patches/gtk2/GDK-W32-Always-process-all-available-messages.patch

   1 From: Jeremy Tan <jtanx@outlook.com>
   2 Date: Sat, 17 Sep 2016 17:19:59 +0800
   3 Subject: GDK W32: Always process all available messages
   4
   5 The GLib main loop blocks on MsgWaitForMultipleObjectsEx to
   6 determine if there are any incoming messages while also allowing
   7 for background tasks to run. If all available messages are not
   8 processed after MsgWaitForMultipleObjectsEx has signaled that
   9 there are available, CPU usage will skyrocket.
  10
  11 From my limited understanding (by inspection of profiling
  12 under Visual Studio):
  13 Key is pressed - MsgWaitForMultipleObjectsEx unblocks, and
  14 sends message to GDK's event handler. Some event is now queued.
  15
  16 g_poll unblocks, calls the g_event_dispatch which finally
  17 resolves to gdk_event_dispatch. This then calls
  18 _gdk_win32_display_queue_events, but since a message is already
  19 queued, it fails to call PeekMessage and returns immediately.
  20
  21 At the next iteration, g_poll again calls MsgWaitForMultipleObjectsEx
  22 which queues yet another event and returns almost immediately, since
  23 there are events available which haven't been processed by PeekMessage.
  24
  25 The dispatch function is then called and the process repeats.
  26
  27 Bug: https://bugzilla.gnome.org/show_bug.cgi?id=771568
  28 Origin: upstream, 2.24.33, commit:bfdac2f70e005b2504cc3f4ebbdab328974d005a
  29 ---
  30  gdk/win32/gdkevents-win32.c | 3 +--
  31  1 file changed, 1 insertion(+), 2 deletions(-)
  32
  33 diff --git a/gdk/win32/gdkevents-win32.c b/gdk/win32/gdkevents-win32.c
  34 index 9b09edd..e52f21c 100644
  35 --- a/gdk/win32/gdkevents-win32.c
  36 +++ b/gdk/win32/gdkevents-win32.c
  37 @@ -3622,8 +3622,7 @@ _gdk_events_queue (GdkDisplay *display)
  38    if (modal_win32_dialog != NULL)
  39      return;
  40
  41 -  while (!_gdk_event_queue_find_first (display) &&
  42 -        PeekMessageW (&msg, NULL, 0, 0, PM_REMOVE))
  43 +  while (PeekMessageW (&msg, NULL, 0, 0, PM_REMOVE))
  44      {
  45        TranslateMessage (&msg);
  46        DispatchMessageW (&msg);