package torrent
import (
+ "context"
"errors"
"io"
"os"
}
func (r *Reader) Read(b []byte) (n int, err error) {
+ return r.ReadContext(b, context.Background())
+}
+
+func (r *Reader) ReadContext(b []byte, ctx context.Context) (n int, err error) {
+ // This is set under the Client lock if the Context is canceled.
+ var ctxErr error
+ if ctx.Done() != nil {
+ ctx, cancel := context.WithCancel(ctx)
+ // Abort the goroutine when the function returns.
+ defer cancel()
+ go func() {
+ <-ctx.Done()
+ r.t.cl.mu.Lock()
+ ctxErr = ctx.Err()
+ r.t.cl.event.Broadcast()
+ r.t.cl.mu.Unlock()
+ }()
+ }
+ // Hmmm, if a Read gets stuck, this means you can't change position for
+ // other purposes. That seems reasonable, but unusual.
r.opMu.Lock()
defer r.opMu.Unlock()
for len(b) != 0 {
var n1 int
- n1, err = r.readOnceAt(b, r.pos)
+ n1, err = r.readOnceAt(b, r.pos, &ctxErr)
if n1 == 0 {
if err == nil {
panic("expected error")
// Wait until some data should be available to read. Tickles the client if it
// isn't. Returns how much should be readable without blocking.
-func (r *Reader) waitAvailable(pos, wanted int64) (avail int64) {
+func (r *Reader) waitAvailable(pos, wanted int64, ctxErr *error) (avail int64) {
r.t.cl.mu.Lock()
defer r.t.cl.mu.Unlock()
- for !r.readable(pos) {
+ for !r.readable(pos) && *ctxErr == nil {
r.waitReadable(pos)
}
return r.available(pos, wanted)
}
// Performs at most one successful read to torrent storage.
-func (r *Reader) readOnceAt(b []byte, pos int64) (n int, err error) {
+func (r *Reader) readOnceAt(b []byte, pos int64, ctxErr *error) (n int, err error) {
if pos >= r.t.length {
err = io.EOF
return
}
for {
- avail := r.waitAvailable(pos, int64(len(b)))
+ avail := r.waitAvailable(pos, int64(len(b)), ctxErr)
if avail == 0 {
if r.torrentClosed() {
err = errors.New("torrent closed")
return
}
+ if *ctxErr != nil {
+ err = *ctxErr
+ return
+ }
}
b1 := b[:avail]
pi := int(pos / r.t.Info().PieceLength)