gio/gdelayedsettingsbackend.c

   1 /*
   2  * Copyright © 2009, 2010 Codethink Limited
   3  *
   4  * This library is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU Lesser General Public
   6  * License as published by the Free Software Foundation; either
   7  * version 2 of the licence, or (at your option) any later version.
   8  *
   9  * This library is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  * Lesser General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU Lesser General Public
  15  * License along with this library; if not, write to the
  16  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  17  * Boston, MA 02111-1307, USA.
  18  *
  19  * Author: Ryan Lortie <desrt@desrt.ca>
  20  */
  21
  22 #include "config.h"
  23
  24 #include "gdelayedsettingsbackend.h"
  25 #include "gsettingsbackendinternal.h"
  26
  27 #include <string.h>
  28
  29
  30 struct _GDelayedSettingsBackendPrivate
  31 {
  32   GSettingsBackend *backend;
  33   GMutex lock;
  34   GTree *delayed;
  35
  36   GMainContext *owner_context;
  37   gpointer owner;
  38 };
  39
  40 G_DEFINE_TYPE_WITH_PRIVATE (GDelayedSettingsBackend,
  41                             g_delayed_settings_backend,
  42                             G_TYPE_SETTINGS_BACKEND)
  43
  44 static gboolean
  45 invoke_notify_unapplied (gpointer data)
  46 {
  47   g_object_notify (data, "has-unapplied");
  48   g_object_unref (data);
  49
  50   return FALSE;
  51 }
  52
  53 static void
  54 g_delayed_settings_backend_notify_unapplied (GDelayedSettingsBackend *delayed)
  55 {
  56   GMainContext *target_context;
  57   GObject *target;
  58
  59   g_mutex_lock (&delayed->priv->lock);
  60   if (delayed->priv->owner)
  61     {
  62       target_context = delayed->priv->owner_context;
  63       target = g_object_ref (delayed->priv->owner);
  64     }
  65   else
  66     {
  67       target_context = NULL;
  68       target = NULL;
  69     }
  70   g_mutex_unlock (&delayed->priv->lock);
  71
  72   if (target != NULL)
  73     g_main_context_invoke (target_context, invoke_notify_unapplied, target);
  74 }
  75
  76
  77 static GVariant *
  78 g_delayed_settings_backend_read (GSettingsBackend   *backend,
  79                                  const gchar        *key,
  80                                  const GVariantType *expected_type,
  81                                  gboolean            default_value)
  82 {
  83   GDelayedSettingsBackend *delayed = G_DELAYED_SETTINGS_BACKEND (backend);
  84   gpointer result = NULL;
  85
  86   if (!default_value)
  87     {
  88       g_mutex_lock (&delayed->priv->lock);
  89       if (g_tree_lookup_extended (delayed->priv->delayed, key, NULL, &result))
  90         {
  91           /* NULL in the tree means we should consult the default value */
  92           if (result != NULL)
  93             g_variant_ref (result);
  94           else
  95             default_value = TRUE;
  96         }
  97       g_mutex_unlock (&delayed->priv->lock);
  98     }
  99
 100   if (result == NULL)
 101     result = g_settings_backend_read (delayed->priv->backend, key,
 102                                       expected_type, default_value);
 103
 104   return result;
 105 }
 106
 107 static GVariant *
 108 g_delayed_settings_backend_read_user_value (GSettingsBackend   *backend,
 109                                             const gchar        *key,
 110                                             const GVariantType *expected_type)
 111 {
 112   GDelayedSettingsBackend *delayed = G_DELAYED_SETTINGS_BACKEND (backend);
 113   gboolean value_found = FALSE;
 114   gpointer result = NULL;
 115
 116   /* If we find an explicit NULL in our changeset then we want to return
 117    * NULL (because the user value has been reset).
 118    *
 119    * Otherwise, chain up.
 120    */
 121   g_mutex_lock (&delayed->priv->lock);
 122   value_found = g_tree_lookup_extended (delayed->priv->delayed, key, NULL, &result);
 123   if (result)
 124     g_variant_ref (result);
 125   g_mutex_unlock (&delayed->priv->lock);
 126
 127   if (value_found)
 128     return result;
 129
 130   return g_settings_backend_read_user_value (delayed->priv->backend, key, expected_type);
 131 }
 132
 133 static gboolean
 134 g_delayed_settings_backend_write (GSettingsBackend *backend,
 135                                   const gchar      *key,
 136                                   GVariant         *value,
 137                                   gpointer          origin_tag)
 138 {
 139   GDelayedSettingsBackend *delayed = G_DELAYED_SETTINGS_BACKEND (backend);
 140   gboolean was_empty;
 141
 142   g_mutex_lock (&delayed->priv->lock);
 143   was_empty = g_tree_nnodes (delayed->priv->delayed) == 0;
 144   g_tree_insert (delayed->priv->delayed, g_strdup (key),
 145                  g_variant_ref_sink (value));
 146   g_mutex_unlock (&delayed->priv->lock);
 147
 148   g_settings_backend_changed (backend, key, origin_tag);
 149
 150   if (was_empty)
 151     g_delayed_settings_backend_notify_unapplied (delayed);
 152
 153   return TRUE;
 154 }
 155
 156 static gboolean
 157 add_to_tree (gpointer key,
 158              gpointer value,
 159              gpointer user_data)
 160 {
 161   g_tree_insert (user_data, g_strdup (key), g_variant_ref (value));
 162   return FALSE;
 163 }
 164
 165 static gboolean
 166 g_delayed_settings_backend_write_tree (GSettingsBackend *backend,
 167                                        GTree            *tree,
 168                                        gpointer          origin_tag)
 169 {
 170   GDelayedSettingsBackend *delayed = G_DELAYED_SETTINGS_BACKEND (backend);
 171   gboolean was_empty;
 172
 173   g_mutex_lock (&delayed->priv->lock);
 174   was_empty = g_tree_nnodes (delayed->priv->delayed) == 0;
 175
 176   g_tree_foreach (tree, add_to_tree, delayed->priv->delayed);
 177   g_mutex_unlock (&delayed->priv->lock);
 178
 179   g_settings_backend_changed_tree (backend, tree, origin_tag);
 180
 181   if (was_empty)
 182     g_delayed_settings_backend_notify_unapplied (delayed);
 183
 184   return TRUE;
 185 }
 186
 187 static gboolean
 188 g_delayed_settings_backend_get_writable (GSettingsBackend *backend,
 189                                          const gchar      *name)
 190 {
 191   GDelayedSettingsBackend *delayed = G_DELAYED_SETTINGS_BACKEND (backend);
 192
 193   return g_settings_backend_get_writable (delayed->priv->backend, name);
 194 }
 195
 196 static void
 197 g_delayed_settings_backend_reset (GSettingsBackend *backend,
 198                                   const gchar      *key,
 199                                   gpointer          origin_tag)
 200 {
 201   GDelayedSettingsBackend *delayed = G_DELAYED_SETTINGS_BACKEND (backend);
 202   gboolean was_empty;
 203
 204   g_mutex_lock (&delayed->priv->lock);
 205   was_empty = g_tree_nnodes (delayed->priv->delayed) == 0;
 206   g_tree_insert (delayed->priv->delayed, g_strdup (key), NULL);
 207   g_mutex_unlock (&delayed->priv->lock);
 208
 209   if (was_empty)
 210     g_delayed_settings_backend_notify_unapplied (delayed);
 211 }
 212
 213 static void
 214 g_delayed_settings_backend_subscribe (GSettingsBackend *backend,
 215                                       const char       *name)
 216 {
 217   GDelayedSettingsBackend *delayed = G_DELAYED_SETTINGS_BACKEND (backend);
 218
 219   g_settings_backend_subscribe (delayed->priv->backend, name);
 220 }
 221
 222 static void
 223 g_delayed_settings_backend_unsubscribe (GSettingsBackend *backend,
 224                                         const char       *name)
 225 {
 226   GDelayedSettingsBackend *delayed = G_DELAYED_SETTINGS_BACKEND (backend);
 227
 228   g_settings_backend_unsubscribe (delayed->priv->backend, name);
 229 }
 230
 231 static GPermission *
 232 g_delayed_settings_backend_get_permission (GSettingsBackend *backend,
 233                                            const gchar      *path)
 234 {
 235   GDelayedSettingsBackend *delayed = G_DELAYED_SETTINGS_BACKEND (backend);
 236
 237   return g_settings_backend_get_permission (delayed->priv->backend, path);
 238 }
 239
 240
 241 /* method calls */
 242 gboolean
 243 g_delayed_settings_backend_get_has_unapplied (GDelayedSettingsBackend *delayed)
 244 {
 245   /* we don't need to lock for this... */
 246
 247   return g_tree_nnodes (delayed->priv->delayed) > 0;
 248 }
 249
 250 void
 251 g_delayed_settings_backend_apply (GDelayedSettingsBackend *delayed)
 252 {
 253   if (g_tree_nnodes (delayed->priv->delayed) > 0)
 254     {
 255       gboolean success;
 256       GTree *tmp;
 257
 258       g_mutex_lock (&delayed->priv->lock);
 259       tmp = delayed->priv->delayed;
 260       delayed->priv->delayed = g_settings_backend_create_tree ();
 261       success = g_settings_backend_write_tree (delayed->priv->backend,
 262                                                tmp, delayed->priv);
 263       g_mutex_unlock (&delayed->priv->lock);
 264
 265       if (!success)
 266         g_settings_backend_changed_tree (G_SETTINGS_BACKEND (delayed),
 267                                          tmp, NULL);
 268
 269       g_tree_unref (tmp);
 270
 271       g_delayed_settings_backend_notify_unapplied (delayed);
 272     }
 273 }
 274
 275 void
 276 g_delayed_settings_backend_revert (GDelayedSettingsBackend *delayed)
 277 {
 278   if (g_tree_nnodes (delayed->priv->delayed) > 0)
 279     {
 280       GTree *tmp;
 281
 282       g_mutex_lock (&delayed->priv->lock);
 283       tmp = delayed->priv->delayed;
 284       delayed->priv->delayed = g_settings_backend_create_tree ();
 285       g_mutex_unlock (&delayed->priv->lock);
 286       g_settings_backend_changed_tree (G_SETTINGS_BACKEND (delayed), tmp, NULL);
 287       g_tree_unref (tmp);
 288
 289       g_delayed_settings_backend_notify_unapplied (delayed);
 290     }
 291 }
 292
 293 /* change notification */
 294 static void
 295 delayed_backend_changed (GObject          *target,
 296                          GSettingsBackend *backend,
 297                          const gchar      *key,
 298                          gpointer          origin_tag)
 299 {
 300   GDelayedSettingsBackend *delayed = G_DELAYED_SETTINGS_BACKEND (target);
 301
 302   if (origin_tag != delayed->priv)
 303     g_settings_backend_changed (G_SETTINGS_BACKEND (delayed),
 304                                 key, origin_tag);
 305 }
 306
 307 static void
 308 delayed_backend_keys_changed (GObject             *target,
 309                               GSettingsBackend    *backend,
 310                               const gchar         *path,
 311                               const gchar * const *items,
 312                               gpointer             origin_tag)
 313 {
 314   GDelayedSettingsBackend *delayed = G_DELAYED_SETTINGS_BACKEND (target);
 315
 316   if (origin_tag != delayed->priv)
 317     g_settings_backend_keys_changed (G_SETTINGS_BACKEND (delayed),
 318                                      path, items, origin_tag);
 319 }
 320
 321 static void
 322 delayed_backend_path_changed (GObject          *target,
 323                               GSettingsBackend *backend,
 324                               const gchar      *path,
 325                               gpointer          origin_tag)
 326 {
 327   GDelayedSettingsBackend *delayed = G_DELAYED_SETTINGS_BACKEND (target);
 328
 329   if (origin_tag != delayed->priv)
 330     g_settings_backend_path_changed (G_SETTINGS_BACKEND (delayed),
 331                                      path, origin_tag);
 332 }
 333
 334 static void
 335 delayed_backend_writable_changed (GObject          *target,
 336                                   GSettingsBackend *backend,
 337                                   const gchar      *key)
 338 {
 339   GDelayedSettingsBackend *delayed = G_DELAYED_SETTINGS_BACKEND (target);
 340   gboolean last_one = FALSE;
 341
 342   g_mutex_lock (&delayed->priv->lock);
 343
 344   if (g_tree_lookup (delayed->priv->delayed, key) != NULL &&
 345       !g_settings_backend_get_writable (delayed->priv->backend, key))
 346     {
 347       /* drop the key from our changeset if it just became read-only.
 348        * no need to signal since the writable change below implies it.
 349        *
 350        * note that the item in the tree may very well be set to NULL in
 351        * the case that the user stored a reset.  we intentionally don't
 352        * drop the key in this case since a reset will always succeed
 353        * (even against a non-writable key).
 354        */
 355       g_tree_remove (delayed->priv->delayed, key);
 356
 357       /* if that was the only key... */
 358       last_one = g_tree_nnodes (delayed->priv->delayed) == 0;
 359     }
 360
 361   g_mutex_unlock (&delayed->priv->lock);
 362
 363   if (last_one)
 364     g_delayed_settings_backend_notify_unapplied (delayed);
 365
 366   g_settings_backend_writable_changed (G_SETTINGS_BACKEND (delayed), key);
 367 }
 368
 369 /* slow method until we get foreach-with-remove in GTree
 370  */
 371 typedef struct
 372 {
 373   const gchar *path;
 374   const gchar **keys;
 375   gsize index;
 376 } CheckPrefixState;
 377
 378 static gboolean
 379 check_prefix (gpointer key,
 380               gpointer value,
 381               gpointer data)
 382 {
 383   CheckPrefixState *state = data;
 384
 385   if (g_str_has_prefix (key, state->path))
 386     state->keys[state->index++] = key;
 387
 388   return FALSE;
 389 }
 390
 391 static void
 392 delayed_backend_path_writable_changed (GObject          *target,
 393                                        GSettingsBackend *backend,
 394                                        const gchar      *path)
 395 {
 396   GDelayedSettingsBackend *delayed = G_DELAYED_SETTINGS_BACKEND (target);
 397   gboolean last_one = FALSE;
 398   gsize n_keys;
 399
 400   g_mutex_lock (&delayed->priv->lock);
 401
 402   n_keys = g_tree_nnodes (delayed->priv->delayed);
 403
 404   if (n_keys > 0)
 405     {
 406       CheckPrefixState state = { path, g_new (const gchar *, n_keys) };
 407       gsize i;
 408
 409       /* collect a list of possibly-affected keys (ie: matching the path) */
 410       g_tree_foreach (delayed->priv->delayed, check_prefix, &state);
 411
 412       /* drop the keys that have been affected.
 413        *
 414        * don't drop 'reset' keys (see above) */
 415       for (i = 0; i < state.index; i++)
 416         if (g_tree_lookup (delayed->priv->delayed, state.keys[i]) != NULL &&
 417             !g_settings_backend_get_writable (delayed->priv->backend,
 418                                               state.keys[i]))
 419           g_tree_remove (delayed->priv->delayed, state.keys[i]);
 420
 421       g_free (state.keys);
 422
 423       last_one = g_tree_nnodes (delayed->priv->delayed) == 0;
 424     }
 425
 426   g_mutex_unlock (&delayed->priv->lock);
 427
 428   if (last_one)
 429     g_delayed_settings_backend_notify_unapplied (delayed);
 430
 431   g_settings_backend_path_writable_changed (G_SETTINGS_BACKEND (delayed),
 432                                             path);
 433 }
 434
 435 static void
 436 g_delayed_settings_backend_finalize (GObject *object)
 437 {
 438   GDelayedSettingsBackend *delayed = G_DELAYED_SETTINGS_BACKEND (object);
 439
 440   g_mutex_clear (&delayed->priv->lock);
 441   g_object_unref (delayed->priv->backend);
 442   g_tree_unref (delayed->priv->delayed);
 443
 444   /* if our owner is still alive, why are we finalizing? */
 445   g_assert (delayed->priv->owner == NULL);
 446
 447   G_OBJECT_CLASS (g_delayed_settings_backend_parent_class)
 448     ->finalize (object);
 449 }
 450
 451 static void
 452 g_delayed_settings_backend_class_init (GDelayedSettingsBackendClass *class)
 453 {
 454   GSettingsBackendClass *backend_class = G_SETTINGS_BACKEND_CLASS (class);
 455   GObjectClass *object_class = G_OBJECT_CLASS (class);
 456
 457   backend_class->read = g_delayed_settings_backend_read;
 458   backend_class->read_user_value = g_delayed_settings_backend_read_user_value;
 459   backend_class->write = g_delayed_settings_backend_write;
 460   backend_class->write_tree = g_delayed_settings_backend_write_tree;
 461   backend_class->reset = g_delayed_settings_backend_reset;
 462   backend_class->get_writable = g_delayed_settings_backend_get_writable;
 463   backend_class->subscribe = g_delayed_settings_backend_subscribe;
 464   backend_class->unsubscribe = g_delayed_settings_backend_unsubscribe;
 465   backend_class->get_permission = g_delayed_settings_backend_get_permission;
 466
 467   object_class->finalize = g_delayed_settings_backend_finalize;
 468 }
 469
 470 static void
 471 g_delayed_settings_backend_init (GDelayedSettingsBackend *delayed)
 472 {
 473   delayed->priv = g_delayed_settings_backend_get_instance_private (delayed);
 474   delayed->priv->delayed = g_settings_backend_create_tree ();
 475   g_mutex_init (&delayed->priv->lock);
 476 }
 477
 478 static void
 479 g_delayed_settings_backend_disown (gpointer  data,
 480                                    GObject  *where_the_object_was)
 481 {
 482   GDelayedSettingsBackend *delayed = data;
 483
 484   g_mutex_lock (&delayed->priv->lock);
 485   delayed->priv->owner_context = NULL;
 486   delayed->priv->owner = NULL;
 487   g_mutex_unlock (&delayed->priv->lock);
 488 }
 489
 490 GDelayedSettingsBackend *
 491 g_delayed_settings_backend_new (GSettingsBackend *backend,
 492                                 gpointer          owner,
 493                                 GMainContext     *owner_context)
 494 {
 495   static GSettingsListenerVTable vtable = {
 496     delayed_backend_changed,
 497     delayed_backend_path_changed,
 498     delayed_backend_keys_changed,
 499     delayed_backend_writable_changed,
 500     delayed_backend_path_writable_changed
 501   };
 502   GDelayedSettingsBackend *delayed;
 503
 504   delayed = g_object_new (G_TYPE_DELAYED_SETTINGS_BACKEND, NULL);
 505   delayed->priv->backend = g_object_ref (backend);
 506   delayed->priv->owner_context = owner_context;
 507   delayed->priv->owner = owner;
 508
 509   g_object_weak_ref (owner, g_delayed_settings_backend_disown, delayed);
 510
 511   g_settings_backend_watch (delayed->priv->backend,
 512                             &vtable, G_OBJECT (delayed), NULL);
 513
 514   return delayed;
 515 }