[mutter] Add support for an extended style of _NET_WM_SYNC_REQUEST_COUNTER

[Owen Taylor <otaylor src gnome org>]

commit 70c0d39fa703daff5d5b3fd677dae6495dedf624
Author: Owen W. Taylor <otaylor fishsoup net>
Date:   Wed Jun 8 13:58:54 2011 -0400

    Add support for an extended style of _NET_WM_SYNC_REQUEST_COUNTER
    
    If an application provides two values in _NET_WM_SYNC_REQUEST_COUNTER,
    use that as a signal that the applications wants an extended behavior
    where it can update the counter as well as the window manager. If the
    application updates the counter to an odd value, updates of the
    window are frozen until the counter is updated again to an even value.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=685463

 src/core/display-private.h |    3 ++
 src/core/display.c         |    2 +-
 src/core/window-private.h  |    8 +++-
 src/core/window-props.c    |   28 ++++++++++++++---
 src/core/window.c          |   73 +++++++++++++++++++++++++++++++++----------
 5 files changed, 89 insertions(+), 25 deletions(-)
---
diff --git a/src/core/display-private.h b/src/core/display-private.h
index 7535112..99984e1 100644
--- a/src/core/display-private.h
+++ b/src/core/display-private.h
@@ -223,6 +223,9 @@ struct _MetaDisplay
   int         xkb_base_event_type;
   guint32     last_bell_time;
 #endif
+#ifdef HAVE_XSYNC
+  gint64      grab_sync_counter_wait_serial;
+#endif
   int	      grab_resize_timeout_id;
 
   /* Keybindings stuff */
diff --git a/src/core/display.c b/src/core/display.c
index dd45633..da735fd 100644
--- a/src/core/display.c
+++ b/src/core/display.c
@@ -1958,7 +1958,7 @@ event_callback (XEvent   *event,
       if (alarm_window != NULL)
         {
           XSyncValue value = ((XSyncAlarmNotifyEvent*)event)->counter_value;
-          guint64 new_counter_value;
+          gint64 new_counter_value;
           new_counter_value = XSyncValueLow32 (value) + ((gint64)XSyncValueHigh32 (value) << 32);
           meta_window_update_sync_request_counter (alarm_window, new_counter_value);
           filter_out_event = TRUE; /* GTK doesn't want to see this really */
diff --git a/src/core/window-private.h b/src/core/window-private.h
index 00f1c7a..04ee110 100644
--- a/src/core/window-private.h
+++ b/src/core/window-private.h
@@ -352,13 +352,17 @@ struct _MetaWindow
   /* if non-NULL, the opaque region _NET_WM_OPAQUE_REGION */
   cairo_region_t *opaque_region;
 
+  /* if TRUE, the we have the new form of sync request counter which
+   * also handles application frames */
+  guint extended_sync_request_counter : 1;
+
   /* Note: can be NULL */
   GSList *struts;
 
 #ifdef HAVE_XSYNC
   /* XSync update counter */
   XSyncCounter sync_request_counter;
-  guint sync_request_serial;
+  gint64 sync_request_serial;
   GTimeVal sync_request_time;
   /* alarm monitoring client's _NET_WM_SYNC_REQUEST_COUNTER */
   XSyncAlarm sync_request_alarm;
@@ -607,7 +611,7 @@ void meta_window_set_gravity (MetaWindow *window,
 
 #ifdef HAVE_XSYNC
 void meta_window_update_sync_request_counter (MetaWindow *window,
-                                              guint64     new_counter_value);
+                                              gint64      new_counter_value);
 #endif /* HAVE_XSYNC */
 
 void meta_window_handle_mouse_grab_op_event (MetaWindow *window,
diff --git a/src/core/window-props.c b/src/core/window-props.c
index 1637c2d..5e7eb8f 100644
--- a/src/core/window-props.c
+++ b/src/core/window-props.c
@@ -921,13 +921,31 @@ reload_update_counter (MetaWindow    *window,
   if (value->type != META_PROP_VALUE_INVALID)
     {
       meta_window_destroy_sync_request_alarm (window);
+      window->sync_request_counter = None;
 
 #ifdef HAVE_XSYNC
-      XSyncCounter counter = value->v.xcounter;
+      if (value->v.xcounter_list.n_counters == 0)
+        {
+          meta_warning ("_NET_WM_SYNC_REQUEST_COUNTER is empty\n");
+          return;
+        }
+
+      if (value->v.xcounter_list.n_counters == 1)
+        {
+          window->sync_request_counter = value->v.xcounter_list.counters[0];
+          window->extended_sync_request_counter = FALSE;
+        }
+      else
+        {
+          window->sync_request_counter = value->v.xcounter_list.counters[1];
+          window->extended_sync_request_counter = TRUE;
+        }
+      meta_verbose ("Window has _NET_WM_SYNC_REQUEST_COUNTER 0x%lx (extended=%s)\n",
+                    window->sync_request_counter,
+                    window->extended_sync_request_counter ? "true" : "false");
 
-      window->sync_request_counter = counter;
-      meta_verbose ("Window has _NET_WM_SYNC_REQUEST_COUNTER 0x%lx\n",
-                    window->sync_request_counter);
+      if (window->extended_sync_request_counter)
+        meta_window_create_sync_request_alarm (window);
 #endif
     }
 }
@@ -1721,7 +1739,7 @@ meta_display_init_window_prop_hooks (MetaDisplay *display)
     { XA_WM_ICON_NAME,                 META_PROP_VALUE_TEXT_PROPERTY, reload_wm_icon_name, TRUE,  FALSE },
     { display->atom__NET_WM_DESKTOP,   META_PROP_VALUE_CARDINAL, reload_net_wm_desktop,    TRUE,  FALSE },
     { display->atom__NET_STARTUP_ID,   META_PROP_VALUE_UTF8,     reload_net_startup_id,    TRUE,  FALSE },
-    { display->atom__NET_WM_SYNC_REQUEST_COUNTER, META_PROP_VALUE_SYNC_COUNTER, reload_update_counter, TRUE, FALSE },
+    { display->atom__NET_WM_SYNC_REQUEST_COUNTER, META_PROP_VALUE_SYNC_COUNTER_LIST, reload_update_counter, TRUE, TRUE },
     { XA_WM_NORMAL_HINTS,              META_PROP_VALUE_SIZE_HINTS, reload_normal_hints,    TRUE,  FALSE },
     { display->atom_WM_PROTOCOLS,      META_PROP_VALUE_ATOM_LIST, reload_wm_protocols,     TRUE,  FALSE },
     { XA_WM_HINTS,                     META_PROP_VALUE_WM_HINTS,  reload_wm_hints,         TRUE,  FALSE },
diff --git a/src/core/window.c b/src/core/window.c
index af7cdb0..5bf8f05 100644
--- a/src/core/window.c
+++ b/src/core/window.c
@@ -4453,17 +4453,38 @@ meta_window_create_sync_request_alarm (MetaWindow *window)
 
   meta_error_trap_push_with_return (window->display);
 
-  /* Set the counter to 0, so we know that the application's
-   * responses to the client messages will always trigger
-   * a PositiveTransition
+  /* In the new (extended style), the counter value is initialized by
+   * the client before mapping the window. In the old style, we're
+   * responsible for setting the initial value of the counter.
    */
-  XSyncIntToValue (&init, 0);
-  XSyncSetCounter (window->display->xdisplay,
-                   window->sync_request_counter, init);
-  window->sync_request_serial = 0;
+  if (window->extended_sync_request_counter)
+    {
+      if (!XSyncQueryCounter(window->display->xdisplay,
+                             window->sync_request_counter,
+                             &init))
+        {
+          meta_error_trap_pop_with_return (window->display);
+          window->sync_request_counter = None;
+          return;
+        }
+
+      window->sync_request_serial =
+        XSyncValueLow32 (init) + ((gint64)XSyncValueHigh32 (init) << 32);
+
+      /* if the value is odd, the window starts off with updates frozen */
+      meta_compositor_set_updates_frozen (window->display->compositor, window,
+                                          meta_window_updates_are_frozen (window));
+    }
+  else
+    {
+      XSyncIntToValue (&init, 0);
+      XSyncSetCounter (window->display->xdisplay,
+                       window->sync_request_counter, init);
+      window->sync_request_serial = 0;
+    }
 
   values.trigger.counter = window->sync_request_counter;
-  values.trigger.test_type = XSyncPositiveTransition;
+  values.trigger.test_type = XSyncPositiveComparison;
 
   /* Initialize to one greater than the current value */
   values.trigger.value_type = XSyncRelative;
@@ -4514,12 +4535,19 @@ meta_window_destroy_sync_request_alarm (MetaWindow *window)
 static void
 send_sync_request (MetaWindow *window)
 {
-  XSyncValue value;
   XClientMessageEvent ev;
+  gint64 wait_serial;
+
+  /* For the old style of _NET_WM_SYNC_REQUEST_COUNTER, we just have to
+   * increase the value, but for the new "extended" style we need to
+   * pick an even (unfrozen) value sufficiently ahead of the last serial
+   * that we received from the client; the same code still works
+   * for the old style. The increment of 240 is specified by the EWMH
+   * and is (1 second) * (60fps) * (an increment of 4 per frame).
+   */
+  wait_serial = window->sync_request_serial + 240;
 
-  window->sync_request_serial++;
-
-  XSyncIntToValue (&value, window->sync_request_serial);
+  window->display->grab_sync_counter_wait_serial = wait_serial;
 
   ev.type = ClientMessage;
   ev.window = window->xwindow;
@@ -4532,8 +4560,9 @@ send_sync_request (MetaWindow *window)
    * want to use _roundtrip, though?
    */
   ev.data.l[1] = meta_display_get_current_time (window->display);
-  ev.data.l[2] = XSyncValueLow32 (value);
-  ev.data.l[3] = XSyncValueHigh32 (value);
+  ev.data.l[2] = wait_serial & G_GUINT64_CONSTANT(0xffffffff);
+  ev.data.l[3] = wait_serial >> 32;
+  ev.data.l[4] = window->extended_sync_request_counter ? 1 : 0;
 
   /* We don't need to trap errors here as we are already
    * inside an error_trap_push()/pop() pair.
@@ -4560,6 +4589,12 @@ send_sync_request (MetaWindow *window)
 gboolean
 meta_window_updates_are_frozen (MetaWindow *window)
 {
+#ifdef HAVE_XSYNC
+  if (window->extended_sync_request_counter &&
+      window->sync_request_serial % 2 == 1)
+    return TRUE;
+#endif
+
   return window->updates_frozen_for_resize;
 }
 
@@ -9456,13 +9491,17 @@ update_tile_mode (MetaWindow *window)
 #ifdef HAVE_XSYNC
 void
 meta_window_update_sync_request_counter (MetaWindow *window,
-                                         guint64     new_counter_value)
+                                         gint64      new_counter_value)
 {
+  window->sync_request_serial = new_counter_value;
+  meta_compositor_set_updates_frozen (window->display->compositor, window,
+                                      meta_window_updates_are_frozen (window));
+
   if (window->display->grab_op != META_GRAB_OP_NONE &&
       window == window->display->grab_window &&
-      meta_grab_op_is_mouse (window->display->grab_op))
+      meta_grab_op_is_mouse (window->display->grab_op) &&
+      new_counter_value >= window->display->grab_sync_counter_wait_serial)
     {
-
       meta_topic (META_DEBUG_RESIZING,
                   "Alarm event received last motion x = %d y = %d\n",
                   window->display->grab_latest_motion_x,