gl/wayland: fix glib mainloop integration

Implement the prepare and check functions according to the
documentation by returning TRUE when events should be dispatched
via the dispatch function.

As wl_display_read_events never blocks we can call it unconditionally
without looking at the poll status.

This simplifies the implementation and gets rid of a race where the
mainloop could get blocked due to nobody actually reading the events
from the wayland connection.

1 files changed, 9 insertions, 20 deletions

diff --git a/gst-libs/gst/gl/wayland/wayland_event_source.c b/gst-libs/gst/gl/wayland/wayland_event_source.c
index 12a066805..3f9d482ff 100644
--- a/gst-libs/gst/gl/wayland/wayland_event_source.c
+++ b/gst-libs/gst/gl/wayland/wayland_event_source.c
@@ -128,19 +128,13 @@ wayland_event_source_prepare (GSource * base, gint * timeout)
     wl_display_cancel_read (source->display);
 
   if (source->queue) {
-    while (wl_display_prepare_read_queue (source->display, source->queue) != 0) {
-      if (wl_display_dispatch_queue_pending (source->display,
-              source->queue) < 0) {
-        g_critical ("Failed to dispatch pending events\n");
-      }
-    }
+    if (wl_display_prepare_read_queue (source->display, source->queue) != 0)
+      return TRUE;
   } else {
-    while (wl_display_prepare_read (source->display) != 0) {
-      if (wl_display_dispatch_pending (source->display) < 0) {
-        g_critical ("Failed to dispatch pending events\n");
-      }
-    }
+    if (wl_display_prepare_read (source->display) != 0)
+      return TRUE;
   }
+
   source->reading = TRUE;
 
   /* FIXME: this may return EAGAIN if the fd is full */
@@ -154,18 +148,13 @@ static gboolean
 wayland_event_source_check (GSource * base)
 {
   WaylandEventSource *source = (WaylandEventSource *) base;
-  gboolean retval;
-
-  retval = source->pfd.revents;
 
-  if (source->pfd.revents & G_IO_IN) {
-    wl_display_read_events (source->display);
-  } else {
-    wl_display_cancel_read (source->display);
-  }
   source->reading = FALSE;
 
-  return retval;
+  if (wl_display_read_events (source->display) == 0)
+    return TRUE;
+
+  return FALSE;
 }
 
 static gboolean