path: root/atk-adaptor/accessible-register.c

/*
 * AT-SPI - Assistive Technology Service Provider Interface
 * (Gnome Accessibility Project; http://developer.gnome.org/projects/gap)
 *
 * Copyright 2008 Novell, Inc.
 * Copyright 2008, 2009 Codethink Ltd.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public
 * License along with this library; if not, write to the
 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 02111-1307, USA.
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "bridge.h"
#include "tree-adaptor.h"
#include "accessible-register.h"

/*
 * This module is responsible for keeping track of all the AtkObjects in
 * the application, so that they can be accessed remotely and placed in
 * a client side cache.
 *
 * To access an AtkObject remotely we need to provide a D-Bus object 
 * path for it. The D-Bus object paths used have a standard prefix
 * (SPI_ATK_OBJECT_PATH_PREFIX). Appended to this prefix is a string
 * representation of an integer reference. So to access an AtkObject 
 * remotely we keep a Hashtable that maps the given reference to 
 * the AtkObject pointer. An object in this hash table is said to be 'registered'.
 *
 * The architecture of AT-SPI dbus is such that AtkObjects are not
 * remotely reference counted. This means that we need to keep track of
 * object destruction. When an object is destroyed it must be 'deregistered'
 * To do this lookup we keep a dbus-id attribute on each AtkObject.
 *
 * In addition to accessing the objects remotely we must be able to update
 * the client side cache. This is done using the 'update' signal of the 
 * org.freedesktop.atspi.Tree interface. The update signal should send out
 * all of the cacheable data for an Accessible object.
 *
 */

/*
 * FIXME
 *
 * This code seems very brittle.
 * I would prefer changes to be made to
 * gail and the ATK interface so that all Accessible
 * objects are registered with an exporting module.
 *
 * This is the same system as Qt has with the QAccessibleBridge
 * and QAccessibleBridgePlugin. It entails some rather
 * large structural changes to ATK though:
 *
 * Removing infinite spaces (Child access no longer references child).
 * Removing lazy creation of accessible objects.
 */

#define SPI_ATK_OBJECT_PATH_PREFIX  "/org/freedesktop/atspi/accessible"
#define SPI_ATK_OBJECT_PATH_DESKTOP "/desktop"

#define SPI_ATK_PATH_PREFIX_LENGTH 33
#define SPI_ATK_OBJECT_REFERENCE_TEMPLATE SPI_ATK_OBJECT_PATH_PREFIX "/%d"


static GHashTable *ref2ptr = NULL; /* Used for converting a D-Bus path (Reference) to the object pointer */
static GHashTable *objects_with_subrefs = NULL;
static GHashTable *leased_refs = NULL;
static int leased_refs_count;

static guint reference_counter = 0;

static GStaticRecMutex registration_mutex = G_STATIC_REC_MUTEX_INIT;

/*---------------------------------------------------------------------------*/

static GStaticMutex   recursion_check_guard = G_STATIC_MUTEX_INIT;
static gboolean       recursion_check = FALSE;
static int last_gc_time;

static void deregister_sub_accessible (gpointer key, gpointer obj_data, gpointer iter);

static void deregister_sub_hyperlink (gpointer key, gpointer obj_data, gpointer iter);

static gboolean
recursion_check_and_set ()
{
  gboolean ret;
  g_static_mutex_lock   (&recursion_check_guard);
  ret = recursion_check;
  recursion_check = TRUE;
  g_static_mutex_unlock (&recursion_check_guard);
  return ret;
}

static void
recursion_check_unset ()
{
  g_static_mutex_lock   (&recursion_check_guard);
  recursion_check = FALSE;
  g_static_mutex_unlock (&recursion_check_guard);
}

/*---------------------------------------------------------------------------*/

/*
 * Each AtkObject must be asssigned a D-Bus path (Reference)
 *
 * This function provides an integer reference for a new
 * AtkObject.
 */
static guint
assign_reference(void)
{
  reference_counter++;
  /* Reference of 0 not allowed as used as direct key in hash table */
  if (reference_counter == 0)
    reference_counter++;
  /* TODO: If we've wrapped, ensure that two objects don't have the same ref */
  return reference_counter;
}

/*
 * Returns the reference of the object, or 0 if it is not registered.
 */
static guint
gobject_to_ref (GObject *gobj)
{
  return GPOINTER_TO_INT(g_object_get_data (gobj, "dbus-id"));
}

static guint
object_to_ref (AtkObject *accessible)
{
  return gobject_to_ref (G_OBJECT (accessible));
}

static guint
hyperlink_to_ref (AtkHyperlink *link)
{
  return gobject_to_ref (G_OBJECT (link));
}

/*
 * Converts the Accessible object reference to its D-Bus object path
 */
gchar *
atk_dbus_ref_to_path (guint ref)
{
  return g_strdup_printf(SPI_ATK_OBJECT_REFERENCE_TEMPLATE, ref);
}

/*---------------------------------------------------------------------------*/

/*
 * Callback for when a registered AtkObject is destroyed.
 *
 * Removes the AtkObject from the reference lookup tables, meaning
 * it is no longer exposed over D-Bus.
 */
static void
deregister_object (gpointer data, GObject *gobj)
{
  guint ref;
  GHashTable *subrefs_atk;
  GHashTable *subrefs_hyperlink;
  g_return_if_fail (ATK_IS_OBJECT (gobj) || ATK_IS_HYPERLINK (gobj));

  subrefs_atk = (GHashTable *) g_object_get_data (gobj, "dbus-subrefs-atk");
  subrefs_hyperlink = (GHashTable *) g_object_get_data (gobj, "dbus-subrefs-hyperlink");

  if (subrefs_atk)
  {
    g_hash_table_foreach (subrefs_atk, deregister_sub_accessible, data);
    g_hash_table_unref (subrefs_atk);
  }
  
  if (subrefs_hyperlink)
  {
    g_hash_table_foreach (subrefs_hyperlink, deregister_sub_hyperlink, data);
    g_hash_table_unref (subrefs_hyperlink);
  }
  
  if (subrefs_atk || subrefs_hyperlink)
    g_hash_table_remove (objects_with_subrefs, gobj);

  if (ATK_IS_OBJECT (gobj))
  {
    ref = object_to_ref (ATK_OBJECT (gobj));
    if (ref != 0)
      {
        spi_emit_cache_removal (ref, atk_adaptor_app_data->bus);
        g_hash_table_remove(ref2ptr, GINT_TO_POINTER(ref));
      }
    }
  }

static void
deregister_sub_accessible (gpointer key, gpointer obj_data, gpointer iter)
{
  GObject *obj = G_OBJECT (obj_data);
  deregister_object (NULL, obj);
  g_hash_table_remove (leased_refs, obj);
  g_object_unref (obj);
}

static void
deregister_sub_hyperlink (gpointer key, gpointer obj_data, gpointer iter)
{
  guint ref;
  GObject *ghyperlink = G_OBJECT (obj_data);

  g_return_if_fail (ATK_IS_HYPERLINK (ghyperlink));

  ref = gobject_to_ref (ghyperlink);
  if (ref != 0)
    {
      g_hash_table_remove(ref2ptr, GINT_TO_POINTER(ref));
    }
  g_object_unref (ghyperlink);
}

static void
register_gobject (GObject *gobj, GObject *container)
{
  guint ref;
  g_return_if_fail (G_IS_OBJECT(gobj));

  ref = assign_reference();

  g_hash_table_insert (ref2ptr, GINT_TO_POINTER(ref), gobj);
  g_object_set_data (G_OBJECT(gobj), "dbus-id", GINT_TO_POINTER(ref));
  g_object_weak_ref(G_OBJECT(gobj), deregister_object, NULL);

  if (container)
  {
    GHashTable *subrefs = (GHashTable *) g_object_get_data (G_OBJECT (container), "dbus-subrefs-atk");
    if (!subrefs)
    {
      subrefs = g_hash_table_new(g_direct_hash, g_direct_equal);
      g_object_set_data (G_OBJECT (container), "dbus-subrefs-atk", subrefs);
    }
    g_hash_table_insert (subrefs, GINT_TO_POINTER(ref), gobj);
    g_hash_table_insert (objects_with_subrefs, gobj, subrefs);
  }

  if (ATK_IS_HYPERLINK (gobj))
    g_object_ref (gobj);
  else if (ATK_IS_OBJECT (gobj))
  {
    AtkObject *accessible = ATK_OBJECT (gobj);
    AtkStateSet *state = atk_object_ref_state_set (accessible);
    if (atk_state_set_contains_state (state, ATK_STATE_TRANSIENT))
    {
      g_object_ref (gobj);
    }
    g_object_unref (state);
  }
}

/*
 * Called to register an AtkObject with AT-SPI and expose it over D-Bus.
 */
static void
register_accessible (AtkObject *accessible, AtkObject *container)
{
  g_return_if_fail (ATK_IS_OBJECT(accessible));

  register_gobject (G_OBJECT (accessible), G_OBJECT (container));
}

static void
register_hyperlink (AtkHyperlink *hyperlink, AtkObject *container)
{
  guint ref;
  g_return_if_fail (ATK_IS_HYPERLINK (hyperlink));
  g_return_if_fail (container);

  ref = assign_reference();

  g_hash_table_insert (ref2ptr, GINT_TO_POINTER(ref), hyperlink);
  g_object_set_data (G_OBJECT(hyperlink), "dbus-id", GINT_TO_POINTER(ref));
  g_object_ref (G_OBJECT (hyperlink));

  GHashTable *subrefs = (GHashTable *) g_object_get_data (G_OBJECT (container), "dbus-subrefs-hyperlink");
  if (!subrefs)
  {
    subrefs = g_hash_table_new(g_direct_hash, g_direct_equal);
    g_object_set_data (G_OBJECT (container), "dbus-subrefs-hyperlink", GINT_TO_POINTER(ref));
  }
  g_hash_table_insert (subrefs, GINT_TO_POINTER(ref), hyperlink);
}

/*---------------------------------------------------------------------------*/

#ifdef SPI_ATK_DEBUG
/*
 * This function checks that the ref-count of an accessible
 * is greater than 1.
 *
 * There is not currently any remote reference counting
 * in AT-SPI D-Bus so objects that are remotely owned are not
 * allowed.
 *
 * TODO Add debug wrapper
 */
static gboolean
non_owned_accessible (AtkObject *accessible)
{
   if ((G_OBJECT (accessible))->ref_count <= 1)
     {
       g_warning ("AT-SPI: Child referenced that is not owned by its parent");
       return TRUE;
     }
   else
     {
       return FALSE;
     }
}
#endif /* SPI_ATK_DEBUG */

/*---------------------------------------------------------------------------*/

/* TRUE if we should not keep this object / tell the AT about it
 * Currently true if TRANSIENT and not SHOWING
 */
static gboolean
object_is_moot (AtkObject *accessible)
{
   AtkStateSet *state;
   gboolean result = FALSE;

   /* This is dangerous, refing the state set
    * seems to do wierd things to the tree & cause recursion
    * by modifying the tree alot.
    */
   state = atk_object_ref_state_set (accessible);
   if ( atk_state_set_contains_state (state, ATK_STATE_TRANSIENT) &&
       !atk_state_set_contains_state (state, ATK_STATE_SHOWING))
     {
       result = TRUE;
     }
   g_object_unref (state);

   return result;
}

static void
append_children (AtkObject *accessible, GQueue *traversal)
{
  AtkObject *current;
  guint i;
  gint count = atk_object_get_n_accessible_children (accessible);

  if (count < 0) count = 0;
  for (i =0; i < count; i++)
    {
      current = atk_object_ref_accessible_child (accessible, i);
      if (current)
        {
#ifdef SPI_ATK_DEBUG
          non_owned_accessible (current);
#endif
          g_queue_push_tail (traversal, current);
        }
    }
}

/*
 * Registers a subtree of accessible objects
 * rooted at the accessible object provided.
 *
 * The leaf nodes do not have their children
 * registered. A node is considered a leaf
 * if it has the state "manages-descendants"
 * or if it has already been registered.
 */
void
register_subtree (AtkObject *accessible)
{
  AtkObject *current;
  GQueue    *traversal;
  GQueue    *emit_update;

  g_return_if_fail (ATK_IS_OBJECT (accessible));

  traversal = g_queue_new ();
  emit_update = g_queue_new ();

  g_object_ref (accessible);
  g_queue_push_tail (traversal, accessible);

  while (!g_queue_is_empty (traversal))
    {
      current = g_queue_pop_head (traversal);
      g_queue_push_tail (emit_update, current);
      if (!object_to_ref (current))
        {
          register_accessible (current, NULL);
#ifdef SPI_ATK_DEBUG
          g_debug ("REG  - %s - %d - %s", atk_object_get_name     (current),
                                          atk_object_get_role     (current),
                                          atk_dbus_object_to_path (current));
#endif
          append_children (current, traversal);
        }
    }

  while (!g_queue_is_empty (emit_update))
    {
      current = g_queue_pop_head (emit_update);
      spi_emit_cache_update (current, atk_adaptor_app_data->bus);
      g_object_unref (G_OBJECT (current));
    }

  g_queue_free (traversal);
  g_queue_free (emit_update);
}

/*---------------------------------------------------------------------------*/

/*
 * Called when an already registered object is updated in such a
 * way that client side cache needs to be updated.
 */
static void
update_accessible (AtkObject *accessible)
{
  guint  ref = 0;
  g_return_if_fail (ATK_IS_OBJECT(accessible));

  ref = object_to_ref (accessible);
  if (ref)
    {
      spi_emit_cache_update (accessible, atk_adaptor_app_data->bus);
    }
}

/*---------------------------------------------------------------------------*/

void
atk_dbus_foreach_registered(GHFunc func, gpointer data)
{
  g_hash_table_foreach(ref2ptr, func, data);
}

/*
 * Used to lookup an AtkObject from its D-Bus path.
 */
GObject *
atk_dbus_path_to_gobject (const char *path)
{
  guint index;
  void *data;

  g_return_val_if_fail (path, NULL);

  if (strncmp(path, SPI_ATK_OBJECT_PATH_PREFIX, SPI_ATK_PATH_PREFIX_LENGTH) != 0)
    return NULL;

  path += SPI_ATK_PATH_PREFIX_LENGTH; /* Skip over the prefix */

  if (!g_strcmp0 (SPI_ATK_OBJECT_PATH_DESKTOP, path))
     return G_OBJECT (atk_get_root());
  if (path[0] != '/')
     return NULL;

  path++;
  index = atoi (path);
  data = g_hash_table_lookup (ref2ptr, GINT_TO_POINTER(index));
  if (data)
  {
    GObject *gobj = G_OBJECT (data);
    g_object_set_data (gobj, "last-ref-time", (gpointer) time (NULL));
    return gobj;
  }
  else
    return NULL;
}

AtkObject *
atk_dbus_path_to_object (const char *path)
{
  return ATK_OBJECT (atk_dbus_path_to_gobject (path));
}

/*
 * TODO WARNING HACK This function is dangerous.
 * It should only be called before sending an event on an
 * object that has not already been registered.
 */
gchar *
atk_dbus_object_attempt_registration (AtkObject *accessible)
{
  guint ref;

  ref = object_to_ref (accessible);
  if (!ref)
    {
      /* See if the object is attached to the main tree */
      AtkObject *current, *prev = NULL;
      guint cref = 0;

      /* This should iterate until it hits a NULL or registered parent */
      prev = accessible;
      current = atk_object_get_parent (accessible);
      if (current)
          cref = object_to_ref (current);
      while (current && !cref)
        {
          prev = current;
          current = atk_object_get_parent (current);
          if (current)
              cref = object_to_ref (current);
        }

      /* A registered parent, with non-registered child, has been found */
      if (current)
        {
          register_subtree (prev);
        }

      /* The object SHOULD be registered now. If it isn't - I give up */
      ref = object_to_ref (accessible);
      if (ref)
        {
          return atk_dbus_ref_to_path (ref);
        }
      else
        {
#ifdef SPI_ATK_DEBUG
          g_debug ("AT-SPI: Could not register a non-attached accessible object");
#endif
          return NULL;
        }
    }
  else
    {
      return atk_dbus_ref_to_path (ref);
    }
}


/*
 * Used to lookup a D-Bus path from the AtkObject.
 */
static gchar *
atk_dbus_gobject_to_path_internal (GObject *gobj, gboolean do_register, GObject *container)
{
  guint ref;

  ref = gobject_to_ref (gobj);
  if (!ref && do_register)
  {
    register_gobject (gobj, container);
    ref = gobject_to_ref (gobj);
  }

  if (!ref)
      return NULL;
  else
      return atk_dbus_ref_to_path (ref);
}

gchar *
atk_dbus_object_to_path (AtkObject *accessible, gboolean do_register)
{
  AtkObject *container = (accessible && do_register? atk_object_get_parent (accessible): NULL);
  return atk_dbus_gobject_to_path_internal (G_OBJECT (accessible), do_register, G_OBJECT (container));
}

gchar *
atk_dbus_sub_object_to_path (GObject *gobj, GObject *container)
{
  return atk_dbus_gobject_to_path_internal (gobj, TRUE, container);
}

gchar *
atk_dbus_hyperlink_to_path (AtkHyperlink *hyperlink, AtkObject *container)
{
  guint ref;

  ref = gobject_to_ref (G_OBJECT (hyperlink));
  if (!ref && container)
  {
    register_hyperlink (hyperlink, container);
    ref = hyperlink_to_ref (hyperlink);
  }

  if (!ref)
      return NULL;
  else
      return atk_dbus_ref_to_path (ref);
}

gchar *
atk_dbus_desktop_object_path ()
{
  return g_strdup (SPI_ATK_OBJECT_PATH_PREFIX SPI_ATK_OBJECT_PATH_DESKTOP);
}

/*---------------------------------------------------------------------------*/

typedef gboolean (*TreeUpdateAction) (GSignalInvocationHint *signal_hint,
                                      guint                  n_param_values,
                                      const GValue          *param_values,
                                      gpointer               data,
                                      AtkObject             *accessible);

/*
 * Events are not evaluated for non-registered accessibles.
 *
 * When a property change is made on a registered accessible
 * the client side cache should be updated.
 *
 * When a parent is changed the subtree is de-registered
 * if the parent is not attached to the root accessible.
 */
/* TODO Turn this function into a macro? */
static gboolean
tree_update_wrapper (GSignalInvocationHint *signal_hint,
                     guint                  n_param_values,
                     const GValue          *param_values,
                     gpointer               data,
                     TreeUpdateAction       action)
{
  AtkObject *accessible;

  g_static_rec_mutex_lock (&registration_mutex);

  /* Ensure that only registered accessibles
   * have their signals processed.
   */
  accessible = ATK_OBJECT(g_value_get_object (&param_values[0]));
  g_return_val_if_fail (ATK_IS_OBJECT (accessible), TRUE);

  if (object_to_ref (accessible))
    {
#ifdef SPI_ATK_DEBUG
      if (recursion_check_and_set ())
          g_warning ("AT-SPI: Recursive use of registration module");

      g_debug ("AT-SPI: Tree update listener");
#endif
      action (signal_hint, n_param_values, param_values, data, accessible);

      recursion_check_unset ();
    }

  g_static_rec_mutex_unlock (&registration_mutex);

  return TRUE;
}

static gboolean
maybe_expire_lease (gpointer key, gpointer obj_data, gpointer iter)
{
  time_t secs = time (NULL) - (time_t)obj_data;

  if (secs < 30)
    return FALSE;
  deregister_sub_accessible (key, obj_data, iter);
  return TRUE;
}

static void
expire_old_leases_in (gpointer key, gpointer obj_data, gpointer iter)
{
  g_hash_table_foreach_remove ((GHashTable *)obj_data, maybe_expire_lease, NULL);
}

static void
expire_old_leases ()
{
  g_hash_table_foreach (objects_with_subrefs, expire_old_leases_in, NULL);
}

static gboolean
tree_update_state_action (GSignalInvocationHint *signal_hint,
                          guint                  n_param_values,
                          const GValue          *param_values,
                          gpointer               data,
                          AtkObject             *accessible)
{
  const gchar *name;
  gboolean state;

  if (n_param_values < 3)
  {
    g_warning ("at-spi: Not enough params in state-changed signal");
				return TRUE;
  }

  name = g_value_get_string (param_values + 1);
  state = g_value_get_boolean (param_values + 2);
  if (!strcmp (name, "visible"))
  {
    AtkStateSet *set = atk_object_ref_state_set (accessible);
    if (atk_state_set_contains_state (set, ATK_STATE_TRANSIENT))
    {
      if (state == 0)
      {
	g_hash_table_insert (leased_refs, accessible, (gpointer) time (NULL));
	leased_refs_count++;
	/* todo: Set to a high number: 5 for dbg. */
	if (leased_refs_count > 5)
	  expire_old_leases ();
      }
      else
      {
	g_hash_table_remove (leased_refs, accessible);
	leased_refs_count--;
      }
    }
    g_object_unref (set);
  }

      update_accessible (accessible);
  return TRUE;
}

static gboolean
tree_update_state_listener (GSignalInvocationHint *signal_hint,
                            guint                  n_param_values,
                            const GValue          *param_values,
                            gpointer               data)
{
      tree_update_wrapper (signal_hint, n_param_values, param_values, data, tree_update_state_action);
  return TRUE;
}

static gboolean
tree_update_property_action (GSignalInvocationHint *signal_hint,
                             guint                  n_param_values,
                             const GValue          *param_values,
                             gpointer               data,
                             AtkObject             *accessible)
{
      AtkPropertyValues *values;
      const gchar *pname = NULL;

      values = (AtkPropertyValues*) g_value_get_pointer (&param_values[1]);
      pname = values[0].property_name;
      if (strcmp (pname, "accessible-name") == 0 ||
          strcmp (pname, "accessible-description") == 0 ||
          strcmp (pname, "accessible-parent") == 0 ||
          strcmp (pname, "accessible-role") == 0)
        {
          update_accessible (accessible);
        }
      /* Parent value us updated by child-add signal of parent object */
      return TRUE;
}

static gboolean
tree_update_property_listener (GSignalInvocationHint *signal_hint,
                               guint                  n_param_values,
                               const GValue          *param_values,
                               gpointer               data)
{
  tree_update_wrapper (signal_hint, n_param_values, param_values, data, tree_update_property_action);
  return TRUE;
}

static gboolean
tree_update_children_action (GSignalInvocationHint *signal_hint,
                             guint                  n_param_values,
                             const GValue          *param_values,
                             gpointer               data,
                             AtkObject             *accessible)
{
      const gchar *detail = NULL;
      AtkObject *child;

      if (signal_hint->detail)
          detail = g_quark_to_string (signal_hint->detail);

      if (!strcmp (detail, "add"))
        {
          gpointer child;
          int index = g_value_get_uint (param_values + 1);
          child = g_value_get_pointer (param_values + 2);

          if (!ATK_IS_OBJECT (child))
            {
              child = atk_object_ref_accessible_child (accessible, index);
#ifdef SPI_ATK_DEBUG
              non_owned_accessible (child);
#endif
            }
          register_subtree (child);
          update_accessible (accessible);
        }
      return TRUE;
}

static gboolean
tree_update_children_listener (GSignalInvocationHint *signal_hint,
                               guint                  n_param_values,
                               const GValue          *param_values,
                               gpointer               data)
{
      tree_update_wrapper (signal_hint, n_param_values, param_values, data, tree_update_children_action);
      return TRUE;
}

/*---------------------------------------------------------------------------*/

static void
spi_atk_register_toplevel_added (AtkObject *accessible,
                                 guint     index,
                                 AtkObject *child)
{
  g_static_rec_mutex_lock (&registration_mutex);

  g_return_if_fail (ATK_IS_OBJECT (accessible));

  if (object_to_ref (accessible))
    {
#ifdef SPI_ATK_DEBUG
      if (recursion_check_and_set ())
          g_warning ("AT-SPI: Recursive use of registration module");

      g_debug ("AT-SPI: Toplevel added listener");
#endif
      if (!ATK_IS_OBJECT (child))
        {
          child = atk_object_ref_accessible_child (accessible, index);
#ifdef SPI_ATK_DEBUG
          non_owned_accessible (child);
#endif
        }
      register_subtree (child);
      update_accessible (accessible);

      recursion_check_unset ();
    }

  g_static_rec_mutex_unlock (&registration_mutex);
}

static void
spi_atk_register_toplevel_removed (AtkObject *accessible,
                                   guint     index,
                                   AtkObject *child)
{
  g_static_rec_mutex_lock (&registration_mutex);

  g_return_if_fail (ATK_IS_OBJECT (accessible));

  if (object_to_ref (accessible))
    {
#ifdef SPI_ATK_DEBUG
      if (recursion_check_and_set ())
          g_warning ("AT-SPI: Recursive use of registration module");

      g_debug ("AT-SPI: Toplevel removed listener");
#endif
      update_accessible (accessible);
      recursion_check_unset ();
    }

  g_static_rec_mutex_unlock (&registration_mutex);
}

/*
 * Initializes required global data. The update and removal lists
 * and the reference lookup tables.
 *
 * Initializes all of the required D-Bus interfaces.
 */
void
atk_dbus_initialize (AtkObject *root)
{
  if (!ref2ptr)
    ref2ptr = g_hash_table_new(g_direct_hash, g_direct_equal);

  if (!objects_with_subrefs)
    objects_with_subrefs = g_hash_table_new(g_direct_hash, g_direct_equal);

  if (!leased_refs)
    leased_refs = g_hash_table_new(g_direct_hash, g_direct_equal);

#ifdef SPI_ATK_DEBUG
  if (g_thread_supported ())
      g_message ("AT-SPI: Threads enabled");

  g_debug ("AT-SPI: Initial Atk tree regisration");
#endif

  register_subtree (root);

  atk_add_global_event_listener (tree_update_property_listener, "Gtk:AtkObject:property-change");
  atk_add_global_event_listener (tree_update_children_listener, "Gtk:AtkObject:children-changed");
  atk_add_global_event_listener (tree_update_state_listener, "Gtk:AtkObject:state-change");

  g_signal_connect (root,
                    "children-changed::add",
                    (GCallback) spi_atk_register_toplevel_added,
                    NULL);
  g_signal_connect (root,
                    "children-changed::remove",
                    (GCallback) spi_atk_register_toplevel_removed,
                    NULL);
}

/*END------------------------------------------------------------------------*/