Avoid extra consing on monitor configuration change

* src/xterm.c (x_find_monitors_changed_event): New function.
(x_monitors_changed_cb, handle_one_xevent): Look through the
entire event queue to skip delivering monitor change events.

1 files changed, 31 insertions, 8 deletions

diff --git a/src/xterm.c b/src/xterm.c
index c34fb3eb362..017e63d8b6b 100644
--- a/src/xterm.c
+++ b/src/xterm.c
@@ -16499,6 +16499,33 @@ x_wait_for_cell_change (Lisp_Object cell, struct timespec timeout)
     }
 }
 
+#if defined USE_GTK || defined HAVE_XRANDR
+
+/* Find whether or not an undelivered MONITORS_CHANGED_EVENT is
+   already on the event queue.  DPYINFO is the display any such event
+   must apply to.  */
+
+static bool
+x_find_monitors_changed_event (struct x_display_info *dpyinfo)
+{
+  union buffered_input_event *event;
+
+  event = kbd_fetch_ptr;
+
+  while (event != kbd_store_ptr)
+    {
+      if (event->ie.kind == MONITORS_CHANGED_EVENT
+          && XTERMINAL (event->ie.arg) == dpyinfo->terminal)
+        return true;
+
+      event = X_NEXT_KBD_EVENT (event);
+    }
+
+  return false;
+}
+
+#endif
+
 #ifdef USE_GTK
 static void
 x_monitors_changed_cb (GdkScreen *gscr, gpointer user_data)
@@ -16516,6 +16543,9 @@ x_monitors_changed_cb (GdkScreen *gscr, gpointer user_data)
   if (!dpyinfo)
     return;
 
+  if (x_find_monitors_changed_event (dpyinfo))
+    return;
+
   XSETTERMINAL (terminal, dpyinfo->terminal);
 
   current_monitors
@@ -22532,7 +22562,6 @@ handle_one_xevent (struct x_display_info *dpyinfo,
               || event->type == (dpyinfo->xrandr_event_base
                                  + RRNotify)))
         {
-          union buffered_input_event *ev;
           Time timestamp;
           Lisp_Object current_monitors;
           XRRScreenChangeNotifyEvent *notify;
@@ -22560,13 +22589,7 @@ handle_one_xevent (struct x_display_info *dpyinfo,
           else
             timestamp = 0;
 
-          ev = (kbd_store_ptr == kbd_buffer
-                ? kbd_buffer + KBD_BUFFER_SIZE - 1
-                : kbd_store_ptr - 1);
-
-          if (kbd_store_ptr != kbd_fetch_ptr
-              && ev->ie.kind == MONITORS_CHANGED_EVENT
-              && XTERMINAL (ev->ie.arg) == dpyinfo->terminal)
+          if (x_find_monitors_changed_event (dpyinfo))
             /* Don't store a MONITORS_CHANGED_EVENT if there is
                already an undelivered event on the queue.  */
             goto OTHER;