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) Client { return &mmapStorage{ baseDir: baseDir, } } func (s *mmapStorage) OpenTorrent(info *metainfo.InfoEx) (t Torrent, err error) { span, err := mMapTorrent(&info.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) Piece { 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 io.ReaderAt io.WriterAt } func (sp mmapStoragePiece) GetIsComplete() bool { return sp.pc.Get(sp.p) } func (sp mmapStoragePiece) MarkComplete() error { sp.pc.Set(sp.p, true) 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 }