some async

src/playbin.vala

@@ -4,6 +4,11 @@ public enum PlaybinState {
     PLAYING,
 }
 
+private struct CommandCallback {
+    unowned SourceFunc callback;
+    int error;
+}
+
 public class Playbin : GLib.Object {
     private Mpv.Handle mpv = new Mpv.Handle ();
 
@@ -55,6 +60,16 @@ public class Playbin : GLib.Object {
     // try to prevent wait_event to be called twice
     private bool is_handling_event = false;
 
+    private async Mpv.Error mpv_command_async (string[] args) {
+        CommandCallback cc = {};
+
+        this.mpv.command_async ((uint64) &cc, args);
+        
+        cc.callback = this.mpv_command_async.callback;
+        yield;
+        return cc.error;
+    }
+
     public Playbin () {
         this._play_queue = new ListStore (typeof (Subsonic.Song));
 
@@ -169,6 +184,12 @@ public class Playbin : GLib.Object {
 
                         break;
 
+                    case Mpv.EventId.COMMAND_REPLY:
+                        unowned CommandCallback *cc = (CommandCallback *) event.reply_userdata;
+                        cc.error = event.error;
+                        cc.callback ();
+                        break;
+                      
                     default:
                         // ignore by default
                         break;
@@ -268,7 +289,7 @@ public class Playbin : GLib.Object {
     }
 
     public void append_track (Subsonic.Song song) {
-        assert (this.mpv.command({
+        assert (this.mpv.command ({
             "loadfile",
             this.api.stream_uri (song.id),
             "append",
@@ -277,6 +298,18 @@ public class Playbin : GLib.Object {
         this._play_queue.append (song);
     }
 
+    public async void append_track_async (Subsonic.Song song) {
+        var err = yield this.mpv_command_async ({
+            "loadfile",
+            this.api.stream_uri (song.id),
+            "append",
+        });
+        assert (err >= 0);
+
+        if (this.state == STOPPED) this.play_queue_position += 1;
+        this._play_queue.append (song);
+    }
+
     public void move_track (uint from, uint to)
             requires (from < this._play_queue.get_n_items ())
             requires (to < this._play_queue.get_n_items ())

src/subsonic.vala

@@ -224,6 +224,9 @@ public class Subsonic.Client : Object {
             reader.read_element (i);
             callback (new Song (reader));
             reader.end_element ();
+
+            Idle.add (this.get_random_songs.callback);
+            yield;
         }
 
         assert (reader.get_error () == null);

src/vapi/mpv.vapi

@@ -65,6 +65,9 @@ namespace Mpv {
         [CCode (cname = "mpv_command")]
         public Error command ([CCode (array_length = false)] string[] args);
 
+        [CCode (cname = "mpv_command_async")]
+        public Error command_async (uint64 reply_userdata, [CCode (array_length = false)] string[] args);
+
         [CCode (cname = "mpv_observe_property")]
         public Error observe_property (uint64 reply_userdata, string name, Format format);
     }