From: Matt Joiner <anacrolix@gmail.com>
Date: Tue, 27 Oct 2020 01:24:43 +0000 (+1100)
Subject: Read from more than a single piece in each read to Torrent storage
X-Git-Tag: v1.19.0~62
X-Git-Url: http://www.git.stargrave.org/?a=commitdiff_plain;h=1bfca56e9452e7883aa2a6669b920573ec499b1c;p=btrtrc.git

Read from more than a single piece in each read to Torrent storage
---

diff --git a/reader.go b/reader.go
index 7e00d4ea..8a74873b 100644
--- a/reader.go
+++ b/reader.go
@@ -204,6 +204,8 @@ func (r *reader) waitAvailable(pos, wanted int64, ctxErr *error) (avail int64, e
 	}
 }
 
+// Adds the reader's torrent offset to the reader object offset (for example the reader might be
+// constrainted to a particular file within the torrent).
 func (r *reader) torrentOffset(readerPos int64) int64 {
 	return r.offset + readerPos
 }
@@ -220,10 +222,9 @@ func (r *reader) readOnceAt(b []byte, pos int64, ctxErr *error) (n int, err erro
 		if avail == 0 {
 			return
 		}
-		pi := pieceIndex(r.torrentOffset(pos) / r.t.info.PieceLength)
-		ip := r.t.info.Piece(pi)
-		po := r.torrentOffset(pos) % r.t.info.PieceLength
-		b1 := missinggo.LimitLen(b, ip.Length()-po, avail)
+		firstPieceIndex := pieceIndex(r.torrentOffset(pos) / r.t.info.PieceLength)
+		firstPieceOffset := r.torrentOffset(pos) % r.t.info.PieceLength
+		b1 := missinggo.LimitLen(b, avail)
 		n, err = r.t.readAt(b1, r.torrentOffset(pos))
 		if n != 0 {
 			err = nil
@@ -233,9 +234,9 @@ func (r *reader) readOnceAt(b []byte, pos int64, ctxErr *error) (n int, err erro
 		// TODO: Just reset pieces in the readahead window. This might help
 		// prevent thrashing with small caches and file and piece priorities.
 		r.log(log.Fstr("error reading torrent %s piece %d offset %d, %d bytes: %v",
-			r.t.infoHash.HexString(), pi, po, len(b1), err))
-		if !r.t.updatePieceCompletion(pi) {
-			r.log(log.Fstr("piece %d completion unchanged", pi))
+			r.t.infoHash.HexString(), firstPieceIndex, firstPieceOffset, len(b1), err))
+		if !r.t.updatePieceCompletion(firstPieceIndex) {
+			r.log(log.Fstr("piece %d completion unchanged", firstPieceIndex))
 		}
 		r.t.cl.unlock()
 	}
diff --git a/torrent.go b/torrent.go
index e034933f..ace386eb 100644
--- a/torrent.go
+++ b/torrent.go
@@ -1147,9 +1147,19 @@ func (t *Torrent) updatePieceCompletion(piece pieceIndex) bool {
 
 // Non-blocking read. Client lock is not required.
 func (t *Torrent) readAt(b []byte, off int64) (n int, err error) {
-	p := &t.pieces[off/t.info.PieceLength]
-	p.waitNoPendingWrites()
-	return p.Storage().ReadAt(b, off-p.Info().Offset())
+	for len(b) != 0 {
+		p := &t.pieces[off/t.info.PieceLength]
+		p.waitNoPendingWrites()
+		var n1 int
+		n1, err = p.Storage().ReadAt(b, off-p.Info().Offset())
+		if n1 == 0 {
+			break
+		}
+		off += int64(n1)
+		n += n1
+		b = b[n1:]
+	}
+	return
 }
 
 // Returns an error if the metadata was completed, but couldn't be set for