11 // Accesses torrent data via a client.
22 var _ io.ReadCloser = &Reader{}
24 // Don't wait for pieces to complete and be verified. Read calls return as
25 // soon as they can when the underlying chunks become available.
26 func (r *Reader) SetResponsive() {
30 // Configure the number of bytes ahead of a read that should also be
31 // prioritized in preparation for further reads.
32 func (r *Reader) SetReadahead(readahead int64) {
35 r.readahead = readahead
38 func (r *Reader) readable(off int64) (ret bool) {
39 if r.torrentClosed() {
42 req, ok := r.t.torrent.offsetRequest(off)
47 return r.t.torrent.haveChunk(req)
49 return r.t.torrent.pieceComplete(int(req.Index))
52 // How many bytes are available to read. Max is the most we could require.
53 func (r *Reader) available(off, max int64) (ret int64) {
55 req, ok := r.t.torrent.offsetRequest(off)
59 if !r.t.torrent.haveChunk(req) {
62 len1 := int64(req.Length) - (off - r.t.torrent.requestOffset(req))
67 // Ensure that ret hasn't exceeded our original max.
74 func (r *Reader) tickleClient() {
75 r.t.torrent.readersChanged()
78 func (r *Reader) waitReadable(off int64) {
79 // We may have been sent back here because we were told we could read but
85 func (r *Reader) Read(b []byte) (n int, err error) {
90 n1, err = r.readOnceAt(b, r.pos)
93 panic("expected error")
101 if r.pos >= r.t.torrent.length {
103 } else if err == io.EOF {
104 err = io.ErrUnexpectedEOF
109 // Safe to call with or without client lock.
110 func (r *Reader) torrentClosed() bool {
111 return r.t.torrent.isClosed()
114 // Wait until some data should be available to read. Tickles the client if it
115 // isn't. Returns how much should be readable without blocking.
116 func (r *Reader) waitAvailable(pos, wanted int64) (avail int64) {
118 defer r.t.cl.mu.Unlock()
119 for !r.readable(pos) {
122 return r.available(pos, wanted)
125 // Performs at most one successful read to torrent storage.
126 func (r *Reader) readOnceAt(b []byte, pos int64) (n int, err error) {
127 if pos >= r.t.torrent.length {
132 avail := r.waitAvailable(pos, int64(len(b)))
134 if r.torrentClosed() {
135 err = errors.New("torrent closed")
140 pi := int(pos / r.t.Info().PieceLength)
141 ip := r.t.Info().Piece(pi)
142 po := pos % ip.Length()
143 if int64(len(b1)) > ip.Length()-po {
144 b1 = b1[:ip.Length()-po]
146 n, err = r.t.torrent.readAt(b1, pos)
150 // log.Printf("%s: error reading from torrent storage pos=%d: %s", r.t, pos, err)
152 r.t.torrent.updateAllPieceCompletions()
153 r.t.torrent.updatePiecePriorities()
158 func (r *Reader) Close() error {
164 func (r *Reader) posChanged() {
166 defer r.t.cl.mu.Unlock()
167 r.t.torrent.readersChanged()
170 func (r *Reader) Seek(off int64, whence int) (ret int64, err error) {
178 r.pos = r.t.torrent.Info.TotalLength() + off
180 err = errors.New("bad whence")