refactoring: add type for needle id, offset

later the type size can possibly be adjusted

weed/storage/store.go

@@ -5,6 +5,7 @@ import (
 	"strconv"
 	"strings"
 
+	. "github.com/chrislusf/seaweedfs/weed/storage/types"
 	"github.com/chrislusf/seaweedfs/weed/glog"
 	"github.com/chrislusf/seaweedfs/weed/pb/master_pb"
 )
@@ -160,7 +161,7 @@ func (s *Store) SetRack(rack string) {
 func (s *Store) CollectHeartbeat() *master_pb.Heartbeat {
 	var volumeMessages []*master_pb.VolumeInformationMessage
 	maxVolumeCount := 0
-	var maxFileKey uint64
+	var maxFileKey NeedleId
 	for _, location := range s.Locations {
 		maxVolumeCount = maxVolumeCount + location.MaxVolumeCount
 		location.Lock()
@@ -199,7 +200,7 @@ func (s *Store) CollectHeartbeat() *master_pb.Heartbeat {
 		Port:           uint32(s.Port),
 		PublicUrl:      s.PublicUrl,
 		MaxVolumeCount: uint32(maxVolumeCount),
-		MaxFileKey:     maxFileKey,
+		MaxFileKey:     NeedleIdToUint64(maxFileKey),
 		DataCenter:     s.dataCenter,
 		Rack:           s.rack,
 		Volumes:        volumeMessages,