Golang leveldb.DB类代码示例

func saveItem(db *leveldb.DB, it *gohn.Item) {
	pbmsg, err := proto.Marshal(it)
	check(err)
	key := []byte(strconv.Itoa(int(it.GetId())))
	err = db.Put(key, pbmsg, nil)
	check(err)
}

func ldbAvailability(db *leveldb.DB, folder, file []byte) []protocol.DeviceID {
	k := globalKey(folder, file)
	bs, err := db.Get(k, nil)
	if err == leveldb.ErrNotFound {
		return nil
	}
	if err != nil {
		panic(err)
	}

	var vl versionList
	err = vl.UnmarshalXDR(bs)
	if err != nil {
		panic(err)
	}

	var devices []protocol.DeviceID
	for _, v := range vl.versions {
		if !v.version.Equal(vl.versions[0].version) {
			break
		}
		n := protocol.DeviceIDFromBytes(v.device)
		devices = append(devices, n)
	}

	return devices
}

func ldbListFolders(db *leveldb.DB) []string {
	runtime.GC()

	start := []byte{keyTypeGlobal}
	limit := []byte{keyTypeGlobal + 1}
	snap, err := db.GetSnapshot()
	if err != nil {
		panic(err)
	}
	defer snap.Release()
	dbi := snap.NewIterator(&util.Range{Start: start, Limit: limit}, nil)
	defer dbi.Release()

	folderExists := make(map[string]bool)
	for dbi.Next() {
		folder := string(globalKeyFolder(dbi.Key()))
		if !folderExists[folder] {
			folderExists[folder] = true
		}
	}

	folders := make([]string, 0, len(folderExists))
	for k := range folderExists {
		folders = append(folders, k)
	}

	sort.Strings(folders)
	return folders
}

// flush a leveldb batch to database and reset batch to 0
func cacheFlush(db *leveldb.DB, batch *leveldb.Batch) {
	err := db.Write(batch, nil)
	if err != nil {
		log.Fatal(err)
	}
	batch.Reset()
}

func cacheLookup(db *leveldb.DB, way *osmpbf.Way) ([]map[string]string, error) {

	var container []map[string]string

	for _, each := range way.NodeIDs {
		stringid := strconv.FormatInt(each, 10)

		data, err := db.Get([]byte(stringid), nil)
		if err != nil {
			log.Println("denormalize failed for way:", way.ID, "node not found:", stringid)
			return container, err
		}

		s := string(data)
		spl := strings.Split(s, ":")

		latlon := make(map[string]string)
		lat, lon := spl[0], spl[1]
		latlon["lat"] = lat
		latlon["lon"] = lon

		container = append(container, latlon)

	}

	return container, nil

	// fmt.Println(way.NodeIDs)
	// fmt.Println(container)
	// os.Exit(1)
}

// write to leveldb immediately
func cacheStore(db *leveldb.DB, node *osmpbf.Node) {
	id, val := formatLevelDB(node)
	err := db.Put([]byte(id), []byte(val), nil)
	if err != nil {
		log.Fatal(err)
	}
}

func read_metadata(filename string, metadatadb *leveldb.DB) (version int, numbytes int, exptime time.Time, exp int, err error) {
	data, err2 := metadatadb.Get([]byte(filename), nil)
	// log.Println(data, filename, err2)
	err = err2
	if err != nil {
		version = 0
		numbytes = 0
		exptime = time.Now()
		exp = 0
	} else {
		line := string(data)
		fields := strings.Fields(line)
		version, _ = strconv.Atoi(fields[0])
		numbytes, _ = strconv.Atoi(fields[1])
		if len(fields) == 7 {
			exptime_str := fields[2] + " " + fields[3] + " " + fields[4] + " " + fields[5]
			layout := "2006-01-02 15:04:05 -0700 MST"
			exptime, _ = time.Parse(layout, exptime_str)
			exp, _ = strconv.Atoi(fields[6])
		} else {
			log.Println("why here?", string(data), string(filename))
		}
	}
	return
}

//从levelDB中载入列表判断是否近期执行
func WalkTasks(base, span int64, db *leveldb.DB) {
	var task Task
	var err error
	var ok bool
	timer.DropMap = nil
	timer.DropMap = make(map[string]bool)
	s := time.Now()
	iter := db.NewIterator(nil, nil)
	parseMap := make(map[string][]string, 1024)
	for iter.Next() {
		key := string(iter.Key())
		val := string(iter.Value())
		if _, ok = parseMap[val]; ok == false {
			parseMap[val] = make([]string, 0)
		}
		parseMap[val] = append(parseMap[val], key)
	}
	iter.Release()
	inWalking = true
	for val, keys := range parseMap {
		task, err = parseTask(val)
		if err == nil {
			task.Base = base
			ret := task.Dispatch(span, true)
			for _, key := range keys {
				task.Key = key
				timer.Add(ret, key)
			}
		}
	}
	inWalking = false
	parseMap = nil
	e := time.Now()
	logPrintln(e.Sub(s))
}

func clearItems(db *leveldb.DB) error {
	snap, err := db.GetSnapshot()
	if err != nil {
		return err
	}
	defer snap.Release()

	// Iterate over k2

	it := snap.NewIterator(util.BytesPrefix([]byte{1}), nil)
	defer it.Release()

	batch := new(leveldb.Batch)
	for it.Next() {
		k1 := it.Key()
		k2 := it.Value()

		// k2 should exist
		_, err := snap.Get(k2, nil)
		if err != nil {
			return err
		}

		// Delete the k1 => k2 mapping first
		batch.Delete(k1)
		// Then the k2 => data mapping
		batch.Delete(k2)
	}
	if testing.Verbose() {
		log.Printf("batch write (clear) %p", batch)
	}
	return db.Write(batch, nil)
}

func ldbWithAllFolderTruncated(db *leveldb.DB, folder []byte, fn func(device []byte, f protocol.FileInfoTruncated) bool) {
	runtime.GC()

	start := deviceKey(folder, nil, nil)                                                  // before all folder/device files
	limit := deviceKey(folder, protocol.LocalDeviceID[:], []byte{0xff, 0xff, 0xff, 0xff}) // after all folder/device files
	snap, err := db.GetSnapshot()
	if err != nil {
		panic(err)
	}
	if debugDB {
		l.Debugf("created snapshot %p", snap)
	}
	defer func() {
		if debugDB {
			l.Debugf("close snapshot %p", snap)
		}
		snap.Release()
	}()

	dbi := snap.NewIterator(&util.Range{Start: start, Limit: limit}, nil)
	defer dbi.Release()

	for dbi.Next() {
		device := deviceKeyDevice(dbi.Key())
		var f protocol.FileInfoTruncated
		err := f.UnmarshalXDR(dbi.Value())
		if err != nil {
			panic(err)
		}
		if cont := fn(device, f); !cont {
			return
		}
	}
}

func ldbWithAllRepoTruncated(db *leveldb.DB, repo []byte, fn func(node []byte, f protocol.FileInfoTruncated) bool) {
	defer runtime.GC()

	start := nodeKey(repo, nil, nil)                                                // before all repo/node files
	limit := nodeKey(repo, protocol.LocalNodeID[:], []byte{0xff, 0xff, 0xff, 0xff}) // after all repo/node files
	snap, err := db.GetSnapshot()
	if err != nil {
		panic(err)
	}
	defer snap.Release()
	dbi := snap.NewIterator(&util.Range{Start: start, Limit: limit}, nil)
	defer dbi.Release()

	for dbi.Next() {
		node := nodeKeyNode(dbi.Key())
		var f protocol.FileInfoTruncated
		err := f.UnmarshalXDR(dbi.Value())
		if err != nil {
			panic(err)
		}
		if cont := fn(node, f); !cont {
			return
		}
	}
}

func ldbListRepos(db *leveldb.DB) []string {
	defer runtime.GC()

	start := []byte{keyTypeGlobal}
	limit := []byte{keyTypeGlobal + 1}
	snap, err := db.GetSnapshot()
	if err != nil {
		panic(err)
	}
	defer snap.Release()
	dbi := snap.NewIterator(&util.Range{Start: start, Limit: limit}, nil)
	defer dbi.Release()

	repoExists := make(map[string]bool)
	for dbi.Next() {
		repo := string(globalKeyRepo(dbi.Key()))
		if !repoExists[repo] {
			repoExists[repo] = true
		}
	}

	repos := make([]string, 0, len(repoExists))
	for k := range repoExists {
		repos = append(repos, k)
	}

	sort.Strings(repos)
	return repos
}

//Function: getFile
//Checkes whether file exists or not
//Parameters:
//    fileName - file name
//    fileDB - database connection
//Return:
//	  true - file found
//	  false - file not found
//	  file itself
func getFile(fileName string, fileDB *leveldb.DB) (bool, []byte, iterator.Iterator) {

	var flag int = 0
	var val []byte

	iter := fileDB.NewIterator(nil, nil)

	//doOperation([]byte(fileNm), nil, "delete", fileDB, wo)

	for iter.Next() {
		key := iter.Key()
		if string(key) == fileName {
			val = iter.Value()
			flag = 1
			break
		}
	}

	if flag == 1 {
		return true, val, iter
	} else {
		return false, nil, iter
	}

}

func clearItems(db *leveldb.DB) error {
	snap, err := db.GetSnapshot()
	if err != nil {
		return err
	}
	defer snap.Release()

	// Iterate from the start of k2 space to the end
	it := snap.NewIterator(&util.Range{Start: []byte{2}, Limit: []byte{2, 0xff, 0xff, 0xff, 0xff}}, nil)
	defer it.Release()

	batch := &leveldb.Batch{}
	for it.Next() {
		k2 := it.Key()
		k1 := it.Value()

		// k1 should exist
		_, err := snap.Get(k1, nil)
		if err != nil {
			return err
		}

		// Delete the k2 => k1 mapping first
		batch.Delete(k2)
		// Then the k1 => key mapping
		batch.Delete(k1)
	}
	return db.Write(batch, nil)
}

/*
	/Read the DATABASE
	/Read the Key and Value by Key
*/
func dbRead(dbObj *leveldb.DB, readDBKey []byte) []byte {
	data, readError := dbObj.Get([]byte(readDBKey), nil)
	if readError != nil {
		fmt.Println("DB Read ERROR")
	}
	return data
}