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logfile.go
191 lines (179 loc) · 4.19 KB
/
logfile.go
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package leveldb
import (
"bufio"
"bytes"
"encoding/binary"
"fmt"
"github.com/robaho/leveldb/skip"
"io"
"os"
"path/filepath"
)
// The log file format is:
//
// StartBatchMarker is { negative int32 length of batch }
// EndBatchMarker is { negative int32 length of batch which matches StartBatchMarker }
// LogEntry is { int32 key len, key bytes, int32 value len, value bytes }
type logFile struct {
file *os.File
w *bufio.Writer
id uint64
inBatch bool
disableFlush bool
}
func newLogFile(path string, id uint64, options Options) (*logFile, error) {
mode := os.O_TRUNC | os.O_WRONLY | os.O_CREATE
if options.EnableSyncWrite {
mode = mode | os.O_SYNC
}
f, err := os.OpenFile(filepath.Join(path, "log."+fmt.Sprint(id)), mode, 0644)
if err != nil {
return nil, err
}
l := logFile{file: f, id: id, w: bufio.NewWriter(f)}
if !options.EnableSyncWrite && options.DisableWriteFlush {
l.disableFlush = true
}
return &l, nil
}
func (f *logFile) StartBatch(len int) error {
f.inBatch = true
return binary.Write(f.w, binary.LittleEndian, int32(-len))
}
func (f *logFile) EndBatch(len int) error {
f.inBatch = false
err := binary.Write(f.w, binary.LittleEndian, int32(-len))
if err != nil {
return err
}
return f.w.Flush()
}
func (f *logFile) Write(key []byte, value []byte) error {
err := binary.Write(f.w, binary.LittleEndian, int32(len(key)))
if err != nil {
return err
}
err = binary.Write(f.w, binary.LittleEndian, key)
if err != nil {
return err
}
err = binary.Write(f.w, binary.LittleEndian, int32(len(value)))
if err != nil {
return err
}
err = binary.Write(f.w, binary.LittleEndian, value)
if err != nil {
return err
}
if !f.inBatch && !f.disableFlush {
return f.w.Flush()
}
return nil
}
func (f *logFile) Close() error {
f.w.Flush()
return f.file.Close()
}
func (f *logFile) Remove() error {
return os.Remove(f.file.Name())
}
func keyValueCompare(options Options) func(a, b KeyValue) int {
if options.UserKeyCompare == nil {
return func(a, b KeyValue) int {
return bytes.Compare(a.key, b.key)
}
} else {
return func(a, b KeyValue) int {
return options.UserKeyCompare(a.key, b.key)
}
}
}
func readLogFile(path string, options Options) (*skip.SkipList[KeyValue], error) {
f, err := os.OpenFile(path, os.O_RDONLY, 0)
if err != nil {
return nil, err
}
defer f.Close()
r := bufio.NewReader(f)
list := skip.NewSkipList(keyValueCompare(options))
var len, kLen, vLen int32
readBatch := func(len int32) error {
var err error
var len0 int32
entries := make([]KeyValue, 0)
// start of batch
for i := 0; i < int(len*-1); i++ {
err = binary.Read(r, binary.LittleEndian, &kLen)
if err != nil {
goto batchReadError
}
key := make([]byte, kLen)
err = binary.Read(r, binary.LittleEndian, &key)
if err != nil {
goto batchReadError
}
err = binary.Read(r, binary.LittleEndian, &vLen)
if err != nil {
goto batchReadError
}
value := make([]byte, vLen)
err = binary.Read(r, binary.LittleEndian, &value)
if err != nil {
goto batchReadError
}
entries = append(entries, KeyValue{key: key, value: value})
}
// read end of batch marker
err = binary.Read(r, binary.LittleEndian, &len0)
if err != nil {
goto batchReadError
}
if len0 != len {
err = DatabaseCorrupted
goto batchReadError
}
batchReadError:
if options.BatchReadMode == ApplyPartial || err == nil {
for _, e := range entries {
list.Put(e)
}
}
return err
}
for {
err := binary.Read(r, binary.LittleEndian, &len)
if err == io.EOF {
return &list, nil
}
if err != nil {
return nil, err
}
if len < 0 {
err = readBatch(len)
if err != nil {
if options.BatchReadMode == ReturnOpenError {
return nil, err
}
return &list, nil
}
} else {
kLen = len
key := make([]byte, kLen)
err = binary.Read(r, binary.LittleEndian, &key)
if err != nil {
return nil, err
}
err = binary.Read(r, binary.LittleEndian, &vLen)
if err != nil {
return nil, err
}
value := make([]byte, vLen)
err = binary.Read(r, binary.LittleEndian, &value)
if err != nil {
return nil, err
}
list.Put(KeyValue{key: key, value: value})
}
}
return &list, nil
}