seaweedfs/weed-fs/src/pkg/storage/volume.go

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package storage
import (
"os"
"path"
"strconv"
"log"
)
type Volume struct {
Id uint64
dir string
dataFile, indexFile *os.File
nm *NeedleMap
accessChannel chan int
}
func NewVolume(dirname string, id uint64) (v *Volume) {
var e os.Error
v = new(Volume)
v.dir = dirname
v.Id = id
fileName := strconv.Uitoa64(v.Id)
v.dataFile, e = os.OpenFile(path.Join(v.dir,fileName+".dat"), os.O_RDWR|os.O_CREATE, 0644)
if e != nil {
log.Fatalf("New Volume [ERROR] %s\n", e)
}
v.indexFile, e = os.OpenFile(path.Join(v.dir,fileName+".idx"), os.O_RDWR|os.O_CREATE, 0644)
if e != nil {
log.Fatalf("New Volume [ERROR] %s\n", e)
}
v.nm = NewNeedleMap()
v.nm.load(v.indexFile)
v.accessChannel = make(chan int, 1)
v.accessChannel <- 0
return
}
func (v *Volume) CanWrite(limit int64) bool {
stat, e:=v.dataFile.Stat()
if e!=nil{
return stat.Size < limit
}
return false
}
func (v *Volume) Close() {
close(v.accessChannel)
v.dataFile.Close()
v.indexFile.Close()
}
func (v *Volume) write(n *Needle) {
counter := <-v.accessChannel
offset, _ := v.dataFile.Seek(0, 2)
n.Append(v.dataFile)
nv, ok := v.nm.get(n.Key, n.AlternateKey)
if !ok || int64(nv.Offset)*8 < offset {
v.nm.put(n.Key, n.AlternateKey, uint32(offset/8), n.Size)
}
v.accessChannel <- counter + 1
}
func (v *Volume) read(n *Needle) {
counter := <-v.accessChannel
nv, ok := v.nm.get(n.Key, n.AlternateKey)
if ok && nv.Offset > 0 {
v.dataFile.Seek(int64(nv.Offset)*8, 0)
n.Read(v.dataFile, nv.Size)
}
v.accessChannel <- counter + 1
}