add warning

This reverts commit 72d4e63249.

more trouble than it's worth

src/playbin.vala

@@ -57,6 +57,9 @@ public class Playbin : GLib.Object {
     public ListStore _play_queue;
     public ListModel play_queue { get { return this._play_queue; } }
 
+    // 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 = {};
 
@@ -67,9 +70,6 @@ public class Playbin : GLib.Object {
         return cc.error;
     }
 
-    // should be Mpv.WakeupCallback, but i think there's a vala bug here
-    private SourceOnceFunc wakeup_callback; // anchor reference here, mpv won't remind us
-
     public Playbin () {
         this._play_queue = new ListStore (typeof (Subsonic.Song));
 
@@ -83,42 +83,13 @@ public class Playbin : GLib.Object {
         assert (this.mpv.observe_property (2, "playlist-pos", Mpv.Format.INT64) >= 0);
         assert (this.mpv.observe_property (3, "pause", Mpv.Format.FLAG) >= 0);
 
-        int wakeup_fds[2];
-        try {
-            assert (Unix.open_pipe (wakeup_fds, 0));
-        } catch (Error e) {
-            error (@"could not open pipe for mpv wakeup: $(e.message)");
-        }
-
-        IOChannel wakeup_read = new IOChannel.unix_new (wakeup_fds[0]);
-        IOChannel wakeup_write = new IOChannel.unix_new (wakeup_fds[1]);
-
-        wakeup_read.set_close_on_unref (true);
-        wakeup_write.set_close_on_unref (true);
-
-        try {
-            wakeup_read.set_encoding (null);
-            wakeup_write.set_encoding (null);
-            wakeup_write.set_buffered (false);
-        } catch (Error e) {
-            error (@"could not set up pipes for mpv wakeup: $(e.message)");
-        }
-
-        this.wakeup_callback = () => {
-            try {
-                wakeup_write.write_chars ({0}, null);
-            } catch (Error e) {
-                error (@"could not write to mpv wakeup pipe: $(e.message)");
-            }
-        };
-        this.mpv.wakeup_callback = this.wakeup_callback;
-
-        assert (0 < wakeup_read.add_watch (IOCondition.IN, (source, condition) => {
-            try {
-                wakeup_read.read_chars ({0}, null);
-            } catch (Error e) {
-                error (@"could not read from mpv wakeup pipe: $(e.message)");
+        this.mpv.wakeup_callback = () => {
+            Idle.add (() => {
+                if (this.is_handling_event) {
+                    warning ("main thread mpv wakeup callback called twice");
+                    return false;
                 }
+                this.is_handling_event = true;
 
                 while (true) {
                     var event = this.mpv.wait_event (0.0);
@@ -228,8 +199,10 @@ public class Playbin : GLib.Object {
                     }
                 }
             
-            return true;
-        }));
+                this.is_handling_event = false;
+                return false;
+            });
+        };
     }
 
     public void seek (double position) {

src/vapi/mpv.vapi

@@ -43,7 +43,7 @@ namespace Mpv {
         [CCode (cname = "mpv_wait_event")]
         public unowned Event? wait_event (double timeout);
 
-        public unowned WakeupCallback wakeup_callback {
+        public WakeupCallback wakeup_callback {
             [CCode (cname = "mpv_set_wakeup_callback")] set;
         }