README.md

@@ -1,108 +0,0 @@
-# zkv
-
-Simple key-value store for single-user applications.
-
-## Pros
-
-* Simple two file structure (data file and index file)
-* Internal Zstandard compression by [klauspost/compress/zstd](https://github.com/klauspost/compress/tree/master/zstd)
-* Threadsafe operations through `sync.RWMutex`
-
-## Cons
-
-* Index stored in memory (`map[key hash (28 bytes)]file offset (int64)`)
-* No transaction system
-* Index file is fully rewrited on every store commit
-* No way to recover disk space from deleted records
-* Write/Delete operations block Read and each other operations
-
-## Usage
-
-Create or open existing file:
-
-```go
-db, err := zkv.Open("path to file")
-```
-
-Data operations:
-
-```go
-// Write data
-err = db.Set(key, value) // key and value can be any of type
-
-// Read data
-var value ValueType
-err = db.Get(key, &value)
-
-// Delete data
-err = db.Delete(key)
-```
-
-Other methods:
-
-```go
-// Flush data to disk
-err = db.Flush()
-
-// Backup data to another file
-err = db.Backup("new/file/path")
-```
-
-## Store options
-
-```go
-type Options struct {
-	// Maximum number of concurrent reads
-	MaxParallelReads int
-
-	// Compression level
-	CompressionLevel zstd.EncoderLevel
-
-	// Memory write buffer size in bytes
-	MemoryBufferSize int
-
-	// Disk write buffer size in bytes
-	DiskBufferSize int
-}
-
-```
-
-## File structure
-
-Record is `encoding/gob` structure:
-
-| Field      | Description                        | Size     |
-| ---------- | ---------------------------------- | -------- |
-| Type       | Record type                        | uint8    |
-| KeyHash    | Key hash                           | 28 bytes |
-| ValueBytes | Value gob-encoded bytes            | variable |
-
-File is log stuctured list of commands:
-
-| Field  | Description              | Size     |
-| -------| ------------------------ | -------- |
-| Length | Record body bytes length | int64    |
-| Body   | Gob-encoded record       | variable |
-
-Index file is simple gob-encoded map:
-
-```go
-map[string]struct {
-	BlockOffset  int64
-	RecordOffset int64
-}
-```
-
-where map key is data key hash and value - data offset in data file.
-
-## Resource consumption
-
-Store requirements:
-
-* around 300 Mb of RAM per 1 million of keys
-* around 34 Mb of disk space for index file per 1 million of keys
-
-## TODO
-
-- [ ] Add recovery previous state of store file on write error
-- [ ] Add method for index rebuild

defaults.go

@@ -1,17 +0,0 @@
-package zkv
-
-import (
-	"runtime"
-
-	"github.com/klauspost/compress/zstd"
-)
-
-var defaultOptions = Options{
-	MaxParallelReads: runtime.NumCPU(),
-	CompressionLevel: zstd.SpeedDefault,
-	MemoryBufferSize: 4 * 1024 * 1024,
-	DiskBufferSize:   1 * 1024 * 1024,
-	useIndexFile:     true,
-}
-
-const indexFileExt = ".idx"

go.mod

@@ -3,8 +3,8 @@ module github.com/nxshock/zkv
 go 1.19
 
 require (
-	github.com/klauspost/compress v1.16.4
+	github.com/klauspost/compress v1.15.12
-	github.com/stretchr/testify v1.8.2
+	github.com/stretchr/testify v1.8.1
 )
 
 require (

go.sum

@@ -1,8 +1,8 @@
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
-github.com/klauspost/compress v1.16.4 h1:91KN02FnsOYhuunwU4ssRe8lc2JosWmizWa91B5v1PU=
+github.com/klauspost/compress v1.15.12 h1:YClS/PImqYbn+UILDnqxQCZ3RehC9N318SU3kElDUEM=
-github.com/klauspost/compress v1.16.4/go.mod h1:ntbaceVETuRiXiv4DpjP66DpAtAGkEQskQzEyD//IeE=
+github.com/klauspost/compress v1.15.12/go.mod h1:QPwzmACJjUTFsnSHH934V6woptycfrDDJnH7hvFVbGM=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
@@ -10,8 +10,8 @@ github.com/stretchr/objx v0.4.0/go.mod h1:YvHI0jy2hoMjB+UWwv71VJQ9isScKT/TqJzVSS
 github.com/stretchr/objx v0.5.0/go.mod h1:Yh+to48EsGEfYuaHDzXPcE3xhTkx73EhmCGUpEOglKo=
 github.com/stretchr/testify v1.7.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
 github.com/stretchr/testify v1.8.0/go.mod h1:yNjHg4UonilssWZ8iaSj1OCr/vHnekPRkoO+kdMU+MU=
-github.com/stretchr/testify v1.8.2 h1:+h33VjcLVPDHtOdpUCuF+7gSuG3yGIftsP1YvFihtJ8=
+github.com/stretchr/testify v1.8.1 h1:w7B6lhMri9wdJUVmEZPGGhZzrYTPvgJArz7wNPgYKsk=
-github.com/stretchr/testify v1.8.2/go.mod h1:w2LPCIKwWwSfY2zedu0+kehJoqGctiVI29o6fzry7u4=
+github.com/stretchr/testify v1.8.1/go.mod h1:w2LPCIKwWwSfY2zedu0+kehJoqGctiVI29o6fzry7u4=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

options.go

@@ -1,40 +0,0 @@
-package zkv
-
-import "github.com/klauspost/compress/zstd"
-
-type Options struct {
-	// Maximum number of concurrent reads
-	MaxParallelReads int
-
-	// Compression level
-	CompressionLevel zstd.EncoderLevel
-
-	// Memory write buffer size in bytes
-	MemoryBufferSize int
-
-	// Disk write buffer size in bytes
-	DiskBufferSize int
-
-	// Use index file
-	useIndexFile bool
-}
-
-func (o *Options) setDefaults() {
-	o.useIndexFile = true // TODO: implement database search without index
-
-	if o.MaxParallelReads == 0 {
-		o.MaxParallelReads = defaultOptions.MaxParallelReads
-	}
-
-	if o.CompressionLevel == 0 {
-		o.CompressionLevel = defaultOptions.CompressionLevel
-	}
-
-	if o.MemoryBufferSize == 0 {
-		o.MemoryBufferSize = defaultOptions.MemoryBufferSize
-	}
-
-	if o.DiskBufferSize == 0 {
-		o.DiskBufferSize = defaultOptions.DiskBufferSize
-	}
-}

record.go

@@ -2,7 +2,6 @@ package zkv
 
 import (
 	"bytes"
-	"crypto/sha256"
 	"encoding/binary"
 	"encoding/gob"
 	"io"
@@ -17,21 +16,12 @@ const (
 
 type Record struct {
 	Type       RecordType
-	KeyHash    [28]byte
+	KeyHash    []byte
 	ValueBytes []byte
 }
 
-func newRecordBytes(recordType RecordType, keyHash [sha256.Size224]byte, valueBytes []byte) (*Record, error) {
-	record := &Record{
-		Type:       recordType,
-		KeyHash:    keyHash,
-		ValueBytes: valueBytes}
-
-	return record, nil
-}
-
 func newRecord(recordType RecordType, key, value interface{}) (*Record, error) {
-	keyHash, err := hashInterface(key)
+	keyBytes, err := encode(key)
 	if err != nil {
 		return nil, err
 	}
@@ -41,7 +31,12 @@ func newRecord(recordType RecordType, key, value interface{}) (*Record, error) {
 		return nil, err
 	}
 
-	return newRecordBytes(recordType, keyHash, valueBytes)
+	record := &Record{
+		Type:       recordType,
+		KeyHash:    hashBytes(keyBytes),
+		ValueBytes: valueBytes}
+
+	return record, nil
 }
 
 func (r *Record) Marshal() ([]byte, error) {

record_test.go

@@ -1,35 +0,0 @@
-package zkv
-
-import (
-	"bytes"
-	"testing"
-
-	"github.com/stretchr/testify/assert"
-)
-
-func TestRecord(t *testing.T) {
-	buf := new(bytes.Buffer)
-
-	var records []Record
-
-	for i := 0; i < 10; i++ {
-		record, err := newRecord(RecordTypeSet, i, i)
-		assert.NoError(t, err)
-
-		records = append(records, *record)
-
-		b, err := record.Marshal()
-		assert.NoError(t, err)
-
-		_, err = buf.Write(b)
-		assert.NoError(t, err)
-	}
-
-	for i := 0; i < 10; i++ {
-		_, record, err := readRecord(buf)
-		assert.NoError(t, err)
-
-		assert.Equal(t, record.KeyHash, records[i].KeyHash)
-		assert.Equal(t, record.ValueBytes, records[i].ValueBytes)
-	}
-}

utils.go

@@ -4,9 +4,7 @@ import (
 	"bytes"
 	"crypto/sha256"
 	"encoding/gob"
-	"errors"
 	"io"
-	"os"
 )
 
 func encode(value interface{}) ([]byte, error) {
@@ -19,17 +17,20 @@ func decode(b []byte, value interface{}) error {
 	return gob.NewDecoder(bytes.NewReader(b)).Decode(value)
 }
 
-func hashInterface(value interface{}) ([sha256.Size224]byte, error) {
+func hashInterface(value interface{}) ([]byte, error) {
 	valueBytes, err := encode(value)
 	if err != nil {
-		return [sha256.Size224]byte{}, err
+		return nil, err
 	}
 
 	return hashBytes(valueBytes), nil
 }
 
-func hashBytes(b []byte) [sha256.Size224]byte {
+func hashBytes(b []byte) []byte {
-	return sha256.Sum224(b)
+	bytes := sha256.Sum224(b)
+
+	return bytes[:]
+
 }
 
 func skip(r io.Reader, count int64) (err error) {
@@ -42,13 +43,3 @@ func skip(r io.Reader, count int64) (err error) {
 
 	return err
 }
-
-func isFileExists(filePath string) (bool, error) {
-	if _, err := os.Stat(filePath); err == nil {
-		return true, nil
-	} else if errors.Is(err, os.ErrNotExist) {
-		return false, nil
-	} else {
-		return false, err
-	}
-}

zkv.go

@@ -1,11 +1,8 @@
 package zkv
 
 import (
-	"bufio"
 	"bytes"
-	"crypto/sha256"
 	"encoding/base64"
-	"encoding/gob"
 	"fmt"
 	"io"
 	"os"
@@ -14,88 +11,156 @@ import (
 	"github.com/klauspost/compress/zstd"
 )
 
-type Offsets struct {
+type Database struct {
-	BlockOffset  int64
+	dataOffset map[string]int64
-	RecordOffset int64
+	file       *os.File
+	compressor *zstd.Encoder
+	filePath   string
+	offset     int64
+
+	mu sync.Mutex
 }
 
-type Store struct {
+func (db *Database) Close() error {
-	dataOffset map[string]Offsets
+	db.mu.Lock()
+	defer db.mu.Unlock()
 
-	filePath string
+	err := db.compressor.Close()
-
-	buffer           *bytes.Buffer
-	bufferDataOffset map[string]int64
-
-	options Options
-
-	readOrderChan chan struct{}
-
-	mu sync.RWMutex
-}
-
-func OpenWithOptions(filePath string, options Options) (*Store, error) {
-	options.setDefaults()
-
-	store := &Store{
-		dataOffset:       make(map[string]Offsets),
-		bufferDataOffset: make(map[string]int64),
-		buffer:           new(bytes.Buffer),
-		filePath:         filePath,
-		options:          options,
-		readOrderChan:    make(chan struct{}, int(options.MaxParallelReads))}
-
-	if options.useIndexFile {
-		idxFile, err := os.Open(filePath + indexFileExt)
-		if err == nil {
-			err = gob.NewDecoder(idxFile).Decode(&store.dataOffset)
-			if err != nil {
-				return nil, err
-			}
-
-			return store, nil
-		}
-	}
-
-	exists, err := isFileExists(filePath)
 	if err != nil {
-		return nil, err
+		return err
 	}
 
+	return db.file.Close()
+}
+
+func (db *Database) Set(key, value interface{}) error {
+	db.mu.Lock()
+	defer db.mu.Unlock()
+
+	record, err := newRecord(RecordTypeSet, key, value)
+	if err != nil {
+		return err
+	}
+
+	b, err := record.Marshal()
+	if err != nil {
+		return err
+	}
+
+	db.dataOffset[string(record.KeyHash)] = db.offset // TODO: удалить хеш и откатить запись в случае ошибки
+
+	_, err = db.compressor.Write(b)
+	if err != nil {
+		return err
+	}
+
+	db.offset += int64(len(b)) // TODO: удалить хеш и откатить запись в случае ошибки
+
+	return nil
+}
+
+func (db *Database) Get(key, value interface{}) error {
+	db.mu.Lock()
+	defer db.mu.Unlock()
+
+	hashToFind, err := hashInterface(key)
+	if err != nil {
+		return err
+	}
+
+	offset, exists := db.dataOffset[string(hashToFind)]
 	if !exists {
-		return store, nil
+		return ErrNotExists
 	}
 
-	err = store.rebuildIndex()
+	readF, err := os.Open(db.filePath)
 	if err != nil {
-		return nil, err
+		return err
+	}
+	defer readF.Close()
+
+	decompressor, err := zstd.NewReader(readF)
+	if err != nil {
+		return err
+	}
+	defer decompressor.Close()
+
+	err = skip(decompressor, offset)
+	if err != nil {
+		return err
 	}
 
-	return store, nil
+	_, record, err := readRecord(decompressor)
+	if err != nil {
+		return err
+	}
+
+	if !bytes.Equal(record.KeyHash, hashToFind) {
+		return fmt.Errorf("wrong hash on this offset: expected %s, got %s", base64.StdEncoding.EncodeToString(hashToFind), base64.StdEncoding.EncodeToString(record.KeyHash)) // TODO: заменить на константную ошибку
+	}
+
+	return decode(record.ValueBytes, value)
 }
 
-func Open(filePath string) (*Store, error) {
+func Open(filePath string) (*Database, error) {
-	options := defaultOptions
+	f, err := os.OpenFile(filePath, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
-	return OpenWithOptions(filePath, options)
+	if err != nil {
+		return nil, fmt.Errorf("ошибка при открытии файла для записи: %v", err)
+	}
+
+	compressor, err := zstd.NewWriter(f)
+	if err != nil {
+		return nil, fmt.Errorf("ошибка при инициализации компрессора: %v", err)
+	}
+
+	database := &Database{
+		dataOffset: make(map[string]int64),
+		offset:     0,
+		file:       f,
+		compressor: compressor,
+		filePath:   filePath}
+
+	// restore file data
+	readF, err := os.Open(filePath)
+	if err != nil {
+		f.Close()
+		return nil, fmt.Errorf("ошибка при открытии файла для чтения: %v", err)
+	}
+	defer readF.Close()
+
+	decompressor, err := zstd.NewReader(readF)
+	if err != nil {
+		return nil, fmt.Errorf("ошибка при инициализации декомпрессора: %v", err)
+	}
+	defer decompressor.Close()
+
+	offset := int64(0)
+	for {
+		n, record, err := readRecord(decompressor)
+		if err == io.EOF {
+			break
+		}
+		if err != nil {
+			f.Close()
+			return nil, fmt.Errorf("ошибка при чтении записи из файла: %v", err)
+		}
+
+		switch record.Type {
+		case RecordTypeSet:
+			database.dataOffset[string(record.KeyHash)] = offset
+		case RecordTypeDelete:
+			delete(database.dataOffset, string(record.KeyHash))
+		}
+
+		offset += n
+	}
+
+	return database, nil
 }
 
-func (s *Store) Set(key, value interface{}) error {
+func (db *Database) Delete(key interface{}) error {
-	s.mu.Lock()
+	db.mu.Lock()
-	defer s.mu.Unlock()
+	defer db.mu.Unlock()
-
-	return s.set(key, value)
-}
-
-func (s *Store) Get(key, value interface{}) error {
-	s.mu.RLock()
-	defer s.mu.RUnlock()
-
-	return s.get(key, value)
-}
-
-func (s *Store) Delete(key interface{}) error {
-	s.mu.Lock()
-	defer s.mu.Unlock()
 
 	keyHash, err := hashInterface(key)
 	if err != nil {
@@ -112,397 +177,14 @@ func (s *Store) Delete(key interface{}) error {
 		return err
 	}
 
-	delete(s.dataOffset, string(record.KeyHash[:]))
+	delete(db.dataOffset, string(record.KeyHash))
-	delete(s.bufferDataOffset, string(record.KeyHash[:]))
 
-	_, err = s.buffer.Write(b)
+	_, err = db.compressor.Write(b)
 	if err != nil {
 		return err
 	}
 
-	if s.buffer.Len() > s.options.MemoryBufferSize {
+	db.offset += int64(len(b))
-		err = s.flush()
-
-		if err != nil {
-			return err
-		}
-	}
 
 	return nil
 }
-
-func (s *Store) Flush() error {
-	s.mu.Lock()
-	defer s.mu.Unlock()
-
-	return s.flush()
-}
-
-func (s *Store) BackupWithOptions(filePath string, newFileOptions Options) error {
-	s.mu.Lock()
-	defer s.mu.Unlock()
-
-	err := s.flush()
-	if err != nil {
-		return err
-	}
-
-	newStore, err := OpenWithOptions(filePath, newFileOptions)
-	if err != nil {
-		return err
-	}
-
-	for keyHashStr := range s.dataOffset {
-		var keyHash [sha256.Size224]byte
-		copy(keyHash[:], keyHashStr)
-
-		valueBytes, err := s.getGobBytes(keyHash)
-		if err != nil {
-			newStore.Close()
-			return err
-		}
-		err = newStore.setBytes(keyHash, valueBytes)
-		if err != nil {
-			newStore.Close()
-			return err
-		}
-	}
-
-	return newStore.Close()
-}
-
-func (s *Store) Backup(filePath string) error {
-	return s.BackupWithOptions(filePath, defaultOptions)
-}
-
-func (s *Store) Close() error {
-	s.mu.Lock()
-	defer s.mu.Unlock()
-
-	err := s.flush()
-	if err != nil {
-		return err
-	}
-
-	return nil
-}
-
-func (s *Store) setBytes(keyHash [sha256.Size224]byte, valueBytes []byte) error {
-	record, err := newRecordBytes(RecordTypeSet, keyHash, valueBytes)
-	if err != nil {
-		return err
-	}
-
-	b, err := record.Marshal()
-	if err != nil {
-		return err
-	}
-
-	s.bufferDataOffset[string(record.KeyHash[:])] = int64(s.buffer.Len())
-
-	_, err = s.buffer.Write(b)
-	if err != nil {
-		return err
-	}
-
-	if s.buffer.Len() > s.options.MemoryBufferSize {
-		err = s.flush()
-
-		if err != nil {
-			return err
-		}
-	}
-
-	return nil
-}
-
-func (s *Store) set(key, value interface{}) error {
-	record, err := newRecord(RecordTypeSet, key, value)
-	if err != nil {
-		return err
-	}
-
-	b, err := record.Marshal()
-	if err != nil {
-		return err
-	}
-
-	s.bufferDataOffset[string(record.KeyHash[:])] = int64(s.buffer.Len())
-
-	_, err = s.buffer.Write(b)
-	if err != nil {
-		return err
-	}
-
-	if s.buffer.Len() > s.options.MemoryBufferSize {
-		err = s.flush()
-
-		if err != nil {
-			return err
-		}
-	}
-
-	return nil
-}
-
-func (s *Store) getGobBytes(keyHash [sha256.Size224]byte) ([]byte, error) {
-	s.readOrderChan <- struct{}{}
-	defer func() { <-s.readOrderChan }()
-
-	offset, exists := s.bufferDataOffset[string(keyHash[:])]
-	if exists {
-		reader := bytes.NewReader(s.buffer.Bytes())
-
-		err := skip(reader, offset)
-		if err != nil {
-			return nil, err
-		}
-
-		_, record, err := readRecord(reader)
-		if err != nil {
-			return nil, err
-		}
-
-		return record.ValueBytes, nil
-	}
-
-	offsets, exists := s.dataOffset[string(keyHash[:])]
-	if !exists {
-		return nil, ErrNotExists
-	}
-
-	readF, err := os.Open(s.filePath)
-	if err != nil {
-		return nil, err
-	}
-	defer readF.Close()
-
-	_, err = readF.Seek(offsets.BlockOffset, io.SeekStart)
-	if err != nil {
-		return nil, err
-	}
-
-	decompressor, err := zstd.NewReader(readF)
-	if err != nil {
-		return nil, err
-	}
-	defer decompressor.Close()
-
-	err = skip(decompressor, offsets.RecordOffset)
-	if err != nil {
-		return nil, err
-	}
-
-	_, record, err := readRecord(decompressor)
-	if err != nil {
-		return nil, err
-	}
-
-	if !bytes.Equal(record.KeyHash[:], keyHash[:]) {
-		expectedHashStr := base64.StdEncoding.EncodeToString(keyHash[:])
-		gotHashStr := base64.StdEncoding.EncodeToString(record.KeyHash[:])
-		return nil, fmt.Errorf("wrong hash of offset %d: expected %s, got %s", offset, expectedHashStr, gotHashStr)
-	}
-
-	return record.ValueBytes, nil
-}
-
-func (s *Store) get(key, value interface{}) error {
-	s.readOrderChan <- struct{}{}
-	defer func() { <-s.readOrderChan }()
-
-	hashToFind, err := hashInterface(key)
-	if err != nil {
-		return err
-	}
-
-	b, err := s.getGobBytes(hashToFind)
-	if err != nil {
-		return err
-	}
-
-	return decode(b, value)
-}
-
-func (s *Store) flush() error {
-	l := int64(s.buffer.Len())
-
-	f, err := os.OpenFile(s.filePath, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
-	if err != nil {
-		return fmt.Errorf("open store file: %v", err)
-	}
-	stat, err := f.Stat()
-	if err != nil {
-		f.Close()
-		return fmt.Errorf("stat store file: %v", err)
-	}
-
-	diskWriteBuffer := bufio.NewWriterSize(f, s.options.DiskBufferSize)
-
-	encoder, err := zstd.NewWriter(diskWriteBuffer, zstd.WithEncoderLevel(s.options.CompressionLevel))
-	if err != nil {
-		f.Close()
-		return fmt.Errorf("init encoder: %v", err)
-	}
-
-	_, err = s.buffer.WriteTo(encoder)
-	if err != nil {
-		return err
-	}
-
-	for key, val := range s.bufferDataOffset {
-		s.dataOffset[key] = Offsets{BlockOffset: stat.Size(), RecordOffset: val}
-	}
-
-	s.bufferDataOffset = make(map[string]int64)
-
-	err = encoder.Close()
-	if err != nil {
-		// TODO: truncate file to previous state
-		return err
-	}
-
-	err = diskWriteBuffer.Flush()
-	if err != nil {
-		// TODO: truncate file to previous state
-		return err
-	}
-
-	err = f.Close()
-	if err != nil {
-		return err
-	}
-
-	// Update index file only on data update
-	if s.options.useIndexFile && l > 0 {
-		err = s.saveIndex()
-		if err != nil {
-			return err
-		}
-	}
-
-	return nil
-}
-
-func readBlock(r *bufio.Reader) (line []byte, n int, err error) {
-	delim := []byte{0x28, 0xb5, 0x2f, 0xfd}
-
-	line = make([]byte, len(delim))
-	copy(line, delim)
-
-	for {
-		s, err := r.ReadBytes(delim[len(delim)-1])
-		line = append(line, []byte(s)...)
-		if err != nil {
-			if bytes.Equal(line, delim) { // contains only magic number
-				return []byte{}, 0, err
-			} else {
-				return line, len(s), err
-			}
-		}
-
-		if bytes.Equal(line, append(delim, delim...)) { // first block
-			line = make([]byte, len(delim))
-			copy(line, delim)
-			continue
-		}
-
-		if bytes.HasSuffix(line, delim) {
-			return line[:len(line)-len(delim)], len(s), nil
-		}
-	}
-}
-
-// RebuildIndex renews index from store file
-func (s *Store) RebuildIndex() error {
-	s.mu.Lock()
-	defer s.mu.Unlock()
-
-	err := s.rebuildIndex()
-	if err != nil {
-		return err
-	}
-
-	if s.options.useIndexFile {
-		return s.saveIndex()
-	}
-
-	return nil
-}
-
-func (s *Store) rebuildIndex() error {
-	f, err := os.Open(s.filePath)
-	if err != nil {
-		return err
-	}
-	defer f.Close()
-
-	r := bufio.NewReader(f)
-
-	var blockOffset int64
-
-	s.dataOffset = make(map[string]Offsets)
-
-	for {
-		l, n, err := readBlock(r)
-		if err != nil {
-			if err != io.EOF {
-				return err
-			} else if err == io.EOF && len(l) == 0 {
-				break
-			}
-		}
-
-		dec, err := zstd.NewReader(bytes.NewReader(l))
-
-		var recordOffset int64
-		for {
-			n, record, err := readRecord(dec)
-			if err != nil {
-				if err == io.EOF {
-					break
-				} else {
-					return err
-				}
-			}
-
-			switch record.Type {
-			case RecordTypeSet:
-				s.dataOffset[string(record.KeyHash[:])] = Offsets{BlockOffset: blockOffset, RecordOffset: recordOffset}
-			case RecordTypeDelete:
-				delete(s.dataOffset, string(record.KeyHash[:]))
-			}
-			recordOffset += n
-		}
-
-		blockOffset += int64(n)
-	}
-
-	idxBuf := new(bytes.Buffer)
-
-	err = gob.NewEncoder(idxBuf).Encode(s.dataOffset)
-	if err != nil {
-		return err
-	}
-
-	err = os.WriteFile(s.filePath+indexFileExt, idxBuf.Bytes(), 0644)
-	if err != nil {
-		return err
-	}
-
-	return nil
-}
-
-func (s *Store) saveIndex() error {
-	f, err := os.OpenFile(s.filePath+indexFileExt, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0644)
-	if err != nil {
-		return err
-	}
-
-	err = gob.NewEncoder(f).Encode(s.dataOffset)
-	if err != nil {
-		return err
-	}
-
-	return f.Close()
-}

zkv_test.go

@@ -1,8 +1,6 @@
 package zkv
 
 import (
-	"bufio"
-	"io"
 	"os"
 	"testing"
 
@@ -13,7 +11,6 @@ func TestReadWriteBasic(t *testing.T) {
 	const filePath = "TestReadWriteBasic.zkv"
 	const recordCount = 100
 	defer os.Remove(filePath)
-	defer os.Remove(filePath + indexFileExt)
 
 	db, err := Open(filePath)
 	assert.NoError(t, err)
@@ -23,16 +20,7 @@ func TestReadWriteBasic(t *testing.T) {
 		assert.NoError(t, err)
 	}
 
-	assert.Len(t, db.dataOffset, 0)
+	assert.Len(t, db.dataOffset, recordCount)
-	assert.Len(t, db.bufferDataOffset, recordCount)
-
-	for i := 1; i <= recordCount; i++ {
-		var gotValue int
-
-		err = db.Get(i, &gotValue)
-		assert.NoError(t, err)
-		assert.Equal(t, i, gotValue)
-	}
 
 	err = db.Close()
 	assert.NoError(t, err)
@@ -59,7 +47,6 @@ func TestSmallWrites(t *testing.T) {
 	const filePath = "TestSmallWrites.zkv"
 	const recordCount = 100
 	defer os.Remove(filePath)
-	defer os.Remove(filePath + indexFileExt)
 
 	for i := 1; i <= recordCount; i++ {
 		db, err := Open(filePath)
@@ -95,7 +82,6 @@ func TestDeleteBasic(t *testing.T) {
 	const filePath = "TestDeleteBasic.zkv"
 	const recordCount = 100
 	defer os.Remove(filePath)
-	defer os.Remove(filePath + indexFileExt)
 
 	db, err := Open(filePath)
 	assert.NoError(t, err)
@@ -105,15 +91,12 @@ func TestDeleteBasic(t *testing.T) {
 		assert.NoError(t, err)
 	}
 
-	assert.Len(t, db.dataOffset, 0)
+	assert.Len(t, db.dataOffset, recordCount)
-	assert.Len(t, db.bufferDataOffset, recordCount)
 
 	err = db.Delete(50)
 	assert.NoError(t, err)
 
-	assert.Len(t, db.dataOffset, 0)
+	assert.Len(t, db.dataOffset, recordCount-1)
-	assert.Len(t, db.bufferDataOffset, recordCount-1)
-
 	var value int
 	err = db.Get(50, &value)
 	assert.Equal(t, 0, value)
@@ -127,8 +110,6 @@ func TestDeleteBasic(t *testing.T) {
 	assert.NoError(t, err)
 
 	assert.Len(t, db.dataOffset, recordCount-1)
-	assert.Len(t, db.bufferDataOffset, 0)
-
 	value = 0
 	err = db.Get(50, &value)
 	assert.Equal(t, 0, value)
@@ -137,276 +118,3 @@ func TestDeleteBasic(t *testing.T) {
 	err = db.Close()
 	assert.NoError(t, err)
 }
-
-func TestBufferBasic(t *testing.T) {
-	const filePath = "TestBuffer.zkv"
-	defer os.Remove(filePath)
-	defer os.Remove(filePath + indexFileExt)
-
-	db, err := OpenWithOptions(filePath, Options{MemoryBufferSize: 100})
-	assert.NoError(t, err)
-
-	err = db.Set(1, make([]byte, 100))
-	assert.NoError(t, err)
-
-	assert.NotEqual(t, 0, db.dataOffset)
-	assert.Len(t, db.bufferDataOffset, 0)
-	assert.Equal(t, 0, db.buffer.Len())
-
-	var gotValue []byte
-	err = db.Get(1, &gotValue)
-	assert.NoError(t, err)
-
-	assert.Equal(t, make([]byte, 100), gotValue)
-
-	err = db.Close()
-	assert.NoError(t, err)
-}
-
-func TestBufferRead(t *testing.T) {
-	const filePath = "TestBufferRead.zkv"
-	const recordCount = 2
-	defer os.Remove(filePath)
-	defer os.Remove(filePath + indexFileExt)
-
-	db, err := OpenWithOptions(filePath, Options{MemoryBufferSize: 100})
-	assert.NoError(t, err)
-
-	for i := 1; i <= recordCount; i++ {
-		err = db.Set(i, i)
-		assert.NoError(t, err)
-	}
-
-	for i := 1; i <= recordCount; i++ {
-		var gotValue int
-
-		err = db.Get(i, &gotValue)
-		assert.NoError(t, err)
-		assert.Equal(t, i, gotValue)
-	}
-
-	for i := 1; i <= recordCount; i++ {
-		var gotValue int
-
-		err = db.Get(i, &gotValue)
-		assert.NoError(t, err)
-		assert.Equal(t, i, gotValue)
-	}
-
-	err = db.Close()
-	assert.NoError(t, err)
-
-	// try to read
-	db, err = Open(filePath)
-	assert.NoError(t, err)
-
-	assert.Len(t, db.dataOffset, recordCount)
-
-	for i := 1; i <= recordCount; i++ {
-		var gotValue int
-
-		err = db.Get(i, &gotValue)
-		assert.NoError(t, err)
-		assert.Equal(t, i, gotValue)
-	}
-
-	err = db.Close()
-	assert.NoError(t, err)
-
-}
-
-func TestBackupBasic(t *testing.T) {
-	const filePath = "TestBackupBasic.zkv"
-	const newFilePath = "TestBackupBasic2.zkv"
-	const recordCount = 100
-	defer os.Remove(filePath)
-	defer os.Remove(filePath + indexFileExt)
-	defer os.Remove(newFilePath)
-	defer os.Remove(newFilePath + indexFileExt)
-
-	db, err := Open(filePath)
-	assert.NoError(t, err)
-
-	for i := 1; i <= recordCount; i++ {
-		err = db.Set(i, i)
-		assert.NoError(t, err)
-	}
-
-	err = db.Backup(newFilePath)
-	assert.NoError(t, err)
-
-	err = db.Close()
-	assert.NoError(t, err)
-
-	db, err = Open(newFilePath)
-	assert.NoError(t, err)
-
-	assert.Len(t, db.dataOffset, recordCount)
-
-	for i := 1; i <= recordCount; i++ {
-		var gotValue int
-
-		err = db.Get(i, &gotValue)
-		assert.NoError(t, err)
-		assert.Equal(t, i, gotValue)
-	}
-
-	err = db.Close()
-	assert.NoError(t, err)
-
-}
-
-func TestBackupWithDeletedRecords(t *testing.T) {
-	const filePath = "TestBackupWithDeletedRecords.zkv"
-	const newFilePath = "TestBackupWithDeletedRecords2.zkv"
-	const recordCount = 100
-	defer os.Remove(filePath)
-	defer os.Remove(filePath + indexFileExt)
-	defer os.Remove(newFilePath)
-	defer os.Remove(newFilePath + indexFileExt)
-
-	db, err := Open(filePath)
-	assert.NoError(t, err)
-
-	for i := 1; i <= recordCount; i++ {
-		err = db.Set(i, i)
-		assert.NoError(t, err)
-	}
-
-	err = db.Flush()
-	assert.NoError(t, err)
-
-	for i := 1; i <= recordCount; i++ {
-		if i%2 == 1 {
-			continue
-		}
-
-		err = db.Delete(i)
-		assert.NoError(t, err)
-	}
-
-	err = db.Backup(newFilePath)
-	assert.NoError(t, err)
-
-	err = db.Close()
-	assert.NoError(t, err)
-
-	db, err = Open(newFilePath)
-	assert.NoError(t, err)
-
-	assert.Len(t, db.dataOffset, recordCount/2)
-
-	for i := 1; i <= recordCount; i++ {
-		var gotValue int
-
-		err = db.Get(i, &gotValue)
-		if i%2 == 0 {
-			assert.ErrorIs(t, err, ErrNotExists)
-		} else {
-			assert.NoError(t, err)
-			assert.Equal(t, i, gotValue)
-		}
-	}
-
-	err = db.Close()
-	assert.NoError(t, err)
-}
-
-func TestIndexFileBasic(t *testing.T) {
-	const filePath = "TestReadWriteBasic.zkv"
-	const recordCount = 100
-	defer os.Remove(filePath)
-	defer os.Remove(filePath + indexFileExt)
-
-	db, err := Open(filePath)
-	assert.NoError(t, err)
-
-	for i := 1; i <= recordCount; i++ {
-		err = db.Set(i, i)
-		assert.NoError(t, err)
-	}
-
-	assert.Len(t, db.dataOffset, 0)
-	assert.Len(t, db.bufferDataOffset, recordCount)
-
-	for i := 1; i <= recordCount; i++ {
-		var gotValue int
-
-		err = db.Get(i, &gotValue)
-		assert.NoError(t, err)
-		assert.Equal(t, i, gotValue)
-	}
-
-	err = db.Close()
-	assert.NoError(t, err)
-
-	// try to read
-	db, err = Open(filePath)
-	assert.NoError(t, err)
-
-	assert.Len(t, db.dataOffset, recordCount)
-
-	for i := 1; i <= recordCount; i++ {
-		var gotValue int
-
-		err = db.Get(i, &gotValue)
-		assert.NoError(t, err)
-		assert.Equal(t, i, gotValue)
-	}
-
-	err = db.Close()
-	assert.NoError(t, err)
-}
-
-func TestReadBlock(t *testing.T) {
-	file, err := os.Open("testdata/TestReadBlock.zkv")
-	assert.NoError(t, err)
-	defer file.Close()
-
-	r := bufio.NewReader(file)
-
-	line, _, err := readBlock(r)
-	assert.Equal(t, []byte{0x28, 0xb5, 0x2f, 0xfd, 0x04, 0x00, 0x99, 0x04, 0x00, 0x8b, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x39, 0xff, 0x81, 0x03, 0x01, 0x01, 0x06, 0x52, 0x65, 0x63, 0x6f, 0x72, 0x64, 0x01, 0xff, 0x82, 0x00, 0x01, 0x03, 0x01, 0x04, 0x54, 0x79, 0x70, 0x65, 0x01, 0x06, 0x00, 0x01, 0x07, 0x4b, 0x65, 0x79, 0x48, 0x61, 0x73, 0x68, 0x01, 0xff, 0x84, 0x00, 0x01, 0x0a, 0x56, 0x61, 0x6c, 0x75, 0x65, 0x42, 0x79, 0x74, 0x65, 0x73, 0x01, 0x0a, 0x00, 0x00, 0x00, 0x19, 0xff, 0x83, 0x01, 0x01, 0x01, 0x09, 0x5b, 0x32, 0x38, 0x5d, 0x75, 0x69, 0x6e, 0x74, 0x38, 0x01, 0xff, 0x84, 0x00, 0x01, 0x06, 0x01, 0x38, 0x00, 0x00, 0x36, 0xff, 0x82, 0x01, 0x01, 0x01, 0x1c, 0xff, 0x90, 0xff, 0xf4, 0x25, 0x15, 0x70, 0x75, 0x5c, 0xff, 0xf4, 0xff, 0xbc, 0xff, 0xf9, 0xff, 0xde, 0xff, 0x93, 0xff, 0xf8, 0x0d, 0x0e, 0x78, 0x5b, 0xff, 0x81, 0xff, 0x95, 0x6e, 0xff, 0xab, 0x4b, 0xff, 0xe8, 0x37, 0xff, 0x97, 0x68, 0x41, 0x3d, 0x01, 0x04, 0x03, 0x04, 0x00, 0x02, 0x00, 0x25, 0xd5, 0x63, 0x21}, line)
-	line, _, err = readBlock(r)
-	assert.Equal(t, []byte{0x28, 0xb5, 0x2f, 0xfd, 0x04, 0x00, 0x89, 0x04, 0x00, 0x89, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x39, 0xff, 0x81, 0x03, 0x01, 0x01, 0x06, 0x52, 0x65, 0x63, 0x6f, 0x72, 0x64, 0x01, 0xff, 0x82, 0x00, 0x01, 0x03, 0x01, 0x04, 0x54, 0x79, 0x70, 0x65, 0x01, 0x06, 0x00, 0x01, 0x07, 0x4b, 0x65, 0x79, 0x48, 0x61, 0x73, 0x68, 0x01, 0xff, 0x84, 0x00, 0x01, 0x0a, 0x56, 0x61, 0x6c, 0x75, 0x65, 0x42, 0x79, 0x74, 0x65, 0x73, 0x01, 0x0a, 0x00, 0x00, 0x00, 0x19, 0xff, 0x83, 0x01, 0x01, 0x01, 0x09, 0x5b, 0x32, 0x38, 0x5d, 0x75, 0x69, 0x6e, 0x74, 0x38, 0x01, 0xff, 0x84, 0x00, 0x01, 0x06, 0x01, 0x38, 0x00, 0x00, 0x34, 0xff, 0x82, 0x01, 0x01, 0x01, 0x1c, 0xff, 0x84, 0xff, 0x84, 0xff, 0xc1, 0x21, 0x02, 0xff, 0x8b, 0xff, 0xd7, 0x6d, 0xff, 0xd0, 0xff, 0xad, 0x1a, 0x55, 0x14, 0x5c, 0xff, 0xb1, 0x04, 0x37, 0x29, 0x2f, 0x78, 0x18, 0xff, 0xb5, 0xff, 0xe4, 0x56, 0x4e, 0xff, 0x8d, 0x19, 0x46, 0x01, 0x04, 0x03, 0x04, 0x00, 0x04, 0x00, 0x0c, 0x3b, 0xbf, 0x39}, line)
-	line, _, err = readBlock(r)
-	assert.Equal(t, []byte{0x28, 0xb5, 0x2f, 0xfd, 0x04, 0x00, 0x99, 0x04, 0x00, 0x8b, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x39, 0xff, 0x81, 0x03, 0x01, 0x01, 0x06, 0x52, 0x65, 0x63, 0x6f, 0x72, 0x64, 0x01, 0xff, 0x82, 0x00, 0x01, 0x03, 0x01, 0x04, 0x54, 0x79, 0x70, 0x65, 0x01, 0x06, 0x00, 0x01, 0x07, 0x4b, 0x65, 0x79, 0x48, 0x61, 0x73, 0x68, 0x01, 0xff, 0x84, 0x00, 0x01, 0x0a, 0x56, 0x61, 0x6c, 0x75, 0x65, 0x42, 0x79, 0x74, 0x65, 0x73, 0x01, 0x0a, 0x00, 0x00, 0x00, 0x19, 0xff, 0x83, 0x01, 0x01, 0x01, 0x09, 0x5b, 0x32, 0x38, 0x5d, 0x75, 0x69, 0x6e, 0x74, 0x38, 0x01, 0xff, 0x84, 0x00, 0x01, 0x06, 0x01, 0x38, 0x00, 0x00, 0x36, 0xff, 0x82, 0x01, 0x01, 0x01, 0x1c, 0x25, 0x79, 0x3e, 0x46, 0x4e, 0xff, 0xac, 0x06, 0x27, 0xff, 0xb1, 0xff, 0xa3, 0xff, 0xaa, 0xff, 0xe3, 0xff, 0xde, 0x37, 0x71, 0x63, 0x72, 0xff, 0x89, 0x0d, 0xff, 0x85, 0x39, 0xff, 0xb5, 0xff, 0xb9, 0xff, 0x8a, 0xff, 0x9e, 0x60, 0xff, 0xad, 0x17, 0x01, 0x04, 0x03, 0x04, 0x00, 0x06, 0x00, 0x52, 0x08, 0x3e, 0x26}, line)
-	line, _, err = readBlock(r)
-	assert.Equal(t, []byte{0x28, 0xb5, 0x2f, 0xfd, 0x04, 0x00, 0xc9, 0x04, 0x00, 0x91, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x39, 0xff, 0x81, 0x03, 0x01, 0x01, 0x06, 0x52, 0x65, 0x63, 0x6f, 0x72, 0x64, 0x01, 0xff, 0x82, 0x00, 0x01, 0x03, 0x01, 0x04, 0x54, 0x79, 0x70, 0x65, 0x01, 0x06, 0x00, 0x01, 0x07, 0x4b, 0x65, 0x79, 0x48, 0x61, 0x73, 0x68, 0x01, 0xff, 0x84, 0x00, 0x01, 0x0a, 0x56, 0x61, 0x6c, 0x75, 0x65, 0x42, 0x79, 0x74, 0x65, 0x73, 0x01, 0x0a, 0x00, 0x00, 0x00, 0x19, 0xff, 0x83, 0x01, 0x01, 0x01, 0x09, 0x5b, 0x32, 0x38, 0x5d, 0x75, 0x69, 0x6e, 0x74, 0x38, 0x01, 0xff, 0x84, 0x00, 0x01, 0x06, 0x01, 0x38, 0x00, 0x00, 0x3c, 0xff, 0x82, 0x01, 0x01, 0x01, 0x1c, 0xff, 0xbf, 0x25, 0xff, 0xef, 0xff, 0xc8, 0xff, 0x85, 0x2c, 0xff, 0xbf, 0xff, 0xb5, 0xff, 0xad, 0xff, 0xfa, 0xff, 0xaf, 0x1c, 0xff, 0xe7, 0x71, 0xff, 0xfa, 0x36, 0xff, 0x95, 0x1b, 0xff, 0x91, 0xff, 0xab, 0x36, 0xff, 0xcd, 0x7a, 0x33, 0xff, 0xf7, 0xff, 0xec, 0xff, 0xee, 0xff, 0xc1, 0x01, 0x04, 0x03, 0x04, 0x00, 0x08, 0x00, 0xa5, 0x0e, 0x62, 0x53}, line)
-
-	line, _, err = readBlock(r)
-	assert.Equal(t, line, []byte{})
-	assert.Equal(t, io.EOF, err)
-}
-
-func TestRebuildIndex(t *testing.T) {
-	const filePath = "TestRebuiltIndex.zkv"
-	const recordCount = 4
-	defer os.Remove(filePath)
-	defer os.Remove(filePath + indexFileExt)
-
-	for i := 1; i <= recordCount; i++ {
-		db, err := Open(filePath)
-		assert.NoError(t, err)
-
-		err = db.Set(i, i)
-		assert.NoError(t, err)
-
-		err = db.Close()
-		assert.NoError(t, err)
-	}
-
-	db, err := Open(filePath)
-	assert.NoError(t, err)
-
-	err = db.RebuildIndex()
-	assert.NoError(t, err)
-
-	for i := 1; i <= recordCount; i++ {
-		var gotValue int
-
-		err = db.Get(i, &gotValue)
-		assert.NoError(t, err)
-		assert.Equal(t, i, gotValue)
-	}
-}