seaweedfs/go/storage/needle_map_leveldb.go

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package storage
import (
"encoding/binary"
"fmt"
"os"
"path/filepath"
"github.com/chrislusf/seaweedfs/go/glog"
"github.com/syndtr/goleveldb/leveldb"
)
type LevelDbNeedleMap struct {
dbFileName string
db *leveldb.DB
baseNeedleMapper
}
func NewLevelDbNeedleMap(dbFileName string, indexFile *os.File) (m *LevelDbNeedleMap, err error) {
m = &LevelDbNeedleMap{dbFileName: dbFileName}
m.indexFile = indexFile
if !isLevelDbFresh(dbFileName, indexFile) {
glog.V(1).Infof("Start to Generate %s from %s", dbFileName, indexFile.Name())
generateLevelDbFile(dbFileName, indexFile)
glog.V(1).Infof("Finished Generating %s from %s", dbFileName, indexFile.Name())
}
glog.V(1).Infof("Opening %s...", dbFileName)
if m.db, err = leveldb.OpenFile(dbFileName, nil); err != nil {
return
}
glog.V(1).Infof("Loading %s...", indexFile.Name())
nm, indexLoadError := LoadNeedleMap(indexFile)
if indexLoadError != nil {
return nil, indexLoadError
}
m.mapMetric = nm.mapMetric
return
}
func isLevelDbFresh(dbFileName string, indexFile *os.File) bool {
// normally we always write to index file first
dbLogFile, err := os.Open(filepath.Join(dbFileName, "LOG"))
if err != nil {
return false
}
defer dbLogFile.Close()
dbStat, dbStatErr := dbLogFile.Stat()
indexStat, indexStatErr := indexFile.Stat()
if dbStatErr != nil || indexStatErr != nil {
glog.V(0).Infof("Can not stat file: %v and %v", dbStatErr, indexStatErr)
return false
}
return dbStat.ModTime().After(indexStat.ModTime())
}
func generateLevelDbFile(dbFileName string, indexFile *os.File) error {
db, err := leveldb.OpenFile(dbFileName, nil)
if err != nil {
return err
}
defer db.Close()
return WalkIndexFile(indexFile, func(key uint64, offset, size uint32) error {
if offset > 0 {
levelDbWrite(db, key, offset, size)
} else {
levelDbDelete(db, key)
}
return nil
})
}
func (m *LevelDbNeedleMap) Get(key uint64) (element *NeedleValue, ok bool) {
bytes := make([]byte, 8)
binary.BigEndian.PutUint64(bytes, key)
data, err := m.db.Get(bytes, nil)
if err != nil || len(data) != 8 {
return nil, false
}
offset := binary.BigEndian.Uint32(data[0:4])
size := binary.BigEndian.Uint32(data[4:8])
return &NeedleValue{Key: Key(key), Offset: offset, Size: size}, true
}
func (m *LevelDbNeedleMap) Put(key uint64, offset uint32, size uint32) error {
var oldSize uint32
if oldNeedle, ok := m.Get(key); ok {
oldSize = oldNeedle.Size
}
m.logPut(key, oldSize, size)
// write to index file first
if err := m.appendToIndexFile(key, offset, size); err != nil {
return fmt.Errorf("cannot write to indexfile %s: %v", m.indexFile.Name(), err)
}
return levelDbWrite(m.db, key, offset, size)
}
func levelDbWrite(db *leveldb.DB,
key uint64, offset uint32, size uint32) error {
bytes := make([]byte, 16)
binary.BigEndian.PutUint64(bytes[0:8], key)
binary.BigEndian.PutUint32(bytes[8:12], offset)
binary.BigEndian.PutUint32(bytes[12:16], size)
if err := db.Put(bytes[0:8], bytes[8:16], nil); err != nil {
return fmt.Errorf("failed to write leveldb: %v", err)
}
return nil
}
func levelDbDelete(db *leveldb.DB, key uint64) error {
bytes := make([]byte, 8)
binary.BigEndian.PutUint64(bytes, key)
return db.Delete(bytes, nil)
}
func (m *LevelDbNeedleMap) Delete(key uint64) error {
if oldNeedle, ok := m.Get(key); ok {
m.logDelete(oldNeedle.Size)
}
// write to index file first
if err := m.appendToIndexFile(key, 0, 0); err != nil {
return err
}
return levelDbDelete(m.db, key)
}
func (m *LevelDbNeedleMap) Close() {
m.db.Close()
}
func (m *LevelDbNeedleMap) Destroy() error {
m.Close()
os.Remove(m.indexFile.Name())
return os.Remove(m.dbFileName)
}