avoid the "src" folder

1 files changed, 71 insertions, 0 deletions

diff --git a/weed/sequence/sequence.go b/weed/sequence/sequence.go
new file mode 100644
index 000000000..c85289468
--- /dev/null
+++ b/weed/sequence/sequence.go
@@ -0,0 +1,71 @@
+package sequence
+
+import (
+	"encoding/gob"
+	"log"
+	"os"
+	"path"
+	"sync"
+)
+
+const (
+	FileIdSaveInterval = 10000
+)
+
+type Sequencer interface {
+	NextFileId(count int) (uint64, int)
+}
+type SequencerImpl struct {
+	dir      string
+	fileName string
+
+	volumeLock   sync.Mutex
+	sequenceLock sync.Mutex
+
+	FileIdSequence uint64
+	fileIdCounter  uint64
+}
+
+func NewSequencer(dirname string, filename string) (m *SequencerImpl) {
+	m = &SequencerImpl{dir: dirname, fileName: filename}
+
+	seqFile, se := os.OpenFile(path.Join(m.dir, m.fileName+".seq"), os.O_RDONLY, 0644)
+	if se != nil {
+		m.FileIdSequence = FileIdSaveInterval
+		log.Println("Setting file id sequence", m.FileIdSequence)
+	} else {
+		decoder := gob.NewDecoder(seqFile)
+		defer seqFile.Close()
+		decoder.Decode(&m.FileIdSequence)
+		log.Println("Loading file id sequence", m.FileIdSequence, "=>", m.FileIdSequence+FileIdSaveInterval)
+		//in case the server stops between intervals
+		m.FileIdSequence += FileIdSaveInterval
+	}
+	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, count
+}
+func (m *SequencerImpl) saveSequence() {
+	log.Println("Saving file id sequence", m.FileIdSequence, "to", path.Join(m.dir, m.fileName+".seq"))
+	seqFile, e := os.OpenFile(path.Join(m.dir, m.fileName+".seq"), os.O_CREATE|os.O_WRONLY, 0644)
+	if e != nil {
+		log.Fatalf("Sequence File Save [ERROR] %s\n", e)
+	}
+	defer seqFile.Close()
+	encoder := gob.NewEncoder(seqFile)
+	encoder.Encode(m.FileIdSequence)
+}