Improve X event timestamp tracking

Fix two problems with our handling of X timestamps

1) We're not properly updating the X interaction timestamp after
receiving certain input events, and

2) X events sent in response to emacsclient commands get stale
timestamps because the timestamp tracking doesn't take into account
that interactions with the user can occur outside the X input
event channel.

* src/xterm.c:
(x_display_set_last_user_time_1): New function.
(x_display_set_last_user_time): Call it.
(x_ewmh_activate_frame): Refactor.
(x_focus_frame): Don't call XSetInputFocus if we can use EWMH activation.
(server_timestamp_predicate): New function.
(x_get_server_time): New function.
(x_note_oob_interaction): New function.
(x_create_terminal): Register new function as terminal hook.

* src/termhooks.h: New hook: note_oob_interaction_hook.

* src/gtkutil.h:
(xg_set_user_timestamp): Declare.

* src/gtkutil.c:
(xg_set_user_timestamp): New function.

* src/frame.c:
(Fframe_note_oob_interaction): New function.
(syms_of_frame): Register it.

* lisp/server.el:
(server-switch-buffer): Call frame-note-oob-interaction when user
requests frame be raised.

1 files changed, 94 insertions, 32 deletions

diff --git a/src/xterm.c b/src/xterm.c
index 97985c8d9e7..29295cfe7bb 100644
--- a/src/xterm.c
+++ b/src/xterm.c
@@ -6581,12 +6581,6 @@ x_set_frame_alpha (struct frame *f)
   x_stop_ignoring_errors (dpyinfo);
 }
 
-/***********************************************************************
-                    Starting and ending an update
- ***********************************************************************/
-
-#if defined HAVE_XSYNC && !defined USE_GTK
-
 /* Wait for an event matching PREDICATE to show up in the event
    queue, or TIMEOUT to elapse.
 
@@ -6640,6 +6634,12 @@ x_if_event (Display *dpy, XEvent *event_return,
     }
 }
 
+/***********************************************************************
+                    Starting and ending an update
+ ***********************************************************************/
+
+#if defined HAVE_XSYNC && !defined USE_GTK
+
 /* Return the monotonic time corresponding to the high-resolution
    server timestamp TIMESTAMP.  Return 0 if the necessary information
    is not available.  */
@@ -7521,26 +7521,25 @@ static void x_check_font (struct frame *, struct font *);
    user time.  We don't sanitize timestamps from events sent by the X
    server itself because some Lisp might have set the user time to a
    ridiculously large value, and this way a more reasonable timestamp
-   can be obtained upon the next event.  */
+   can be obtained upon the next event.  If EXPLICIT_FRAME is NULL,
+   update the focused frame's timestamp; otherwise, update
+   EXPLICIT_FRAME's. */
 
 static void
-x_display_set_last_user_time (struct x_display_info *dpyinfo, Time time,
-                              bool send_event)
+x_display_set_last_user_time_1 (struct x_display_info *dpyinfo, Time time,
+                                bool send_event,
+                                struct frame *explicit_frame)
 {
-#ifndef USE_GTK
-  struct frame *focus_frame;
+  struct frame *frame;
   Time old_time;
-#if defined HAVE_XSYNC
+#if defined HAVE_XSYNC && !defined USE_GTK
   uint64_t monotonic_time;
 #endif
 
-  focus_frame = dpyinfo->x_focus_frame;
+  frame = explicit_frame ? explicit_frame : dpyinfo->x_focus_frame;
   old_time = dpyinfo->last_user_time;
-#endif
 
-#ifdef ENABLE_CHECKING
   eassert (time <= X_ULONG_MAX);
-#endif
 
   if (!send_event || time > dpyinfo->last_user_time)
     dpyinfo->last_user_time = time;
@@ -7567,23 +7566,35 @@ x_display_set_last_user_time (struct x_display_info *dpyinfo, Time time,
     }
 #endif
 
-#ifndef USE_GTK
-  /* Don't waste bandwidth if the time hasn't actually changed.  */
-  if (focus_frame && old_time != dpyinfo->last_user_time)
+  /* Don't waste bandwidth if the time hasn't actually changed.
+     Update anyway if we're updating the timestamp for a non-focused
+     frame, since the event loop might not have gotten around to
+     updating that frame's timestamp.  */
+  if (frame && (explicit_frame || old_time != dpyinfo->last_user_time))
     {
       time = dpyinfo->last_user_time;
 
-      while (FRAME_PARENT_FRAME (focus_frame))
-        focus_frame = FRAME_PARENT_FRAME (focus_frame);
+      while (FRAME_PARENT_FRAME (frame))
+        frame = FRAME_PARENT_FRAME (frame);
 
-      if (FRAME_X_OUTPUT (focus_frame)->user_time_window != None)
+#if defined USE_GTK
+      xg_set_user_timestamp (frame, time);
+#else
+      if (FRAME_X_OUTPUT (frame)->user_time_window != None)
         XChangeProperty (dpyinfo->display,
-                         FRAME_X_OUTPUT (focus_frame)->user_time_window,
+                         FRAME_X_OUTPUT (frame)->user_time_window,
                          dpyinfo->Xatom_net_wm_user_time,
                          XA_CARDINAL, 32, PropModeReplace,
                          (unsigned char *) &time, 1);
-    }
 #endif
+    }
+}
+
+static void
+x_display_set_last_user_time (struct x_display_info *dpyinfo, Time time,
+                              bool send_event)
+{
+  x_display_set_last_user_time_1 (dpyinfo, time, send_event, NULL);
 }
 
 #ifdef USE_GTK
@@ -25883,9 +25894,11 @@ xembed_request_focus (struct frame *f)
                          XEMBED_REQUEST_FOCUS, 0, 0, 0);
 }
 
-/* Activate frame with Extended Window Manager Hints */
+/* Activate frame with Extended Window Manager Hints
 
-static void
+Return whether we were successful in doing so.  */
+
+static bool
 x_ewmh_activate_frame (struct frame *f)
 {
   XEvent msg;
@@ -25893,8 +25906,7 @@ x_ewmh_activate_frame (struct frame *f)
 
   dpyinfo = FRAME_DISPLAY_INFO (f);
 
-  if (FRAME_VISIBLE_P (f)
-      && x_wm_supports (f, dpyinfo->Xatom_net_active_window))
+  if (x_wm_supports (f, dpyinfo->Xatom_net_active_window))
     {
       /* See the documentation at
          https://specifications.freedesktop.org/wm-spec/wm-spec-latest.html
@@ -25914,7 +25926,9 @@ x_ewmh_activate_frame (struct frame *f)
       XSendEvent (dpyinfo->display, dpyinfo->root_window,
                   False, (SubstructureRedirectMask
                           | SubstructureNotifyMask), &msg);
+      return true;
     }
+  return false;
 }
 
 static Lisp_Object
@@ -25952,16 +25966,14 @@ x_focus_frame (struct frame *f, bool noactivate)
        events.  See XEmbed Protocol Specification at
        https://freedesktop.org/wiki/Specifications/xembed-spec/  */
     xembed_request_focus (f);
-  else
+  else if (noactivate ||
+           (!FRAME_PARENT_FRAME (f) && !x_ewmh_activate_frame (f)))
     {
       /* Ignore any BadMatch error this request might result in.  */
       x_ignore_errors_for_next_request (dpyinfo);
       XSetInputFocus (FRAME_X_DISPLAY (f), FRAME_OUTER_WINDOW (f),
                       RevertToParent, CurrentTime);
       x_stop_ignoring_errors (dpyinfo);
-
-      if (!noactivate)
-        x_ewmh_activate_frame (f);
     }
 }
 
@@ -28576,6 +28588,55 @@ x_have_any_grab (struct x_display_info *dpyinfo)
 }
 #endif
 
+static Bool
+server_timestamp_predicate (Display *display,
+                            XEvent *xevent,
+                            XPointer arg)
+{
+  XID *args = (XID *) arg;
+
+  if (xevent->type == PropertyNotify
+      && xevent->xproperty.window == args[0]
+      && xevent->xproperty.atom == args[1])
+    return True;
+
+  return False;
+}
+
+static bool
+x_get_server_time (struct frame *f, Time *time)
+{
+  struct x_display_info *dpyinfo = FRAME_DISPLAY_INFO (f);
+  Atom property_atom = dpyinfo->Xatom_EMACS_SERVER_TIME_PROP;
+  XEvent event;
+
+  XChangeProperty (dpyinfo->display, FRAME_OUTER_WINDOW (f),
+                   property_atom, XA_ATOM, 32,
+                   PropModeReplace, (unsigned char *) &property_atom, 1);
+
+  if (x_if_event (dpyinfo->display, &event, server_timestamp_predicate,
+                  (XPointer) &(XID[]) {FRAME_OUTER_WINDOW (f), property_atom},
+                  dtotimespec (XFLOAT_DATA (Vx_wait_for_event_timeout))))
+    return false;
+  *time = event.xproperty.time;
+  return true;
+}
+
+static void
+x_note_oob_interaction (struct frame *f)
+{
+  while (FRAME_PARENT_FRAME (f))
+    f = FRAME_PARENT_FRAME (f);
+  if (FRAME_LIVE_P (f))
+    {
+      Time server_time;
+      if (!x_get_server_time (f, &server_time))
+        error ("Timed out waiting for server timestamp");
+      x_display_set_last_user_time_1 (
+        FRAME_DISPLAY_INFO (f), server_time, false, f);
+    }
+}
+
 /* Create a struct terminal, initialize it with the X11 specific
    functions and make DISPLAY->TERMINAL point to it.  */
 
@@ -28646,6 +28707,7 @@ x_create_terminal (struct x_display_info *dpyinfo)
 #ifdef HAVE_XINPUT2
   terminal->any_grab_hook = x_have_any_grab;
 #endif
+  terminal->note_oob_interaction_hook = x_note_oob_interaction;
   /* Other hooks are NULL by default.  */
 
   return terminal;