[player] Fix commit 3e9f8ef, input_resume() must be non-blocking (possibly issue #773)

src/input.c

@@ -50,6 +50,8 @@
 #define INPUT_OPEN_TIMEOUT 600
 
 //#define DEBUG_INPUT 1
+// For testing http stream underruns
+//#define DEBUG_UNDERRUN 1
 
 extern struct input_definition input_file;
 extern struct input_definition input_http;
@@ -142,6 +144,9 @@ static struct event *input_open_timeout_ev;
 #ifdef DEBUG_INPUT
 static size_t debug_elapsed;
 #endif
+#ifdef DEBUG_UNDERRUN
+int debug_underrun_trigger;
+#endif
 
 
 /* ------------------------------- MISC HELPERS ----------------------------- */
@@ -578,6 +583,16 @@ input_write(struct evbuffer *evbuf, struct media_quality *quality, short flags)
   if (evbuf)
     {
       len = evbuffer_get_length(evbuf);
+#ifdef DEBUG_UNDERRUN
+      // Starves the player so it underruns after a few minutes
+      debug_underrun_trigger++;
+      if (debug_underrun_trigger % 10 == 0)
+	{
+	  DPRINTF(E_DBG, L_PLAYER, "Underrun debug mode: Dropping audio buffer length %zu\n", len);
+	  evbuffer_drain(evbuf, len);
+	  len = 0;
+	}
+#endif
       input_buffer.bytes_written += len;
       ret = evbuffer_add_buffer(input_buffer.evbuf, evbuf);
       if (ret < 0)
@@ -778,16 +793,18 @@ input_seek(uint32_t item_id, int seek_ms)
   return commands_exec_sync(cmdbase, start, NULL, &cmdarg);
 }
 
-int
+void
 input_resume(uint32_t item_id, int seek_ms)
 {
-  struct input_arg cmdarg;
+  struct input_arg *cmdarg;
 
-  cmdarg.item_id = item_id;
+  CHECK_NULL(L_PLAYER, cmdarg = malloc(sizeof(struct input_arg)));
-  cmdarg.seek_ms = seek_ms;
-  cmdarg.resume  = true;
 
-  return commands_exec_sync(cmdbase, start, NULL, &cmdarg);
+  cmdarg->item_id = item_id;
+  cmdarg->seek_ms = seek_ms;
+  cmdarg->resume  = true;
+
+  commands_exec_async(cmdbase, start, cmdarg);
 }
 
 void

src/input.h

@@ -196,17 +196,6 @@ input_buffer_full_cb(input_cb cb);
 int
 input_seek(uint32_t item_id, int seek_ms);
 
-/*
- * Same as input_seek(), except if the item is already being read we don't do
- * anything (no flush & seek)
- *
- * @in  item_id  Queue item id to start playing
- * @in  seek_ms  Position to start playing
- * @return       Actual seek position if seekable, 0 otherwise, -1 on error
- */
-int
-input_resume(uint32_t item_id, int seek_ms);
-
 /*
  * Same as input_seek(), just non-blocking and does not offer seek.
  *
@@ -215,6 +204,16 @@ input_resume(uint32_t item_id, int seek_ms);
 void
 input_start(uint32_t item_id);
 
+/*
+ * Same as input_seek(), but non-blocking and if the item is already being read
+ * we don't do anything (no flush & seek)
+ *
+ * @in  item_id  Queue item id to start playing
+ * @in  seek_ms  Position to start playing
+ */
+void
+input_resume(uint32_t item_id, int seek_ms);
+
 /*
  * Stops the input and clears everything. Flushes the input buffer.
  */

src/player.c

@@ -649,6 +649,9 @@ source_restart(void)
 
   DPRINTF(E_DBG, L_PLAYER, "Restarting track: '%s' (id=%d, pos=%d)\n", pb_session.playing_now->path, pb_session.playing_now->item_id, pb_session.playing_now->pos_ms);
 
+  // Must be non-blocking, because otherwise we get a deadlock via the input
+  // thread making a sync call to player_playback_start() -> pb_resume() ->
+  // source_restart() -> input_resume()
   input_resume(pb_session.playing_now->item_id, pb_session.playing_now->pos_ms);
 
   return 0;