Move logging inside client lock, for Torrent.String

Fixes #163

reader.go

@@ -208,8 +208,8 @@ func (r *Reader) readOnceAt(b []byte, pos int64, ctxErr *error) (n int, err erro
 			err = nil
 			return
 		}
-		log.Printf("error reading torrent %q piece %d offset %d, %d bytes: %s", r.t, pi, po, len(b1), err)
 		r.t.cl.mu.Lock()
+		log.Printf("error reading torrent %q piece %d offset %d, %d bytes: %s", r.t, pi, po, len(b1), err)
 		r.t.updateAllPieceCompletions()
 		r.t.updateAllPiecePriorities()
 		r.t.cl.mu.Unlock()

torrent.go

@@ -1245,13 +1245,15 @@ func (t *Torrent) dhtAnnouncer() {
 			return
 		}
 		err := t.announceDHT(true)
-		if err == nil {
+		func() {
 			cl.mu.Lock()
-			t.numDHTAnnounces++
-			cl.mu.Unlock()
-		} else {
-			log.Printf("error announcing %q to DHT: %s", t, err)
-		}
+			defer cl.mu.Unlock()
+			if err == nil {
+				t.numDHTAnnounces++
+			} else {
+				log.Printf("error announcing %q to DHT: %s", t, err)
+			}
+		}()
 		select {
 		case <-t.closed.LockedChan(&cl.mu):
 			return