9 // Accesses torrent data via a client.
17 var _ io.ReadCloser = &Reader{}
19 // Don't wait for pieces to complete and be verified. Read calls return as
20 // soon as they can when the underlying chunks become available.
21 func (r *Reader) SetResponsive() {
25 // Configure the number of bytes ahead of a read that should also be
26 // prioritized in preparation for further reads.
27 func (r *Reader) SetReadahead(readahead int64) {
28 r.readahead = readahead
31 func (r *Reader) raisePriorities(off int64, n int) {
33 r.t.cl.addUrgentRequests(r.t.torrent, off, n)
35 if !r.responsive || r.readahead != 0 {
36 r.t.cl.readRaisePiecePriorities(r.t.torrent, off, int64(n)+r.readahead)
40 func (r *Reader) readable(off int64) (ret bool) {
41 // log.Println("readable", off)
43 // log.Println("readable", ret)
45 req, ok := r.t.offsetRequest(off)
50 return r.t.haveChunk(req)
52 return r.t.pieceComplete(int(req.Index))
55 // How many bytes are available to read. Max is the most we could require.
56 func (r *Reader) available(off, max int64) (ret int64) {
58 req, ok := r.t.offsetRequest(off)
62 if !r.t.haveChunk(req) {
65 len1 := int64(req.Length) - (off - r.t.requestOffset(req))
70 // Ensure that ret hasn't exceeded our original max.
77 func (r *Reader) waitReadable(off int64) {
78 r.t.Pieces[off/int64(r.t.usualPieceSize())].Event.Wait()
81 func (r *Reader) ReadAt(b []byte, off int64) (n int, err error) {
84 n1, err = r.readAt(b, off)
88 if err != nil || len(b) == 0 || n1 == 0 {
94 func (r *Reader) Read(b []byte) (n int, err error) {
95 n, err = r.readAt(b, r.pos)
100 // Must only return EOF at the end of the torrent.
101 func (r *Reader) readAt(b []byte, pos int64) (n int, err error) {
103 // log.Println(pos, n, err)
106 defer r.t.cl.mu.Unlock()
107 maxLen := r.t.torrent.Info.TotalLength() - pos
112 if int64(len(b)) > maxLen {
116 r.raisePriorities(pos, len(b))
117 for !r.readable(pos) {
118 r.raisePriorities(pos, len(b))
121 avail := r.available(pos, int64(len(b)))
122 // log.Println("available", avail)
124 pi := int(pos / r.t.Info().PieceLength)
125 tp := r.t.torrent.Pieces[pi]
126 ip := r.t.Info().Piece(pi)
127 po := pos % ip.Length()
128 if int64(len(b1)) > ip.Length()-po {
129 b1 = b1[:ip.Length()-po]
131 tp.pendingWrites.Wait()
132 n, err = dataReadAt(r.t.data, b1, pos)
137 if err == io.ErrUnexpectedEOF {
143 func (r *Reader) Close() error {
148 func (r *Reader) Seek(off int64, whence int) (ret int64, err error) {
155 r.pos = r.t.torrent.Info.TotalLength() + off
157 err = errors.New("bad whence")