X-Git-Url: http://www.git.stargrave.org/?a=blobdiff_plain;f=reader.go;h=4b20206cbf2ecc675ccde147cecc278ebc688040;hb=HEAD;hp=c8af14640bb813e98eabeca5305aa02532ffaba1;hpb=9cc3201df96f024e0bdbe73b767cfba151466b27;p=btrtrc.git

diff --git a/reader.go b/reader.go
index c8af1464..4b20206c 100644
--- a/reader.go
+++ b/reader.go
@@ -12,7 +12,7 @@ import (
 )
 
 // Accesses Torrent data via a Client. Reads block until the data is available. Seeks and readahead
-// also drive Client behaviour.
+// also drive Client behaviour. Not safe for concurrent use.
 type Reader interface {
 	io.ReadSeekCloser
 	missinggo.ReadContexter
@@ -22,7 +22,7 @@ type Reader interface {
 	// If non-nil, the provided function is called when the implementation needs to know the
 	// readahead for the current reader. Calls occur during Reads and Seeks, and while the Client is
 	// locked.
-	SetReadaheadFunc(func() int64)
+	SetReadaheadFunc(ReadaheadFunc)
 	// Don't wait for pieces to complete and be verified. Read calls return as soon as they can when
 	// the underlying chunks become available.
 	SetResponsive()
@@ -33,13 +33,21 @@ type pieceRange struct {
 	begin, end pieceIndex
 }
 
+type ReadaheadContext struct {
+	ContiguousReadStartPos int64
+	CurrentPos             int64
+}
+
+// Returns the desired readahead for a Reader.
+type ReadaheadFunc func(ReadaheadContext) int64
+
 type reader struct {
 	t *Torrent
 	// Adjust the read/seek window to handle Readers locked to File extents and the like.
 	offset, length int64
 
 	// Function to dynamically calculate readahead. If nil, readahead is static.
-	readaheadFunc func() int64
+	readaheadFunc ReadaheadFunc
 
 	// Required when modifying pos and readahead.
 	mu sync.Locker
@@ -79,7 +87,7 @@ func (r *reader) SetReadahead(readahead int64) {
 	r.mu.Unlock()
 }
 
-func (r *reader) SetReadaheadFunc(f func() int64) {
+func (r *reader) SetReadaheadFunc(f ReadaheadFunc) {
 	r.mu.Lock()
 	r.readaheadFunc = f
 	r.posChanged()
@@ -116,7 +124,10 @@ func (r *reader) available(off, max int64) (ret int64) {
 func (r *reader) piecesUncached() (ret pieceRange) {
 	ra := r.readahead
 	if r.readaheadFunc != nil {
-		ra = r.readaheadFunc()
+		ra = r.readaheadFunc(ReadaheadContext{
+			ContiguousReadStartPos: r.contiguousReadStartPos,
+			CurrentPos:             r.pos,
+		})
 	}
 	if ra < 1 {
 		// Needs to be at least 1, because [x, x) means we don't want
@@ -234,24 +245,37 @@ func (r *reader) readOnceAt(ctx context.Context, b []byte, pos int64) (n int, er
 			err = nil
 			return
 		}
-		r.t.cl.lock()
-		// 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(), firstPieceIndex, firstPieceOffset, len(b1), err))
-		if !r.t.updatePieceCompletion(firstPieceIndex) {
-			r.log(log.Fstr("piece %d completion unchanged", firstPieceIndex))
-		}
-		// Update the rest of the piece completions in the readahead window, without alerting to
-		// changes (since only the first piece, the one above, could have generated the read error
-		// we're currently handling).
-		if r.pieces.begin != firstPieceIndex {
-			panic(fmt.Sprint(r.pieces.begin, firstPieceIndex))
-		}
-		for index := r.pieces.begin + 1; index < r.pieces.end; index++ {
-			r.t.updatePieceCompletion(index)
+		if r.t.closed.IsSet() {
+			err = fmt.Errorf("reading from closed torrent: %w", err)
+			return
 		}
-		r.t.cl.unlock()
+		r.t.cl.lock()
+		// I think there's a panic here caused by the Client being closed before obtaining this
+		// lock. TestDropTorrentWithMmapStorageWhileHashing seems to tickle occasionally in CI.
+		func() {
+			// Just add exceptions already.
+			defer r.t.cl.unlock()
+			if r.t.closed.IsSet() {
+				// Can't update because Torrent's piece order is removed from Client.
+				return
+			}
+			// 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(), firstPieceIndex, firstPieceOffset, len(b1), err))
+			if !r.t.updatePieceCompletion(firstPieceIndex) {
+				r.log(log.Fstr("piece %d completion unchanged", firstPieceIndex))
+			}
+			// Update the rest of the piece completions in the readahead window, without alerting to
+			// changes (since only the first piece, the one above, could have generated the read error
+			// we're currently handling).
+			if r.pieces.begin != firstPieceIndex {
+				panic(fmt.Sprint(r.pieces.begin, firstPieceIndex))
+			}
+			for index := r.pieces.begin + 1; index < r.pieces.end; index++ {
+				r.t.updatePieceCompletion(index)
+			}
+		}()
 	}
 }
 
@@ -299,10 +323,10 @@ func (r *reader) Seek(off int64, whence int) (newPos int64, err error) {
 }
 
 func (r *reader) log(m log.Msg) {
-	r.t.logger.Log(m.Skip(1))
+	r.t.logger.LogLevel(log.Debug, m.Skip(1))
 }
 
 // Implementation inspired by https://news.ycombinator.com/item?id=27019613.
-func (r *reader) defaultReadaheadFunc() int64 {
-	return r.pos - r.contiguousReadStartPos
+func defaultReadaheadFunc(r ReadaheadContext) int64 {
+	return r.CurrentPos - r.ContiguousReadStartPos
 }