memory allocation optimization

backend/trackiterator.go

@@ -76,14 +76,10 @@ func (s *searchTracksIterator) Next() *subsonic.Child {
 	}
 
 	// prefetch more search results from server
-	if s.prefetched == nil {
+	if len(s.prefetched) == 0 {
 		results := s.searchIterBase.fetchResults()
-		if results == nil {
-			s.done = true
-			s.trackIDset = nil
-			return nil
-		}
 
+		if results != nil {
 			// add results from songs search
 			s.addNewTracks(results.Song)
 			s.songOffset += len(results.Song)
@@ -103,19 +99,23 @@ func (s *searchTracksIterator) Next() *subsonic.Child {
 			s.addNewTracksFromAlbums(results.Album)
 			s.albumOffset += len(results.Album)
 		}
+	}
 
 	// return from prefetched results
 	if len(s.prefetched) > 0 {
 		tr := s.prefetched[s.prefetchedPos]
 		s.prefetchedPos++
 		if s.prefetchedPos == len(s.prefetched) {
-			s.prefetched = nil
+			s.prefetched = s.prefetched[:0]
 			s.prefetchedPos = 0
 		}
-
 		return tr
 	}
 
+	// no more results
+	s.done = true
+	s.prefetched = nil
+	s.trackIDset = nil
 	return nil
 }