Piece.WriteTo wrap Piece.NewReader

diff --git a/storage/wrappers.go b/storage/wrappers.go
index 640b53a2d394e296fabb387fff3d7707758ad952..2d42d059edb7265d3b653039d0c712f3ee6f8322 100644 (file)
--- a/storage/wrappers.go
+++ b/storage/wrappers.go
@@ -2,6 +2,7 @@ package storage
 
 import (
        "context"
+       "fmt"
        "io"
        "os"
 
@@ -59,12 +60,20 @@ var _ io.WriterTo = Piece{}
 
 // Why do we have this wrapper? Well PieceImpl doesn't implement io.Reader, so we can't let io.Copy
 // and friends check for io.WriterTo and fallback for us since they expect an io.Reader.
-func (p Piece) WriteTo(w io.Writer) (int64, error) {
+func (p Piece) WriteTo(w io.Writer) (_ int64, err error) {
        if i, ok := p.PieceImpl.(io.WriterTo); ok {
                return i.WriteTo(w)
        }
        n := p.mip.Length()
-       r := io.NewSectionReader(p, 0, n)
+       // NewReader will do the next smartest thing which may allow more efficient resource use between
+       // ReadAt calls. Worst case it gives us a nopCloser+p.
+       rc, err := p.NewReader()
+       if err != nil {
+               err = fmt.Errorf("opening reader: %w", err)
+               return
+       }
+       defer rc.Close()
+       r := io.NewSectionReader(rc, 0, n)
        return io.CopyN(w, r, n)
 }