10 // Accesses torrent data via a client.
20 var _ io.ReadCloser = &Reader{}
22 // Don't wait for pieces to complete and be verified. Read calls return as
23 // soon as they can when the underlying chunks become available.
24 func (r *Reader) SetResponsive() {
28 // Configure the number of bytes ahead of a read that should also be
29 // prioritized in preparation for further reads.
30 func (r *Reader) SetReadahead(readahead int64) {
33 r.readahead = readahead
36 func (r *Reader) readable(off int64) (ret bool) {
37 // log.Println("readable", off)
39 // log.Println("readable", ret)
41 if r.t.torrent.isClosed() {
44 req, ok := r.t.torrent.offsetRequest(off)
49 return r.t.torrent.haveChunk(req)
51 return r.t.torrent.pieceComplete(int(req.Index))
54 // How many bytes are available to read. Max is the most we could require.
55 func (r *Reader) available(off, max int64) (ret int64) {
57 req, ok := r.t.torrent.offsetRequest(off)
61 if !r.t.torrent.haveChunk(req) {
64 len1 := int64(req.Length) - (off - r.t.torrent.requestOffset(req))
69 // Ensure that ret hasn't exceeded our original max.
76 func (r *Reader) waitReadable(off int64) {
80 func (r *Reader) Read(b []byte) (n int, err error) {
84 n, err = r.readAt(b, pos)
92 // Must only return EOF at the end of the torrent.
93 func (r *Reader) readAt(b []byte, pos int64) (n int, err error) {
95 // log.Println(pos, n, err)
97 maxLen := r.t.torrent.Info.TotalLength() - pos
102 if int64(len(b)) > maxLen {
107 for !r.readable(pos) {
110 avail := r.available(pos, int64(len(b)))
111 // log.Println("available", avail)
114 pi := int(pos / r.t.Info().PieceLength)
115 tp := &r.t.torrent.Pieces[pi]
116 ip := r.t.Info().Piece(pi)
117 po := pos % ip.Length()
118 if int64(len(b1)) > ip.Length()-po {
119 b1 = b1[:ip.Length()-po]
121 tp.waitNoPendingWrites()
122 n, err = dataReadAt(r.t.torrent.data, b1, pos)
127 if r.t.torrent.isClosed() {
129 err = errors.New("torrent closed")
133 if err == io.ErrUnexpectedEOF {
139 func (r *Reader) Close() error {
145 func (r *Reader) posChanged() {
147 defer r.t.cl.mu.Unlock()
148 r.t.torrent.readersChanged(r.t.cl)
151 func (r *Reader) Seek(off int64, whence int) (ret int64, err error) {
159 r.pos = r.t.torrent.Info.TotalLength() + off
161 err = errors.New("bad whence")