Ensure unlock occurs on panic in reader

diff --git a/reader.go b/reader.go
index 34e0f48927b7b466382598897a1537e03bced6d5..c2f3de89bcdef01765b4a201ca0c984abaf536fd 100644 (file)
--- a/reader.go
+++ b/reader.go
@@ -246,23 +246,28 @@ func (r *reader) readOnceAt(ctx context.Context, b []byte, pos int64) (n int, er
                        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)
-               }
-               r.t.cl.unlock()
+               // 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()
+                       // 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)
+                       }
+               }()
        }
 }