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store.go
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store.go
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package core
import (
"encoding/binary"
"fmt"
"io"
"os"
"path/filepath"
"strconv"
"strings"
"sync"
"time"
"io/ioutil"
"github.com/hmli/simplefs/utils"
)
const (
TruncateSize uint64 = 1 << 30 //1GB
MaxVolumeSize uint64 = 128 * TruncateSize // 128GB
InitIndexSize uint64 = 8
DefaultDir string = "/tmp/fs"
)
// TODO Compression
// TODO Several volumes make up a Store
type Volume struct {
ID uint64
File *os.File
Directory Directory
Size uint64
Path string
CurrentOffset uint64 // 从文件中恢复的时候, 第一个byte就是currentoffset. 每次写入文件也要更新此offset。
lock sync.Mutex
}
func NewVolume(id uint64, dir string) (v *Volume, err error) {
if dir == "" {
dir = DefaultDir
}
pathMustExists(dir)
filepath := filepath.Join(dir, strconv.FormatUint(id, 10)+".data")
v = new(Volume)
v.ID = id
v.Path = dir
v.File, err = os.OpenFile(filepath, os.O_CREATE|os.O_RDWR, 0666)
if err != nil {
return nil, fmt.Errorf("Open file: ", err)
}
v.Directory, err = NewLeveldbDirectory(dir)
if err != nil {
return nil, fmt.Errorf("Leveldb: ", err)
}
var oldCurrentIndex []byte = make([]byte, InitIndexSize)
_, err = v.File.ReadAt(oldCurrentIndex, 0) // Read old current index from file
if err != nil && err != io.EOF{
return nil, err
}
oldCurrentIndexNum := binary.BigEndian.Uint64(oldCurrentIndex)
if oldCurrentIndexNum > InitIndexSize {
v.setCurrentIndex(oldCurrentIndexNum)
} else {
v.setCurrentIndex(InitIndexSize)
}
v.Size = MaxVolumeSize
v.lock = sync.Mutex{}
return
}
func (v *Volume) GetNeedle(id uint64) (n *Needle, err error) {
n, err = v.Directory.Get(id)
if err != nil {
return
}
n.File = v.File
return
}
func (v *Volume) GetFile(id uint64) (data []byte, ext string, err error) {
needle, err := v.GetNeedle(id)
if err != nil {
return data, ext, fmt.Errorf("Get needle ", err)
}
ext = needle.FileExt
data, err = ioutil.ReadAll(needle)
if err != nil {
return nil, "", err
}
checksum := utils.Checksum(data)
if checksum != needle.Checksum {
return nil, "", ErrWrongCheckSum
}
return
}
func (v *Volume) DelNeedle(id uint64) (err error) {
v.lock.Lock()
defer v.lock.Unlock()
_, err = v.GetNeedle(id)
if err != nil && err != ErrDeleted{
return err
}
return v.Directory.Del(id)
}
// NewNeedle allocate a new needle.
func (v *Volume) NewNeedle(id uint64, data []byte, filename string) (n *Needle, err error) {
size := uint64(len(data))
v.lock.Lock()
defer v.lock.Unlock()
// 1. alloc space
// 2. set needle's header
// 3. make needle
ext := Ext(filename)
offset, err := v.allocSpace(size, uint64(len(ext)))
if err != nil {
return nil, err
}
n = new(Needle)
n.ID = id
n.Size = size
n.Offset = offset
n.Checksum = utils.Checksum(data)
now := time.Now()
n.CreatedAt = now
n.UpdatedAt = now
n.File = v.File
n.FileExt = ext
needleData, err := NeedleMarshal(n)
if err != nil {
return
}
v.File.WriteAt(needleData, int64(n.Offset))
err = v.Directory.New(n)
if err != nil {
err = fmt.Errorf("Leveldb: ", err)
}
return n, err
}
func (v *Volume) NewFile(data []byte, filename string) (id uint64, err error) {
id = utils.UniqueId()
//needle, err := v.NewNeedle(id, uint64(len(data)), filename)
needle, err := v.NewNeedle(id, data, filename)
if err != nil {
return id, fmt.Errorf("New needle : ", err)
}
_, err = needle.Write(data)
if err != nil {
return
}
return id, err
}
func (v *Volume) currentOffset() (offset uint64, err error) {
var i []byte = make([]byte, 8)
_, err = v.File.ReadAt(i, 0)
if err != nil {
return 0, err
}
offset = binary.BigEndian.Uint64(i)
return
}
func (v *Volume) allocSpace(filesize uint64, extsize uint64) (offset uint64, err error) {
remainingSize := v.RemainingSpace()
totalSize := filesize + HeaderSize(extsize)
if remainingSize < totalSize {
return v.CurrentOffset, ErrLeakSpace
}
offset = v.CurrentOffset
v.setCurrentIndex( v.CurrentOffset + HeaderSize(extsize) + filesize)
return
}
func (v *Volume) setCurrentIndex(currentOffset uint64) (err error) {
v.CurrentOffset = currentOffset
var offsetByte []byte = make([]byte, 8) // starts with 1 byte storing current index
binary.BigEndian.PutUint64(offsetByte, v.CurrentOffset)
_, err = v.File.WriteAt(offsetByte, 0)
return
}
func (v *Volume) RemainingSpace() (size uint64) {
return v.Size - v.CurrentOffset
}
func (v *Volume) Fragment() (err error) {
v.lock.Lock()
defer v.lock.Unlock()
newFilePath := v.File.Name() + ".temp" // filepath.Join(v.Path, strconv.FormatUint(v.ID, 10)+".temp")
newFile, err := os.OpenFile(newFilePath, os.O_CREATE|os.O_RDWR, 0666)
if err != nil {
return fmt.Errorf("Open file: ", err)
}
iter := v.Directory.Iter()
var key []byte = make([]byte, 8)
var exists bool = true
var currentOffset int64 = int64(InitIndexSize)
for exists {
key, exists = iter.Next()
if !exists {
break
}
id := binary.BigEndian.Uint64(key)
needle, err := v.GetNeedle(id) // 读取一个needle
if err != nil {
fmt.Println("Read needle err: ", err)
continue
}
offset := int64(needle.Offset)
size := int64(needle.Size) + int64(HeaderSize(uint64(len(needle.FileExt))))
var needleData []byte = make([]byte, size)
v.File.ReadAt(needleData, offset)
_, err = newFile.WriteAt(needleData, currentOffset) // 修改 offset, 并写到新文件中
fmt.Println("Write: ", currentOffset, needleData)
if err != nil {
fmt.Println("Write err: ",err)
continue
}
fmt.Println("Current offset: ", currentOffset)
needle.Offset = uint64(currentOffset)
v.Directory.Set(needle.ID, needle) // 更新 needle
currentOffset += size
}
var currentOffsetByte = make([]byte, InitIndexSize)
binary.BigEndian.PutUint64(currentOffsetByte, uint64(currentOffset))
newFile.WriteAt(currentOffsetByte, 0)
v.setCurrentIndex(uint64(currentOffset))
fullpath:= v.File.Name()
// 给老文件改名
delpath := fullpath + ".del"
fmt.Println("Old change name: ", fullpath, delpath)
delFile , err := os.OpenFile(delpath, os.O_CREATE|os.O_RDWR, 0666)
if err != nil {
return
}
if delFile != nil {
defer delFile.Close()
}
err = os.Rename(fullpath, delpath)
if err != nil {
return
}
err = os.Rename(newFilePath, fullpath)
if err != nil {
os.Rename(delpath, fullpath) // 出错, 把已经改掉的老文件的名字改回去
return
}
v.File = newFile
v.Path = newFilePath
fmt.Println("New change name: ", delpath, fullpath)
err = os.Remove(delpath)
fmt.Println("Deleted: ", delpath)
return
}
func (v *Volume) Print() {
iter := v.Directory.Iter()
var hasNext bool = true
for hasNext {
var key []byte
key, hasNext = iter.Next()
if hasNext {
id := binary.BigEndian.Uint64(key)
n, err := v.GetNeedle(id)
if err != nil && err != ErrDeleted {
fmt.Println("Err: ", err)
}
fmt.Printf("id: %d, offset: %d \n", id, n.Offset)
var b []byte = make([]byte, n.Size)
dataOffset := n.Offset + HeaderSize(uint64(len(n.FileExt)))
v.File.ReadAt(b, int64(dataOffset))
fmt.Println("data: ", n.FileExt, string(b))
} else {
fmt.Println("-------- Finish-------")
}
}
iter.Release()
}
func (v *Volume) CheckCurrentIndex() (same bool) {
i1 := v.CurrentOffset
b := make([]byte, InitIndexSize)
v.File.ReadAt(b, 0)
fmt.Println(b)
i2 := binary.BigEndian.Uint64(b)
return i1 == i2
}
func (v *Volume) ReadHeader(offset int64) (header []byte, err error) {
var b []byte = make([]byte, NeedleFixSize)
v.File.ReadAt(b, offset)
fmt.Println(b)
n, err := NeedleUnmarshal(b)
if err != nil {
return
}
header = make([]byte, len(b) + len(n.FileExt))
v.File.ReadAt(header[:len(b)], offset)
v.File.ReadAt(header[len(b):], offset + int64(len(b)))
return
}
// 从完整文件名中获取扩展名
func Ext(filename string) (ext string) {
index := strings.LastIndex(filename, ".")
fmt.Println(index)
if index == -1 {
return ""
}
return strings.TrimSpace(filename[index+1:])
}
func pathExist(path string) bool {
_, err := os.Stat(path)
if err != nil && os.IsNotExist(err) {
return false
}
return true
}
func pathMustExists(path string) {
exists := pathExist(path)
if !exists {
err := os.MkdirAll(path, 0755)
if err != nil {
panic("Path Must exists: " + err.Error())
}
}
}