/
store.go
277 lines (249 loc) · 5.33 KB
/
store.go
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package blob
import (
"bytes"
"crypto/sha1"
"encoding/hex"
"errors"
"fmt"
"io"
"os"
"path/filepath"
"sort"
"sync"
"time"
"github.com/anacrolix/missinggo"
dataPkg "github.com/anacrolix/torrent/data"
"github.com/anacrolix/torrent/metainfo"
)
const (
filePerm = 0640
dirPerm = 0750
)
type store struct {
baseDir string
capacity int64
mu sync.Mutex
completed map[[20]byte]struct{}
}
func (me *store) OpenTorrent(info *metainfo.Info) dataPkg.Data {
return &data{info, me}
}
type StoreOption func(*store)
func Capacity(bytes int64) StoreOption {
return func(s *store) {
s.capacity = bytes
}
}
func NewStore(baseDir string, opt ...StoreOption) dataPkg.Store {
s := &store{baseDir, -1, sync.Mutex{}, nil}
for _, o := range opt {
o(s)
}
s.initCompleted()
return s
}
// Turns 40 byte hex string into its equivalent binary byte array.
func hexStringPieceHashArray(s string) (ret [20]byte, ok bool) {
if len(s) != 40 {
return
}
n, err := hex.Decode(ret[:], []byte(s))
if err != nil {
return
}
if n != 20 {
panic(n)
}
ok = true
return
}
func (me *store) initCompleted() {
fis, err := me.readCompletedDir()
if err != nil {
panic(err)
}
me.mu.Lock()
me.completed = make(map[[20]byte]struct{}, len(fis))
for _, fi := range fis {
binHash, ok := hexStringPieceHashArray(fi.Name())
if !ok {
continue
}
me.completed[binHash] = struct{}{}
}
me.mu.Unlock()
}
func (me *store) completePieceDirPath() string {
return filepath.Join(me.baseDir, "complete")
}
func (me *store) path(p metainfo.Piece, completed bool) string {
return filepath.Join(me.baseDir, func() string {
if completed {
return "complete"
} else {
return "incomplete"
}
}(), fmt.Sprintf("%x", p.Hash()))
}
func sliceToPieceHashArray(b []byte) (ret [20]byte) {
n := copy(ret[:], b)
if n != 20 {
panic(n)
}
return
}
func (me *store) pieceComplete(p metainfo.Piece) bool {
me.mu.Lock()
defer me.mu.Unlock()
_, ok := me.completed[sliceToPieceHashArray(p.Hash())]
return ok
}
func (me *store) pieceWrite(p metainfo.Piece) (f *os.File) {
if me.pieceComplete(p) {
return
}
name := me.path(p, false)
os.MkdirAll(filepath.Dir(name), dirPerm)
f, err := os.OpenFile(name, os.O_CREATE|os.O_WRONLY, filePerm)
if err != nil {
panic(err)
}
return
}
// Returns the file for the given piece, if it exists. It could be completed,
// or incomplete.
func (me *store) pieceRead(p metainfo.Piece) (f *os.File) {
f, err := os.Open(me.path(p, true))
if err == nil {
return
}
if !os.IsNotExist(err) {
panic(err)
}
// Mark the file not completed, in case we thought it was. TODO: Trigger
// an asynchronous initCompleted to reinitialize the entire completed map
// as there are likely other files missing.
me.mu.Lock()
delete(me.completed, sliceToPieceHashArray(p.Hash()))
me.mu.Unlock()
f, err = os.Open(me.path(p, false))
if err == nil {
return
}
if !os.IsNotExist(err) {
panic(err)
}
return
}
func (me *store) readCompletedDir() (fis []os.FileInfo, err error) {
f, err := os.Open(me.completePieceDirPath())
if err != nil {
if os.IsNotExist(err) {
err = nil
}
return
}
fis, err = f.Readdir(-1)
f.Close()
return
}
func (me *store) removeCompleted(name string) (err error) {
err = os.Remove(filepath.Join(me.completePieceDirPath(), name))
if os.IsNotExist(err) {
err = nil
}
if err != nil {
return err
}
binHash, ok := hexStringPieceHashArray(name)
if ok {
me.mu.Lock()
delete(me.completed, binHash)
me.mu.Unlock()
}
return
}
type fileInfoSorter struct {
fis []os.FileInfo
}
func (me fileInfoSorter) Len() int {
return len(me.fis)
}
func lastTime(fi os.FileInfo) (ret time.Time) {
ret = fi.ModTime()
atime := missinggo.FileInfoAccessTime(fi)
if atime.After(ret) {
ret = atime
}
return
}
func (me fileInfoSorter) Less(i, j int) bool {
return lastTime(me.fis[i]).Before(lastTime(me.fis[j]))
}
func (me fileInfoSorter) Swap(i, j int) {
me.fis[i], me.fis[j] = me.fis[j], me.fis[i]
}
func sortFileInfos(fis []os.FileInfo) {
sorter := fileInfoSorter{fis}
sort.Sort(sorter)
}
func (me *store) makeSpace(space int64) error {
if me.capacity < 0 {
return nil
}
if space > me.capacity {
return errors.New("space requested exceeds capacity")
}
fis, err := me.readCompletedDir()
if err != nil {
return err
}
var size int64
for _, fi := range fis {
size += fi.Size()
}
sortFileInfos(fis)
for size > me.capacity-space {
me.removeCompleted(fis[0].Name())
size -= fis[0].Size()
fis = fis[1:]
}
return nil
}
func (me *store) PieceCompleted(p metainfo.Piece) (err error) {
err = me.makeSpace(p.Length())
if err != nil {
return
}
var (
incompletePiecePath = me.path(p, false)
completedPiecePath = me.path(p, true)
)
fSrc, err := os.Open(incompletePiecePath)
if err != nil {
return
}
defer fSrc.Close()
os.MkdirAll(filepath.Dir(completedPiecePath), dirPerm)
fDst, err := os.OpenFile(completedPiecePath, os.O_EXCL|os.O_CREATE|os.O_WRONLY, filePerm)
if err != nil {
return
}
defer fDst.Close()
hasher := sha1.New()
r := io.TeeReader(io.LimitReader(fSrc, p.Length()), hasher)
_, err = io.Copy(fDst, r)
if err != nil {
return
}
if !bytes.Equal(hasher.Sum(nil), p.Hash()) {
err = errors.New("piece incomplete")
os.Remove(completedPiecePath)
return
}
os.Remove(incompletePiecePath)
me.mu.Lock()
me.completed[sliceToPieceHashArray(p.Hash())] = struct{}{}
me.mu.Unlock()
return
}