directory structure change to work with glide

glide has its own requirements. My previous workaround caused me some
code checkin errors. Need to fix this.

weed/storage/needle_map_leveldb.go

@@ -0,0 +1,134 @@
+package storage
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+
+	"github.com/chrislusf/seaweedfs/weed/glog"
+	"github.com/chrislusf/seaweedfs/weed/util"
+	"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)
+	util.Uint64toBytes(bytes, key)
+	data, err := m.db.Get(bytes, nil)
+	if err != nil || len(data) != 8 {
+		return nil, false
+	}
+	offset := util.BytesToUint32(data[0:4])
+	size := util.BytesToUint32(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)
+	util.Uint64toBytes(bytes[0:8], key)
+	util.Uint32toBytes(bytes[8:12], offset)
+	util.Uint32toBytes(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)
+	util.Uint64toBytes(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)
+}