directory: serialize song deletes from playlist during update

This makes the update code thread-safe and doesn't penalize
the playlist code by complicating it with complicated and
error-prone locks (and the associated overhead, not everybody
has a thread-implementation as good as NPTL).

The update task blocks during the delete; but the update task is
a slow task anyways so we can block w/o people caring too much.

This was also our only freeSong call site, so remove that
function.

Note that deleting entire directories is not fully thread-safe,
yet; as their traversals are not yet locked.

1 files changed, 0 insertions, 2 deletions

diff --git a/src/song.h b/src/song.h
index d8189d42c..9aa9efa94 100644
--- a/src/song.h
+++ b/src/song.h
@@ -42,8 +42,6 @@ typedef struct _Song {
 
 Song *newSong(const char *url, struct _Directory *parentDir);
 
-void freeSong(Song *);
-
 void freeJustSong(Song *);
 
 ssize_t song_print_info(Song * song, int fd);