state_file: save only if something has changed

If nothing has changed since the last save, don't save the state
file.  Saving will spin up the hard drive, which is undesirable on
hosts where MPD is idling in background.

1 files changed, 9 insertions, 0 deletions

diff --git a/src/playlist_state.h b/src/playlist_state.h
index 7ed7e8c8..d116aaeb 100644
--- a/src/playlist_state.h
+++ b/src/playlist_state.h
@@ -36,4 +36,13 @@ playlist_state_save(FILE *fp, const struct playlist *playlist);
 bool
 playlist_state_restore(const char *line, FILE *fp, struct playlist *playlist);
 
+/**
+ * Generates a hash number for the current state of the playlist and
+ * the playback options.  This is used by timer_save_state_file() to
+ * determine whether the state has changed and the state file should
+ * be saved.
+ */
+unsigned
+playlist_state_get_hash(const struct playlist *playlist);
+
 #endif