apps: Ensure running apps override new .desktop file data

This patch fixes the "apps vanish from alt-TAB bug".

If a "package system" rips away and possibly replaces .desktop files
at some random time, we have historically used inotify to detect this
and reread state (in a racy way, but...).  In GNOME 2, this was
generally not too problematic because the menu widget was totally
separate from the list of windows - and the data they operate on was
disjoint as well.

In GNOME 3 we unify these, and this creates architectural problems
because the windows are tied to the app.

What this patch tries to do is, when rereading the application state,
if we have a running application, we keep that app around instead of
making a new instance.  This ensures we preserve any state such as the
set of open windows.

This requires moving the running state into ShellAppSystem.  Adjust
callers as necessary, and while we're at it drop the unused "contexts"
stuff.

This is just a somewhat quick band-aid; a REAL fix would require us
having low-level control over application installation.  As long as
we're on top of random broken tar+wget wrappers, it will be gross.

A slight future improvement to this patch would add an explicit
"merge" between the old and new data.  I think probably we always keep
around the ShellApp corresponding to a given ID, but replace its
GMenuTreeEntry.

https://bugzilla.gnome.org/show_bug.cgi?id=657990

js/ui/altTab.js

@@ -122,8 +122,8 @@ AltTabPopup.prototype = {
     },
 
     show : function(backward, binding) {
-        let tracker = Shell.WindowTracker.get_default();
+        let appSys = Shell.AppSystem.get_default();
-        let apps = tracker.get_running_apps ('');
+        let apps = appSys.get_running ();
 
         if (!apps.length)
             return false;

js/ui/dash.js

@@ -275,7 +275,7 @@ Dash.prototype = {
 
         this._appSystem.connect('installed-changed', Lang.bind(this, this._queueRedisplay));
         AppFavorites.getAppFavorites().connect('changed', Lang.bind(this, this._queueRedisplay));
-        this._tracker.connect('app-state-changed', Lang.bind(this, this._queueRedisplay));
+        this._appSystem.connect('app-state-changed', Lang.bind(this, this._queueRedisplay));
 
         Main.overview.connect('item-drag-begin',
                               Lang.bind(this, this._onDragBegin));
@@ -471,10 +471,7 @@ Dash.prototype = {
     _redisplay: function () {
         let favorites = AppFavorites.getAppFavorites().getFavoriteMap();
 
-        /* hardcode here pending some design about how exactly desktop contexts behave */
+        let running = this._appSystem.get_running();
-        let contextId = '';
-
-        let running = this._tracker.get_running_apps(contextId);
 
         let children = this._box.get_children().filter(function(actor) {
                 return actor._delegate.child &&

js/ui/panel.js

@@ -292,8 +292,9 @@ AppMenuButton.prototype = {
         this._spinner.actor.lower_bottom();
 
         let tracker = Shell.WindowTracker.get_default();
+        let appSys = Shell.AppSystem.get_default();
         tracker.connect('notify::focus-app', Lang.bind(this, this._sync));
-        tracker.connect('app-state-changed', Lang.bind(this, this._onAppStateChanged));
+        appSys.connect('app-state-changed', Lang.bind(this, this._onAppStateChanged));
 
         global.window_manager.connect('switch-workspace', Lang.bind(this, this._sync));
 
@@ -457,7 +458,7 @@ AppMenuButton.prototype = {
         this._targetApp.request_quit();
     },
 
-    _onAppStateChanged: function(tracker, app) {
+    _onAppStateChanged: function(appSys, app) {
         let state = app.state;
         if (state != Shell.AppState.STARTING) {
             this._startingApps = this._startingApps.filter(function(a) {

src/Makefile.am

@@ -126,6 +126,7 @@ libgnome_shell_la_SOURCES =		\
 	$(shell_built_sources)		\
 	$(shell_public_headers_h)	\
 	shell-app-private.h		\
+	shell-app-system-private.h	\
 	shell-embedded-window-private.h	\
 	shell-global-private.h		\
 	shell-jsapi-compat-private.h	\

src/shell-app-system-private.h

@@ -0,0 +1,9 @@
+/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*- */
+#ifndef __SHELL_APP_SYSTEM_PRIVATE_H__
+#define __SHELL_APP_SYSTEM_PRIVATE_H__
+
+#include "shell-app-system.h"
+
+void _shell_app_system_notify_app_state_changed (ShellAppSystem *self, ShellApp *app);
+
+#endif

src/shell-app-system.c

@@ -14,6 +14,7 @@
 
 #include "shell-app-private.h"
 #include "shell-window-tracker-private.h"
+#include "shell-app-system-private.h"
 #include "shell-global.h"
 #include "shell-util.h"
 #include "st.h"
@@ -32,6 +33,7 @@ enum {
 };
 
 enum {
+  APP_STATE_CHANGED,
   INSTALLED_CHANGED,
   LAST_SIGNAL
 };
@@ -43,6 +45,8 @@ struct _ShellAppSystemPrivate {
 
   GHashTable *entry_to_app;
 
+  GHashTable *running_apps;
+
   GSList *known_vendor_prefixes;
 
   GMenuTree *settings_tree;
@@ -61,6 +65,14 @@ static void shell_app_system_class_init(ShellAppSystemClass *klass)
 
   gobject_class->finalize = shell_app_system_finalize;
 
+  signals[APP_STATE_CHANGED] = g_signal_new ("app-state-changed",
+                                             SHELL_TYPE_APP_SYSTEM,
+                                             G_SIGNAL_RUN_LAST,
+                                             0,
+                                             NULL, NULL,
+                                             g_cclosure_marshal_VOID__OBJECT,
+                                             G_TYPE_NONE, 1,
+                                             SHELL_TYPE_APP);
   signals[INSTALLED_CHANGED] =
     g_signal_new ("installed-changed",
 		  SHELL_TYPE_APP_SYSTEM,
@@ -82,6 +94,9 @@ shell_app_system_init (ShellAppSystem *self)
                                                    SHELL_TYPE_APP_SYSTEM,
                                                    ShellAppSystemPrivate);
 
+  priv->running_apps = g_hash_table_new_full (g_str_hash, g_str_equal,
+                                              NULL, (GDestroyNotify) g_object_unref);
+
   priv->entry_to_app = g_hash_table_new_full (NULL, NULL,
                                               (GDestroyNotify)gmenu_tree_item_unref,
                                               (GDestroyNotify)g_object_unref);
@@ -112,6 +127,7 @@ shell_app_system_finalize (GObject *object)
   g_object_unref (priv->apps_tree);
   g_object_unref (priv->settings_tree);
 
+  g_hash_table_destroy (priv->running_apps);
   g_hash_table_destroy (priv->entry_to_app);
   g_hash_table_destroy (priv->setting_entry_to_app);
 
@@ -248,6 +264,13 @@ load_app_entry (ShellAppSystem *self,
   else
     g_free (prefix);
 
+  /* Here we check to see whether the app is still running; if so, we
+   * keep the old data around.
+   */
+  app = g_hash_table_lookup (self->priv->running_apps, gmenu_tree_entry_get_desktop_file_id (entry));
+  if (app != NULL)
+    app = g_object_ref (app);
+  else
     app = _shell_app_new (entry);
 
   g_hash_table_insert (self->priv->entry_to_app, gmenu_tree_item_ref (entry), app);
@@ -492,7 +515,10 @@ ShellApp *
 shell_app_system_lookup_app_by_tree_entry (ShellAppSystem  *self,
                                            GMenuTreeEntry  *entry)
 {
-  return g_hash_table_lookup (self->priv->entry_to_app, entry);
+  /* If we looked up directly in ->entry_to_app, we'd lose the
+   * override of running apps.  Thus, indirect through the id.
+   */
+  return shell_app_system_lookup_app (self, gmenu_tree_entry_get_desktop_file_id (entry));
 }
 
 /**
@@ -582,12 +608,67 @@ shell_app_system_get_all (ShellAppSystem  *self)
   while (g_hash_table_iter_next (&iter, &key, &value))
     {
       ShellApp *app = value;
+      
       if (!g_desktop_app_info_get_nodisplay (shell_app_get_app_info (app)))
         result = g_slist_prepend (result, app);
     }
   return result;
 }
 
+void
+_shell_app_system_notify_app_state_changed (ShellAppSystem *self,
+                                            ShellApp       *app)
+{
+  ShellAppState state = shell_app_get_state (app);
+
+  switch (state)
+    {
+    case SHELL_APP_STATE_RUNNING:
+      /* key is owned by the app */
+      g_hash_table_insert (self->priv->running_apps, (char*)shell_app_get_id (app), g_object_ref (app));
+      break;
+    case SHELL_APP_STATE_STARTING:
+      break;
+    case SHELL_APP_STATE_STOPPED:
+      g_hash_table_remove (self->priv->running_apps, shell_app_get_id (app));
+      break;
+    }
+  g_signal_emit (self, signals[APP_STATE_CHANGED], 0, app);
+}
+
+/**
+ * shell_app_system_get_running:
+ * @self: A #ShellAppSystem
+ *
+ * Returns the set of applications which currently have at least one
+ * open window in the given context.  The returned list will be sorted
+ * by shell_app_compare().
+ *
+ * Returns: (element-type ShellApp) (transfer container): Active applications
+ */
+GSList *
+shell_app_system_get_running (ShellAppSystem *self)
+{
+  gpointer key, value;
+  GSList *ret;
+  GHashTableIter iter;
+
+  g_hash_table_iter_init (&iter, self->priv->running_apps);
+
+  ret = NULL;
+  while (g_hash_table_iter_next (&iter, &key, &value))
+    {
+      ShellApp *app = value;
+
+      ret = g_slist_prepend (ret, app);
+    }
+
+  ret = g_slist_sort (ret, (GCompareFunc)shell_app_compare);
+
+  return ret;
+}
+
+
 static gint
 compare_apps_by_name (gconstpointer a,
                       gconstpointer b,

src/shell-app-system.h

@@ -53,6 +53,8 @@ ShellApp       *shell_app_system_lookup_heuristic_basename    (ShellAppSystem  *
 
 GSList         *shell_app_system_get_all                   (ShellAppSystem  *system);
 
+GSList         *shell_app_system_get_running               (ShellAppSystem  *self);
+
 GSList         *shell_app_system_initial_search            (ShellAppSystem  *system,
                                                             GSList          *terms);
 GSList         *shell_app_system_subsearch                 (ShellAppSystem  *system,

src/shell-app.c

@@ -12,6 +12,7 @@
 #include "shell-enum-types.h"
 #include "shell-global.h"
 #include "shell-util.h"
+#include "shell-app-system-private.h"
 #include "shell-window-tracker-private.h"
 #include "st.h"
 
@@ -840,7 +841,7 @@ shell_app_state_transition (ShellApp      *app,
       app->running_state = NULL;
     }
 
-  _shell_window_tracker_notify_app_state_changed (shell_window_tracker_get_default (), app);
+  _shell_app_system_notify_app_state_changed (shell_app_system_get_default (), app);
 
   g_object_notify (G_OBJECT (app), "state");
 }

src/shell-window-tracker-private.h

@@ -4,8 +4,6 @@
 
 #include "shell-window-tracker.h"
 
-void _shell_window_tracker_notify_app_state_changed (ShellWindowTracker *tracker, ShellApp *self);
-
 void _shell_window_tracker_add_child_process_app (ShellWindowTracker *tracker,
                                                   GPid                pid,
                                                   ShellApp           *app);

src/shell-window-tracker.c

@@ -49,9 +49,6 @@ struct _ShellWindowTracker
   /* <MetaWindow * window, ShellApp *app> */
   GHashTable *window_to_app;
 
-  /* <const char *id, ShellApp *app> */
-  GHashTable *running_apps;
-
   /* <int, ShellApp *app> */
   GHashTable *launched_pid_to_app;
 };
@@ -64,7 +61,6 @@ enum {
 };
 
 enum {
-  APP_STATE_CHANGED,
   STARTUP_SEQUENCE_CHANGED,
   TRACKED_WINDOWS_CHANGED,
 
@@ -117,14 +113,6 @@ shell_window_tracker_class_init (ShellWindowTrackerClass *klass)
                                                         SHELL_TYPE_APP,
                                                         G_PARAM_READABLE));
 
-  signals[APP_STATE_CHANGED] = g_signal_new ("app-state-changed",
-                                             SHELL_TYPE_WINDOW_TRACKER,
-                                             G_SIGNAL_RUN_LAST,
-                                             0,
-                                             NULL, NULL,
-                                             g_cclosure_marshal_VOID__OBJECT,
-                                             G_TYPE_NONE, 1,
-                                             SHELL_TYPE_APP);
   signals[STARTUP_SEQUENCE_CHANGED] = g_signal_new ("startup-sequence-changed",
                                    SHELL_TYPE_WINDOW_TRACKER,
                                    G_SIGNAL_RUN_LAST,
@@ -579,27 +567,6 @@ init_window_tracking (ShellWindowTracker *self)
   shell_window_tracker_on_n_workspaces_changed (screen, NULL, self);
 }
 
-void
-_shell_window_tracker_notify_app_state_changed (ShellWindowTracker *self,
-                                                ShellApp           *app)
-{
-  ShellAppState state = shell_app_get_state (app);
-
-  switch (state)
-    {
-    case SHELL_APP_STATE_RUNNING:
-      /* key is owned by the app */
-      g_hash_table_insert (self->running_apps, (char*)shell_app_get_id (app), app);
-      break;
-    case SHELL_APP_STATE_STARTING:
-      break;
-    case SHELL_APP_STATE_STOPPED:
-      g_hash_table_remove (self->running_apps, shell_app_get_id (app));
-      break;
-    }
-  g_signal_emit (self, signals[APP_STATE_CHANGED], 0, app);
-}
-
 static void
 on_startup_sequence_changed (MetaScreen            *screen,
                              SnStartupSequence     *sequence,
@@ -622,8 +589,6 @@ shell_window_tracker_init (ShellWindowTracker *self)
   self->window_to_app = g_hash_table_new_full (g_direct_hash, g_direct_equal,
                                                NULL, (GDestroyNotify) g_object_unref);
 
-  self->running_apps = g_hash_table_new (g_str_hash, g_str_equal);
-
   self->launched_pid_to_app = g_hash_table_new_full (NULL, NULL, NULL, (GDestroyNotify) g_object_unref);
 
   screen = shell_global_get_screen (shell_global_get ());
@@ -640,7 +605,6 @@ shell_window_tracker_finalize (GObject *object)
 {
   ShellWindowTracker *self = SHELL_WINDOW_TRACKER (object);
 
-  g_hash_table_destroy (self->running_apps);
   g_hash_table_destroy (self->window_to_app);
   g_hash_table_destroy (self->launched_pid_to_app);
 
@@ -686,7 +650,7 @@ ShellApp *
 shell_window_tracker_get_app_from_pid (ShellWindowTracker *self, 
                                        int                 pid)
 {
-  GSList *running = shell_window_tracker_get_running_apps (self, "");
+  GSList *running = shell_app_system_get_running (shell_app_system_get_default());
   GSList *iter;
   ShellApp *result = NULL;
 
@@ -716,43 +680,6 @@ shell_window_tracker_get_app_from_pid (ShellWindowTracker *self,
   return result;
 }
 
-/**
- * shell_window_tracker_get_running_apps:
- * @tracker: An app monitor instance
- * @context: Activity identifier
- *
- * Returns the set of applications which currently have at least one open
- * window in the given context.  The returned list will be sorted
- * by shell_app_compare().
- *
- * Returns: (element-type ShellApp) (transfer full): Active applications
- */
-GSList *
-shell_window_tracker_get_running_apps (ShellWindowTracker *tracker,
-                                       const char         *context)
-{
-  gpointer key, value;
-  GSList *ret;
-  GHashTableIter iter;
-
-  g_hash_table_iter_init (&iter, tracker->running_apps);
-
-  ret = NULL;
-  while (g_hash_table_iter_next (&iter, &key, &value))
-    {
-      ShellApp *app = value;
-
-      if (strcmp (context, _shell_window_tracker_get_app_context (tracker, app)) != 0)
-        continue;
-
-      ret = g_slist_prepend (ret, g_object_ref (app));
-    }
-
-  ret = g_slist_sort (ret, (GCompareFunc)shell_app_compare);
-
-  return ret;
-}
-
 static void
 on_child_exited (GPid      pid,
                  gint      status,

src/shell-window-tracker.h

@@ -31,9 +31,6 @@ GType shell_window_tracker_get_type (void) G_GNUC_CONST;
 
 ShellWindowTracker* shell_window_tracker_get_default(void);
 
-GSList * shell_window_tracker_get_running_apps (ShellWindowTracker *tracker,
-                                                const char         *context);
-
 ShellApp *shell_window_tracker_get_window_app (ShellWindowTracker *tracker, MetaWindow *metawin);
 
 ShellApp *shell_window_tracker_get_app_from_pid (ShellWindowTracker *tracker, int pid);