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