1. volume server now sends master server its max file key, so that

master server does not need to store the sequence on disk any more
2. fix raft server's failure to init cluster during bootstrapping

go/sequence/sequence.go

@@ -1,89 +1,9 @@
 package sequence
 
-import (
-	"bytes"
-	"code.google.com/p/weed-fs/go/glog"
-	"code.google.com/p/weed-fs/go/metastore"
-	"encoding/gob"
-	"sync"
-)
-
-const (
-	FileIdSaveInterval = 10000
-)
+import ()
 
 type Sequencer interface {
 	NextFileId(count int) (uint64, int)
-}
-type SequencerImpl struct {
-	fileFullPath string
-
-	volumeLock   sync.Mutex
-	sequenceLock sync.Mutex
-
-	FileIdSequence uint64
-	fileIdCounter  uint64
-
-	metaStore *metastore.MetaStore
-}
-
-func NewFileSequencer(filepath string) (m *SequencerImpl) {
-	m = &SequencerImpl{fileFullPath: filepath}
-	m.metaStore = &metastore.MetaStore{metastore.NewMetaStoreFileBacking()}
-	m.initilize()
-	return
-}
-
-func (m *SequencerImpl) initilize() {
-	if !m.metaStore.Has(m.fileFullPath) {
-		m.FileIdSequence = FileIdSaveInterval
-		glog.V(0).Infoln("Setting file id sequence", m.FileIdSequence)
-	} else {
-		var err error
-		if m.FileIdSequence, err = m.metaStore.GetUint64(m.fileFullPath); err != nil {
-			if data, err := m.metaStore.Get(m.fileFullPath); err == nil {
-				m.FileIdSequence = decode(data)
-				glog.V(0).Infoln("Decoding old version of FileIdSequence", m.FileIdSequence)
-			} else {
-				glog.V(0).Infof("No existing FileIdSequence: %s", err)
-			}
-		} else {
-			glog.V(0).Infoln("Loading file id sequence", m.FileIdSequence)
-		}
-		//in case the server stops between intervals
-	}
-	return
-}
-
-//count should be 1 or more
-func (m *SequencerImpl) NextFileId(count int) (uint64, int) {
-	if count <= 0 {
-		return 0, 0
-	}
-	m.sequenceLock.Lock()
-	defer m.sequenceLock.Unlock()
-	if m.fileIdCounter < uint64(count) {
-		m.fileIdCounter = FileIdSaveInterval
-		m.FileIdSequence += FileIdSaveInterval
-		m.saveSequence()
-	}
-	m.fileIdCounter = m.fileIdCounter - uint64(count)
-	return m.FileIdSequence - m.fileIdCounter - uint64(count), count
-}
-func (m *SequencerImpl) saveSequence() {
-	glog.V(0).Infoln("Saving file id sequence", m.FileIdSequence, "to", m.fileFullPath)
-	if e := m.metaStore.SetUint64(m.fileFullPath, m.FileIdSequence); e != nil {
-		glog.Fatalf("Sequence id Save [ERROR] %s", e)
-	}
-}
-
-//decode are for backward compatible purpose
-func decode(input string) uint64 {
-	var x uint64
-	b := bytes.NewReader([]byte(input))
-	decoder := gob.NewDecoder(b)
-	if e := decoder.Decode(&x); e == nil {
-		return x
-	}
-	return 0
+	SetMax(uint64)
+	Peek() uint64
 }