wp

2026-06-14 23:12:03 +03:00
parent 181031a753
commit b32279deaf
35 changed files with 1395 additions and 1062 deletions
--- a/client/client.go
+++ b/client/client.go
@@ -149,26 +149,32 @@ func (s *Connection) DeleteMetric(metricID uint32) (err error) {
 	return s.mustSuccess(s.src)
 }

-func (s *Connection) AppendMeasure(req proto.AppendMeasureReq) (err error) {
-	arr := []byte{
-		proto.TypeAppendMeasure,
-		0, 0, 0, 0, // metricID
-		0, 0, 0, 0, // timestamp
-		0, 0, 0, 0, 0, 0, 0, 0, // value
-	}
-	bin.PutUint32(arr[1:], req.MetricID)
-	bin.PutUint32(arr[5:], req.Timestamp)
-	bin.PutFloat64(arr[9:], req.Value)
-	// req
-	if _, err = s.conn.Write(arr); err != nil {
-		return
-	}
-	return s.mustSuccess(s.src)
+// func (s *Connection) AppendMeasure(req proto.AppendMeasureReq) (err error) {
+// 	arr := []byte{
+// 		proto.TypeAppendMeasure,
+// 		0, 0, 0, 0, // metricID
+// 		0, 0, 0, 0, // timestamp
+// 		0, 0, 0, 0, 0, 0, 0, 0, // value
+// 	}
+// 	bin.PutUint32(arr[1:], req.MetricID)
+// 	bin.PutUint32(arr[5:], req.Timestamp)
+// 	bin.PutFloat64(arr[9:], req.Value)
+// 	// req
+// 	if _, err = s.conn.Write(arr); err != nil {
+// 		return
+// 	}
+// 	return s.mustSuccess(s.src)
+// }
+
+type AppendMeasuresResult struct {
+	WrittenCount int
+	ErrorCode    byte
 }

-func (s *Connection) AppendMeasures(req proto.AppendMeasuresReq) (err error) {
+func (s *Connection) AppendMeasures(req proto.AppendMeasuresReq) (result AppendMeasuresResult, err error) {
 	if len(req.Measures) > 65535 {
-		return fmt.Errorf("wrong measures qty: %d", len(req.Measures))
+		err = fmt.Errorf("wrong measures qty: %d", len(req.Measures))
+		return
 	}
 	var (
 		prefixSize = 7
@@ -188,37 +194,6 @@ func (s *Connection) AppendMeasures(req proto.AppendMeasuresReq) (err error) {
 	if _, err = s.conn.Write(arr); err != nil {
 		return
 	}
-	return s.mustSuccess(s.src)
-}
-
-// type AppendMeasurePerMetricReq struct {
-// 	MetricID uint32
-// 	Measures []Measure
-// }
-
-func (s *Connection) AppendMeasurePerMetric(list []proto.MetricMeasure) (_ []proto.AppendError, err error) {
-	if len(list) > 65535 {
-		return nil, fmt.Errorf("wrong measures qty: %d", len(list))
-	}
-	var (
-		// 3 bytes: 1b message type + 2b records qty
-		fixedSize  = 3
-		recordSize = 16
-		arr        = make([]byte, fixedSize+len(list)*recordSize)
-	)
-	arr[0] = proto.TypeAppendMeasures
-	bin.PutUint16(arr[1:], uint16(len(list)))
-	pos := fixedSize
-	for _, item := range list {
-		bin.PutUint32(arr[pos:], item.MetricID)
-		bin.PutUint32(arr[pos+4:], item.Timestamp)
-		bin.PutFloat64(arr[pos+8:], item.Value)
-		pos += recordSize
-	}
-	// req
-	if _, err = s.conn.Write(arr); err != nil {
-		return
-	}
 	// answer
 	code, err := s.src.ReadByte()
 	if err != nil {
@@ -226,32 +201,82 @@ func (s *Connection) AppendMeasurePerMetric(list []proto.MetricMeasure) (_ []pro
 	}
 	switch code {
 	case proto.RespValue:
-		var (
-			count        int
-			appendErrors []proto.AppendError
-		)
-		count, err = bin.ReadUint16AsInt(s.src)
+		result.WrittenCount, err = bin.ReadUint16AsInt(s.src)
 		if err != nil {
 			return
 		}
-		for range count {
-			var ae proto.AppendError
-			ae.MetricID, err = bin.ReadUint32(s.src)
+		result.ErrorCode, err = bin.ReadByte(s.src)
 		if err != nil {
 			return
 		}
-			ae.ErrorCode, err = bin.ReadUint16(s.src)
-			if err != nil {
-				return
-			}
-			appendErrors = append(appendErrors, ae)
-		}
-		return appendErrors, nil
 	default:
-		return nil, fmt.Errorf("unknown reponse code %d", code)
+		err = fmt.Errorf("unknown reponse code %d", code)
+		return
 	}
+	return
 }

+// type AppendMeasurePerMetricReq struct {
+// 	MetricID uint32
+// 	Measures []Measure
+// }
+
+// func (s *Connection) AppendMeasurePerMetric(list []proto.MetricMeasure) (_ []proto.AppendError, err error) {
+// 	if len(list) > 65535 {
+// 		return nil, fmt.Errorf("wrong measures qty: %d", len(list))
+// 	}
+// 	var (
+// 		// 3 bytes: 1b message type + 2b records qty
+// 		fixedSize  = 3
+// 		recordSize = 16
+// 		arr        = make([]byte, fixedSize+len(list)*recordSize)
+// 	)
+// 	arr[0] = proto.TypeAppendMeasures
+// 	bin.PutUint16(arr[1:], uint16(len(list)))
+// 	pos := fixedSize
+// 	for _, item := range list {
+// 		bin.PutUint32(arr[pos:], item.MetricID)
+// 		bin.PutUint32(arr[pos+4:], item.Timestamp)
+// 		bin.PutFloat64(arr[pos+8:], item.Value)
+// 		pos += recordSize
+// 	}
+// 	// req
+// 	if _, err = s.conn.Write(arr); err != nil {
+// 		return
+// 	}
+// 	// answer
+// 	code, err := s.src.ReadByte()
+// 	if err != nil {
+// 		return
+// 	}
+// 	switch code {
+// 	case proto.RespValue:
+// 		var (
+// 			count        int
+// 			appendErrors []proto.AppendError
+// 		)
+// 		count, err = bin.ReadUint16AsInt(s.src)
+// 		if err != nil {
+// 			return
+// 		}
+// 		for range count {
+// 			var ae proto.AppendError
+// 			ae.MetricID, err = bin.ReadUint32(s.src)
+// 			if err != nil {
+// 				return
+// 			}
+// 			ae.ErrorCode, err = bin.ReadUint16(s.src)
+// 			if err != nil {
+// 				return
+// 			}
+// 			appendErrors = append(appendErrors, ae)
+// 		}
+// 		return appendErrors, nil
+// 	default:
+// 		return nil, fmt.Errorf("unknown reponse code %d", code)
+// 	}
+// }
+
 func (s *Connection) ListAllInstantMeasures(metricID uint32) (_ []proto.InstantMeasure, err error) {
 	arr := []byte{
 		proto.TypeListAllInstantMeasures,
@@ -361,8 +386,10 @@ func (s *Connection) readCumulativeMeasures() (_ []proto.CumulativeMeasure, err
 		if err != nil {
 			return nil, fmt.Errorf("read response code: %s", err)
 		}
+		fmt.Println("code", code)
 		switch code {
 		case proto.RespPartOfValue:
+			fmt.Println("RespPartOfValue")
 			var count int
 			count, err = bin.ReadUint32AsInt(s.src)
 			if err != nil {
@@ -385,8 +412,10 @@ func (s *Connection) readCumulativeMeasures() (_ []proto.CumulativeMeasure, err
 				result = append(result, measure)
 			}
 		case proto.RespEndOfValue:
+			fmt.Println("RespEndOfValue")
 			return result, nil
 		case proto.RespError:
+			fmt.Println("RespError")
 			return nil, s.onError()
 		default:
 			return nil, fmt.Errorf("unknown reponse code %d", code)
--- a/database/api.go
+++ b/database/api.go
@@ -11,6 +11,7 @@ import (
 	"gordenko.dev/dima/qb/atree"
 	"gordenko.dev/dima/qb/bufreader"
 	"gordenko.dev/dima/qb/proto"
+	"gordenko.dev/dima/qb/storage"
 	"gordenko.dev/dima/qb/transform"
 	"gordenko.dev/dima/qb/worker"
 )
@@ -60,7 +61,7 @@ func (s *Database) handleTCPConn(conn net.Conn) {
 }

 func (s *Database) processRequest(conn net.Conn, r *bufreader.BufferedReader) (err error) {
-	fmt.Println("process request")
+	//fmt.Println("process request")
 	messageType, err := r.ReadByte()
 	if err != nil {
 		if err != io.EOF {
@@ -70,7 +71,7 @@ func (s *Database) processRequest(conn net.Conn, r *bufreader.BufferedReader) (e
 		}
 	}

-	fmt.Println("messageType:", messageType)
+	//fmt.Println("messageType:", messageType)

 	switch messageType {
 	case proto.TypeGetMetric:
@@ -111,7 +112,9 @@ func (s *Database) processRequest(conn net.Conn, r *bufreader.BufferedReader) (e
 			return fmt.Errorf("proto.ReadAppendMeasuresReq: %s", err)
 		}
 		//fmt.Println("append measure", req.MetricID, conn.RemoteAddr().String())
-		reply(conn, s.AppendMeasures(req))
+		if err = s.AppendMeasures(conn, req); err != nil {
+			return fmt.Errorf("AppendMeasures: %s", err)
+		}

 	case proto.TypeListInstantMeasures:
 		req, err := proto.ReadListInstantMeasuresReq(r)
@@ -195,7 +198,7 @@ func (s *Database) processRequest(conn net.Conn, r *bufreader.BufferedReader) (e
 // API

 func (s *Database) AddMetric(req proto.AddMetricReq) uint16 {
-	fmt.Println("database.AddMetric")
+	//fmt.Println("database.AddMetric")
 	// Валидация
 	if req.MetricID == 0 {
 		return proto.ErrEmptyMetricID
@@ -216,6 +219,8 @@ func (s *Database) AddMetric(req proto.AddMetricReq) uint16 {

 	s.workerInbox.Push(worker.AddMetricReq{
 		MetricID:   req.MetricID,
+		MetricType: req.MetricType,
+		FracDigits: req.FracDigits,
 		ResultCh:   resultCh,
 	})

@@ -226,19 +231,13 @@ func (s *Database) AddMetric(req proto.AddMetricReq) uint16 {
 	switch resultCode {
 	case worker.Succeed:
 		fmt.Println("OK")
-		// s.storage.Append(storage.MetricAddRecord{
-		// 	MetricID:   req.MetricID,
-		// 	MetricType: req.MetricType,
-		// 	FracDigits: req.FracDigits,
-		// })
-		//<-waitCh

 	case worker.MetricDuplicate:
-		fmt.Println("ErrDuplicate")
+		//fmt.Println("ErrDuplicate")
 		return proto.ErrDuplicate

 	default:
-		fmt.Println("ErrWrongResultCodeBug")
+		//fmt.Println("ErrWrongResultCodeBug")
 		qb.Abort(qb.WrongResultCodeBug, ErrWrongResultCodeBug)
 	}
 	return 0
@@ -325,8 +324,8 @@ type FilledPage struct {
 	ValuesSize       uint16
 }

-func (s *Database) AppendMeasures(req proto.AppendMeasuresReq) uint16 {
-	resultCh := make(chan worker.AppendMeasuresResult, 1)
+func (s *Database) AppendMeasures(conn io.Writer, req proto.AppendMeasuresReq) error {
+	resultCh := make(chan storage.MeasuresAppendResult, 1)

 	s.workerInbox.Push(worker.AppendMeasuresReq{
 		MetricID: req.MetricID,
@@ -337,32 +336,30 @@ func (s *Database) AppendMeasures(req proto.AppendMeasuresReq) uint16 {
 	result := <-resultCh

 	switch result.ResultCode {
-	case worker.CanAppend:
-
-		// report, err := s.atree.AppendDataPage(atree.AppendDataPageReq{})
-		// if err != nil {
-		// 	qb.Abort(qb.WriteToAtreeFailed, err)
-		// }
-		// _ = report
-
-		// if len(toAppendMeasures) > 0 {
-		// 	waitCh := s.storage.WriteAppendMeasures(
-		// 		storage.AppendedMeasures{
-		// 			MetricID: req.MetricID,
-		// 			Measures: toAppendMeasures,
-		// 		},
-		// 		false,
-		// 	)
-		// 	<-waitCh
-		// }
-
+	case worker.Succeed, worker.NonMonotonicValue, worker.ExpiredMeasure:
+		var errorCode byte
+		switch result.ResultCode {
+		case worker.NonMonotonicValue:
+			errorCode = proto.ErrNonMonotonicValue
+		case worker.ExpiredMeasure:
+			errorCode = proto.ErrExpiredMeasure
+		}
+		answer := []byte{
+			proto.RespValue,
+			0, 0, // written count
+			errorCode,
+		}
+		bin.PutIntAsUint16(answer[1:], result.WrittenCount)
+		_, err := conn.Write(answer)
+		if err != nil {
+			return err
+		}
 	case worker.NoMetric:
-		return proto.ErrNoMetric
-
+		reply(conn, proto.ErrNoMetric)
 	default:
 		qb.Abort(qb.WrongResultCodeBug, ErrWrongResultCodeBug)
 	}
-	return 0
+	return nil
 }

 func (s *Database) DeleteMeasures(req proto.DeleteMeasuresReq) uint16 {
@@ -380,14 +377,14 @@ func (s *Database) DeleteMeasures(req proto.DeleteMeasuresReq) uint16 {
 	case worker.NoMeasuresToDelete:
 		// ok

-	case worker.DeleteFromAtreeNotNeeded:
+	//case worker.DeleteFromAtreeNotNeeded:
 	// регистрирую удаление в TransactionLog
 	// s.storage.Append(storage.MeasuresDeleteRecord{
 	// 	MetricID: req.MetricID,
 	// })
 	//<-waitCh

-	case worker.DeleteFromAtreeRequired:
+	//case worker.DeleteFromAtreeRequired:
 	// собираю номера всех data и index страниц метрики (типа запись REDO лога).
 	// pageNumbers, err := s.atree.GetAllPages(req.MetricID)
 	// if err != nil {
@@ -615,6 +612,7 @@ func (s *Database) fullScan(req fullScanReq) error {

 	switch result.ResultCode {
 	case worker.QueryDone:
+		fmt.Printf("query done")
 		req.ResponseWriter.Close()

 	case worker.UntilFound:
--- a/database/database.go
+++ b/database/database.go
@@ -9,7 +9,6 @@ import (
 	"sync"
 	"time"

-	"gordenko.dev/dima/qb"
 	"gordenko.dev/dima/qb/inbox"
 	"gordenko.dev/dima/qb/recovery"
 	"gordenko.dev/dima/qb/storage"
@@ -69,9 +68,6 @@ func New(opt Options) (_ *Database, err error) {
 	s := &Database{
 		dir:          opt.Dir,
 		databaseName: opt.DatabaseName,
-		//metricLockEntries: make(map[uint32]*metricLockEntry),
-		//dataFreeList:  dataFreeList,
-		//indexFreeList: indexFreeList,
 		tcpPort:      opt.TCPPort,
 		logfile:      opt.Logfile,
 		logger:       log.New(opt.Logfile, "", log.LstdFlags),
@@ -81,9 +77,11 @@ func New(opt Options) (_ *Database, err error) {

 	recoveryReport, err := recovery.Recovery(s.dir, s.databaseName)
 	if err != nil {
-		return
+		return nil, fmt.Errorf("recovery.Recovery: %s", err)
 	}

+	fmt.Printf("%#v\n", recoveryReport)
+
 	storageInbox := inbox.New()
 	s.workerInbox = inbox.New()

@@ -99,18 +97,21 @@ func New(opt Options) (_ *Database, err error) {
 		WaitGroup:     s.waitGroup,
 	})
 	if err != nil {
-		qb.Abort(qb.CreateChangesWriterFailed, err)
-
+		return nil, fmt.Errorf("storage.NewWriter: %s", err)
 	}

+	fmt.Println("storage created")
+
 	s.worker = worker.New(worker.Options{
 		Inbox:         s.workerInbox,
 		StorageInbox:  storageInbox,
-		//Metrics: make(map[uint32]*_metric), FIX
+		ReplayMetrics: recoveryReport.ReplayMetrics,
 		Dir:           opt.Dir,
+		DatabaseName:  opt.DatabaseName,
 		ExitCh:        opt.ExitCh,
 		WaitGroup:     opt.WaitGroup,
 	})
+	fmt.Println("worker created")
 	return s, nil
 }

@@ -120,6 +121,7 @@ func (s *Database) ListenAndServe() (err error) {
 		return fmt.Errorf("net.Listen: %s; port=%d", err, s.tcpPort)
 	}

+	//s.waitGroup.Add(1)
 	go s.storage.Run()

 	// s.atree, err = atree.New(atree.Options{
--- a/BIN
+++ b/BIN
--- a/enc/enc_test.go
+++ b/enc/enc_test.go
@@ -31,9 +31,25 @@ var (
 	}{
 		{
 			Nums: []float64{
+				0,
+			},
+			Name:       "add 1st value zero",
+			Offset:     0,
+			ChangeSize: 3,
+			Buf: []byte{
+				0x8f, // base value
+				0x80, // delta 0
+				0x80, // literal (len = 1)
+				0x00, 0x00, 0x00, 0x00, 0x00,
+			},
+			BaseValue: 0,
+			LastDelta: 0,
+		},
+		{
+			Nums: []float64{
 				1.5,
 			},
-			Name:       "add 1st value",
+			Name:       "add 1st value non zero",
 			Offset:     0,
 			ChangeSize: 3,
 			Buf: []byte{
--- a/enc/time_delta.go
+++ b/enc/time_delta.go
@@ -1,6 +1,7 @@
 package enc

 import (
+	"fmt"
 	"io"
 	"log"

@@ -159,7 +160,7 @@ func (s *TimeDeltaCompressor) Evaluate(tmp []byte, timestamp uint32) qb.TimeEval
 	}
 	return qb.TimeEvaluationReport{
 		RewindOffset: rewindOffset,
-		Offset:       s.pos + rewindOffset,
+		Offset:       len(s.buf) - s.pos - rewindOffset,
 		ChangeSize:   i,
 		TotalSpace:   s.pos - rewindOffset + i,
 	}
@@ -185,13 +186,21 @@ func (s *TimeDeltaCompressor) Append(rewindOffset int, change []byte, timestamp
 // }

 func (s *TimeDeltaCompressor) getState() qb.TimeDeltaCapturedState {
-	bound := s.pos + 1 + bin.CountVarUint64(uint64(s.lastDelta))
-	return qb.TimeDeltaCapturedState{
-		H:            s.buf[s.pos],
+	state := qb.TimeDeltaCapturedState{
 		LastUnixtime: s.lastUnixtime,
 		LastDelta:    s.lastDelta,
-		Payload:      s.buf[bound:],
 	}
+	if s.pos < len(s.buf) {
+		var bound int
+		if s.lastDelta > 0 {
+			state.H = s.buf[s.pos]
+			bound = s.pos + 1 + bin.CountVarUint64(uint64(s.lastDelta))
+		} else {
+			bound = s.pos // only since encoded
+		}
+		state.Payload = s.buf[bound:]
+	}
+	return state
 }

 func (s *TimeDeltaCompressor) CaptureState() {
@@ -204,6 +213,7 @@ func (s *TimeDeltaCompressor) ForgetCapturedState() {
 }

 func (s *TimeDeltaCompressor) Tail(offset int) []byte {
+	fmt.Println("time tail:", s.pos, len(s.buf), offset)
 	return s.buf[s.pos : len(s.buf)-offset]
 }

@@ -220,11 +230,19 @@ func (s *TimeDeltaCompressor) Size() int {
 	return len(s.buf) - s.pos
 }

-func (s *TimeDeltaCompressor) StoredSize() int {
+func (s *TimeDeltaCompressor) CommitedSize() int {
 	if s.state == nil {
 		return len(s.buf) - s.pos
 	} else {
+		if len(s.state.Payload) > 0 {
+			if s.state.LastDelta > 0 {
 				return bin.CountVarUint64(uint64(s.state.LastDelta)) + 1 + len(s.state.Payload)
+			} else {
+				return 4 // since
+			}
+		} else {
+			return 0
+		}
 	}
 }

@@ -240,9 +258,9 @@ func (s *TimeDeltaCompressor) StoredSize() int {
 // 	}
 // }

-func (s *TimeDeltaCompressor) WriteStoredTo(w io.Writer) (err error) {
+func (s *TimeDeltaCompressor) WriteCommitedTo(w io.Writer) (err error) {
 	if s.state == nil {
-		_, err = w.Write(s.buf[:s.pos])
+		_, err = w.Write(s.buf[s.pos:])
 		return
 	} else {
 		_, err = w.Write(s.state.Payload)
@@ -308,6 +326,7 @@ func NewTimeDeltaDecompressor() *TimeDeltaDecompressor {
 // викликається для повних сторінок
 func (s *TimeDeltaDecompressor) RestoreFromEnd(buf []byte) {
 	s.buf = buf
+	if len(s.buf) > 0 {
 		var err error
 		s.lastUnixtime, err = bin.GetUint32(buf[len(buf)-4:])
 		if err != nil {
@@ -317,6 +336,9 @@ func (s *TimeDeltaDecompressor) RestoreFromEnd(buf []byte) {
 			s.readHeader()
 			s.readDelta()
 		}
+	} else {
+		s.done = true
+	}
 	// fmt.Printf("h: % x\n", s.buf[s.pos])
 	// fmt.Printf("lastUnixtime: %d\n", s.lastUnixtime)
 	// fmt.Printf("lastDelta: %d\n", s.lastDelta)
@@ -326,11 +348,15 @@ func (s *TimeDeltaDecompressor) RestoreFromEnd(buf []byte) {
 // викликається для data level tail
 func (s *TimeDeltaDecompressor) RestoreFromState(state qb.TimeDeltaCapturedState) {
 	s.buf = state.Payload
+	if len(s.buf) > 0 {
 		s.lastUnixtime = state.LastUnixtime
 		if state.LastDelta > 0 {
 			s.lastDelta = state.LastDelta
 			s.decodeHeaderByte(state.H)
 		}
+	} else {
+		s.done = true
+	}
 }

 func (s *TimeDeltaDecompressor) NextValue() (value uint32, done bool) {
--- a/enc/value_delta.go
+++ b/enc/value_delta.go
@@ -1,6 +1,7 @@
 package enc

 import (
+	"fmt"
 	"io"
 	"log"
 	"math"
@@ -48,9 +49,6 @@ func NewValueDeltaCompressor(metricType qb.MetricType, fracDigits byte, buf []by
 		s.toFloat64 = toInstantFloat64
 	}
 	if payloadSize > 0 {
-		// fmt.Printf("% x\n", buf)
-		// fmt.Printf("% x\n", buf[:s.pos])
-		// fmt.Printf("pos: %d\n", s.pos)
 		u64, _, err := bin.GetVarUint64(s.buf)
 		if err != nil {
 			log.Fatalf("bug: get base value: %s", err)
@@ -145,13 +143,21 @@ func (s *ValueDeltaCompressor) Evaluate(tmp []byte, value float64) qb.ValueEvalu

 // pos завжди вказує на h
 func (s *ValueDeltaCompressor) Append(rewindOffset int, change []byte, value float64, delta uint64) {
+	// fmt.Printf("append value:\n")
+	// fmt.Printf("rewind offset: %d\n", rewindOffset)
+	// fmt.Printf("change: % x\n", change)
+	// fmt.Printf("value: %v\n", value)
+	// fmt.Printf("delta: %d\n", delta)
 	if s.pos > 0 {
 		s.lastDelta = delta
 	} else {
 		s.baseValue = value
 	}
+	//fmt.Printf("buf before: % x\n", s.buf[:s.pos])
 	copy(s.buf[s.pos-rewindOffset:], change)
 	s.pos += len(change) - rewindOffset
+	//fmt.Printf("buf after: % x\n", s.buf[:s.pos])
+	//fmt.Printf("buf after: % x\n", s.buf[:s.pos])
 }

 func (s *ValueDeltaCompressor) DeleteLast() {
@@ -159,12 +165,21 @@ func (s *ValueDeltaCompressor) DeleteLast() {
 }

 func (s *ValueDeltaCompressor) getState() qb.ValueDeltaCapturedState {
+	if s.pos > 0 {
+		// fmt.Println("getState")
+		// fmt.Printf("pos: %d\n", s.pos)
+		// fmt.Printf("buf: % x\n", s.buf[:s.pos])
+		// fmt.Printf("h: %d\n", s.buf[s.pos-1])
+		// fmt.Printf("lastDelta: %d\n", s.lastDelta)
 		bound := s.pos - 1 - bin.CountVarUint64(s.lastDelta)
 		return qb.ValueDeltaCapturedState{
 			H:         s.buf[s.pos-1],
 			LastDelta: s.lastDelta,
 			Payload:   s.buf[:bound],
 		}
+	} else {
+		return qb.ValueDeltaCapturedState{}
+	}
 }

 func (s *ValueDeltaCompressor) CaptureState() {
@@ -185,11 +200,15 @@ func (s *ValueDeltaCompressor) Size() int {
 	return s.pos
 }

-func (s *ValueDeltaCompressor) StoredSize() int {
+func (s *ValueDeltaCompressor) CommitedSize() int {
 	if s.state == nil {
-		return len(s.buf) - s.pos
+		return s.pos
 	} else {
+		if len(s.state.Payload) > 0 {
 			return bin.CountVarUint64(uint64(s.state.LastDelta)) + 1 + len(s.state.Payload)
+		} else {
+			return 0
+		}
 	}
 }

@@ -202,7 +221,7 @@ func (s *ValueDeltaCompressor) StoredSize() int {
 // 	}
 // }

-func (s *ValueDeltaCompressor) WriteStoredTo(w io.Writer) (err error) {
+func (s *ValueDeltaCompressor) WriteCommitedTo(w io.Writer) (err error) {
 	if s.state == nil {
 		_, err = w.Write(s.buf[:s.pos])
 		return
@@ -289,17 +308,26 @@ func NewValueDeltaDecompressor(metricType qb.MetricType, fracDigits byte) *Value
 func (s *ValueDeltaDecompressor) RestoreFromEnd(buf []byte) {
 	s.buf = buf
 	s.pos = len(buf) // first free
+	if len(buf) > 0 {
 		s.readBaseValue()
 		s.readHeader()
 		s.readValue()
+	} else {
+		s.done = true
+	}
 }

 func (s *ValueDeltaDecompressor) RestoreFromState(state qb.ValueDeltaCapturedState) {
+	fmt.Printf("%#v\n", state)
 	s.buf = state.Payload
 	s.pos = len(s.buf) // first free
+	if len(s.buf) > 0 {
 		s.readBaseValue()
 		s.lastValue = s.baseValue + s.toFloat64(state.LastDelta, s.coef)
 		s.decodeHeaderByte(state.H)
+	} else {
+		s.done = true
+	}
 }

 func (s *ValueDeltaDecompressor) readBaseValue() {
--- a/examples/play/main.go
+++ b/examples/play/main.go
@@ -101,21 +101,24 @@ func sendRequests(conn *client.Connection) {
 		err                error
 	)

+	_ = cumulativeMetricID
+	_ = fracDigits
+
 	//conn.DeleteMetric(instantMetricID)
 	//conn.DeleteMetric(cumulativeMetricID)

 	// ADD INSTANT METRIC

-	err = conn.AddMetric(proto.AddMetricReq{
-		MetricID:   cumulativeMetricID,
-		MetricType: qb.Instant,
-		FracDigits: fracDigits,
-	})
-	if err != nil {
-		log.Fatalf("conn.AddMetric: %s\n", err)
-	} else {
-		fmt.Printf("\nInstant metric %d added\n", cumulativeMetricID)
-	}
+	// err = conn.AddMetric(proto.AddMetricReq{
+	// 	MetricID:   cumulativeMetricID,
+	// 	MetricType: qb.Instant,
+	// 	FracDigits: fracDigits,
+	// })
+	// if err != nil {
+	// 	log.Fatalf("conn.AddMetric: %s\n", err)
+	// } else {
+	// 	fmt.Printf("\nInstant metric %d added\n", cumulativeMetricID)
+	// }

 	// GET INSTANT METRIC

@@ -130,7 +133,7 @@ func sendRequests(conn *client.Connection) {
 	//   fracDigits: %d
 	// `,
 	// 		iMetric.MetricID, metricTypeToName[iMetric.MetricType], fracDigits)
-	//}
+	// }

 	// APPEND MEASURES

@@ -287,50 +290,62 @@ func sendRequests(conn *client.Connection) {
 	// 		fmt.Printf("\nInstant metric %d deleted\n", instantMetricID)
 	// 	}

-	// 	// ADD CUMULATIVE METRIC
+	// ADD CUMULATIVE METRIC

-	// 	err = conn.AddMetric(proto.AddMetricReq{
-	// 		MetricID:   cumulativeMetricID,
-	// 		MetricType: qb.Cumulative,
-	// 		FracDigits: fracDigits,
+	err = conn.AddMetric(proto.AddMetricReq{
+		MetricID:   cumulativeMetricID,
+		MetricType: qb.Cumulative,
+		FracDigits: fracDigits,
+	})
+	if err != nil {
+		log.Fatalf("conn.AddMetric: %s\n", err)
+	} else {
+		fmt.Printf("\nCumulative metric %d added\n", cumulativeMetricID)
+	}
+
+	// GET CUMULATIVE METRIC
+
+	cMetric, err := conn.GetMetric(cumulativeMetricID)
+	if err != nil {
+		log.Fatalf("conn.GetMetric: %s\n", err)
+	} else {
+		fmt.Printf(`
+	GetMetric:
+	  metricID: %d
+	  metricType: %s
+	  fracDigits: %d
+	`,
+			cMetric.MetricID, metricTypeToName[cMetric.MetricType], cMetric.FracDigits)
+	}
+
+	// APPEND MEASURES
+
+	cumulativeMeasures := GenerateCumulativeMeasures(62)
+
+	result, err := conn.AppendMeasures(proto.AppendMeasuresReq{
+		MetricID: cumulativeMetricID,
+		Measures: cumulativeMeasures[:1],
+	})
+	if err != nil {
+		log.Fatalf("conn.AppendMeasures: %s\n", err)
+	} else {
+		fmt.Printf("\nAppended %d measures for the metric %d: count=%d, errorCode=%d\n",
+			len(cumulativeMeasures), cumulativeMetricID, result.WrittenCount, result.ErrorCode)
+	}
+
+	// currentValues, err := conn.ListCurrentValues([]uint32{
+	// 	cumulativeMetricID,
 	// })
 	// if err != nil {
-	// 		log.Fatalf("conn.AddMetric: %s\n", err)
+	// 	log.Fatalf("conn.ListCurrentValues: %s\n", err)
 	// } else {
-	// 		fmt.Printf("\nCumulative metric %d added\n", cumulativeMetricID)
+	// 	for _, v := range currentValues {
+	// 		fmt.Println(v.MetricID, v.Timestamp, v.Value)
+	// 	}
 	// }

-	// 	// GET CUMULATIVE METRIC
-
-	// 	cMetric, err := conn.GetMetric(cumulativeMetricID)
-	// 	if err != nil {
-	// 		log.Fatalf("conn.GetMetric: %s\n", err)
-	// 	} else {
-	// 		fmt.Printf(`
-	// GetMetric:
-	//   metricID: %d
-	//   metricType: %s
-	//   fracDigits: %d
-	// `,
-	// 			cMetric.MetricID, metricTypeToName[cMetric.MetricType], fracDigits)
-	// 	}
-
-	// 	// APPEND MEASURES
-
-	// 	cumulativeMeasures := GenerateCumulativeMeasures(62)
-
-	// 	err = conn.AppendMeasures(proto.AppendMeasuresReq{
-	// 		MetricID: cumulativeMetricID,
-	// 		Measures: cumulativeMeasures,
-	// 	})
-	// 	if err != nil {
-	// 		log.Fatalf("conn.AppendMeasures: %s\n", err)
-	// 	} else {
-	// 		fmt.Printf("\nAppended %d measures for the metric %d\n",
-	// 			len(cumulativeMeasures), cumulativeMetricID)
-	// 	}
-
-	// 	// LIST CUMULATIVE MEASURES
+	// LIST CUMULATIVE MEASURES
+	var cumulativeList []proto.CumulativeMeasure

 	// 	lastTimestamp = cumulativeMeasures[len(cumulativeMeasures)-1].Timestamp
 	// 	until = time.Unix(int64(lastTimestamp), 0)
@@ -352,17 +367,18 @@ func sendRequests(conn *client.Connection) {
 	// 		}
 	// 	}

-	// 	// LIST ALL CUMULATIVE MEASURES
+	// LIST ALL CUMULATIVE MEASURES

-	// 	cumulativeList, err = conn.ListAllCumulativeMeasures(cumulativeMetricID)
-	// 	if err != nil {
-	// 		log.Fatalf("conn.ListAllCumulativeMeasures: %s\n", err)
-	// 	} else {
-	// 		fmt.Printf("\nListAllCumulativeMeasures (last 15 items):\n")
-	// 		for _, item := range cumulativeList[:15] {
-	// 			fmt.Printf("  %s => %.2f\n", formatTime(item.Timestamp), item.Value)
-	// 		}
-	// 	}
+	cumulativeList, err = conn.ListAllCumulativeMeasures(cumulativeMetricID)
+	if err != nil {
+		log.Fatalf("conn.ListAllCumulativeMeasures: %s\n", err)
+	} else {
+		fmt.Printf("\nListAllCumulativeMeasures (last 15 items):\n")
+		fmt.Printf("%#v\n", cumulativeList)
+		for _, item := range cumulativeList {
+			fmt.Printf("  %s => %.2f\n", formatTime(item.Timestamp), item.Value)
+		}
+	}

 	// 	// LIST CUMULATIVE PERIODS (group by hour)

--- a/examples/play/play
+++ b/examples/play/play
--- a/examples/requests/requests.go
+++ b/examples/requests/requests.go
@@ -53,15 +53,15 @@ GetMetric:

 	instantMeasures := GenerateInstantMeasures(62, 220)

-	err = conn.AppendMeasures(proto.AppendMeasuresReq{
+	result, err := conn.AppendMeasures(proto.AppendMeasuresReq{
 		MetricID: instantMetricID,
 		Measures: instantMeasures,
 	})
 	if err != nil {
 		log.Fatalf("conn.AppendMeasures: %s\n", err)
 	} else {
-		fmt.Printf("\nAppended %d measures for the metric %d\n",
-			len(instantMeasures), instantMetricID)
+		fmt.Printf("\nAppended %d measures for the metric %d: writtenCount=%d, errorCode=%d\n",
+			len(instantMeasures), instantMetricID, result.WrittenCount, result.ErrorCode)
 	}

 	// LIST INSTANT MEASURES
@@ -236,15 +236,15 @@ GetMetric:

 	cumulativeMeasures := GenerateCumulativeMeasures(62)

-	err = conn.AppendMeasures(proto.AppendMeasuresReq{
+	result, err = conn.AppendMeasures(proto.AppendMeasuresReq{
 		MetricID: cumulativeMetricID,
 		Measures: cumulativeMeasures,
 	})
 	if err != nil {
 		log.Fatalf("conn.AppendMeasures: %s\n", err)
 	} else {
-		fmt.Printf("\nAppended %d measures for the metric %d\n",
-			len(cumulativeMeasures), cumulativeMetricID)
+		fmt.Printf("\nAppended %d measures for the metric %d: writtenCount=%d, errorCode=%d\n",
+			len(cumulativeMeasures), cumulativeMetricID, result.WrittenCount, result.ErrorCode)
 	}

 	// LIST CUMULATIVE MEASURES
--- a/go.sum
+++ b/go.sum
@@ -18,10 +18,6 @@ gopkg.in/ini.v1 v1.67.1/go.mod h1:x/cyOwCgZqOkJoDIJ3c1KNHMo10+nLGAhh+kn3Zizss=
 gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
 gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
 gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
-gordenko.dev/dima/bin v0.0.0-20260606153512-101b10d92a39 h1:qW3SnQ9HAcJpfj8ottBfPGTzHX+cX2vM8B6TVOgnypE=
-gordenko.dev/dima/bin v0.0.0-20260606153512-101b10d92a39/go.mod h1:up64wpJp9xI+HqACtMDBIfPNUH6BYY/b3inKpUfrqDQ=
-gordenko.dev/dima/bin v0.0.0-20260608125602-78363e903696 h1:JY91JYvv1g+XbaKdGmLFDBueUTx51RdW9mnbNYhiUdw=
-gordenko.dev/dima/bin v0.0.0-20260608125602-78363e903696/go.mod h1:up64wpJp9xI+HqACtMDBIfPNUH6BYY/b3inKpUfrqDQ=
 gordenko.dev/dima/bin v0.0.0-20260612161453-4ee9be3474fb h1:XBYZbK5Z+yfpKmSR2wuPLyW14ReCRSNdOlL5MWro8ns=
 gordenko.dev/dima/bin v0.0.0-20260612161453-4ee9be3474fb/go.mod h1:up64wpJp9xI+HqACtMDBIfPNUH6BYY/b3inKpUfrqDQ=
 gordenko.dev/dima/pretty v0.0.0-20221225212746-0c27d8c0ac69 h1:nyJ3mzTQ46yUeMZCdLyYcs7B5JCS54c67v84miyhq2E=
--- a/inbox/inbox.go
+++ b/inbox/inbox.go
@@ -1,6 +1,8 @@
 package inbox

-import "sync"
+import (
+	"sync"
+)

 type Inbox struct {
 	mutex    *sync.Mutex
@@ -20,9 +22,11 @@ func (s *Inbox) Ready() chan struct{} {
 }

 func (s *Inbox) Push(x any) {
+	//fmt.Printf("inbox.Push: %#v\n", x)
 	s.mutex.Lock()
 	s.items = append(s.items, x)
 	s.mutex.Unlock()
+	//fmt.Printf("inbox.Pushed\n")
 	select {
 	case s.signalCh <- struct{}{}:
 	default:
@@ -30,9 +34,11 @@ func (s *Inbox) Push(x any) {
 }

 func (s *Inbox) Drain() []any {
+	//fmt.Printf("inbox.Drain\n")
 	s.mutex.Lock()
 	items := s.items
 	s.items = nil
 	s.mutex.Unlock()
+	//fmt.Printf("inbox.Drained: %#v\n", items)
 	return items
 }
--- a/qb.go
+++ b/qb.go
@@ -30,7 +30,7 @@ type TimestampCompressor interface {
 	// (rewindOffset, change, timestamp)
 	Append(int, []byte, uint32)
 	Size() int
-	StoredSize() int
+	CommitedSize() int
 	//DeleteLast()
 	CaptureState()
 	ForgetCapturedState()
@@ -40,7 +40,7 @@ type TimestampCompressor interface {
 	//Payload() []byte // для снапшота
 	//	Offset() int
 	ReplaceBuffer([]byte)
-	WriteStoredTo(io.Writer) error
+	WriteCommitedTo(io.Writer) error
 	LastTimestamp() uint32
 	ReplaceSinceWithUntil() uint32
 }
@@ -65,7 +65,7 @@ type ValueCompressor interface {
 	// (rewindOffset, change, value, delta)
 	Append(int, []byte, float64, uint64)
 	Size() int
-	StoredSize() int
+	CommitedSize() int
 	//Chunks() [][]byte
 	//DeleteLast()
 	CaptureState()
@@ -77,7 +77,7 @@ type ValueCompressor interface {
 	//Payload() []byte // для снапшота
 	//Offset() int
 	ReplaceBuffer([]byte)
-	WriteStoredTo(io.Writer) error
+	WriteCommitedTo(io.Writer) error
 	LastValue() float64
 }

--- a/recovery/recovery.go
+++ b/recovery/recovery.go
@@ -2,6 +2,7 @@ package recovery

 import (
 	"errors"
+	"fmt"
 	"os"
 	"path/filepath"
 	"strconv"
@@ -113,6 +114,7 @@ func resolveRecoveryFiles(dir string) (_ RecoveryFiles, err error) {
 type RecoveryReport struct {
 	SnapshotNumber int
 	WAL            string
+	ReplayMetrics  map[uint32]*storage.ReplayMetric
 	IndexFreeList  *freelist.FreeList
 	DataFreeList   *freelist.FreeList
 }
@@ -122,6 +124,7 @@ func Recovery(dir string, databaseName string) (_ RecoveryReport, err error) {
 	if err != nil {
 		return
 	}
+	fmt.Printf("recovery files: %#v\n", recoveryFiles)
 	var (
 		frozenIndexPageCount int
 		frozenDataPageCount  int
@@ -131,27 +134,33 @@ func Recovery(dir string, databaseName string) (_ RecoveryReport, err error) {
 	)
 	if recoveryFiles.Snapshot != "" {
 		var snapshot worker.ReadSnapshotOut
-		snapshot, err = worker.ReadSnapshot(recoveryFiles.Snapshot)
+		snapshot, err = worker.ReadSnapshot(filepath.Join(dir, recoveryFiles.Snapshot))
 		if err != nil {
 			return
 		}
-		//
+		fmt.Printf("snapshot: %#v\n", snapshot)
 		frozenIndexPageCount = snapshot.FrozenIndexPagesCount
 		frozenDataPageCount = snapshot.FrozenDataPagesCount
 		freeIndexPages = snapshot.IndexPageNumbers
 		freeDataPages = snapshot.DataPageNumbers
 		metrics = snapshot.Metrics
+	} else {
+		metrics = make(map[uint32]*storage.ReplayMetric)
 	}

 	if recoveryFiles.WAL != "" {
 		var (
+			wal         *os.File
 			walReader   *storage.WALReader
 			walReplayer *storage.WALReplayer
 		)
-		walReader, err = storage.NewWALReader(storage.WALReaderOptions{
-			FileName:   recoveryFiles.WAL,
-			BufferSize: 8 * 1024 * 1024,
-		})
+		wal, err = os.Open(filepath.Join(dir, recoveryFiles.WAL))
+		if err != nil {
+			return
+		}
+		defer wal.Close()
+
+		walReader, err = storage.NewWALReader(wal)
 		if err != nil {
 			return
 		}
@@ -166,13 +175,15 @@ func Recovery(dir string, databaseName string) (_ RecoveryReport, err error) {
 			return
 		}

+		fmt.Printf("before replay\n")
 		err = walReplayer.Replay()
 		if err != nil {
 			return
 		}
+		fmt.Printf("after replay\n")
 		// перезаписую сторінки із останнього комміта
 		var dataFile *os.File
-		dataFile, err = os.OpenFile(qb.GetDataFilePath(dir, databaseName), os.O_WRONLY, 0666)
+		dataFile, err = os.OpenFile(qb.GetDataFilePath(dir, databaseName), os.O_CREATE|os.O_WRONLY, 0666)
 		if err != nil {
 			return
 		}
@@ -185,7 +196,7 @@ func Recovery(dir string, databaseName string) (_ RecoveryReport, err error) {
 			return
 		}
 		var indexFile *os.File
-		indexFile, err = os.OpenFile(qb.GetIndexFilePath(dir, databaseName), os.O_WRONLY, 0666)
+		indexFile, err = os.OpenFile(qb.GetIndexFilePath(dir, databaseName), os.O_CREATE|os.O_WRONLY, 0666)
 		if err != nil {
 			return
 		}
@@ -221,6 +232,7 @@ func Recovery(dir string, databaseName string) (_ RecoveryReport, err error) {
 	return RecoveryReport{
 		SnapshotNumber: recoveryFiles.SnapshotNumber,
 		WAL:            recoveryFiles.WAL,
+		ReplayMetrics:  metrics,
 		IndexFreeList:  indexFreeList,
 		DataFreeList:   dataFreeList,
 	}, nil
--- a/storage/replay_metric.go
+++ b/storage/replay_metric.go
@@ -43,14 +43,14 @@ func (s *ReplayMetric) MeasuresAppend(rec MeasuresAppendRecord) {
 		rec.Values, rec.ValuesRewindOffset)
 }

-type AppendMeasuresResult struct {
+type ReplayMeasuresAppendWithGrowResult struct {
 	IndexPagesToRewrite   []PageToWrite
 	DataPagesToRewrite    []PageToWrite
 	ReusedIndexPagesCount int
 	ReusedDataPagesCount  int
 }

-func (s *ReplayMetric) MeasuresAppendWithGrow(rec MeasuresAppendWithGrowRecord, isLastPacket bool) (_ AppendMeasuresResult) {
+func (s *ReplayMetric) MeasuresAppendWithGrow(rec MeasuresAppendWithGrowRecord, isLastPacket bool) (_ ReplayMeasuresAppendWithGrowResult) {
 	var (
 		reusedIndexPages int
 		reusedDataPages  int
@@ -82,6 +82,7 @@ func (s *ReplayMetric) MeasuresAppendWithGrow(rec MeasuresAppendWithGrowRecord,
 			if head != nil {
 				// попередній хвіст індексного рівня перетворився на head сторінку,
 				// отже TailRecords - це новий хвіст
+				clear(level.Buffer)
 				copy(level.Buffer, change.TailRecords)
 				level.RecordsCount = newRecordsCount
 			} else {
@@ -138,6 +139,7 @@ func (s *ReplayMetric) MeasuresAppendWithGrow(rec MeasuresAppendWithGrowRecord,
 	}
 	// HeadDataPage є полюбому, оскільки це транзакція із мінімум однією заповненою
 	// data сторінкою. Отже TailTimestamps і TailValues - це нові хвости data рівня.
+	clear(s.Buf)
 	copy(s.Buf, rec.TailValues)
 	s.ValuesSize = len(rec.TailValues)

@@ -151,7 +153,7 @@ func (s *ReplayMetric) MeasuresAppendWithGrow(rec MeasuresAppendWithGrowRecord,
 		s.LastPageNo = rec.DataPages[len(rec.DataPages)-1].PageNo
 	}

-	return AppendMeasuresResult{
+	return ReplayMeasuresAppendWithGrowResult{
 		IndexPagesToRewrite:   indexPages,
 		DataPagesToRewrite:    dataPages,
 		ReusedIndexPagesCount: reusedIndexPages,
@@ -192,9 +194,9 @@ func (s *ReplayMetric) composeHeadDataPage(head DataPageTail) PageToWrite {
 	page := make([]byte, DataPageSize)
 	copy(page, s.Buf)
 	// append data
-	timestampsSize := writeTimestampsWithRewind(s.Buf, s.TimestampsSize,
+	timestampsSize := writeTimestampsWithRewind(page, s.TimestampsSize,
 		head.Timestamps, head.TimestampsRewindOffset)
-	valuesSize := writeValuesWithRewind(s.Buf, s.ValuesSize,
+	valuesSize := writeValuesWithRewind(page, s.ValuesSize,
 		head.Values, head.ValuesRewindOffset)
 	// запечатати сторінку
 	calculatedCRC := SealDataPage(SealDataPageIn{
--- a/storage/storage.go
+++ b/storage/storage.go
@@ -49,14 +49,19 @@ type MetricAdd struct {
 	MetricID   uint32
 	MetricType qb.MetricType
 	FracDigits byte
-	ResultCh   chan struct{}
+	ResultCh   chan byte
 }

 type MetricDelete struct {
 	MetricID       uint32
 	FreeIndexPages []uint32
 	FreeDataPages  []uint32
-	ResultCh       chan struct{}
+	ResultCh       chan byte
+}
+
+type MeasuresAppendResult struct {
+	ResultCode   byte
+	WrittenCount int
 }

 type MeasuresAppendWithGrow struct {
@@ -72,7 +77,7 @@ type MeasuresAppendWithGrow struct {
 	IndexLevelTails        []IndexLevelTail
 	ResultCode             byte
 	WrittenCount           int
-	ResultCh               chan AppendMeasuresResult
+	ResultCh               chan MeasuresAppendResult
 }

 type MeasuresAppend struct {
@@ -83,14 +88,14 @@ type MeasuresAppend struct {
 	Values                 []byte
 	ResultCode             byte
 	WrittenCount           int
-	ResultCh               chan AppendMeasuresResult
+	ResultCh               chan MeasuresAppendResult
 }

 type MeasuresDelete struct {
 	MetricID       uint32
 	FreeIndexPages []uint32
 	FreeDataPages  []uint32
-	ResultCh       chan struct{}
+	ResultCh       chan byte
 }

 // WRITE RESULTS
@@ -100,7 +105,7 @@ type MeasuresAppendCommited struct {
 	MetricID     uint32
 	ResultCode   byte
 	WrittenCount int
-	ResultCh     chan AppendMeasuresResult
+	ResultCh     chan MeasuresAppendResult
 }

 type MeasuresAppendWithGrowCommited struct {
@@ -109,20 +114,20 @@ type MeasuresAppendWithGrowCommited struct {
 	Index        []IndexLevelTail
 	ResultCode   byte
 	WrittenCount int
-	ResultCh     chan AppendMeasuresResult
+	ResultCh     chan MeasuresAppendResult
 }

 type MeasuresDeleteCommited struct {
 	MetricID uint32
-	ResultCh chan struct{}
+	ResultCh chan byte
 }

 type MetricAddCommited struct {
 	MetricID uint32
-	ResultCh chan struct{}
+	ResultCh chan byte
 }

 type MetricDeleteCommited struct {
 	MetricID uint32
-	ResultCh chan struct{}
+	ResultCh chan byte
 }
--- a/storage/storage_test.go
+++ b/storage/storage_test.go
@@ -3,6 +3,7 @@ package storage
 import (
 	"bytes"
 	"fmt"
+	"io"
 	"math"
 	"reflect"
 	"slices"
@@ -914,3 +915,169 @@ func TestWriteValuesWithRewind(t *testing.T) {
 		t.Fatalf("got buf % x are not equal expected % x", before, after)
 	}
 }
+
+func TestWALReader(t *testing.T) {
+	rec1 := MetricAddRecord{
+		MetricID:   100,
+		MetricType: qb.Cumulative,
+		FracDigits: 4,
+	}
+	rec2 := MetricAddRecord{
+		MetricID:   200,
+		MetricType: qb.Instant,
+		FracDigits: 1,
+	}
+	rec3 := MetricDeleteRecord{
+		MetricID: 100,
+		FreeIndexPages: []uint32{
+			1, 2, 3,
+		},
+		FreeDataPages: []uint32{
+			10, 20,
+		},
+	}
+	rec4 := MetricDeleteRecord{
+		MetricID: 200,
+	}
+
+	packet1 := createPacket([]Packable{rec1, rec2})
+	packet2 := createPacket([]Packable{rec3, rec4})
+
+	src := bytes.NewBuffer(nil)
+	src.Write(packet1)
+	src.Write(packet2)
+
+	walReader, err := NewWALReader(src)
+	if err != nil {
+		t.Fatal(err)
+	}
+	i := 0
+	for {
+		records, isLastPacket, err := walReader.NextPacket()
+		if err != nil {
+			t.Fatal(err)
+		}
+		if records == nil {
+			break
+		}
+		switch i {
+		case 0:
+			if isLastPacket {
+				t.Fatalf("1st packet can't be the last packet in WAL")
+			}
+			if !reflect.DeepEqual(records, []any{rec1, rec2}) {
+				t.Fatalf("1st packet decoded incorrectly")
+			}
+		case 1:
+			if !isLastPacket {
+				t.Fatalf("2nd packet must be the last packet in WAL")
+			}
+			if !reflect.DeepEqual(records, []any{rec3, rec4}) {
+				t.Fatalf("2nd packet decoded incorrectly")
+			}
+		}
+		i++
+	}
+}
+
+func createPacket(records []Packable) []byte {
+	w := bytes.NewBuffer(nil)
+	w.Write([]byte{
+		0, 0, 0, 0, 0, 0, 0, 0, 0, // size (max 9 byte)
+	})
+	hasher := util.NewHasher()
+	multi := io.MultiWriter(w, hasher)
+	for _, rec := range records {
+		rec.Pack(multi)
+	}
+	return finalizePacket(w, hasher.Sum32())
+}
+
+func TestReplayMetric(t *testing.T) {
+	// data
+	DataPageSize = 24
+	DataPagePayloadSize = 12
+	dataCRC32Idx = DataPageSize - 4
+	timestampsSizeIdx = DataPageSize - 6
+	valuesSizeIdx = DataPageSize - 8
+	prevPageIdx = DataPageSize - 12
+	// index
+	IndexPageSize = 24
+	indexCRC32Idx = IndexPageSize - 4
+	indexRecordsCountIdx = IndexPageSize - 6
+	isZeroLevelIdx = IndexPageSize - 7
+	maxRecordsOnIndexPage = 2
+	//
+	metric := &ReplayMetric{
+		Buf: []byte{
+			0xa1, 0xa2, 0xa3, 0xa4,
+			0x00, 0x00, 0x00, 0x00,
+			0xb4, 0xb3, 0xb2, 0xb1,
+			0x01, 0x00, 0x00, 0x00,
+			0x00, 0x00, 0x00, 0x00,
+			0x00, 0x00, 0x00, 0x00,
+		},
+		TimestampsSize: 4,
+		ValuesSize:     4,
+		IndexLevelTails: []IndexLevelTail{
+			{
+				Buffer: []byte{
+					0x01, 0x01, 0x01, 0x01,
+					0x02, 0x02, 0x02, 0x02,
+					0x00, 0x00, 0x00, 0x00,
+					0x00, 0x00, 0x00, 0x00,
+					0x00, 0x00, 0x00, 0x00,
+					0x00, 0x00, 0x00, 0x00,
+				},
+				RecordsCount: 1,
+			},
+		},
+	}
+
+	result := metric.MeasuresAppendWithGrow(MeasuresAppendWithGrowRecord{
+		DataPageTail: DataPageTail{
+			PrevPageNo:             1,
+			CRC32:                  3235260875,
+			TimestampsRewindOffset: 1,
+			Timestamps:             []byte{0x55, 0x44},
+			ValuesRewindOffset:     2,
+			Values:                 []byte{0x33, 0x44},
+		},
+		TailTimestamps: []byte{
+			0xf3, 0xf2, 0xf1,
+		},
+		TailValues: []byte{
+			0xd1, 0xd2,
+		},
+		ChangedIndexLevels: []ChangedIndexLevel{
+			{
+				IndexPageTail: &IndexPageTail{
+					CRC32: 2138044007,
+					Records: []byte{
+						0x03, 0x03, 0x03, 0x03,
+						0x04, 0x04, 0x04, 0x04,
+					},
+				},
+				TailRecords: []byte{
+					0x08, 0x08, 0x08, 0x08,
+					0x09, 0x09, 0x09, 0x09,
+				},
+			},
+			{
+				TailRecords: []byte{
+					0x01, 0x01, 0x01, 0x01,
+					0x02, 0x02, 0x02, 0x02,
+				},
+			},
+		},
+	}, true) // last packet
+
+	fmt.Printf("% x\n", metric.Buf)
+
+	fmt.Printf("% x\n", result.DataPagesToRewrite[0].Content)
+
+	fmt.Printf("% x\n", result.IndexPagesToRewrite[0].Content)
+
+	fmt.Printf("%d: % x\n", metric.IndexLevelTails[0].RecordsCount, metric.IndexLevelTails[0].Buffer)
+	fmt.Printf("%d: % x\n", metric.IndexLevelTails[1].RecordsCount, metric.IndexLevelTails[1].Buffer)
+}
--- a/storage/wal_reader.go
+++ b/storage/wal_reader.go
@@ -3,10 +3,8 @@ package storage
 import (
 	"bufio"
 	"bytes"
-	"errors"
 	"fmt"
 	"io"
-	"os"

 	bin "gordenko.dev/dima/bin/little"
 	"gordenko.dev/dima/qb/util"
@@ -15,155 +13,133 @@ import (
 const readBufferSize = 8 * 1024 * 1024

 type WALReader struct {
-	file    *os.File
+	//file   *os.File
 	reader *bufio.Reader
-	current []any
 	next   []any
+	done   bool
 }

-type WALReaderOptions struct {
-	FileName   string
-	BufferSize int
-}
+// type WALReaderOptions struct {
+// 	File       *os.File
+// 	BufferSize int
+// }

-func NewWALReader(opt WALReaderOptions) (*WALReader, error) {
-	if opt.FileName == "" {
-		return nil, errors.New("FileName option is required")
-	}
-	if opt.BufferSize <= 0 {
-		return nil, errors.New("BufferSize option is required")
-	}
-
-	file, err := os.Open(opt.FileName)
-	if err != nil {
-		return nil, err
-	}
+func NewWALReader(src io.Reader) (*WALReader, error) {
+	// if opt.FileName == "" {
+	// 	return nil, errors.New("FileName option is required")
+	// }
+	// if opt.BufferSize <= 0 {
+	// 	return nil, errors.New("BufferSize option is required")
+	// }

 	return &WALReader{
-		file:   file,
-		reader: bufio.NewReaderSize(file, readBufferSize),
+		//file:   file,
+		reader: bufio.NewReaderSize(src, readBufferSize),
 	}, nil
 }

-func (s *WALReader) Close() {
-	s.file.Close()
-}
+// func (s *WALReader) Close() {
+// 	s.file.Close()
+// }

-func (s *WALReader) NextPacket() ([]any, bool, error) {
-	var err error
-	if s.current == nil {
-		s.current, err = s.readPacket()
-		if err != nil {
-			return nil, false, err
+// (packet records, isLastPacket, error)
+func (s *WALReader) NextPacket() (_ []any, _ bool, err error) {
+	if s.done {
+		return
+	}
+	var current []any
+	if s.next != nil {
+		current = s.next
+	} else {
+		current, err = s.readPacket()
+		if err != nil {
+			return
+		}
+		if current == nil {
+			return
+		}
 	}
-		if len(s.current) > 0 {
 	s.next, err = s.readPacket()
 	if err != nil {
-				return nil, false, err
+		return
 	}
-		}
-	}
-
-	current := s.current
-	done := s.next == nil
-
-	s.current = s.next
-	s.next, err = s.readPacket()
-	if err != nil {
-		return nil, false, err
-	}
-	return current, done, nil
+	return current, s.next == nil, nil
 }

 func (s *WALReader) readPacket() (_ []any, err error) {
-	payloadSize, err := bin.ReadVarSize(s.reader)
+	bodySize, err := bin.ReadVarSize(s.reader) // fix add n
 	if err != nil {
 		if err == io.EOF {
+			s.done = true
 			return nil, nil
-		} else {
+		}
 		return
 	}
-	}
-
-	storedCRC, err := bin.ReadUint32(s.reader)
+	body, err := bin.ReadN(s.reader, int(bodySize))
 	if err != nil {
 		return
 	}
-
-	body, err := bin.ReadN(s.reader, int(payloadSize))
+	writtenCRC, err := bin.ReadUint32(s.reader)
 	if err != nil {
 		return
 	}
-
-	hasher := util.NewHasher()
-	hasher.Write(body)
-
-	calculatedCRC := hasher.Sum32()
-
-	if calculatedCRC == storedCRC {
+	calculatedCRC := util.CalculateCRC32(body)
+	if calculatedCRC != writtenCRC {
+		return nil, fmt.Errorf("written CRC %d != calculated CRC %d",
+			writtenCRC, calculatedCRC)
+	}
 	return s.parseRecords(body)
-	}
-	//s.logger.Printf("stored CRC %d != calculated CRC %d", storedCRC, calculatedCRC)
-	return nil, nil
 }

-func (s *WALReader) parseRecords(body []byte) ([]any, error) {
+func (s *WALReader) parseRecords(body []byte) (_ []any, err error) {
 	var (
 		src     = bytes.NewBuffer(body)
 		records []any
 	)
-
 	for {
-		recordType, err := src.ReadByte()
+		var recordType byte
+		recordType, err = src.ReadByte()
 		if err != nil {
 			if err == io.EOF {
 				return records, nil
 			}
-			return nil, err
+			return
 		}
-
 		switch recordType {
 		case CodeMetricAdd:
 			rec := new(MetricAddRecord)
 			if err = rec.Parse(src); err != nil {
-				return nil, err
+				return
 			}
-			records = append(records, rec)
+			records = append(records, *rec)

 		case CodeMetricDelete:
 			rec := new(MetricDeleteRecord)
 			if err = rec.Parse(src); err != nil {
-				return nil, err
+				return
 			}
-			records = append(records, rec)
+			records = append(records, *rec)

-		// case CodeAppendedMeasure:
-		// 	rec := new(AppendedMeasure)
-		// 	if err = rec.Parse(src); err != nil {
-		// 		return nil, err
-		// 	}
-		// 	records = append(records, rec)
+		case CodeMeasuresAppend:
+			rec := new(MeasuresAppendRecord)
+			if err = rec.Parse(src); err != nil {
+				return
+			}
+			records = append(records, *rec)

-		// case CodeAppendedMeasures:
-		// 	rec := new(AppendedMeasures)
-		// 	if err = rec.Parse(src); err != nil {
-		// 		return nil, err
-		// 	}
-		// 	records = append(records, rec)
-
-		// case CodeAppendedPages:
-		// 	rec := new(AppendedPages)
-		// 	if err = rec.Parse(src); err != nil {
-		// 		return nil, err
-		// 	}
-		// 	records = append(records, rec)
+		case CodeMeasuresAppendWithGrow:
+			rec := new(MeasuresAppendWithGrowRecord)
+			if err = rec.Parse(src); err != nil {
+				return
+			}
+			records = append(records, *rec)

 		case CodeMeasuresDelete:
 			rec := new(MeasuresDeleteRecord)
 			if err = rec.Parse(src); err != nil {
-				return nil, err
+				return
 			}
-			records = append(records, rec)
+			records = append(records, *rec)

 		default:
 			return nil, fmt.Errorf("unknown record type code: %d", recordType)
--- a/storage/wal_replayer.go
+++ b/storage/wal_replayer.go
@@ -58,6 +58,9 @@ func (s *WALReplayer) Replay() error {
 		if err != nil {
 			return err
 		}
+		if len(records) == 0 {
+			return nil
+		}
 		for _, rec := range records {
 			if err = s.replayRecord(rec, isLastPacket); err != nil {
 				return err
--- a/storage/write_preparer.go
+++ b/storage/write_preparer.go
@@ -9,6 +9,10 @@ import (
 	"gordenko.dev/dima/qb/util"
 )

+type Packable interface {
+	Pack(io.Writer)
+}
+
 type WritePreparer struct {
 	pagePreparer *PageIngester
 	//dataPagePayloadBound int
@@ -39,15 +43,19 @@ type PreparedData struct {
 	Commits      []any
 }

+// const (
+// 	prefixSize = 9
+// 	crc32Size  = 4
+// )
+
 func (s *WritePreparer) Prepare(input []any) PreparedData {
 	s.w.Write([]byte{
 		0, 0, 0, 0, 0, 0, 0, 0, 0, // size (max 9 byte)
-		0, 0, 0, 0, // crc32
 	})

 	hasher := util.NewHasher()

-	w := io.MultiWriter(s.w, hasher)
+	multi := io.MultiWriter(s.w, hasher)

 	// 1. Пакую всі дані в  WAL буфер запису
 	for _, untyped := range input {
@@ -58,7 +66,7 @@ func (s *WritePreparer) Prepare(input []any) PreparedData {
 				MetricType: x.MetricType,
 				FracDigits: x.FracDigits,
 			}
-			rec.Pack(w)
+			rec.Pack(multi)
 			s.commits = append(s.commits, MetricAddCommited{
 				MetricID: x.MetricID,
 				ResultCh: x.ResultCh,
@@ -76,7 +84,7 @@ func (s *WritePreparer) Prepare(input []any) PreparedData {
 				FreeIndexPages: x.FreeIndexPages,
 				FreeDataPages:  x.FreeDataPages,
 			}
-			rec.Pack(w)
+			rec.Pack(multi)
 			s.commits = append(s.commits, MetricDeleteCommited{
 				MetricID: x.MetricID,
 				ResultCh: x.ResultCh,
@@ -90,7 +98,7 @@ func (s *WritePreparer) Prepare(input []any) PreparedData {
 				ValuesRewindOffset:     x.ValuesRewindOffset,
 				Values:                 x.Values,
 			}
-			rec.Pack(w)
+			rec.Pack(multi)
 			// Дані для Worker
 			s.commits = append(s.commits, MeasuresAppendCommited{
 				MetricID:     x.MetricID,
@@ -188,9 +196,9 @@ func (s *WritePreparer) Prepare(input []any) PreparedData {
 				ChangedIndexLevels: changedIndexPages,
 			}

-			fmt.Printf("%#v\ns", rec.ChangedIndexLevels[0].IndexPageTail)
+			//fmt.Printf("%#v\ns", rec.ChangedIndexLevels[0].IndexPageTail)

-			rec.Pack(w)
+			rec.Pack(multi)
 			// Дані для Worker
 			s.commits = append(s.commits, MeasuresAppendWithGrowCommited{
 				MetricID:     x.MetricID,
@@ -213,7 +221,7 @@ func (s *WritePreparer) Prepare(input []any) PreparedData {
 				FreeIndexPages: x.FreeIndexPages,
 				FreeDataPages:  x.FreeDataPages,
 			}
-			rec.Pack(w)
+			rec.Pack(multi)
 			s.commits = append(s.commits, MeasuresDeleteCommited{
 				MetricID: x.MetricID,
 				ResultCh: x.ResultCh,
@@ -222,19 +230,11 @@ func (s *WritePreparer) Prepare(input []any) PreparedData {
 		}
 	}
 	// 2. Додаю розмір пакету і чексуму
-
+	packet := finalizePacket(s.w, hasher.Sum32())
 	//s.written += int64(len(packet)) + 12
-
-	packet := s.w.Bytes()
-	// write size
-	payloadSize := len(packet) - 13
-	start := 9 - bin.CountVarSize(payloadSize)
-	bin.PutVarSize(packet[start:], payloadSize)
-	// CRC32
-	bin.PutUint32(packet[9:], hasher.Sum32())
 	//
 	return PreparedData{
-		Packet:       packet[start:],
+		Packet:       packet,
 		WriteToIndex: s.indexPages,
 		WriteToData:  s.dataPages,
 		Commits:      s.commits,
@@ -260,3 +260,13 @@ func getIndexRecords(buf []byte, count int) (list []IndexRecord) {
 	}
 	return
 }
+
+func finalizePacket(w *bytes.Buffer, checksum uint32) []byte {
+	bin.WriteUint32(w, checksum)
+	packet := w.Bytes()
+	bodySize := len(packet) - 13 // 9 bytes prefix + 4 bytes crc32
+	// cut empty bytes at start
+	start := 9 - bin.CountVarSize(bodySize)
+	bin.PutVarSize(packet[start:], bodySize)
+	return packet[start:]
+}
--- a/storage/wal_writer.go
+++ b/storage/wal_writer.go
@@ -4,7 +4,6 @@ import (
 	"bytes"
 	"errors"
 	"fmt"
-	"math"
 	"os"
 	"path/filepath"
 	"sync"
@@ -203,37 +202,8 @@ func (s *Writer) Run() {
 	}
 }

-func (s *Writer) getDataPageNumber() (uint32, bool, error) {
-	pageNo, err := s.dataFreeList.GetPageNumber()
-	if err != nil {
-		return 0, false, err
-	}
-	if pageNo > 0 {
-		return pageNo, true, nil
-	}
-	if s.dataPagesCount < math.MaxUint32 {
-		s.dataPagesCount++
-		return s.dataPagesCount, false, nil
-	}
-	return 0, false, errors.New("no space")
-}
-
-func (s *Writer) getIndexPageNumber() (uint32, bool, error) {
-	pageNo, err := s.indexFreeList.GetPageNumber()
-	if err != nil {
-		return 0, false, err
-	}
-	if pageNo > 0 {
-		return pageNo, true, nil
-	}
-	if s.indexPagesCount < math.MaxUint32 {
-		s.indexPagesCount++
-		return s.indexPagesCount, false, nil
-	}
-	return 0, false, errors.New("no space")
-}
-
 func (s *Writer) packAndWrite() (err error) {
+	//fmt.Println("packAndWrite")
 	//s.mutex.Lock()
 	//isExited := s.isExited

@@ -245,15 +215,19 @@ func (s *Writer) packAndWrite() (err error) {

 	input := s.inbox.Drain()

+	//fmt.Printf("Drain: %#v\n", input)
+
 	prepared := s.writePreparer.Prepare(input)

+	//fmt.Printf("prepared: %#v\n", prepared)
+
 	// 3. Пишу на диск WAL (append)
 	n, err := s.wal.Write(prepared.Packet)
 	if err != nil {
 		return
 	}
 	if n != len(prepared.Packet) {
-		return fmt.Errorf("written %d != total size %d", n, len(prepared.Packet))
+		return fmt.Errorf("written %d != packet size %d", n, len(prepared.Packet))
 	}
 	if err = s.wal.Sync(); err != nil {
 		return
--- a/testdir/test.data
+++ b/testdir/test.data
--- a/testdir/test.data_free
+++ b/testdir/test.data_free
--- a/testdir/test.data_free_delta
+++ b/testdir/test.data_free_delta
--- a/testdir/test.index
+++ b/testdir/test.index
--- a/testdir/test.index_free
+++ b/testdir/test.index_free
--- a/testdir/test.index_free_delta
+++ b/testdir/test.index_free_delta
--- a/testdir/test.wal_0
+++ b/testdir/test.wal_0
--- a/transform/raw.go
+++ b/transform/raw.go
@@ -1,6 +1,7 @@
 package transform

 import (
+	"fmt"
 	"io"

 	bin "gordenko.dev/dima/bin/little"
@@ -101,6 +102,7 @@ type CumulativeMeasureWriter struct {
 }

 func NewCumulativeMeasureWriter(dst io.Writer, since uint32) *CumulativeMeasureWriter {
+	fmt.Println("NewCumulativeMeasureWriter")
 	// 20 - это timestamp, value, total
 	return &CumulativeMeasureWriter{
 		arr:       make([]byte, 20),
@@ -126,11 +128,13 @@ func (s *CumulativeMeasureWriter) feed(timestamp uint32, value float64, isBuffer
 			s.responder.AppendRecord(s.arr)
 		}
 	}
+	fmt.Println("feed:", timestamp, value, isBuffer)
 	s.endTimestamp = timestamp
 	s.endValue = value
 }

 func (s *CumulativeMeasureWriter) pack(total float64) {
+	fmt.Println("PACK")
 	bin.PutUint32(s.arr[0:], s.endTimestamp)
 	bin.PutFloat64(s.arr[4:], s.endValue)
 	bin.PutFloat64(s.arr[12:], total)
@@ -141,6 +145,7 @@ func (s *CumulativeMeasureWriter) Close() error {
 		// endTimestamp внутри заданного периода. Других показаний нет,
 		// поэтому время добавляю, но накопленную сумму ставлю 0.
 		s.pack(0)
+		s.responder.BufferRecord(s.arr)
 		// Если < since - ничего делать не нужно, ибо накопленная сумма уже добавлена
 	}
 	return s.responder.Flush()
--- a/transform/responder.go
+++ b/transform/responder.go
@@ -38,11 +38,13 @@ func NewChunkedResponder(dst io.Writer) *ChunkedResponder {
 func (s *ChunkedResponder) BufferRecord(rec []byte) {
 	s.buf.Write(rec)
 	s.recordsQty++
+	fmt.Println("BufferRecord", s.recordsQty)
 }

 func (s *ChunkedResponder) AppendRecord(rec []byte) error {
 	s.buf.Write(rec)
 	s.recordsQty++
+	fmt.Println("AppendRecord", s.recordsQty)

 	if s.buf.Len() < 1500 {
 		return nil
@@ -61,6 +63,7 @@ func (s *ChunkedResponder) AppendRecord(rec []byte) error {
 }

 func (s *ChunkedResponder) Flush() error {
+	fmt.Println("Flush", s.recordsQty)
 	if s.recordsQty > 0 {
 		if err := s.sendBuffered(); err != nil {
 			return err
@@ -75,13 +78,14 @@ func (s *ChunkedResponder) Flush() error {
 }

 func (s *ChunkedResponder) sendBuffered() (err error) {
+	fmt.Println("sendBuffered", s.recordsQty)
 	msg := s.buf.Bytes()
 	bin.PutUint32(msg[1:], uint32(s.recordsQty))
-	//fmt.Printf("put uint16: %d\n", msg[:3])
+	fmt.Printf("put uint16: %d\n", msg[:3])

-	//fmt.Printf("send %d records\n", s.recordsQty)
+	fmt.Printf("send %d records\n", s.recordsQty)

-	//fmt.Printf("send buffered: %d, qty: %d\n", msg, s.recordsQty)
+	fmt.Printf("send buffered: %d, qty: %d\n", msg, s.recordsQty)

 	n, err := s.dst.Write(msg)
 	if err != nil {
--- a/worker/metric.go
+++ b/worker/metric.go
@@ -2,6 +2,7 @@ package worker

 import (
 	"errors"
+	"fmt"
 	"io"

 	bin "gordenko.dev/dima/bin/little"
@@ -30,8 +31,8 @@ type Metric struct {
 	buffer          []byte
 	timestamps      qb.TimestampCompressor
 	values          qb.ValueCompressor
-	XLock           bool
-	RLocks          int
+	xLock           bool
+	rLocks          int
 	WaitQueue       []any
 	indexLevelTails []storage.IndexLevelTail // root - last element
 	capturedState   *CapturedState
@@ -62,7 +63,7 @@ func (s *Metric) LastTimestamp() uint32 {
 func (s *Metric) OnMeasuresDeleteCommited(rec storage.MeasuresDeleteCommited) {
 	//s.timestamps.Reset()
 	//s.values.Reset()
-	s.XLock = false
+	s.xLock = false
 	// s.Timestamps.Renew()
 	// s.Values.Renew()

@@ -75,8 +76,7 @@ func (s *Metric) OnMeasuresDeleteCommited(rec storage.MeasuresDeleteCommited) {
 	s.lastValue = 0
 }

-// func (s *_metric) startAppendMeasures(req tryAppendMeasuresReq, sendToStorage func(storage.AppendedMeasures)) {
-func (s *Metric) StartAppendMeasures(req AppendMeasuresReq, tmp []byte, storageInbox *inbox.Inbox) {
+func (s *Metric) AppendMeasures(req AppendMeasuresReq, tmp []byte, storageInbox *inbox.Inbox) {
 	if s.capturedState != nil {
 		s.WaitQueue = append(s.WaitQueue, req)
 	}
@@ -96,7 +96,7 @@ func (s *Metric) StartAppendMeasures(req AppendMeasuresReq, tmp []byte, storageI
 		pages []storage.DataPayload

 		written    int
-		resultCode byte
+		resultCode byte = Succeed
 	)

 	s.capturedState = &CapturedState{
@@ -117,8 +117,10 @@ func (s *Metric) StartAppendMeasures(req AppendMeasuresReq, tmp []byte, storageI
 			break
 		}

-		tReport := timestamps.Evaluate(tmp, measure.Timestamp)
-		vReport := values.Evaluate(tmp, measure.Value)
+		tReport := timestamps.Evaluate(tmp[:7], measure.Timestamp)
+		fmt.Printf("tReport: %#v\n", tReport)
+		vReport := values.Evaluate(tmp[7:], measure.Value)
+		fmt.Printf("vReport: %#v\n", vReport)

 		totalRequiredSpace := tReport.TotalSpace + vReport.TotalSpace

@@ -169,7 +171,7 @@ func (s *Metric) StartAppendMeasures(req AppendMeasuresReq, tmp []byte, storageI

 	if written == 0 {
 		s.capturedState = nil
-		req.ResultCh <- AppendMeasuresResult{
+		req.ResultCh <- storage.MeasuresAppendResult{
 			ResultCode: resultCode,
 		}
 		return
@@ -193,7 +195,7 @@ func (s *Metric) StartAppendMeasures(req AppendMeasuresReq, tmp []byte, storageI
 			TailValues:             values.Tail(0),
 			ResultCode:             resultCode,
 			WrittenCount:           written,
-			//ResultCh:        req.ResultCh,
+			ResultCh:               req.ResultCh,
 		})
 	} else {
 		// короткий шлях - запис лише в storage
@@ -205,7 +207,7 @@ func (s *Metric) StartAppendMeasures(req AppendMeasuresReq, tmp []byte, storageI
 			Values:                 values.Tail(valuesOffset),
 			ResultCode:             resultCode,
 			WrittenCount:           written,
-			//ResultCh:         req.ResultCh,
+			ResultCh:               req.ResultCh,
 		})
 	}
 }
@@ -215,6 +217,11 @@ func (s *Metric) OnMeasuresAppendCommited(rec storage.MeasuresAppendCommited) {
 	s.capturedState = nil
 	s.timestamps.ForgetCapturedState()
 	s.values.ForgetCapturedState()
+
+	rec.ResultCh <- storage.MeasuresAppendResult{
+		ResultCode:   rec.ResultCode,
+		WrittenCount: rec.WrittenCount,
+	}
 }

 func (s *Metric) OnMeasuresAppendWithGrowCommited(rec storage.MeasuresAppendWithGrowCommited) {
@@ -229,6 +236,11 @@ func (s *Metric) OnMeasuresAppendWithGrowCommited(rec storage.MeasuresAppendWith
 	// В storage я передав повний індекс. У нього додали елементи (можливо нові рівні).
 	// Тому проста заміна
 	s.indexLevelTails = rec.Index
+
+	rec.ResultCh <- storage.MeasuresAppendResult{
+		ResultCode:   rec.ResultCode,
+		WrittenCount: rec.WrittenCount,
+	}
 }

 // READ
@@ -317,10 +329,12 @@ func (s *Metric) StartFullScan(req FullScanReq) {
 		if done {
 			break
 		}
+		fmt.Println("ts:", timestamp)
 		value, done := valueDecompressor.NextValue()
 		if done {
 			qb.Abort(qb.HasTimestampNoValueBug, ErrNoValueBug)
 		}
+		fmt.Println("value:", value)
 		req.ResponseWriter.FeedNoSend(timestamp, value)
 	}

@@ -330,7 +344,7 @@ func (s *Metric) StartFullScan(req FullScanReq) {
 			LastPageNo: s.lastPageNo,
 			FracDigits: s.fracDigits,
 		}
-		s.RLocks++
+		s.rLocks++
 	} else {
 		req.ResultCh <- FullScanResult{
 			ResultCode: QueryDone,
@@ -366,21 +380,21 @@ func (s *Metric) WriteTo(w io.Writer) (err error) {
 	if err != nil {
 		return
 	}
-	err = bin.WriteUint16(w, uint16(s.timestamps.StoredSize()))
+	err = bin.WriteUint16(w, uint16(s.timestamps.CommitedSize()))
 	if err != nil {
 		return
 	}
-	err = bin.WriteUint16(w, uint16(s.values.StoredSize()))
+	err = bin.WriteUint16(w, uint16(s.values.CommitedSize()))
 	if err != nil {
 		return
 	}
 	// timestamps payload
-	err = s.timestamps.WriteStoredTo(w)
+	err = s.timestamps.WriteCommitedTo(w)
 	if err != nil {
 		return
 	}
 	// values payload
-	err = s.values.WriteStoredTo(w)
+	err = s.values.WriteCommitedTo(w)
 	if err != nil {
 		return
 	}
@@ -394,7 +408,7 @@ func (s *Metric) WriteTo(w io.Writer) (err error) {
 		if err != nil {
 			return
 		}
-		_, err = w.Write(level.Buffer)
+		_, err = w.Write(level.Buffer[:level.RecordsCount*storage.IndexRecordSize])
 		if err != nil {
 			return
 		}
--- a/worker/snapshot.go
+++ b/worker/snapshot.go
@@ -5,7 +5,6 @@ import (
 	"fmt"
 	"io"
 	"os"
-	"path/filepath"

 	bin "gordenko.dev/dima/bin/little"
 	"gordenko.dev/dima/qb"
@@ -30,11 +29,10 @@ dataFreeList - Nb
 CRC32 - 4b
 */

-const readBufferSize = 4 * 1024 * 1024 // 8mb
+const readBufferSize = 4 * 1024 * 1024

 type WriteSnapshotIn struct {
 	SnapshotNumber        int
-	Dir                   string
 	WriteBufferSize       int
 	Metrics               map[uint32]*Metric
 	FrozenIndexPagesCount int
@@ -43,24 +41,21 @@ type WriteSnapshotIn struct {
 	DataPageNumbers       []uint32
 }

-func WriteSnapshot(in WriteSnapshotIn) (err error) {
+func writeSnapshot(filePath string, in WriteSnapshotIn) (err error) {
+	file, err := os.OpenFile(filePath, os.O_CREATE|os.O_WRONLY|os.O_TRUNC, 0666)
+	if err != nil {
+		qb.Abort(qb.WriteSnapshotFailed, err)
+	}
 	var (
-		fileName = filepath.Join(in.Dir, fmt.Sprintf("%d.snapshot", in.SnapshotNumber))
+		bufferedWriter = bufio.NewWriterSize(file, in.WriteBufferSize)
 		hasher         = util.NewHasher()
 	)
-
-	file, err := os.OpenFile(fileName, os.O_CREATE|os.O_WRONLY, 0666) //0770)
-	if err != nil {
-		return
-	}
-
-	dst := io.MultiWriter(bufio.NewWriterSize(file, in.WriteBufferSize), hasher)
-
+	dst := io.MultiWriter(bufferedWriter, hasher)
+	//
 	_, err = bin.WriteVarSize(dst, len(in.Metrics))
 	if err != nil {
 		return
 	}
-
 	for metricID, metric := range in.Metrics {
 		err = bin.WriteUint32(dst, metricID)
 		if err != nil {
@@ -81,13 +76,16 @@ func WriteSnapshot(in WriteSnapshotIn) (err error) {
 	if err != nil {
 		return
 	}
-	// CRC32
-	bin.WriteUint32(file, hasher.Sum32())
-
-	err = file.Close()
+	err = bufferedWriter.Flush()
 	if err != nil {
 		return
 	}
+	// CRC32
+	err = bin.WriteUint32(file, hasher.Sum32())
+	if err != nil {
+		return
+	}
+	return file.Close()

 	// prevLogNumber := logNumber - 1
 	// prevChanges := filepath.Join(s.dir, fmt.Sprintf("%d.changes", prevLogNumber))
@@ -116,7 +114,6 @@ func WriteSnapshot(in WriteSnapshotIn) (err error) {
 	// 		qb.Abort(qb.DeletePrevSnapshotFileFailed, err)
 	// 	}
 	// }
-	return
 }

 type ReadSnapshotOut struct {
@@ -127,7 +124,7 @@ type ReadSnapshotOut struct {
 	DataPageNumbers       []uint32
 }

-func ReadSnapshot(fileName string) (out ReadSnapshotOut, err error) {
+func ReadSnapshot(filePath string) (out ReadSnapshotOut, err error) {
 	var (
 		metrics               = make(map[uint32]*storage.ReplayMetric)
 		frozenIndexPagesCount int
@@ -137,7 +134,7 @@ func ReadSnapshot(fileName string) (out ReadSnapshotOut, err error) {
 		hasher                = util.NewHasher()
 	)

-	file, err := os.Open(fileName)
+	file, err := os.Open(filePath)
 	if err != nil {
 		return
 	}
@@ -148,25 +145,16 @@ func ReadSnapshot(fileName string) (out ReadSnapshotOut, err error) {
 		return
 	}
 	fileSize := stat.Size()
-
-	if fileSize == 0 {
-		return ReadSnapshotOut{
-			Metrics: metrics,
-		}, nil
-	}
-
 	if fileSize < 4 {
-		err = fmt.Errorf("%s is corrupted", fileName)
+		err = fmt.Errorf("snapshot %s is corrupted", filePath)
 		return
 	}
 	payloadSize := fileSize - 4

 	// 2. Створюємо великий буфер для NVMe (4 MB)
 	bufferedReader := bufio.NewReaderSize(file, readBufferSize)
-
 	// 3. Обмежуємо читання лише розміром Payload
 	limitReader := io.LimitReader(bufferedReader, payloadSize)
-
 	// 4. Створюємо хеш та обгортку TeeReader, яка рахує CRC32 на льоту
 	src := io.TeeReader(limitReader, hasher)

@@ -189,6 +177,7 @@ func ReadSnapshot(fileName string) (out ReadSnapshotOut, err error) {
 		if err != nil {
 			return
 		}
+		fmt.Println("metricID", metricID)
 		metricType, err = bin.ReadByte(src)
 		if err != nil {
 			return
@@ -198,10 +187,13 @@ func ReadSnapshot(fileName string) (out ReadSnapshotOut, err error) {
 		if err != nil {
 			return
 		}
+		fmt.Println("m.MetricType", m.MetricType)
+		fmt.Println("m.FracDigits", m.FracDigits)
 		m.LastPageNo, err = bin.ReadUint32(src)
 		if err != nil {
 			return
 		}
+		fmt.Println("m.LastPageNo", m.LastPageNo)
 		m.TimestampsSize, err = bin.ReadUint16AsInt(src)
 		if err != nil {
 			return
@@ -210,7 +202,8 @@ func ReadSnapshot(fileName string) (out ReadSnapshotOut, err error) {
 		if err != nil {
 			return
 		}
-		err = bin.ReadNInto(src, buf[len(buf)-m.TimestampsSize:])
+		fmt.Println("m.TimestampsSize", m.TimestampsSize, "m.ValuesSize", m.ValuesSize)
+		err = bin.ReadNInto(src, buf[storage.DataPagePayloadSize-m.TimestampsSize:storage.DataPagePayloadSize])
 		if err != nil {
 			return
 		}
@@ -218,11 +211,13 @@ func ReadSnapshot(fileName string) (out ReadSnapshotOut, err error) {
 		if err != nil {
 			return
 		}
+		fmt.Printf("% x\n", buf)
 		//
 		levelsCount, err = bin.ReadVarSize(src)
 		if err != nil {
 			return
 		}
+		fmt.Println("levels count:", levelsCount)
 		for range levelsCount {
 			var (
 				buf   = make([]byte, storage.IndexPageSize)
@@ -232,10 +227,12 @@ func ReadSnapshot(fileName string) (out ReadSnapshotOut, err error) {
 			if err != nil {
 				return
 			}
+			fmt.Println("records count:", count)
 			err = bin.ReadNInto(src, buf[:count*storage.IndexRecordSize])
 			if err != nil {
 				return
 			}
+			fmt.Printf("% x\n", buf)
 			m.IndexLevelTails = append(m.IndexLevelTails, storage.IndexLevelTail{
 				Buffer:       buf,
 				RecordsCount: count,
@@ -258,12 +255,10 @@ func ReadSnapshot(fileName string) (out ReadSnapshotOut, err error) {
 	if err != nil {
 		return
 	}
-
 	calculatedCRC := hasher.Sum32()
-
 	if expectedCRC != calculatedCRC {
 		err = fmt.Errorf("%s is corrupted. Calculated CRC %d not equal expected CRC %d",
-			fileName, calculatedCRC, expectedCRC)
+			filePath, calculatedCRC, expectedCRC)
 		return
 	}

@@ -283,6 +278,7 @@ func writeFreePages(dst io.Writer, frozenPagesCount int, pageNumbers []uint32) (
 	if err != nil {
 		return
 	}
+	fmt.Println("write frozenPagesCount:", frozenPagesCount)
 	_, err = bin.WriteVarSize(dst, len(pageNumbers))
 	if err != nil {
 		return
@@ -305,6 +301,7 @@ func readFreePages(src io.Reader) (_ int, _ []uint32, err error) {
 	if err != nil {
 		return
 	}
+	fmt.Println("read frozenPagesCount:", frozenPagesCount)
 	pageNumbersCount, err := bin.ReadVarSize(src)
 	if err != nil {
 		return
--- a/worker/snapshot_test.go
+++ b/worker/snapshot_test.go
@@ -1,25 +1,74 @@
 package worker

 import (
+	"bytes"
 	"fmt"
+	"os"
+	"reflect"
 	"slices"
 	"testing"

 	"gordenko.dev/dima/qb"
+	"gordenko.dev/dima/qb/enc"
 	"gordenko.dev/dima/qb/storage"
 )

 func TestWriteReadSnapshot(t *testing.T) {
-	metrics := make(map[uint32]*Metric)
-	metrics[1] = &Metric{
+	storage.DataPageSize = 32
+	storage.DataPagePayloadSize = 20
+	storage.IndexPageSize = 16
+
+	buf := []byte{
+		// values
+		0x8f, // base value
+		0x80, // delta 0
+		0x01, // run (len = 3)
+		0x81, // delta 1
+		0x81, // literal (len = 2)
+		// empty space
+		0x00, 0x00, 0x00, 0x00,
+		0x00, 0x00, 0x00,
+		// timestamps
+		0x80,                   // h-byte (literal, len=1)
+		0x94,                   // delta 20
+		0x01,                   // h-byte (run, len=3)
+		0xbc,                   // delta 60
+		0x28, 0x80, 0x24, 0x6a, // since
+		// footer
+		0x00, 0x00, 0x00, 0x00,
+		0x00, 0x00, 0x00, 0x00,
+		0x00, 0x00, 0x00, 0x00,
+	}
+
+	databuf := buf[:storage.DataPagePayloadSize]
+	timestampsSize := 8
+	valuesSize := 5
+
+	metrics := map[uint32]*Metric{
+		1: {
 			metricType: qb.Cumulative,
 			fracDigits: 3,
 			lastPageNo: 1000,
-		buffer:     []byte{},
+			buffer:     buf,
+			timestamps: enc.NewTimeDeltaCompressor(databuf, timestampsSize),
+			values:     enc.NewValueDeltaCompressor(qb.Cumulative, 3, databuf, valuesSize),
+			indexLevelTails: []storage.IndexLevelTail{
+				{
+					Buffer: []byte{
+						0x01, 0x01, 0x01, 0x01,
+						0x02, 0x02, 0x02, 0x02,
+						0x00,
+						// footer
+						0x00, 0x00, 0x00, 0x00,
+						0x00, 0x00, 0x00,
+					},
+					RecordsCount: 1,
+				},
+			},
+		},
 	}
 	in := WriteSnapshotIn{
 		SnapshotNumber:        1,
-		Dir:                   ".",
 		WriteBufferSize:       8 * 1024 * 1024,
 		Metrics:               metrics,
 		FrozenIndexPagesCount: 7,
@@ -31,14 +80,17 @@ func TestWriteReadSnapshot(t *testing.T) {
 			6, 7, 8,
 		},
 	}
-	err := WriteSnapshot(in)
+
+	fileName := "test.snapshot"
+
+	err := writeSnapshot(fileName, in)
 	if err != nil {
 		t.Fatalf("writeSnapshot: %s", err)
 	}

-	out, err := ReadSnapshot("1.snapshot")
+	out, err := ReadSnapshot(fileName)
 	if err != nil {
-		return
+		t.Fatal(err)
 	}

 	if out.FrozenIndexPagesCount != in.FrozenIndexPagesCount {
@@ -67,6 +119,7 @@ func TestWriteReadSnapshot(t *testing.T) {
 			t.Fatalf("metric %d: %s", metricID, err)
 		}
 	}
+	os.Remove(fileName)
 }

 func cmpMetric(replay *storage.ReplayMetric, origin *Metric) error {
@@ -82,9 +135,21 @@ func cmpMetric(replay *storage.ReplayMetric, origin *Metric) error {
 		return fmt.Errorf("lastPageNo: got %d are not equal expected %d",
 			replay.LastPageNo, origin.lastPageNo)
 	}
-	// if !reflect.DeepEqual() {
-	// 	return fmt.Errorf("lastPageNo: got %d are not equal expected %d",
-	// 		replay.LastPageNo, origin.lastPageNo)
-	// }
+	if !reflect.DeepEqual(replay.IndexLevelTails, origin.indexLevelTails) {
+		return fmt.Errorf("indexLevelTails: got %#v are not equal expected %#v",
+			replay.IndexLevelTails, origin.indexLevelTails)
+	}
+	if !bytes.Equal(replay.Buf, origin.buffer) {
+		return fmt.Errorf("buffer: got % x are not equal expected % x",
+			replay.Buf, origin.buffer)
+	}
+	if replay.TimestampsSize != origin.timestamps.Size() {
+		return fmt.Errorf("timestampsSize: got %d are not equal expected %d",
+			replay.TimestampsSize, origin.timestamps.Size())
+	}
+	if replay.ValuesSize != origin.values.Size() {
+		return fmt.Errorf("valuesSize: got %d are not equal expected %d",
+			replay.ValuesSize, origin.values.Size())
+	}
 	return nil
 }
--- a/worker/worker.go
+++ b/worker/worker.go
@@ -27,20 +27,19 @@ const (
 	NoMetric           = 4
 	MetricDuplicate    = 5
 	Succeed            = 6
-	NewPage                  = 7
 	ExpiredMeasure     = 8
 	NonMonotonicValue  = 9
-	CanAppend                = 10
 	WrongMetricType    = 11
 	NoMeasuresToDelete = 12
-	DeleteFromAtreeNotNeeded = 13
-	DeleteFromAtreeRequired  = 14
+	//DeleteFromAtreeNotNeeded = 13
+	//DeleteFromAtreeRequired = 14
 )

 type Worker struct {
 	inbox          *inbox.Inbox
 	storageInbox   *inbox.Inbox
 	dir            string
+	databaseName   string
 	snapshotNumber int
 	tmp            []byte
 	metrics        map[uint32]*Metric
@@ -53,6 +52,7 @@ type Options struct {
 	StorageInbox  *inbox.Inbox
 	ReplayMetrics map[uint32]*storage.ReplayMetric
 	Dir           string
+	DatabaseName  string
 	ExitCh        chan struct{}
 	WaitGroup     *sync.WaitGroup
 }
@@ -62,6 +62,7 @@ func New(opt Options) *Worker {
 		inbox:        opt.Inbox,
 		storageInbox: opt.StorageInbox,
 		dir:          opt.Dir,
+		databaseName: opt.DatabaseName,
 		tmp:          make([]byte, 26),
 		metrics:      make(map[uint32]*Metric),
 		exitCh:       opt.ExitCh,
@@ -151,13 +152,13 @@ func (s *Worker) doWork() {
 			s.applyCommits(req) // all metrics only

 		case ListCurrentValuesReq:
-			s.tryListCurrentValues(req) // all metrics only
+			s.ListCurrentValues(req) // all metrics only

 		case RangeScanReq:
 			s.RangeScan(req)

 		case FullScanReq:
-			s.tryFullScan(req)
+			s.FullScan(req)

 		case AddMetricReq:
 			s.AddMetric(req)
@@ -196,7 +197,7 @@ func (s *Worker) processMetricQueue(metricID uint32, metric *Metric, tmp []byte)
 			s.GetMetric(req)

 		case AppendMeasuresReq:
-			metric.StartAppendMeasures(req, tmp, s.storageInbox)
+			metric.AppendMeasures(req, tmp, s.storageInbox)

 		case DeleteMetricReq:
 			s.startDeleteMetric(metric, req)
@@ -213,27 +214,36 @@ func (s *Worker) processMetricQueue(metricID uint32, metric *Metric, tmp []byte)

 type AddMetricReq struct {
 	MetricID   uint32
+	MetricType qb.MetricType
+	FracDigits byte
 	ResultCh   chan byte
 }

 func (s *Worker) AddMetric(req AddMetricReq) {
 	_, ok := s.metrics[req.MetricID]
 	if ok {
+		fmt.Println("add metric duplicate")
 		req.ResultCh <- MetricDuplicate
 		return
 	}
-	fmt.Println("metric not found. Success")
-	req.ResultCh <- Succeed // new
-
-	// lockEntry, ok := s.metricLockEntries[req.MetricID]
-	// if ok {
-	// 	lockEntry.WaitQueue = append(lockEntry.WaitQueue, req)
-	// } else {
-	// 	s.metricLockEntries[req.MetricID] = &metricLockEntry{
-	// 		XLock: true,
-	// 	}
-	// 	req.ResultCh <- Succeed
-	// }
+	var (
+		buf     = make([]byte, storage.DataPageSize)
+		databuf = buf[:storage.DataPagePayloadSize]
+	)
+	s.metrics[req.MetricID] = &Metric{
+		metricType: req.MetricType,
+		fracDigits: req.FracDigits,
+		buffer:     buf,
+		timestamps: enc.NewTimeDeltaCompressor(databuf, 0),
+		values:     enc.NewValueDeltaCompressor(req.MetricType, req.FracDigits, databuf, 0),
+		xLock:      true,
+	}
+	s.storageInbox.Push(storage.MetricAdd{
+		MetricID:   req.MetricID,
+		MetricType: req.MetricType,
+		FracDigits: req.FracDigits,
+		ResultCh:   req.ResultCh,
+	})
 }

 func (s *Worker) processTryAddMetricReqsImmediatelyAfterDelete(reqs []AddMetricReq) {
@@ -379,7 +389,7 @@ func (s *Worker) onMeasuresAppendCommited(rec storage.MeasuresAppendCommited) {
 	metric, ok := s.metrics[rec.MetricID]
 	if !ok {
 		qb.Abort(qb.NoMetricBug,
-			fmt.Errorf("finAppendMeasures: metric %d not found",
+			fmt.Errorf("onMeasuresAppendCommited: metric %d not found",
 				rec.MetricID))
 	}
 	metric.OnMeasuresAppendCommited(rec)
@@ -395,30 +405,25 @@ func (s *Worker) onMeasuresAppendWithGrowCommited(rec storage.MeasuresAppendWith
 	metric.OnMeasuresAppendWithGrowCommited(rec)
 }

-type AppendMeasuresResult struct {
-	ResultCode byte
-	Written    int
-}
-
 type AppendMeasuresReq struct {
 	MetricID uint32
 	Measures []proto.Measure
-	ResultCh chan AppendMeasuresResult
+	ResultCh chan storage.MeasuresAppendResult
 }

 func (s *Worker) AppendMeasures(req AppendMeasuresReq) {
 	metric, ok := s.metrics[req.MetricID]
 	if !ok {
-		req.ResultCh <- AppendMeasuresResult{
+		req.ResultCh <- storage.MeasuresAppendResult{
 			ResultCode: NoMetric,
 		}
 		return
 	}
-	if metric.XLock {
+	if metric.xLock {
 		metric.WaitQueue = append(metric.WaitQueue, req)
 		return
 	}
-	metric.StartAppendMeasures(req, s.tmp, s.storageInbox)
+	metric.AppendMeasures(req, s.tmp, s.storageInbox)
 }

 type RangeScanResult struct {
@@ -452,7 +457,7 @@ func (s *Worker) RangeScan(req RangeScanReq) {
 		return
 	}

-	if metric.XLock {
+	if metric.xLock {
 		metric.WaitQueue = append(metric.WaitQueue, req)
 		return
 	}
@@ -473,7 +478,7 @@ type FullScanReq struct {
 	ResultCh       chan FullScanResult
 }

-func (s *Worker) tryFullScan(req FullScanReq) {
+func (s *Worker) FullScan(req FullScanReq) {
 	metric, ok := s.metrics[req.MetricID]
 	if !ok {
 		req.ResultCh <- FullScanResult{
@@ -488,7 +493,7 @@ func (s *Worker) tryFullScan(req FullScanReq) {
 		return
 	}

-	if metric.XLock {
+	if metric.xLock {
 		metric.WaitQueue = append(metric.WaitQueue, req)
 		return
 	}
@@ -501,7 +506,7 @@ type ListCurrentValuesReq struct {
 	ResultCh       chan struct{}
 }

-func (s *Worker) tryListCurrentValues(req ListCurrentValuesReq) {
+func (s *Worker) ListCurrentValues(req ListCurrentValuesReq) {
 	for _, metricID := range req.MetricIDs {
 		metric, ok := s.metrics[metricID]
 		if ok {
@@ -539,10 +544,11 @@ func (s *Worker) applyCommits(req storage.Changes) {

 	if req.SnapshotNumberCh != nil {
 		s.snapshotNumber++
-		err := WriteSnapshot(WriteSnapshotIn{
+		err := writeSnapshot(
+			qb.GetSnapshotFilePath(s.dir, s.databaseName, s.snapshotNumber),
+			WriteSnapshotIn{
 				SnapshotNumber:        s.snapshotNumber,
-			Dir:                   s.dir,
-			WriteBufferSize:       4 * 1024 * 1024, // 1mb
+				WriteBufferSize:       4 * 1024 * 1024, // 4mb
 				Metrics:               s.metrics,
 				FrozenIndexPagesCount: req.FrozenIndexPagesCount,
 				IndexPageNumbers:      req.IndexPageNumbers,
@@ -552,42 +558,18 @@ func (s *Worker) applyCommits(req storage.Changes) {
 		if err != nil {
 			qb.Abort(qb.WriteSnapshotFailed, err)
 		}
-
 		req.SnapshotNumberCh <- s.snapshotNumber
 	}
 }

 func (s *Worker) onMetricAddCommited(rec storage.MetricAddCommited) {
-	// fix lock
-	_, ok := s.metrics[rec.MetricID]
-	if ok {
+	metric, ok := s.metrics[rec.MetricID]
+	if !ok {
 		qb.Abort(qb.MetricAddedBug,
-			fmt.Errorf("addMetric: metric %d already added",
-				rec.MetricID))
-	}
-
-	// if !lockEntry.XLock {
-	// 	qb.Abort(qb.NoXLockBug,
-	// 		fmt.Errorf("addMetric: xlock not set for the metric %d",
-	// 			rec.MetricID))
-	// }
-
-	// lockEntry.XLock = false
-	// delete(s.metricLockEntries, rec.MetricID)
-}
-
-func (s *Worker) addMetric(rec storage.MetricAddRecord) {
-	var (
-		buf     = make([]byte, storage.DataPageSize)
-		databuf = buf[:storage.DataPagePayloadSize]
-	)
-	s.metrics[rec.MetricID] = &Metric{
-		metricType: rec.MetricType,
-		fracDigits: rec.FracDigits,
-		buffer:     buf,
-		timestamps: enc.NewTimeDeltaCompressor(databuf, 0),
-		values:     enc.NewValueDeltaCompressor(rec.MetricType, rec.FracDigits, databuf, 0),
+			fmt.Errorf("metric %d not found after commit", rec.MetricID))
 	}
+	metric.xLock = false
+	rec.ResultCh <- Succeed // new
 }

 func (s *Worker) onMetricDeleteCommited(rec storage.MetricDeleteCommited) {
@@ -598,7 +580,7 @@ func (s *Worker) onMetricDeleteCommited(rec storage.MetricDeleteCommited) {
 				rec.MetricID))
 	}

-	if !metric.XLock {
+	if !metric.xLock {
 		qb.Abort(qb.NoXLockBug,
 			fmt.Errorf("deleteMetric: xlock not set for the metric %d",
 				rec.MetricID))
@@ -669,13 +651,13 @@ func (s *Worker) onMeasuresDeleteCommited(rec storage.MeasuresDeleteCommited) {
 				rec.MetricID))
 	}

-	if !metric.XLock {
+	if !metric.xLock {
 		qb.Abort(qb.NoXLockBug,
 			fmt.Errorf("deleteMeasures: xlock not set for the metric %d",
 				rec.MetricID))
 	}
 	metric.OnMeasuresDeleteCommited(rec)
-	metric.XLock = false
+	metric.xLock = false
 	// FIX add in storage
 	// if len(rec.FreePageNumbers) > 0 {
 	// 	s.freeList.AddPages(rec.FreePageNumbers)