[mutter] display: Make check-alive timeout configureable

[Florian Müllner <fmuellner src gnome org>]

commit 2da27720ca5d3742803d17de679e1b9dc7998f4c
Author: Jonas Ådahl <jadahl gmail com>
Date:   Fri Feb 21 21:03:16 2020 +0100

    display: Make check-alive timeout configureable
    
    The check-alive feature is there for the user to be able to terminate
    frozen applications more easily. However, sometimes applications are
    implemented in a way where they fail to be reply to ping requests in a
    timely manner, resulting in that, to the compositor, they are
    indistinguishable from clients that have frozen indefinitely.
    
    When using an application that has these issues, the GUI showed in
    response to the failure to respond to ping requests can become annoying,
    as it disrupts the visual presentation of the application.
    
    To allow users to work-around these issues, add a setting allowing them
    to configure the timeout waited until an application is considered
    frozen, or disabling the check completely.
    
    https://gitlab.gnome.org/GNOME/mutter/merge_requests/1080

 data/org.gnome.mutter.gschema.xml.in | 10 ++++++
 src/core/display.c                   | 18 +++++-----
 src/core/prefs.c                     | 68 ++++++++++++++++++++++++++++++++++++
 src/meta/prefs.h                     |  4 +++
 4 files changed, 91 insertions(+), 9 deletions(-)
---
diff --git a/data/org.gnome.mutter.gschema.xml.in b/data/org.gnome.mutter.gschema.xml.in
index 7d36c06bd..5acc70502 100644
--- a/data/org.gnome.mutter.gschema.xml.in
+++ b/data/org.gnome.mutter.gschema.xml.in
@@ -137,6 +137,16 @@
       </description>
     </key>
 
+    <key name="check-alive-timeout" type="u">
+      <default>5000</default>
+      <summary>Timeout for check-alive ping</summary>
+      <description>
+        Number of milliseconds a client has to respond to a ping request in
+        order to not be detected as frozen. Using 0 will disable the alive check
+        completely.
+      </description>
+    </key>
+
     <child name="keybindings" schema="org.gnome.mutter.keybindings"/>
 
   </schema>
diff --git a/src/core/display.c b/src/core/display.c
index f4d4c2090..a61959cc5 100644
--- a/src/core/display.c
+++ b/src/core/display.c
@@ -2002,12 +2002,6 @@ meta_set_syncing (gboolean setting)
     }
 }
 
-/*
- * How long, in milliseconds, we should wait after pinging a window
- * before deciding it's not going to get back to us.
- */
-#define PING_TIMEOUT_DELAY 5000
-
 /**
  * meta_display_ping_timeout:
  * @data: All the information about this ping. It is a #MetaPingData
@@ -2066,6 +2060,11 @@ meta_display_ping_window (MetaWindow *window,
   GSList *l;
   MetaDisplay *display = window->display;
   MetaPingData *ping_data;
+  unsigned int check_alive_timeout;
+
+  check_alive_timeout = meta_prefs_get_check_alive_timeout ();
+  if (check_alive_timeout == 0)
+    return;
 
   if (serial == 0)
     {
@@ -2101,9 +2100,10 @@ meta_display_ping_window (MetaWindow *window,
   ping_data = g_new (MetaPingData, 1);
   ping_data->window = window;
   ping_data->serial = serial;
-  ping_data->ping_timeout_id = g_timeout_add (PING_TIMEOUT_DELAY,
-                                             meta_display_ping_timeout,
-                                             ping_data);
+  ping_data->ping_timeout_id =
+    g_timeout_add (check_alive_timeout,
+                   meta_display_ping_timeout,
+                   ping_data);
   g_source_set_name_by_id (ping_data->ping_timeout_id, "[mutter] meta_display_ping_timeout");
 
   display->pending_pings = g_slist_prepend (display->pending_pings, ping_data);
diff --git a/src/core/prefs.c b/src/core/prefs.c
index f9b473ab3..3dc194aa7 100644
--- a/src/core/prefs.c
+++ b/src/core/prefs.c
@@ -102,6 +102,7 @@ static gboolean bell_is_audible = TRUE;
 static gboolean gnome_accessibility = FALSE;
 static gboolean gnome_animations = TRUE;
 static gboolean locate_pointer_is_enabled = FALSE;
+static unsigned int check_alive_timeout = 5000;
 static char *cursor_theme = NULL;
 /* cursor_size will, when running as an X11 compositing window manager, be the
  * actual cursor size, multiplied with the global window scaling factor. On
@@ -218,6 +219,12 @@ typedef struct
   gint *target;
 } MetaIntPreference;
 
+typedef struct
+{
+  MetaBasePreference base;
+  unsigned int *target;
+} MetaUintPreference;
+
 
 /* All preferences that are not keybindings must be listed here,
  * plus in the GSettings schemas and the MetaPreference enum.
@@ -511,6 +518,18 @@ static MetaIntPreference preferences_int[] =
     { { NULL, 0, 0 }, NULL },
   };
 
+static MetaUintPreference preferences_uint[] =
+  {
+    {
+      { "check-alive-timeout",
+        SCHEMA_MUTTER,
+        META_PREF_CHECK_ALIVE_TIMEOUT,
+      },
+      &check_alive_timeout,
+    },
+    { { NULL, 0, 0 }, NULL },
+  };
+
 static void
 handle_preference_init_enum (void)
 {
@@ -633,6 +652,21 @@ handle_preference_init_int (void)
     }
 }
 
+static void
+handle_preference_init_uint (void)
+{
+  MetaUintPreference *cursor = preferences_uint;
+
+  while (cursor->base.key != NULL)
+    {
+      if (cursor->target)
+        *cursor->target = g_settings_get_uint (SETTINGS (cursor->base.schema),
+                                               cursor->base.key);
+
+      ++cursor;
+    }
+}
+
 static void
 handle_preference_update_enum (GSettings *settings,
                                gchar *key)
@@ -808,6 +842,28 @@ handle_preference_update_int (GSettings *settings,
     }
 }
 
+static void
+handle_preference_update_uint (GSettings *settings,
+                               char *key)
+{
+  MetaUintPreference *cursor = preferences_uint;
+  unsigned int new_value;
+
+  while (cursor->base.key && strcmp (key, cursor->base.key) != 0)
+    ++cursor;
+
+  if (!cursor->base.key || !cursor->target)
+    return;
+
+  new_value = g_settings_get_uint (SETTINGS (cursor->base.schema), key);
+
+  if (*cursor->target != new_value)
+    {
+      *cursor->target = new_value;
+      queue_changed (cursor->base.pref);
+    }
+}
+
 
 /****************************************************************************/
 /* Listeners.                                                               */
@@ -986,6 +1042,7 @@ meta_prefs_init (void)
   handle_preference_init_string ();
   handle_preference_init_string_array ();
   handle_preference_init_int ();
+  handle_preference_init_uint ();
 
   init_bindings ();
 }
@@ -1039,6 +1096,8 @@ settings_changed (GSettings *settings,
     handle_preference_update_bool (settings, key);
   else if (g_variant_type_equal (type, G_VARIANT_TYPE_INT32))
     handle_preference_update_int (settings, key);
+  else if (g_variant_type_equal (type, G_VARIANT_TYPE_UINT32))
+    handle_preference_update_uint (settings, key);
   else if (g_variant_type_equal (type, G_VARIANT_TYPE_STRING_ARRAY))
     handle_preference_update_string_array (settings, key);
   else if (g_variant_type_equal (type, G_VARIANT_TYPE_STRING))
@@ -1695,6 +1754,9 @@ meta_preference_to_string (MetaPreference pref)
 
     case META_PREF_LOCATE_POINTER:
       return "LOCATE_POINTER";
+
+    case META_PREF_CHECK_ALIVE_TIMEOUT:
+      return "CHECK_ALIVE_TIMEOUT";
     }
 
   return "(unknown)";
@@ -2041,6 +2103,12 @@ meta_prefs_is_locate_pointer_enabled (void)
   return locate_pointer_is_enabled;
 }
 
+unsigned int
+meta_prefs_get_check_alive_timeout (void)
+{
+  return check_alive_timeout;
+}
+
 const char *
 meta_prefs_get_iso_next_group_option (void)
 {
diff --git a/src/meta/prefs.h b/src/meta/prefs.h
index c5e91a435..e2c8b46cf 100644
--- a/src/meta/prefs.h
+++ b/src/meta/prefs.h
@@ -105,6 +105,7 @@ typedef enum
   META_PREF_CENTER_NEW_WINDOWS,
   META_PREF_DRAG_THRESHOLD,
   META_PREF_LOCATE_POINTER,
+  META_PREF_CHECK_ALIVE_TIMEOUT,
 } MetaPreference;
 
 typedef void (* MetaPrefsChangedFunc) (MetaPreference pref,
@@ -481,4 +482,7 @@ gboolean           meta_prefs_bell_is_audible      (void);
 META_EXPORT
 GDesktopVisualBellType meta_prefs_get_visual_bell_type (void);
 
+META_EXPORT
+unsigned int meta_prefs_get_check_alive_timeout (void);
+
 #endif