frametimings: reuse previous frame timing in common case

Typically, there won't be any references on old frame timings except for
the most recent timing. So instead of discarding these and re-entering
gslice twice, just steal the old frame timing and reuse it.

https://bugzilla.gnome.org/show_bug.cgi?id=765592

1 files changed, 17 insertions, 0 deletions

diff --git a/gdk/gdkframetimings.c b/gdk/gdkframetimings.c
index 0245d469d2..7b8a3dd88c 100644
--- a/gdk/gdkframetimings.c
+++ b/gdk/gdkframetimings.c
@@ -17,6 +17,8 @@
 
 #include "config.h"
 
+#include <string.h>
+
 #include "gdkframeclockprivate.h"
 
 /**
@@ -48,6 +50,21 @@ _gdk_frame_timings_new (gint64 frame_counter)
   return timings;
 }
 
+gboolean
+_gdk_frame_timings_steal (GdkFrameTimings *timings,
+                          gint64           frame_counter)
+{
+  if (timings->ref_count == 1)
+    {
+      memset (timings, 0, sizeof *timings);
+      timings->ref_count = 1;
+      timings->frame_counter = frame_counter;
+      return TRUE;
+    }
+
+  return FALSE;
+}
+
 /**
  * gdk_frame_timings_ref:
  * @timings: a #GdkFrameTimings