FedP2P/storage/mmap.go

135 lines
2.8 KiB
Go

package storage
import (
"fmt"
"io"
"os"
"path/filepath"
"github.com/anacrolix/missinggo"
"github.com/edsrzf/mmap-go"
"github.com/anacrolix/torrent/metainfo"
"github.com/anacrolix/torrent/mmap_span"
)
type mmapStorage struct {
baseDir string
}
func NewMMap(baseDir string) ClientImpl {
return &mmapStorage{
baseDir: baseDir,
}
}
func (s *mmapStorage) OpenTorrent(info *metainfo.Info, infoHash metainfo.Hash) (t TorrentImpl, err error) {
span, err := mMapTorrent(info, s.baseDir)
t = &mmapTorrentStorage{
span: span,
pc: pieceCompletionForDir(s.baseDir),
}
return
}
type mmapTorrentStorage struct {
span mmap_span.MMapSpan
pc pieceCompletion
}
func (ts *mmapTorrentStorage) Piece(p metainfo.Piece) PieceImpl {
return mmapStoragePiece{
pc: ts.pc,
p: p,
ReaderAt: io.NewSectionReader(ts.span, p.Offset(), p.Length()),
WriterAt: missinggo.NewSectionWriter(ts.span, p.Offset(), p.Length()),
}
}
func (ts *mmapTorrentStorage) Close() error {
ts.pc.Close()
return ts.span.Close()
}
type mmapStoragePiece struct {
pc pieceCompletion
p metainfo.Piece
ih metainfo.Hash
io.ReaderAt
io.WriterAt
}
func (me mmapStoragePiece) pieceKey() metainfo.PieceKey {
return metainfo.PieceKey{me.ih, me.p.Index()}
}
func (sp mmapStoragePiece) GetIsComplete() (ret bool) {
ret, _ = sp.pc.Get(sp.pieceKey())
return
}
func (sp mmapStoragePiece) MarkComplete() error {
sp.pc.Set(sp.pieceKey(), true)
return nil
}
func (sp mmapStoragePiece) MarkNotComplete() error {
sp.pc.Set(sp.pieceKey(), false)
return nil
}
func mMapTorrent(md *metainfo.Info, location string) (mms mmap_span.MMapSpan, err error) {
defer func() {
if err != nil {
mms.Close()
}
}()
for _, miFile := range md.UpvertedFiles() {
fileName := filepath.Join(append([]string{location, md.Name}, miFile.Path...)...)
err = os.MkdirAll(filepath.Dir(fileName), 0777)
if err != nil {
err = fmt.Errorf("error creating data directory %q: %s", filepath.Dir(fileName), err)
return
}
var file *os.File
file, err = os.OpenFile(fileName, os.O_CREATE|os.O_RDWR, 0666)
if err != nil {
return
}
func() {
defer file.Close()
var fi os.FileInfo
fi, err = file.Stat()
if err != nil {
return
}
if fi.Size() < miFile.Length {
err = file.Truncate(miFile.Length)
if err != nil {
return
}
}
if miFile.Length == 0 {
// Can't mmap() regions with length 0.
return
}
var mMap mmap.MMap
mMap, err = mmap.MapRegion(file,
int(miFile.Length), // Probably not great on <64 bit systems.
mmap.RDWR, 0, 0)
if err != nil {
err = fmt.Errorf("error mapping file %q, length %d: %s", file.Name(), miFile.Length, err)
return
}
if int64(len(mMap)) != miFile.Length {
panic("mmap has wrong length")
}
mms.Append(mMap)
}()
if err != nil {
return
}
}
return
}