efficiently assign file id

git-svn-id: https://weed-fs.googlecode.com/svn/trunk@17 282b0af5-e82d-9cf1-ede4-77906d7719d0

weed-fs/src/cmd/weeds.go

@@ -8,6 +8,7 @@ import (
 	"http"
 	"json"
 	"log"
+	"rand"
 	"strconv"
 	"strings"
 )
@@ -17,6 +18,7 @@ var (
 	metaFolder = flag.String("mdir", "/tmp", "data directory to store mappings")
 	capacity   = flag.Int("capacity", 100, "maximum number of volumes to hold")
 	mapper     *directory.Mapper
+	
 )
 
 func dirReadHandler(w http.ResponseWriter, r *http.Request) {
@@ -25,12 +27,14 @@ func dirReadHandler(w http.ResponseWriter, r *http.Request) {
 	writeJson(w, r, machine.Server)
 }
 func dirWriteHandler(w http.ResponseWriter, r *http.Request) {
-	machine := mapper.PickForWrite()
+	_, machine := mapper.PickForWrite()
 	writeJson(w, r, machine)
 }
 func dirPickHandler(w http.ResponseWriter, r *http.Request) {
-    machine := mapper.PickForWrite()
-    writeJson(w, r, machine)
+    vid, machine := mapper.PickForWrite()
+    hashcode := rand.Uint32()
+    fid := strconv.Uitoa64(vid) + "," + strconv.Uitoa64(mapper.NextFileId())+","+strconv.Uitoa64(uint64(hashcode))
+    writeJson(w, r, map[string]string{"fid":fid,"url":machine.Url})
 }
 func dirJoinHandler(w http.ResponseWriter, r *http.Request) {
 	s := r.RemoteAddr[0:strings.Index(r.RemoteAddr, ":")+1] + r.FormValue("port")

weed-fs/src/pkg/directory/volume_mapping.go

@@ -11,7 +11,8 @@ import (
 )
 
 const (
-	ChunkSizeLimit = 1 * 1024 * 1024 * 1024 //1G, can not be more than max(uint32)*8
+	ChunkSizeLimit     = 1 * 1000 * 1000 * 1000 //1G, can not be more than max(uint32)*8
+	FileIdSaveInterval = 10000
 )
 
 type MachineInfo struct {
@@ -35,6 +36,9 @@ type Mapper struct {
 	Writers       []int // transient array of Writers volume id
 
 	GlobalVolumeSequence uint64
+
+	FileIdSequence uint64
+	fileIdCounter  uint64
 }
 
 func NewMachine(server, publicServer string, volumes []storage.VolumeInfo, capacity int) *Machine {
@@ -67,11 +71,33 @@ func NewMapper(dirname string, filename string, capacity int) (m *Mapper) {
 		}
 		log.Println("Loaded mapping size", len(m.Machines))
 	}
+
+	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
 }
-func (m *Mapper) PickForWrite() MachineInfo {
-	vid := rand.Intn(len(m.Writers))
-	return m.Machines[m.Writers[vid]].Server
+func (m *Mapper) PickForWrite() (vid uint64, server MachineInfo) {
+	machine := m.Machines[m.Writers[rand.Intn(len(m.Writers))]]
+	vid = machine.Volumes[rand.Intn(len(machine.Volumes))].Id
+	return vid, machine.Server
+}
+func (m *Mapper) NextFileId() uint64 {
+    if m.fileIdCounter <= 0 {
+        m.fileIdCounter = FileIdSaveInterval
+        m.saveSequence()
+    }
+	m.fileIdCounter--
+	return m.FileIdSequence - m.fileIdCounter
 }
 func (m *Mapper) Get(vid uint64) *Machine {
 	return m.Machines[m.vid2machineId[vid]]
@@ -141,3 +167,13 @@ func (m *Mapper) Save() {
 	encoder.Encode(m.Machines)
 	encoder.Encode(m.GlobalVolumeSequence)
 }
+func (m *Mapper) 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)
+}