return nil
 }
diff --git a/weed/mount/dirty_pages_chunked.go b/weed/mount/dirty_pages_chunked.go
index 78e7b7877..56c97549f 100644
--- a/weed/mount/dirty_pages_chunked.go
+++ b/weed/mount/dirty_pages_chunked.go
@@ -7,7 +7,6 @@ import (
 	"github.com/seaweedfs/seaweedfs/weed/pb/filer_pb"
 	"io"
 	"sync"
-	"time"
 )
 
 type ChunkedDirtyPages struct {
@@ -38,11 +37,11 @@ func newMemoryChunkPages(fh *FileHandle, chunkSize int64) *ChunkedDirtyPages {
 	return dirtyPages
 }
 
-func (pages *ChunkedDirtyPages) AddPage(offset int64, data []byte, isSequential bool) {
+func (pages *ChunkedDirtyPages) AddPage(offset int64, data []byte, isSequential bool, tsNs int64) {
 	pages.hasWrites = true
 
 	glog.V(4).Infof("%v memory AddPage [%d, %d)", pages.fh.fh, offset, offset+int64(len(data)))
-	pages.uploadPipeline.SaveDataAt(data, offset, isSequential)
+	pages.uploadPipeline.SaveDataAt(data, offset, isSequential, tsNs)
 
 	return
 }
@@ -58,28 +57,27 @@ func (pages *ChunkedDirtyPages) FlushData() error {
 	return nil
 }
 
-func (pages *ChunkedDirtyPages) ReadDirtyDataAt(data []byte, startOffset int64) (maxStop int64) {
+func (pages *ChunkedDirtyPages) ReadDirtyDataAt(data []byte, startOffset int64, tsNs int64) (maxStop int64) {
 	if !pages.hasWrites {
 		return
 	}
-	return pages.uploadPipeline.MaybeReadDataAt(data, startOffset)
+	return pages.uploadPipeline.MaybeReadDataAt(data, startOffset, tsNs)
 }
 
-func (pages *ChunkedDirtyPages) saveChunkedFileIntervalToStorage(reader io.Reader, offset int64, size int64, cleanupFn func()) {
+func (pages *ChunkedDirtyPages) saveChunkedFileIntervalToStorage(reader io.Reader, offset int64, size int64, modifiedTsNs int64, cleanupFn func()) {
 
-	mtime := time.Now().UnixNano()
 	defer cleanupFn()
 
 	fileFullPath := pages.fh.FullPath()
 	fileName := fileFullPath.Name()
-	chunk, err := pages.fh.wfs.saveDataAsChunk(fileFullPath)(reader, fileName, offset)
+	chunk, err := pages.fh.wfs.saveDataAsChunk(fileFullPath)(reader, fileName, offset, modifiedTsNs)
 	if err != nil {
 		glog.V(0).Infof("%v saveToStorage [%d,%d): %v", fileFullPath, offset, offset+size, err)
 		pages.lastErr = err
 		return
 	}
-	chunk.ModifiedTsNs = mtime
 	pages.fh.AddChunks([]*filer_pb.FileChunk{chunk})
+	pages.fh.entryChunkGroup.AddChunk(chunk)
 	glog.V(3).Infof("%v saveToStorage %s [%d,%d)", fileFullPath, chunk.FileId, offset, offset+size)
 
 }
diff --git a/weed/mount/filehandle.go b/weed/mount/filehandle.go
index b6ec3d2da..67298b047 100644
--- a/weed/mount/filehandle.go
+++ b/weed/mount/filehandle.go
@@ -5,50 +5,60 @@ import (
 	"github.com/seaweedfs/seaweedfs/weed/glog"
 	"github.com/seaweedfs/seaweedfs/weed/pb/filer_pb"
 	"github.com/seaweedfs/seaweedfs/weed/util"
-	"golang.org/x/exp/slices"
-	"golang.org/x/sync/semaphore"
-	"math"
+	"os"
 	"sync"
 )
 
 type FileHandleId uint64
 
+var IsDebugFileReadWrite = false
+
 type FileHandle struct {
-	fh        FileHandleId
-	counter   int64
-	entry     *LockedEntry
-	entryLock sync.Mutex
-	inode     uint64
-	wfs       *WFS
+	fh              FileHandleId
+	counter         int64
+	entry           *LockedEntry
+	entryLock       sync.Mutex
+	entryChunkGroup *filer.ChunkGroup
+	inode           uint64
+	wfs             *WFS
 
 	// cache file has been written to
-	dirtyMetadata  bool
-	dirtyPages     *PageWriter
-	entryViewCache []filer.VisibleInterval
-	reader         *filer.ChunkReadAt
-	contentType    string
-	handle         uint64
-	orderedMutex   *semaphore.Weighted
+	dirtyMetadata bool
+	dirtyPages    *PageWriter
+	reader        *filer.ChunkReadAt
+	contentType   string
+	handle        uint64
+	sync.Mutex
 
 	isDeleted bool
+
+	// for debugging
+	mirrorFile *os.File
 }
 
 func newFileHandle(wfs *WFS, handleId FileHandleId, inode uint64, entry *filer_pb.Entry) *FileHandle {
 	fh := &FileHandle{
-		fh:           handleId,
-		counter:      1,
-		inode:        inode,
-		wfs:          wfs,
-		orderedMutex: semaphore.NewWeighted(int64(math.MaxInt64)),
+		fh:      handleId,
+		counter: 1,
+		inode:   inode,
+		wfs:     wfs,
 	}
 	// dirtyPages: newContinuousDirtyPages(file, writeOnly),
 	fh.dirtyPages = newPageWriter(fh, wfs.option.ChunkSizeLimit)
-	if entry != nil {
-		entry.Attributes.FileSize = filer.FileSize(entry)
-	}
 	fh.entry = &LockedEntry{
 		Entry: entry,
 	}
+	if entry != nil {
+		fh.SetEntry(entry)
+	}
+
+	if IsDebugFileReadWrite {
+		var err error
+		fh.mirrorFile, err = os.OpenFile("/tmp/sw/"+entry.Name, os.O_RDWR|os.O_CREATE, 0600)
+		if err != nil {
+			println("failed to create mirror:", err.Error())
+		}
+	}
 
 	return fh
 }
@@ -63,6 +73,17 @@ func (fh *FileHandle) GetEntry() *filer_pb.Entry {
 }
 
 func (fh *FileHandle) SetEntry(entry *filer_pb.Entry) {
+	if entry != nil {
+		fileSize := filer.FileSize(entry)
+		entry.Attributes.FileSize = fileSize
+		var resolveManifestErr error
+		fh.entryChunkGroup, resolveManifestErr = filer.NewChunkGroup(fh.wfs.LookupFn(), fh.wfs.chunkCache, entry.Chunks)
+		if resolveManifestErr != nil {
+			glog.Warningf("failed to resolve manifest chunks in %+v", entry)
+		}
+	} else {
+		glog.Fatalf("setting file handle entry to nil")
+	}
 	fh.entry.SetEntry(entry)
 }
 
@@ -78,43 +99,17 @@ func (fh *FileHandle) AddChunks(chunks []*filer_pb.FileChunk) {
 		return
 	}
 
-	// find the earliest incoming chunk
-	newChunks := chunks
-	earliestChunk := newChunks[0]
-	for i := 1; i < len(newChunks); i++ {
-		if lessThan(earliestChunk, newChunks[i]) {
-			earliestChunk = newChunks[i]
-		}
-	}
-
-	// pick out-of-order chunks from existing chunks
-	for _, chunk := range fh.entry.GetChunks() {
-		if lessThan(earliestChunk, chunk) {
-			chunks = append(chunks, chunk)
-		}
-	}
-
-	// sort incoming chunks
-	slices.SortFunc(chunks, func(a, b *filer_pb.FileChunk) bool {
-		return lessThan(a, b)
-	})
-
-	glog.V(4).Infof("%s existing %d chunks adds %d more", fh.FullPath(), len(fh.entry.GetChunks()), len(chunks))
-
-	fh.entry.AppendChunks(newChunks)
-	fh.entryViewCache = nil
+	fh.entry.AppendChunks(chunks)
 }
 
-func (fh *FileHandle) CloseReader() {
-	if fh.reader != nil {
-		_ = fh.reader.Close()
-		fh.reader = nil
-	}
-}
+func (fh *FileHandle) ReleaseHandle() {
+	fh.entryLock.Lock()
+	defer fh.entryLock.Unlock()
 
-func (fh *FileHandle) Release() {
 	fh.dirtyPages.Destroy()
-	fh.CloseReader()
+	if IsDebugFileReadWrite {
+		fh.mirrorFile.Close()
+	}
 }
 
 func lessThan(a, b *filer_pb.FileChunk) bool {
diff --git a/weed/mount/filehandle_map.go b/weed/mount/filehandle_map.go
index cc5885ffc..f0051f061 100644
--- a/weed/mount/filehandle_map.go
+++ b/weed/mount/filehandle_map.go
@@ -65,7 +65,7 @@ func (i *FileHandleToInode) ReleaseByInode(inode uint64) {
 		if fh.counter <= 0 {
 			delete(i.inode2fh, inode)
 			delete(i.fh2inode, fh.fh)
-			fh.Release()
+			fh.ReleaseHandle()
 		}
 	}
 }
@@ -82,7 +82,7 @@ func (i *FileHandleToInode) ReleaseByHandle(fh FileHandleId) {
 			if fhHandle.counter <= 0 {
 				delete(i.inode2fh, inode)
 				delete(i.fh2inode, fhHandle.fh)
-				fhHandle.Release()
+				fhHandle.ReleaseHandle()
 			}
 		}
 
diff --git a/weed/mount/filehandle_read.go b/weed/mount/filehandle_read.go
index a316a16cd..be6d5d984 100644
--- a/weed/mount/filehandle_read.go
+++ b/weed/mount/filehandle_read.go
@@ -17,18 +17,20 @@ func (fh *FileHandle) unlockForRead(startOffset int64, size int) {
 	fh.dirtyPages.UnlockForRead(startOffset, startOffset+int64(size))
 }
 
-func (fh *FileHandle) readFromDirtyPages(buff []byte, startOffset int64) (maxStop int64) {
-	maxStop = fh.dirtyPages.ReadDirtyDataAt(buff, startOffset)
+func (fh *FileHandle) readFromDirtyPages(buff []byte, startOffset int64, tsNs int64) (maxStop int64) {
+	maxStop = fh.dirtyPages.ReadDirtyDataAt(buff, startOffset, tsNs)
 	return
 }
 
-func (fh *FileHandle) readFromChunks(buff []byte, offset int64) (int64, error) {
+func (fh *FileHandle) readFromChunks(buff []byte, offset int64) (int64, int64, error) {
+	fh.entryLock.Lock()
+	defer fh.entryLock.Unlock()
 
 	fileFullPath := fh.FullPath()
 
 	entry := fh.GetEntry()
 	if entry == nil {
-		return 0, io.EOF
+		return 0, 0, io.EOF
 	}
 
 	if entry.IsInRemoteOnly() {
@@ -36,43 +38,28 @@ func (fh *FileHandle) readFromChunks(buff []byte, offset int64) (int64, error) {
 		newEntry, err := fh.downloadRemoteEntry(entry)
 		if err != nil {
 			glog.V(1).Infof("download remote entry %s: %v", fileFullPath, err)
-			return 0, err
+			return 0, 0, err
 		}
 		entry = newEntry
 	}
 
-	fileSize := int64(filer.FileSize(entry))
+	fileSize := int64(entry.Attributes.FileSize)
+	if fileSize == 0 {
+		fileSize = int64(filer.FileSize(entry))
+	}
 
 	if fileSize == 0 {
 		glog.V(1).Infof("empty fh %v", fileFullPath)
-		return 0, io.EOF
+		return 0, 0, io.EOF
 	}
 
 	if offset+int64(len(buff)) <= int64(len(entry.Content)) {
 		totalRead := copy(buff, entry.Content[offset:])
 		glog.V(4).Infof("file handle read cached %s [%d,%d] %d", fileFullPath, offset, offset+int64(totalRead), totalRead)
-		return int64(totalRead), nil
-	}
-
-	var chunkResolveErr error
-	if fh.entryViewCache == nil {
-		fh.entryViewCache, chunkResolveErr = filer.NonOverlappingVisibleIntervals(fh.wfs.LookupFn(), entry.GetChunks(), 0, fileSize)
-		if chunkResolveErr != nil {
-			return 0, fmt.Errorf("fail to resolve chunk manifest: %v", chunkResolveErr)
-		}
-		fh.CloseReader()
-	}
-
-	if fh.reader == nil {
-		chunkViews := filer.ViewFromVisibleIntervals(fh.entryViewCache, 0, fileSize)
-		glog.V(4).Infof("file handle read %s [%d,%d) from %d views", fileFullPath, offset, offset+int64(len(buff)), len(chunkViews))
-		for _, chunkView := range chunkViews {
-			glog.V(4).Infof("  read %s [%d,%d) from chunk %+v", fileFullPath, chunkView.LogicOffset, chunkView.LogicOffset+int64(chunkView.Size), chunkView.FileId)
-		}
-		fh.reader = filer.NewChunkReaderAtFromClient(fh.wfs.LookupFn(), chunkViews, fh.wfs.chunkCache, fileSize)
+		return int64(totalRead), 0, nil
 	}
 
-	totalRead, err := fh.reader.ReadAt(buff, offset)
+	totalRead, ts, err := fh.entryChunkGroup.ReadDataAt(fileSize, buff, offset)
 
 	if err != nil && err != io.EOF {
 		glog.Errorf("file handle read %s: %v", fileFullPath, err)
@@ -80,7 +67,7 @@ func (fh *FileHandle) readFromChunks(buff []byte, offset int64) (int64, error) {
 
 	// glog.V(4).Infof("file handle read %s [%d,%d] %d : %v", fileFullPath, offset, offset+int64(totalRead), totalRead, err)
 
-	return int64(totalRead), err
+	return int64(totalRead), ts, err
 }
 
 func (fh *FileHandle) downloadRemoteEntry(entry *filer_pb.Entry) (*filer_pb.Entry, error) {
diff --git a/weed/mount/page_writer.go b/weed/mount/page_writer.go
index 1f31b5300..c9470c440 100644
--- a/weed/mount/page_writer.go
+++ b/weed/mount/page_writer.go
@@ -29,35 +29,35 @@ func newPageWriter(fh *FileHandle, chunkSize int64) *PageWriter {
 	return pw
 }
 
-func (pw *PageWriter) AddPage(offset int64, data []byte, isSequential bool) {
+func (pw *PageWriter) AddPage(offset int64, data []byte, isSequential bool, tsNs int64) {
 
 	glog.V(4).Infof("%v AddPage [%d, %d)", pw.fh.fh, offset, offset+int64(len(data)))
 
 	chunkIndex := offset / pw.chunkSize
 	for i := chunkIndex; len(data) > 0; i++ {
 		writeSize := min(int64(len(data)), (i+1)*pw.chunkSize-offset)
-		pw.addToOneChunk(i, offset, data[:writeSize], isSequential)
+		pw.addToOneChunk(i, offset, data[:writeSize], isSequential, tsNs)
 		offset += writeSize
 		data = data[writeSize:]
 	}
 }
 
-func (pw *PageWriter) addToOneChunk(chunkIndex, offset int64, data []byte, isSequential bool) {
-	pw.randomWriter.AddPage(offset, data, isSequential)
+func (pw *PageWriter) addToOneChunk(chunkIndex, offset int64, data []byte, isSequential bool, tsNs int64) {
+	pw.randomWriter.AddPage(offset, data, isSequential, tsNs)
 }
 
 func (pw *PageWriter) FlushData() error {
 	return pw.randomWriter.FlushData()
 }
 
-func (pw *PageWriter) ReadDirtyDataAt(data []byte, offset int64) (maxStop int64) {
+func (pw *PageWriter) ReadDirtyDataAt(data []byte, offset int64, tsNs int64) (maxStop int64) {
 	glog.V(4).Infof("ReadDirtyDataAt %v [%d, %d)", pw.fh.fh, offset, offset+int64(len(data)))
 
 	chunkIndex := offset / pw.chunkSize
 	for i := chunkIndex; len(data) > 0; i++ {
 		readSize := min(int64(len(data)), (i+1)*pw.chunkSize-offset)
 
-		maxStop = pw.randomWriter.ReadDirtyDataAt(data[:readSize], offset)
+		maxStop = pw.randomWriter.ReadDirtyDataAt(data[:readSize], offset, tsNs)
 
 		offset += readSize
 		data = data[readSize:]
diff --git a/weed/mount/page_writer/activity_score.go b/weed/mount/page_writer/activity_score.go
new file mode 100644
index 000000000..22da87e37
--- /dev/null
+++ b/weed/mount/page_writer/activity_score.go
@@ -0,0 +1,39 @@
+package page_writer
+
+import "time"
+
+type ActivityScore struct {
+	lastActiveTsNs         int64
+	decayedActivenessScore int64
+}
+
+func NewActivityScore() *ActivityScore {
+	return &ActivityScore{}
+}
+
+func (as ActivityScore) MarkRead() {
+	now := time.Now().UnixNano()
+	deltaTime := (now - as.lastActiveTsNs) >> 30 // about number of seconds
+	as.lastActiveTsNs = now
+
+	as.decayedActivenessScore = as.decayedActivenessScore>>deltaTime + 256
+	if as.decayedActivenessScore < 0 {
+		as.decayedActivenessScore = 0
+	}
+}
+
+func (as ActivityScore) MarkWrite() {
+	now := time.Now().UnixNano()
+	deltaTime := (now - as.lastActiveTsNs) >> 30 // about number of seconds
+	as.lastActiveTsNs = now
+
+	as.decayedActivenessScore = as.decayedActivenessScore>>deltaTime + 1024
+	if as.decayedActivenessScore < 0 {
+		as.decayedActivenessScore = 0
+	}
+}
+
+func (as ActivityScore) ActivityScore() int64 {
+	deltaTime := (time.Now().UnixNano() - as.lastActiveTsNs) >> 30 // about number of seconds
+	return as.decayedActivenessScore >> deltaTime
+}
diff --git a/weed/mount/page_writer/chunk_interval_list.go b/weed/mount/page_writer/chunk_interval_list.go
index a9d64c8e4..005385c1a 100644
--- a/weed/mount/page_writer/chunk_interval_list.go
+++ b/weed/mount/page_writer/chunk_interval_list.go
@@ -8,6 +8,7 @@ import (
 type ChunkWrittenInterval struct {
 	StartOffset int64
 	stopOffset  int64
+	TsNs        int64
 	prev        *ChunkWrittenInterval
 	next        *ChunkWrittenInterval
 }
@@ -42,10 +43,14 @@ func newChunkWrittenIntervalList() *ChunkWrittenIntervalList {
 	return list
 }
 
-func (list *ChunkWrittenIntervalList) MarkWritten(startOffset, stopOffset int64) {
+func (list *ChunkWrittenIntervalList) MarkWritten(startOffset, stopOffset, tsNs int64) {
+	if startOffset >= stopOffset {
+		return
+	}
 	interval := &ChunkWrittenInterval{
 		StartOffset: startOffset,
 		stopOffset:  stopOffset,
+		TsNs:        tsNs,
 	}
 	list.addInterval(interval)
 }
@@ -62,50 +67,54 @@ func (list *ChunkWrittenIntervalList) WrittenSize() (writtenByteCount int64) {
 
 func (list *ChunkWrittenIntervalList) addInterval(interval *ChunkWrittenInterval) {
 
+	//t := list.head
+	//for ; t.next != nil; t = t.next {
+	//	if t.TsNs > interval.TsNs {
+	//		println("writes is out of order", t.TsNs-interval.TsNs, "ns")
+	//	}
+	//}
+
 	p := list.head
-	for ; p.next != nil && p.next.StartOffset <= interval.StartOffset; p = p.next {
+	for ; p.next != nil && p.next.stopOffset <= interval.StartOffset; p = p.next {
 	}
 	q := list.tail
-	for ; q.prev != nil && q.prev.stopOffset >= interval.stopOffset; q = q.prev {
+	for ; q.prev != nil && q.prev.StartOffset >= interval.stopOffset; q = q.prev {
 	}
 
-	if interval.StartOffset <= p.stopOffset && q.StartOffset <= interval.stopOffset {
-		// merge p and q together
-		p.stopOffset = q.stopOffset
-		unlinkNodesBetween(p, q.next)
-		return
+	// left side
+	// interval after p.next start
+	if p.next.StartOffset < interval.StartOffset {
+		t := &ChunkWrittenInterval{
+			StartOffset: p.next.StartOffset,
+			stopOffset:  interval.StartOffset,
+			TsNs:        p.next.TsNs,
+		}
+		p.next = t
+		t.prev = p
+		t.next = interval
+		interval.prev = t
+	} else {
+		p.next = interval
+		interval.prev = p
 	}
-	if interval.StartOffset <= p.stopOffset {
-		// merge new interval into p
-		p.stopOffset = interval.stopOffset
-		unlinkNodesBetween(p, q)
-		return
-	}
-	if q.StartOffset <= interval.stopOffset {
-		// merge new interval into q
-		q.StartOffset = interval.StartOffset
-		unlinkNodesBetween(p, q)
-		return
-	}
-
-	// add the new interval between p and q
-	unlinkNodesBetween(p, q)
-	p.next = interval
-	interval.prev = p
-	q.prev = interval
-	interval.next = q
-
-}
 
-// unlinkNodesBetween remove all nodes after start and before stop, exclusive
-func unlinkNodesBetween(start *ChunkWrittenInterval, stop *ChunkWrittenInterval) {
-	if start.next == stop {
-		return
+	// right side
+	// interval ends before p.prev
+	if interval.stopOffset < q.prev.stopOffset {
+		t := &ChunkWrittenInterval{
+			StartOffset: interval.stopOffset,
+			stopOffset:  q.prev.stopOffset,
+			TsNs:        q.prev.TsNs,
+		}
+		q.prev = t
+		t.next = q
+		interval.next = t
+		t.prev = interval
+	} else {
+		q.prev = interval
+		interval.next = q
 	}
-	start.next.prev = nil
-	start.next = stop
-	stop.prev.next = nil
-	stop.prev = start
+
 }
 
 func (list *ChunkWrittenIntervalList) size() int {
diff --git a/weed/mount/page_writer/chunk_interval_list_test.go b/weed/mount/page_writer/chunk_interval_list_test.go
index b22f5eb5d..eb1d5ff46 100644
--- a/weed/mount/page_writer/chunk_interval_list_test.go
+++ b/weed/mount/page_writer/chunk_interval_list_test.go
@@ -10,40 +10,72 @@ func Test_PageChunkWrittenIntervalList(t *testing.T) {
 
 	assert.Equal(t, 0, list.size(), "empty list")
 
-	list.MarkWritten(0, 5)
+	list.MarkWritten(0, 5, 1)
 	assert.Equal(t, 1, list.size(), "one interval")
 
-	list.MarkWritten(0, 5)
+	list.MarkWritten(0, 5, 2)
 	assert.Equal(t, 1, list.size(), "duplicated interval2")
 
-	list.MarkWritten(95, 100)
+	list.MarkWritten(95, 100, 3)
 	assert.Equal(t, 2, list.size(), "two intervals")
 
-	list.MarkWritten(50, 60)
+	list.MarkWritten(50, 60, 4)
 	assert.Equal(t, 3, list.size(), "three intervals")
 
-	list.MarkWritten(50, 55)
-	assert.Equal(t, 3, list.size(), "three intervals merge")
+	list.MarkWritten(50, 55, 5)
+	assert.Equal(t, 4, list.size(), "three intervals merge")
 
-	list.MarkWritten(40, 50)
-	assert.Equal(t, 3, list.size(), "three intervals grow forward")
+	list.MarkWritten(40, 50, 6)
+	assert.Equal(t, 5, list.size(), "three intervals grow forward")
 
-	list.MarkWritten(50, 65)
-	assert.Equal(t, 3, list.size(), "three intervals grow backward")
+	list.MarkWritten(50, 65, 7)
+	assert.Equal(t, 4, list.size(), "three intervals grow backward")
 
-	list.MarkWritten(70, 80)
-	assert.Equal(t, 4, list.size(), "four intervals")
+	list.MarkWritten(70, 80, 8)
+	assert.Equal(t, 5, list.size(), "four intervals")
 
-	list.MarkWritten(60, 70)
-	assert.Equal(t, 3, list.size(), "three intervals merged")
+	list.MarkWritten(60, 70, 9)
+	assert.Equal(t, 6, list.size(), "three intervals merged")
 
-	list.MarkWritten(59, 71)
-	assert.Equal(t, 3, list.size(), "covered three intervals")
+	list.MarkWritten(59, 71, 10)
+	assert.Equal(t, 6, list.size(), "covered three intervals")
 
-	list.MarkWritten(5, 59)
-	assert.Equal(t, 2, list.size(), "covered two intervals")
+	list.MarkWritten(5, 59, 11)
+	assert.Equal(t, 5, list.size(), "covered two intervals")
 
-	list.MarkWritten(70, 99)
-	assert.Equal(t, 1, list.size(), "covered one intervals")
+	list.MarkWritten(70, 99, 12)
+	assert.Equal(t, 5, list.size(), "covered one intervals")
 
 }
+
+type interval struct {
+	start    int64
+	stop     int64
+	expected bool
+}
+
+func Test_PageChunkWrittenIntervalList1(t *testing.T) {
+	list := newChunkWrittenIntervalList()
+	inputs := []interval{
+		{1, 5, true},
+		{2, 3, true},
+	}
+	for i, input := range inputs {
+		list.MarkWritten(input.start, input.stop, int64(i)+1)
+		actual := hasData(list, 0, 4)
+		if actual != input.expected {
+			t.Errorf("input [%d,%d) expected %v actual %v", input.start, input.stop, input.expected, actual)
+		}
+	}
+}
+
+func hasData(usage *ChunkWrittenIntervalList, chunkStartOffset, x int64) bool {
+	for t := usage.head.next; t != usage.tail; t = t.next {
+		logicStart := chunkStartOffset + t.StartOffset
+		logicStop := chunkStartOffset + t.stopOffset
+		if logicStart <= x && x < logicStop {
+			return true
+		}
+	}
+	return false
+}
diff --git a/weed/mount/page_writer/dirty_pages.go b/weed/mount/page_writer/dirty_pages.go
index 44f879afc..7cddcf69e 100644
--- a/weed/mount/page_writer/dirty_pages.go
+++ b/weed/mount/page_writer/dirty_pages.go
@@ -1,9 +1,9 @@
 package page_writer
 
 type DirtyPages interface {
-	AddPage(offset int64, data []byte, isSequential bool)
+	AddPage(offset int64, data []byte, isSequential bool, tsNs int64)
 	FlushData() error
-	ReadDirtyDataAt(data []byte, startOffset int64) (maxStop int64)
+	ReadDirtyDataAt(data []byte, startOffset int64, tsNs int64) (maxStop int64)
 	Destroy()
 	LockForRead(startOffset, stopOffset int64)
 	UnlockForRead(startOffset, stopOffset int64)
diff --git a/weed/mount/page_writer/page_chunk.go b/weed/mount/page_writer/page_chunk.go
index 4e8f31425..32d246deb 100644
--- a/weed/mount/page_writer/page_chunk.go
+++ b/weed/mount/page_writer/page_chunk.go
@@ -4,13 +4,13 @@ import (
 	"io"
 )
 
-type SaveToStorageFunc func(reader io.Reader, offset int64, size int64, cleanupFn func())
+type SaveToStorageFunc func(reader io.Reader, offset int64, size int64, modifiedTsNs int64, cleanupFn func())
 
 type PageChunk interface {
 	FreeResource()
-	WriteDataAt(src []byte, offset int64) (n int)
-	ReadDataAt(p []byte, off int64) (maxStop int64)
+	WriteDataAt(src []byte, offset int64, tsNs int64) (n int)
+	ReadDataAt(p []byte, off int64, tsNs int64) (maxStop int64)
 	IsComplete() bool
-	WrittenSize() int64
+	ActivityScore() int64
 	SaveContent(saveFn SaveToStorageFunc)
 }
diff --git a/weed/mount/page_writer/page_chunk_mem.go b/weed/mount/page_writer/page_chunk_mem.go
index 8cccded67..1ec8cecb4 100644
--- a/weed/mount/page_writer/page_chunk_mem.go
+++ b/weed/mount/page_writer/page_chunk_mem.go
@@ -19,6 +19,7 @@ type MemChunk struct {
 	usage           *ChunkWrittenIntervalList
 	chunkSize       int64
 	logicChunkIndex LogicChunkIndex
+	activityScore   *ActivityScore
 }
 
 func NewMemChunk(logicChunkIndex LogicChunkIndex, chunkSize int64) *MemChunk {
@@ -28,6 +29,7 @@ func NewMemChunk(logicChunkIndex LogicChunkIndex, chunkSize int64) *MemChunk {
 		chunkSize:       chunkSize,
 		buf:             mem.Allocate(int(chunkSize)),
 		usage:           newChunkWrittenIntervalList(),
+		activityScore:   NewActivityScore(),
 	}
 }
 
@@ -39,29 +41,37 @@ func (mc *MemChunk) FreeResource() {
 	mem.Free(mc.buf)
 }
 
-func (mc *MemChunk) WriteDataAt(src []byte, offset int64) (n int) {
+func (mc *MemChunk) WriteDataAt(src []byte, offset int64, tsNs int64) (n int) {
 	mc.Lock()
 	defer mc.Unlock()
 
 	innerOffset := offset % mc.chunkSize
 	n = copy(mc.buf[innerOffset:], src)
-	mc.usage.MarkWritten(innerOffset, innerOffset+int64(n))
+	mc.usage.MarkWritten(innerOffset, innerOffset+int64(n), tsNs)
+	mc.activityScore.MarkWrite()
+
 	return
 }
 
-func (mc *MemChunk) ReadDataAt(p []byte, off int64) (maxStop int64) {
+func (mc *MemChunk) ReadDataAt(p []byte, off int64, tsNs int64) (maxStop int64) {
 	mc.RLock()
 	defer mc.RUnlock()
 
 	memChunkBaseOffset := int64(mc.logicChunkIndex) * mc.chunkSize
 	for t := mc.usage.head.next; t != mc.usage.tail; t = t.next {
-		logicStart := max(off, int64(mc.logicChunkIndex)*mc.chunkSize+t.StartOffset)
+		logicStart := max(off, memChunkBaseOffset+t.StartOffset)
 		logicStop := min(off+int64(len(p)), memChunkBaseOffset+t.stopOffset)
 		if logicStart < logicStop {
-			copy(p[logicStart-off:logicStop-off], mc.buf[logicStart-memChunkBaseOffset:logicStop-memChunkBaseOffset])
-			maxStop = max(maxStop, logicStop)
+			if t.TsNs >= tsNs {
+				copy(p[logicStart-off:logicStop-off], mc.buf[logicStart-memChunkBaseOffset:logicStop-memChunkBaseOffset])
+				maxStop = max(maxStop, logicStop)
+			} else {
+				println("read old data1", tsNs-t.TsNs, "ns")
+			}
 		}
 	}
+	mc.activityScore.MarkRead()
+
 	return
 }
 
@@ -72,11 +82,8 @@ func (mc *MemChunk) IsComplete() bool {
 	return mc.usage.IsComplete(mc.chunkSize)
 }
 
-func (mc *MemChunk) WrittenSize() int64 {
-	mc.RLock()
-	defer mc.RUnlock()
-
-	return mc.usage.WrittenSize()
+func (mc *MemChunk) ActivityScore() int64 {
+	return mc.activityScore.ActivityScore()
 }
 
 func (mc *MemChunk) SaveContent(saveFn SaveToStorageFunc) {
@@ -88,7 +95,7 @@ func (mc *MemChunk) SaveContent(saveFn SaveToStorageFunc) {
 	}
 	for t := mc.usage.head.next; t != mc.usage.tail; t = t.next {
 		reader := util.NewBytesReader(mc.buf[t.StartOffset:t.stopOffset])
-		saveFn(reader, int64(mc.logicChunkIndex)*mc.chunkSize+t.StartOffset, t.Size(), func() {
+		saveFn(reader, int64(mc.logicChunkIndex)*mc.chunkSize+t.StartOffset, t.Size(), t.TsNs, func() {
 		})
 	}
 }
diff --git a/weed/mount/page_writer/page_chunk_swapfile.go b/weed/mount/page_writer/page_chunk_swapfile.go
index bf2cdb256..6cedc64df 100644
--- a/weed/mount/page_writer/page_chunk_swapfile.go
+++ b/weed/mount/page_writer/page_chunk_swapfile.go
@@ -15,12 +15,12 @@ var (
 type ActualChunkIndex int
 
 type SwapFile struct {
-	dir                         string
-	file                        *os.File
-	logicToActualChunkIndex     map[LogicChunkIndex]ActualChunkIndex
-	logicToActualChunkIndexLock sync.Mutex
-	chunkSize                   int64
-	freeActualChunkList         []ActualChunkIndex
+	dir                 string
+	file                *os.File
+	chunkSize           int64
+	chunkTrackingLock   sync.Mutex
+	activeChunkCount    int
+	freeActualChunkList []ActualChunkIndex
 }
 
 type SwapFileChunk struct {
@@ -29,14 +29,15 @@ type SwapFileChunk struct {
 	usage            *ChunkWrittenIntervalList
 	logicChunkIndex  LogicChunkIndex
 	actualChunkIndex ActualChunkIndex
+	activityScore    *ActivityScore
+	//memChunk         *MemChunk
 }
 
 func NewSwapFile(dir string, chunkSize int64) *SwapFile {
 	return &SwapFile{
-		dir:                     dir,
-		file:                    nil,
-		logicToActualChunkIndex: make(map[LogicChunkIndex]ActualChunkIndex),
-		chunkSize:               chunkSize,
+		dir:       dir,
+		file:      nil,
+		chunkSize: chunkSize,
 	}
 }
 func (sf *SwapFile) FreeResource() {
@@ -46,7 +47,7 @@ func (sf *SwapFile) FreeResource() {
 	}
 }
 
-func (sf *SwapFile) NewTempFileChunk(logicChunkIndex LogicChunkIndex) (tc *SwapFileChunk) {
+func (sf *SwapFile) NewSwapFileChunk(logicChunkIndex LogicChunkIndex) (tc *SwapFileChunk) {
 	if sf.file == nil {
 		var err error
 		sf.file, err = os.CreateTemp(sf.dir, "")
@@ -55,70 +56,98 @@ func (sf *SwapFile) NewTempFileChunk(logicChunkIndex LogicChunkIndex) (tc *SwapF
 			return nil
 		}
 	}
-	sf.logicToActualChunkIndexLock.Lock()
-	defer sf.logicToActualChunkIndexLock.Unlock()
-	actualChunkIndex, found := sf.logicToActualChunkIndex[logicChunkIndex]
-	if !found {
-		if len(sf.freeActualChunkList) > 0 {
-			actualChunkIndex = sf.freeActualChunkList[0]
-			sf.freeActualChunkList = sf.freeActualChunkList[1:]
-		} else {
-			actualChunkIndex = ActualChunkIndex(len(sf.logicToActualChunkIndex))
-		}
-		sf.logicToActualChunkIndex[logicChunkIndex] = actualChunkIndex
+	sf.chunkTrackingLock.Lock()
+	defer sf.chunkTrackingLock.Unlock()
+
+	sf.activeChunkCount++
+
+	// assign a new physical chunk
+	var actualChunkIndex ActualChunkIndex
+	if len(sf.freeActualChunkList) > 0 {
+		actualChunkIndex = sf.freeActualChunkList[0]
+		sf.freeActualChunkList = sf.freeActualChunkList[1:]
+	} else {
+		actualChunkIndex = ActualChunkIndex(sf.activeChunkCount)
 	}
 
-	return &SwapFileChunk{
+	swapFileChunk := &SwapFileChunk{
 		swapfile:         sf,
 		usage:            newChunkWrittenIntervalList(),
 		logicChunkIndex:  logicChunkIndex,
 		actualChunkIndex: actualChunkIndex,
+		activityScore:    NewActivityScore(),
+		// memChunk:         NewMemChunk(logicChunkIndex, sf.chunkSize),
 	}
+
+	// println(logicChunkIndex, "|", "++++", swapFileChunk.actualChunkIndex, swapFileChunk, sf)
+	return swapFileChunk
 }
 
 func (sc *SwapFileChunk) FreeResource() {
-	sc.swapfile.logicToActualChunkIndexLock.Lock()
-	defer sc.swapfile.logicToActualChunkIndexLock.Unlock()
 
 	sc.Lock()
 	defer sc.Unlock()
 
+	sc.swapfile.chunkTrackingLock.Lock()
+	defer sc.swapfile.chunkTrackingLock.Unlock()
+
 	sc.swapfile.freeActualChunkList = append(sc.swapfile.freeActualChunkList, sc.actualChunkIndex)
-	delete(sc.swapfile.logicToActualChunkIndex, sc.logicChunkIndex)
+	sc.swapfile.activeChunkCount--
+	// println(sc.logicChunkIndex, "|", "----", sc.actualChunkIndex, sc, sc.swapfile)
 }
 
-func (sc *SwapFileChunk) WriteDataAt(src []byte, offset int64) (n int) {
+func (sc *SwapFileChunk) WriteDataAt(src []byte, offset int64, tsNs int64) (n int) {
 	sc.Lock()
 	defer sc.Unlock()
 
+	// println(sc.logicChunkIndex, "|", tsNs, "write at", offset, len(src), sc.actualChunkIndex)
+
 	innerOffset := offset % sc.swapfile.chunkSize
 	var err error
 	n, err = sc.swapfile.file.WriteAt(src, int64(sc.actualChunkIndex)*sc.swapfile.chunkSize+innerOffset)
-	if err == nil {
-		sc.usage.MarkWritten(innerOffset, innerOffset+int64(n))
-	} else {
+	sc.usage.MarkWritten(innerOffset, innerOffset+int64(n), tsNs)
+	if err != nil {
 		glog.Errorf("failed to write swap file %s: %v", sc.swapfile.file.Name(), err)
 	}
+	//sc.memChunk.WriteDataAt(src, offset, tsNs)
+	sc.activityScore.MarkWrite()
+
 	return
 }
 
-func (sc *SwapFileChunk) ReadDataAt(p []byte, off int64) (maxStop int64) {
+func (sc *SwapFileChunk) ReadDataAt(p []byte, off int64, tsNs int64) (maxStop int64) {
 	sc.RLock()
 	defer sc.RUnlock()
 
+	// println(sc.logicChunkIndex, "|", tsNs, "read at", off, len(p), sc.actualChunkIndex)
+
+	//memCopy := make([]byte, len(p))
+	//copy(memCopy, p)
+
 	chunkStartOffset := int64(sc.logicChunkIndex) * sc.swapfile.chunkSize
 	for t := sc.usage.head.next; t != sc.usage.tail; t = t.next {
 		logicStart := max(off, chunkStartOffset+t.StartOffset)
 		logicStop := min(off+int64(len(p)), chunkStartOffset+t.stopOffset)
 		if logicStart < logicStop {
-			actualStart := logicStart - chunkStartOffset + int64(sc.actualChunkIndex)*sc.swapfile.chunkSize
-			if _, err := sc.swapfile.file.ReadAt(p[logicStart-off:logicStop-off], actualStart); err != nil {
-				glog.Errorf("failed to reading swap file %s: %v", sc.swapfile.file.Name(), err)
-				break
+			if t.TsNs >= tsNs {
+				actualStart := logicStart - chunkStartOffset + int64(sc.actualChunkIndex)*sc.swapfile.chunkSize
+				if _, err := sc.swapfile.file.ReadAt(p[logicStart-off:logicStop-off], actualStart); err != nil {
+					glog.Errorf("failed to reading swap file %s: %v", sc.swapfile.file.Name(), err)
+					break
+				}
+				maxStop = max(maxStop, logicStop)
+			} else {
+				println("read old data2", tsNs-t.TsNs, "ns")
 			}
-			maxStop = max(maxStop, logicStop)
 		}
 	}
+	//sc.memChunk.ReadDataAt(memCopy, off, tsNs)
+	//if bytes.Compare(memCopy, p) != 0 {
+	//	println("read wrong data from swap file", off, sc.logicChunkIndex)
+	//}
+
+	sc.activityScore.MarkRead()
+
 	return
 }
 
@@ -128,27 +157,27 @@ func (sc *SwapFileChunk) IsComplete() bool {
 	return sc.usage.IsComplete(sc.swapfile.chunkSize)
 }
 
-func (sc *SwapFileChunk) WrittenSize() int64 {
-	sc.RLock()
-	defer sc.RUnlock()
-	return sc.usage.WrittenSize()
+func (sc *SwapFileChunk) ActivityScore() int64 {
+	return sc.activityScore.ActivityScore()
 }
 
 func (sc *SwapFileChunk) SaveContent(saveFn SaveToStorageFunc) {
+	sc.RLock()
+	defer sc.RUnlock()
+
 	if saveFn == nil {
 		return
 	}
-	sc.Lock()
-	defer sc.Unlock()
-
+	// println(sc.logicChunkIndex, "|", "save")
 	for t := sc.usage.head.next; t != sc.usage.tail; t = t.next {
 		data := mem.Allocate(int(t.Size()))
-		sc.swapfile.file.ReadAt(data, t.StartOffset+int64(sc.actualChunkIndex)*sc.swapfile.chunkSize)
-		reader := util.NewBytesReader(data)
-		saveFn(reader, int64(sc.logicChunkIndex)*sc.swapfile.chunkSize+t.StartOffset, t.Size(), func() {
-		})
+		n, _ := sc.swapfile.file.ReadAt(data, t.StartOffset+int64(sc.actualChunkIndex)*sc.swapfile.chunkSize)
+		if n > 0 {
+			reader := util.NewBytesReader(data[:n])
+			saveFn(reader, int64(sc.logicChunkIndex)*sc.swapfile.chunkSize+t.StartOffset, int64(n), t.TsNs, func() {
+			})
+		}
 		mem.Free(data)
 	}
 
-	sc.usage = newChunkWrittenIntervalList()
 }
diff --git a/weed/mount/page_writer/upload_pipeline.go b/weed/mount/page_writer/upload_pipeline.go
index 252dddc06..6065f2f76 100644
--- a/weed/mount/page_writer/upload_pipeline.go
+++ b/weed/mount/page_writer/upload_pipeline.go
@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"github.com/seaweedfs/seaweedfs/weed/glog"
 	"github.com/seaweedfs/seaweedfs/weed/util"
+	"math"
 	"sync"
 	"sync/atomic"
 )
@@ -55,7 +56,8 @@ func NewUploadPipeline(writers *util.LimitedConcurrentExecutor, chunkSize int64,
 	return t
 }
 
-func (up *UploadPipeline) SaveDataAt(p []byte, off int64, isSequential bool) (n int) {
+func (up *UploadPipeline) SaveDataAt(p []byte, off int64, isSequential bool, tsNs int64) (n int) {
+
 	up.chunksLock.Lock()
 	defer up.chunksLock.Unlock()
 
@@ -65,33 +67,39 @@ func (up *UploadPipeline) SaveDataAt(p []byte, off int64, isSequential bool) (n
 	if !found {
 		if len(up.writableChunks) > up.writableChunkLimit {
 			// if current file chunks is over the per file buffer count limit
-			fullestChunkIndex, fullness := LogicChunkIndex(-1), int64(0)
-			for lci, mc := range up.writableChunks {
-				chunkFullness := mc.WrittenSize()
-				if fullness < chunkFullness {
-					fullestChunkIndex = lci
-					fullness = chunkFullness
+			laziestChunkIndex, lowestActivityScore := LogicChunkIndex(-1), int64(math.MaxInt64)
+			for wci, wc := range up.writableChunks {
+				activityScore := wc.ActivityScore()
+				if lowestActivityScore > activityScore {
+					laziestChunkIndex = wci
+					lowestActivityScore = activityScore
 				}
 			}
-			up.moveToSealed(up.writableChunks[fullestChunkIndex], fullestChunkIndex)
-			// fmt.Printf("flush chunk %d with %d bytes written\n", logicChunkIndex, fullness)
+			up.moveToSealed(up.writableChunks[laziestChunkIndex], laziestChunkIndex)
+			// fmt.Printf("flush chunk %d with %d bytes written\n", logicChunkIndex, oldestTs)
 		}
 		if isSequential &&
 			len(up.writableChunks) < up.writableChunkLimit &&
 			atomic.LoadInt64(&memChunkCounter) < 4*int64(up.writableChunkLimit) {
 			pageChunk = NewMemChunk(logicChunkIndex, up.ChunkSize)
 		} else {
-			pageChunk = up.swapFile.NewTempFileChunk(logicChunkIndex)
+			pageChunk = up.swapFile.NewSwapFileChunk(logicChunkIndex)
 		}
 		up.writableChunks[logicChunkIndex] = pageChunk
 	}
-	n = pageChunk.WriteDataAt(p, off)
+	//if _, foundSealed := up.sealedChunks[logicChunkIndex]; foundSealed {
+	//	println("found already sealed chunk", logicChunkIndex)
+	//}
+	//if _, foundReading := up.activeReadChunks[logicChunkIndex]; foundReading {
+	//	println("found active read chunk", logicChunkIndex)
+	//}
+	n = pageChunk.WriteDataAt(p, off, tsNs)
 	up.maybeMoveToSealed(pageChunk, logicChunkIndex)
 
 	return
 }
 
-func (up *UploadPipeline) MaybeReadDataAt(p []byte, off int64) (maxStop int64) {
+func (up *UploadPipeline) MaybeReadDataAt(p []byte, off int64, tsNs int64) (maxStop int64) {
 	logicChunkIndex := LogicChunkIndex(off / up.ChunkSize)
 
 	up.chunksLock.Lock()
@@ -103,12 +111,8 @@ func (up *UploadPipeline) MaybeReadDataAt(p []byte, off int64) (maxStop int64) {
 	// read from sealed chunks first
 	sealedChunk, found := up.sealedChunks[logicChunkIndex]
 	if found {
-		sealedChunk.referenceCounter++
-	}
-	if found {
-		maxStop = sealedChunk.chunk.ReadDataAt(p, off)
+		maxStop = sealedChunk.chunk.ReadDataAt(p, off, tsNs)
 		glog.V(4).Infof("%s read sealed memchunk [%d,%d)", up.filepath, off, maxStop)
-		sealedChunk.FreeReference(fmt.Sprintf("%s finish reading chunk %d", up.filepath, logicChunkIndex))
 	}
 
 	// read from writable chunks last
@@ -116,7 +120,7 @@ func (up *UploadPipeline) MaybeReadDataAt(p []byte, off int64) (maxStop int64) {
 	if !found {
 		return
 	}
-	writableMaxStop := writableChunk.ReadDataAt(p, off)
+	writableMaxStop := writableChunk.ReadDataAt(p, off, tsNs)
 	glog.V(4).Infof("%s read writable memchunk [%d,%d)", up.filepath, off, writableMaxStop)
 	maxStop = max(maxStop, writableMaxStop)
 
diff --git a/weed/mount/page_writer/upload_pipeline_test.go b/weed/mount/page_writer/upload_pipeline_test.go
index 27da7036d..2d803f6af 100644
--- a/weed/mount/page_writer/upload_pipeline_test.go
+++ b/weed/mount/page_writer/upload_pipeline_test.go
@@ -31,14 +31,14 @@ func writeRange(uploadPipeline *UploadPipeline, startOff, stopOff int64) {
 	p := make([]byte, 4)
 	for i := startOff / 4; i < stopOff/4; i += 4 {
 		util.Uint32toBytes(p, uint32(i))
-		uploadPipeline.SaveDataAt(p, i, false)
+		uploadPipeline.SaveDataAt(p, i, false, 0)
 	}
 }
 
 func confirmRange(t *testing.T, uploadPipeline *UploadPipeline, startOff, stopOff int64) {
 	p := make([]byte, 4)
 	for i := startOff; i < stopOff/4; i += 4 {
-		uploadPipeline.MaybeReadDataAt(p, i)
+		uploadPipeline.MaybeReadDataAt(p, i, 0)
 		x := util.BytesToUint32(p)
 		if x != uint32(i) {
 			t.Errorf("expecting %d found %d at offset [%d,%d)", i, x, i, i+4)
diff --git a/weed/mount/weedfs_attr.go b/weed/mount/weedfs_attr.go
index 1d58e0852..7dc3c6b50 100644
--- a/weed/mount/weedfs_attr.go
+++ b/weed/mount/weedfs_attr.go
@@ -20,12 +20,12 @@ func (wfs *WFS) GetAttr(cancel <-chan struct{}, input *fuse.GetAttrIn, out *fuse
 	_, _, entry, status := wfs.maybeReadEntry(inode)
 	if status == fuse.OK {
 		out.AttrValid = 1
-		wfs.setAttrByPbEntry(&out.Attr, inode, entry)
+		wfs.setAttrByPbEntry(&out.Attr, inode, entry, true)
 		return status
 	} else {
 		if fh, found := wfs.fhmap.FindFileHandle(inode); found {
 			out.AttrValid = 1
-			wfs.setAttrByPbEntry(&out.Attr, inode, fh.entry.GetEntry())
+			wfs.setAttrByPbEntry(&out.Attr, inode, fh.entry.GetEntry(), true)
 			out.Nlink = 0
 			return fuse.OK
 		}
@@ -75,7 +75,7 @@ func (wfs *WFS) SetAttr(cancel <-chan struct{}, input *fuse.SetAttrIn, out *fuse
 			// set the new chunks and reset entry cache
 			entry.Chunks = chunks
 			if fh != nil {
-				fh.entryViewCache = nil
+				fh.entryChunkGroup.SetChunks(chunks)
 			}
 		}
 		entry.Attributes.Mtime = time.Now().Unix()
@@ -114,7 +114,11 @@ func (wfs *WFS) SetAttr(cancel <-chan struct{}, input *fuse.SetAttrIn, out *fuse
 	}
 
 	out.AttrValid = 1
-	wfs.setAttrByPbEntry(&out.Attr, input.NodeId, entry)
+	size, includeSize := input.GetSize()
+	if includeSize {
+		out.Attr.Size = size
+	}
+	wfs.setAttrByPbEntry(&out.Attr, input.NodeId, entry, !includeSize)
 
 	if fh != nil {
 		fh.dirtyMetadata = true
@@ -139,12 +143,14 @@ func (wfs *WFS) setRootAttr(out *fuse.AttrOut) {
 	out.Nlink = 1
 }
 
-func (wfs *WFS) setAttrByPbEntry(out *fuse.Attr, inode uint64, entry *filer_pb.Entry) {
+func (wfs *WFS) setAttrByPbEntry(out *fuse.Attr, inode uint64, entry *filer_pb.Entry, calculateSize bool) {
 	out.Ino = inode
 	if entry.Attributes != nil && entry.Attributes.Inode != 0 {
 		out.Ino = entry.Attributes.Inode
 	}
-	out.Size = filer.FileSize(entry)
+	if calculateSize {
+		out.Size = filer.FileSize(entry)
+	}
 	if entry.FileMode()&os.ModeSymlink != 0 {
 		out.Size = uint64(len(entry.Attributes.SymlinkTarget))
 	}
@@ -194,7 +200,7 @@ func (wfs *WFS) outputPbEntry(out *fuse.EntryOut, inode uint64, entry *filer_pb.
 	out.Generation = 1
 	out.EntryValid = 1
 	out.AttrValid = 1
-	wfs.setAttrByPbEntry(&out.Attr, inode, entry)
+	wfs.setAttrByPbEntry(&out.Attr, inode, entry, true)
 }
 
 func (wfs *WFS) outputFilerEntry(out *fuse.EntryOut, inode uint64, entry *filer.Entry) {
diff --git a/weed/mount/weedfs_file_copy_range.go b/weed/mount/weedfs_file_copy_range.go
index bc092a252..e3f841b02 100644
--- a/weed/mount/weedfs_file_copy_range.go
+++ b/weed/mount/weedfs_file_copy_range.go
@@ -1,8 +1,8 @@
 package mount
 
 import (
-	"context"
 	"net/http"
+	"time"
 
 	"github.com/hanwen/go-fuse/v2/fuse"
 
@@ -44,8 +44,8 @@ func (wfs *WFS) CopyFileRange(cancel <-chan struct{}, in *fuse.CopyFileRangeIn)
 	}
 
 	// lock source and target file handles
-	fhOut.orderedMutex.Acquire(context.Background(), 1)
-	defer fhOut.orderedMutex.Release(1)
+	fhOut.Lock()
+	defer fhOut.Unlock()
 	fhOut.entryLock.Lock()
 	defer fhOut.entryLock.Unlock()
 
@@ -54,8 +54,8 @@ func (wfs *WFS) CopyFileRange(cancel <-chan struct{}, in *fuse.CopyFileRangeIn)
 	}
 
 	if fhIn.fh != fhOut.fh {
-		fhIn.orderedMutex.Acquire(context.Background(), 1)
-		defer fhIn.orderedMutex.Release(1)
+		fhIn.Lock()
+		defer fhIn.Unlock()
 		fhIn.entryLock.Lock()
 		defer fhIn.entryLock.Unlock()
 	}
@@ -88,7 +88,7 @@ func (wfs *WFS) CopyFileRange(cancel <-chan struct{}, in *fuse.CopyFileRangeIn)
 	// put data at the specified offset in target file
 	fhOut.dirtyPages.writerPattern.MonitorWriteAt(int64(in.OffOut), int(in.Len))
 	fhOut.entry.Content = nil
-	fhOut.dirtyPages.AddPage(int64(in.OffOut), data, fhOut.dirtyPages.writerPattern.IsSequentialMode())
+	fhOut.dirtyPages.AddPage(int64(in.OffOut), data, fhOut.dirtyPages.writerPattern.IsSequentialMode(), time.Now().UnixNano())
 	fhOut.entry.Attributes.FileSize = uint64(max(int64(in.OffOut)+totalRead, int64(fhOut.entry.Attributes.FileSize)))
 	fhOut.dirtyMetadata = true
 	written = uint32(totalRead)
diff --git a/weed/mount/weedfs_file_lseek.go b/weed/mount/weedfs_file_lseek.go
index 9d6402f96..93fc65247 100644
--- a/weed/mount/weedfs_file_lseek.go
+++ b/weed/mount/weedfs_file_lseek.go
@@ -1,7 +1,6 @@
 package mount
 
 import (
-	"context"
 	"syscall"
 
 	"github.com/hanwen/go-fuse/v2/fuse"
@@ -36,8 +35,8 @@ func (wfs *WFS) Lseek(cancel <-chan struct{}, in *fuse.LseekIn, out *fuse.LseekO
 	}
 
 	// lock the file until the proper offset was calculated
-	fh.orderedMutex.Acquire(context.Background(), 1)
-	defer fh.orderedMutex.Release(1)
+	fh.Lock()
+	defer fh.Unlock()
 	fh.entryLock.Lock()
 	defer fh.entryLock.Unlock()
 
@@ -56,17 +55,8 @@ func (wfs *WFS) Lseek(cancel <-chan struct{}, in *fuse.LseekIn, out *fuse.LseekO
 		return ENXIO
 	}
 
-	// refresh view cache if necessary
-	if fh.entryViewCache == nil {
-		var err error
-		fh.entryViewCache, err = filer.NonOverlappingVisibleIntervals(fh.wfs.LookupFn(), fh.entry.GetChunks(), 0, fileSize)
-		if err != nil {
-			return fuse.EIO
-		}
-	}
-
 	// search chunks for the offset
-	found, offset := searchChunks(fh, offset, fileSize, in.Whence)
+	found, offset := fh.entryChunkGroup.SearchChunks(offset, fileSize, in.Whence)
 	if found {
 		out.Offset = uint64(offset)
 		return fuse.OK
@@ -82,30 +72,3 @@ func (wfs *WFS) Lseek(cancel <-chan struct{}, in *fuse.LseekIn, out *fuse.LseekO
 
 	return fuse.OK
 }
-
-// searchChunks goes through all chunks to find the correct offset
-func searchChunks(fh *FileHandle, offset, fileSize int64, whence uint32) (found bool, out int64) {
-	chunkViews := filer.ViewFromVisibleIntervals(fh.entryViewCache, offset, fileSize)
-
-	for _, chunkView := range chunkViews {
-		if offset < chunkView.LogicOffset {
-			if whence == SEEK_HOLE {
-				out = offset
-			} else {
-				out = chunkView.LogicOffset
-			}
-
-			return true, out
-		}
-
-		if offset >= chunkView.LogicOffset && offset < chunkView.Offset+int64(chunkView.Size) && whence == SEEK_DATA {
-			out = offset
-
-			return true, out
-		}
-
-		offset += int64(chunkView.Size)
-	}
-
-	return
-}
diff --git a/weed/mount/weedfs_file_read.go b/weed/mount/weedfs_file_read.go
index 8375f9a5d..cedece137 100644
--- a/weed/mount/weedfs_file_read.go
+++ b/weed/mount/weedfs_file_read.go
@@ -1,7 +1,8 @@
 package mount
 
 import (
-	"context"
+	"bytes"
+	"fmt"
 	"io"
 
 	"github.com/hanwen/go-fuse/v2/fuse"
@@ -40,8 +41,8 @@ func (wfs *WFS) Read(cancel <-chan struct{}, in *fuse.ReadIn, buff []byte) (fuse
 		return nil, fuse.ENOENT
 	}
 
-	fh.orderedMutex.Acquire(context.Background(), 1)
-	defer fh.orderedMutex.Release(1)
+	fh.Lock()
+	defer fh.Unlock()
 
 	offset := int64(in.Offset)
 	totalRead, err := readDataByFileHandle(buff, fh, offset)
@@ -50,6 +51,23 @@ func (wfs *WFS) Read(cancel <-chan struct{}, in *fuse.ReadIn, buff []byte) (fuse
 		return nil, fuse.EIO
 	}
 
+	if IsDebugFileReadWrite {
+		// print(".")
+		mirrorData := make([]byte, totalRead)
+		fh.mirrorFile.ReadAt(mirrorData, offset)
+		if bytes.Compare(mirrorData, buff[:totalRead]) != 0 {
+
+			againBuff := make([]byte, len(buff))
+			againRead, _ := readDataByFileHandle(buff, fh, offset)
+			againCorrect := bytes.Compare(mirrorData, againBuff[:againRead]) == 0
+			againSame := bytes.Compare(buff[:totalRead], againBuff[:againRead]) == 0
+
+			fmt.Printf("\ncompare %v [%d,%d) size:%d againSame:%v againCorrect:%v\n", fh.mirrorFile.Name(), offset, offset+totalRead, totalRead, againSame, againCorrect)
+			//fmt.Printf("read mirrow data: %v\n", mirrorData)
+			//fmt.Printf("read actual data: %v\n", buff[:totalRead])
+		}
+	}
+
 	return fuse.ReadResultData(buff[:totalRead]), fuse.OK
 }
 
@@ -59,9 +77,9 @@ func readDataByFileHandle(buff []byte, fhIn *FileHandle, offset int64) (int64, e
 	fhIn.lockForRead(offset, size)
 	defer fhIn.unlockForRead(offset, size)
 
-	n, err := fhIn.readFromChunks(buff, offset)
+	n, tsNs, err := fhIn.readFromChunks(buff, offset)
 	if err == nil || err == io.EOF {
-		maxStop := fhIn.readFromDirtyPages(buff, offset)
+		maxStop := fhIn.readFromDirtyPages(buff, offset, tsNs)
 		n = max(maxStop-offset, n)
 	}
 	if err == io.EOF {
diff --git a/weed/mount/weedfs_file_sync.go b/weed/mount/weedfs_file_sync.go
index 7b7c66680..ac18e05ea 100644
--- a/weed/mount/weedfs_file_sync.go
+++ b/weed/mount/weedfs_file_sync.go
@@ -89,8 +89,8 @@ func (wfs *WFS) Fsync(cancel <-chan struct{}, in *fuse.FsyncIn) (code fuse.Statu
 }
 
 func (wfs *WFS) doFlush(fh *FileHandle, uid, gid uint32) fuse.Status {
-	fh.orderedMutex.Acquire(context.Background(), 1)
-	defer fh.orderedMutex.Release(1)
+	fh.Lock()
+	defer fh.Unlock()
 
 	// flush works at fh level
 	fileFullPath := fh.FullPath()
@@ -145,9 +145,9 @@ func (wfs *WFS) doFlush(fh *FileHandle, uid, gid uint32) fuse.Status {
 		}
 
 		glog.V(4).Infof("%s set chunks: %v", fileFullPath, len(entry.GetChunks()))
-		for i, chunk := range entry.GetChunks() {
-			glog.V(4).Infof("%s chunks %d: %v [%d,%d)", fileFullPath, i, chunk.GetFileIdString(), chunk.Offset, chunk.Offset+int64(chunk.Size))
-		}
+		//for i, chunk := range entry.GetChunks() {
+		//	glog.V(4).Infof("%s chunks %d: %v [%d,%d)", fileFullPath, i, chunk.GetFileIdString(), chunk.Offset, chunk.Offset+int64(chunk.Size))
+		//}
 
 		manifestChunks, nonManifestChunks := filer.SeparateManifestChunks(entry.GetChunks())
 
@@ -158,6 +158,7 @@ func (wfs *WFS) doFlush(fh *FileHandle, uid, gid uint32) fuse.Status {
 			glog.V(0).Infof("MaybeManifestize: %v", manifestErr)
 		}
 		entry.Chunks = append(chunks, manifestChunks...)
+		fh.entryChunkGroup.SetChunks(entry.Chunks)
 
 		wfs.mapPbIdFromLocalToFiler(request.Entry)
 		defer wfs.mapPbIdFromFilerToLocal(request.Entry)
@@ -181,5 +182,9 @@ func (wfs *WFS) doFlush(fh *FileHandle, uid, gid uint32) fuse.Status {
 		return fuse.EIO
 	}
 
+	if IsDebugFileReadWrite {
+		fh.mirrorFile.Sync()
+	}
+
 	return fuse.OK
 }
diff --git a/weed/mount/weedfs_file_write.go b/weed/mount/weedfs_file_write.go
index 7b13d54ff..5a9a21ded 100644
--- a/weed/mount/weedfs_file_write.go
+++ b/weed/mount/weedfs_file_write.go
@@ -1,10 +1,10 @@
 package mount
 
 import (
-	"context"
 	"github.com/hanwen/go-fuse/v2/fuse"
 	"net/http"
 	"syscall"
+	"time"
 )
 
 /**
@@ -46,8 +46,10 @@ func (wfs *WFS) Write(cancel <-chan struct{}, in *fuse.WriteIn, data []byte) (wr
 
 	fh.dirtyPages.writerPattern.MonitorWriteAt(int64(in.Offset), int(in.Size))
 
-	fh.orderedMutex.Acquire(context.Background(), 1)
-	defer fh.orderedMutex.Release(1)
+	tsNs := time.Now().UnixNano()
+
+	fh.Lock()
+	defer fh.Unlock()
 
 	entry := fh.GetEntry()
 	if entry == nil {
@@ -59,7 +61,7 @@ func (wfs *WFS) Write(cancel <-chan struct{}, in *fuse.WriteIn, data []byte) (wr
 	entry.Attributes.FileSize = uint64(max(offset+int64(len(data)), int64(entry.Attributes.FileSize)))
 	// glog.V(4).Infof("%v write [%d,%d) %d", fh.f.fullpath(), req.Offset, req.Offset+int64(len(req.Data)), len(req.Data))
 
-	fh.dirtyPages.AddPage(offset, data, fh.dirtyPages.writerPattern.IsSequentialMode())
+	fh.dirtyPages.AddPage(offset, data, fh.dirtyPages.writerPattern.IsSequentialMode(), tsNs)
 
 	written = uint32(len(data))
 
@@ -70,5 +72,10 @@ func (wfs *WFS) Write(cancel <-chan struct{}, in *fuse.WriteIn, data []byte) (wr
 
 	fh.dirtyMetadata = true
 
+	if IsDebugFileReadWrite {
+		// print("+")
+		fh.mirrorFile.WriteAt(data, offset)
+	}
+
 	return written, fuse.OK
 }
diff --git a/weed/mount/weedfs_write.go b/weed/mount/weedfs_write.go
index e18a4a358..4c8470245 100644
--- a/weed/mount/weedfs_write.go
+++ b/weed/mount/weedfs_write.go
@@ -13,7 +13,7 @@ import (
 
 func (wfs *WFS) saveDataAsChunk(fullPath util.FullPath) filer.SaveDataAsChunkFunctionType {
 
-	return func(reader io.Reader, filename string, offset int64) (chunk *filer_pb.FileChunk, err error) {
+	return func(reader io.Reader, filename string, offset int64, tsNs int64) (chunk *filer_pb.FileChunk, err error) {
 
 		fileId, uploadResult, err, data := operation.UploadWithRetry(
 			wfs,
@@ -56,7 +56,7 @@ func (wfs *WFS) saveDataAsChunk(fullPath util.FullPath) filer.SaveDataAsChunkFun
 			wfs.chunkCache.SetChunk(fileId, data)
 		}
 
-		chunk = uploadResult.ToPbFileChunk(fileId, offset)
+		chunk = uploadResult.ToPbFileChunk(fileId, offset, tsNs)
 		return chunk, nil
 	}
 }
diff --git a/weed/operation/upload_content.go b/weed/operation/upload_content.go
index ed38dfa6b..0c3e29a43 100644
--- a/weed/operation/upload_content.go
+++ b/weed/operation/upload_content.go
@@ -45,13 +45,13 @@ type UploadResult struct {
 	RetryCount int    `json:"-"`
 }
 
-func (uploadResult *UploadResult) ToPbFileChunk(fileId string, offset int64) *filer_pb.FileChunk {
+func (uploadResult *UploadResult) ToPbFileChunk(fileId string, offset int64, tsNs int64) *filer_pb.FileChunk {
 	fid, _ := filer_pb.ToFileIdObject(fileId)
 	return &filer_pb.FileChunk{
 		FileId:       fileId,
 		Offset:       offset,
 		Size:         uint64(uploadResult.Size),
-		ModifiedTsNs: time.Now().UnixNano(),
+		ModifiedTsNs: tsNs,
 		ETag:         uploadResult.ContentMd5,
 		CipherKey:    uploadResult.CipherKey,
 		IsCompressed: uploadResult.Gzip > 0,
diff --git a/weed/replication/repl_util/replication_util.go b/weed/replication/repl_util/replication_util.go
index ec0e80b2e..9682ca623 100644
--- a/weed/replication/repl_util/replication_util.go
+++ b/weed/replication/repl_util/replication_util.go
@@ -7,9 +7,10 @@ import (
 	"github.com/seaweedfs/seaweedfs/weed/util"
 )
 
-func CopyFromChunkViews(chunkViews []*filer.ChunkView, filerSource *source.FilerSource, writeFunc func(data []byte) error) error {
+func CopyFromChunkViews(chunkViews *filer.IntervalList[*filer.ChunkView], filerSource *source.FilerSource, writeFunc func(data []byte) error) error {
 
-	for _, chunk := range chunkViews {
+	for x := chunkViews.Front(); x != nil; x = x.Next {
+		chunk := x.Value
 
 		fileUrls, err := filerSource.LookupFileId(chunk.FileId)
 		if err != nil {
@@ -20,7 +21,7 @@ func CopyFromChunkViews(chunkViews []*filer.ChunkView, filerSource *source.Filer
 		var shouldRetry bool
 
 		for _, fileUrl := range fileUrls {
-			shouldRetry, err = util.ReadUrlAsStream(fileUrl, chunk.CipherKey, chunk.IsGzipped, chunk.IsFullChunk(), chunk.Offset, int(chunk.Size), func(data []byte) {
+			shouldRetry, err = util.ReadUrlAsStream(fileUrl, chunk.CipherKey, chunk.IsGzipped, chunk.IsFullChunk(), chunk.OffsetInChunk, int(chunk.ViewSize), func(data []byte) {
 				writeErr = writeFunc(data)
 			})
 			if err != nil {
diff --git a/weed/server/filer_server_handlers_write_autochunk.go b/weed/server/filer_server_handlers_write_autochunk.go
index c671deb76..8b3fc45fb 100644
--- a/weed/server/filer_server_handlers_write_autochunk.go
+++ b/weed/server/filer_server_handlers_write_autochunk.go
@@ -256,7 +256,7 @@ func (fs *FilerServer) saveMetaData(ctx context.Context, r *http.Request, fileNa
 
 func (fs *FilerServer) saveAsChunk(so *operation.StorageOption) filer.SaveDataAsChunkFunctionType {
 
-	return func(reader io.Reader, name string, offset int64) (*filer_pb.FileChunk, error) {
+	return func(reader io.Reader, name string, offset int64, tsNs int64) (*filer_pb.FileChunk, error) {
 		var fileId string
 		var uploadResult *operation.UploadResult
 
@@ -290,7 +290,7 @@ func (fs *FilerServer) saveAsChunk(so *operation.StorageOption) filer.SaveDataAs
 			return nil, err
 		}
 
-		return uploadResult.ToPbFileChunk(fileId, offset), nil
+		return uploadResult.ToPbFileChunk(fileId, offset, tsNs), nil
 	}
 }
 
diff --git a/weed/server/filer_server_handlers_write_cipher.go b/weed/server/filer_server_handlers_write_cipher.go
index bd8761077..bb5659437 100644
--- a/weed/server/filer_server_handlers_write_cipher.go
+++ b/weed/server/filer_server_handlers_write_cipher.go
@@ -59,7 +59,7 @@ func (fs *FilerServer) encrypt(ctx context.Context, w http.ResponseWriter, r *ht
 	}
 
 	// Save to chunk manifest structure
-	fileChunks := []*filer_pb.FileChunk{uploadResult.ToPbFileChunk(fileId, 0)}
+	fileChunks := []*filer_pb.FileChunk{uploadResult.ToPbFileChunk(fileId, 0, time.Now().UnixNano())}
 
 	// fmt.Printf("uploaded: %+v\n", uploadResult)
 
diff --git a/weed/server/filer_server_handlers_write_upload.go b/weed/server/filer_server_handlers_write_upload.go
index 95920583d..cc43eba64 100644
--- a/weed/server/filer_server_handlers_write_upload.go
+++ b/weed/server/filer_server_handlers_write_upload.go
@@ -214,5 +214,5 @@ func (fs *FilerServer) dataToChunk(fileName, contentType string, data []byte, ch
 	if uploadResult.Size == 0 {
 		return nil, nil
 	}
-	return []*filer_pb.FileChunk{uploadResult.ToPbFileChunk(fileId, chunkOffset)}, nil
+	return []*filer_pb.FileChunk{uploadResult.ToPbFileChunk(fileId, chunkOffset, time.Now().UnixNano())}, nil
 }
diff --git a/weed/server/webdav_server.go b/weed/server/webdav_server.go
index 80b882181..79416d519 100644
--- a/weed/server/webdav_server.go
+++ b/weed/server/webdav_server.go
@@ -102,14 +102,14 @@ func (fi *FileInfo) IsDir() bool        { return fi.isDirectory }
 func (fi *FileInfo) Sys() interface{}   { return nil }
 
 type WebDavFile struct {
-	fs             *WebDavFileSystem
-	name           string
-	isDirectory    bool
-	off            int64
-	entry          *filer_pb.Entry
-	entryViewCache []filer.VisibleInterval
-	reader         io.ReaderAt
-	bufWriter      *buffered_writer.BufferedWriteCloser
+	fs               *WebDavFileSystem
+	name             string
+	isDirectory      bool
+	off              int64
+	entry            *filer_pb.Entry
+	visibleIntervals *filer.IntervalList[*filer.VisibleInterval]
+	reader           io.ReaderAt
+	bufWriter        *buffered_writer.BufferedWriteCloser
 }
 
 func NewWebDavFileSystem(option *WebDavOption) (webdav.FileSystem, error) {
@@ -381,7 +381,7 @@ func (fs *WebDavFileSystem) Stat(ctx context.Context, name string) (os.FileInfo,
 	return fs.stat(ctx, name)
 }
 
-func (f *WebDavFile) saveDataAsChunk(reader io.Reader, name string, offset int64) (chunk *filer_pb.FileChunk, err error) {
+func (f *WebDavFile) saveDataAsChunk(reader io.Reader, name string, offset int64, tsNs int64) (chunk *filer_pb.FileChunk, err error) {
 
 	fileId, uploadResult, flushErr, _ := operation.UploadWithRetry(
 		f.fs,
@@ -413,7 +413,7 @@ func (f *WebDavFile) saveDataAsChunk(reader io.Reader, name string, offset int64
 		glog.V(0).Infof("upload failure %v: %v", f.name, flushErr)
 		return nil, fmt.Errorf("upload result: %v", uploadResult.Error)
 	}
-	return uploadResult.ToPbFileChunk(fileId, offset), nil
+	return uploadResult.ToPbFileChunk(fileId, offset, tsNs), nil
 }
 
 func (f *WebDavFile) Write(buf []byte) (int, error) {
@@ -439,7 +439,7 @@ func (f *WebDavFile) Write(buf []byte) (int, error) {
 		f.bufWriter.FlushFunc = func(data []byte, offset int64) (flushErr error) {
 
 			var chunk *filer_pb.FileChunk
-			chunk, flushErr = f.saveDataAsChunk(util.NewBytesReader(data), f.name, offset)
+			chunk, flushErr = f.saveDataAsChunk(util.NewBytesReader(data), f.name, offset, time.Now().UnixNano())
 
 			if flushErr != nil {
 				return fmt.Errorf("%s upload result: %v", f.name, flushErr)
@@ -498,7 +498,7 @@ func (f *WebDavFile) Close() error {
 
 	if f.entry != nil {
 		f.entry = nil
-		f.entryViewCache = nil
+		f.visibleIntervals = nil
 	}
 
 	return err
@@ -521,12 +521,12 @@ func (f *WebDavFile) Read(p []byte) (readSize int, err error) {
 	if fileSize == 0 {
 		return 0, io.EOF
 	}
-	if f.entryViewCache == nil {
-		f.entryViewCache, _ = filer.NonOverlappingVisibleIntervals(filer.LookupFn(f.fs), f.entry.GetChunks(), 0, fileSize)
+	if f.visibleIntervals == nil {
+		f.visibleIntervals, _ = filer.NonOverlappingVisibleIntervals(filer.LookupFn(f.fs), f.entry.GetChunks(), 0, fileSize)
 		f.reader = nil
 	}
 	if f.reader == nil {
-		chunkViews := filer.ViewFromVisibleIntervals(f.entryViewCache, 0, fileSize)
+		chunkViews := filer.ViewFromVisibleIntervals(f.visibleIntervals, 0, fileSize)
 		f.reader = filer.NewChunkReaderAtFromClient(filer.LookupFn(f.fs), chunkViews, f.fs.chunkCache, fileSize)
 	}
 
diff --git a/weed/shell/command_fs_verify.go b/weed/shell/command_fs_verify.go
index 11cc64d78..07f3fd9c1 100644
--- a/weed/shell/command_fs_verify.go
+++ b/weed/shell/command_fs_verify.go
@@ -117,7 +117,7 @@ type ItemEntry struct {
 
 func (c *commandFsVerify) verifyTraverseBfs(path string) (fileCount int64, errCount int64, err error) {
 	timeNowAtSec := time.Now().Unix()
-	return fileCount, errCount, doTraverseBfsAndSaving(c.env, nil, path, false,
+	return fileCount, errCount, doTraverseBfsAndSaving(c.env, c.writer, path, false,
 		func(entry *filer_pb.FullEntry, outputChan chan interface{}) (err error) {
 			if c.modifyTimeAgoAtSec > 0 {
 				if entry.Entry.Attributes != nil && c.modifyTimeAgoAtSec < timeNowAtSec-entry.Entry.Attributes.Mtime {
diff --git a/weed/shell/command_volume_fsck.go b/weed/shell/command_volume_fsck.go
index 559b11cd3..be9bd2db2 100644
--- a/weed/shell/command_volume_fsck.go
+++ b/weed/shell/command_volume_fsck.go
@@ -211,7 +211,7 @@ func (c *commandVolumeFsck) collectFilerFileIdAndPaths(dataNodeVolumeIdToVInfo m
 		}
 	}()
 
-	return doTraverseBfsAndSaving(c.env, nil, c.getCollectFilerFilePath(), false,
+	return doTraverseBfsAndSaving(c.env, c.writer, c.getCollectFilerFilePath(), false,
 		func(entry *filer_pb.FullEntry, outputChan chan interface{}) (err error) {
 			if *c.verbose && entry.Entry.IsDirectory {
 				fmt.Fprintf(c.writer, "checking directory %s\n", util.NewFullPath(entry.Dir, entry.Entry.Name))
author	Chris Lu <chrislusf@users.noreply.github.com>	2023-01-02 23:20:45 -0800
committer	GitHub <noreply@github.com>	2023-01-02 23:20:45 -0800
commit	d4566d4aaa426b33015780c7cc18f887fc07cca4 (patch)
tree	7c3b5cb3d9e54297b9d4213b67408f86149013f7
parent	367353b936c450906e88e850c7d1e804f97c3560 (diff)
download	seaweedfs-d4566d4aaa426b33015780c7cc18f887fc07cca4.tar.xz seaweedfs-d4566d4aaa426b33015780c7cc18f887fc07cca4.zip