[player] Add config option to disable clearing the queue after playback

stops (default is clearing the queue) and if true do not clear the
queue.

This option is necessary because some dacp clients rely on the queue
being empty if player is stopped. Retune for example does not always
show the queue contents if player state is stopped.

forked-daapd.conf

@@ -217,6 +217,11 @@ mpd {
 	# and will need additional configuration in the MPD client to work).
 	# Set to 0 to disable serving artwork over http.
 #	http_port = 0
+
+	# By default forked-daapd will - like iTunes - clear the playqueue if playback stops. 
+	# Setting clear_queue_on_stop_disable to true will keep the playlist like MPD does.
+	# Note that some dacp clients do not show the playqueue if playback is stopped.
+#	clear_queue_on_stop_disable = false
 }
 
 # SQLite configuration (allows to modify the operation of the SQLite databases)

src/conffile.c

@@ -139,6 +139,7 @@ static cfg_opt_t sec_mpd[] =
   {
     CFG_INT("port", 6600, CFGF_NONE),
     CFG_INT("http_port", 0, CFGF_NONE),
+    CFG_BOOL("clear_queue_on_stop_disable", cfg_false, CFGF_NONE),
     CFG_END()
   };
 

src/player.c

@@ -244,6 +244,9 @@ static struct event *exitev;
 static struct event *cmdev;
 static pthread_t tid_player;
 
+/* Config values */
+static int clear_queue_on_stop_disabled;
+
 /* Player status */
 static enum play_status player_state;
 static enum repeat_mode repeat;
@@ -2167,10 +2170,11 @@ playback_abort(void)
 
   source_stop();
 
-  playerqueue_clear(NULL);
-
   evbuffer_drain(audio_buf, evbuffer_get_length(audio_buf));
 
+  if (!clear_queue_on_stop_disabled)
+    playerqueue_clear(NULL);
+
   status_update(PLAY_STOPPED);
 
   metadata_purge();
@@ -4590,6 +4594,8 @@ player_init(void)
 
   player_exit = 0;
 
+  clear_queue_on_stop_disabled = cfg_getbool(cfg_getsec(cfg, "mpd"), "clear_queue_on_stop_disable");
+
   dev_autoselect = 1;
   dev_list = NULL;