gio/gasyncinitable.c

   1 /* GIO - GLib Input, Output and Streaming Library
   2  *
   3  * Copyright (C) 2009 Red Hat, Inc.
   4  *
   5  * This library is free software; you can redistribute it and/or
   6  * modify it under the terms of the GNU Lesser General Public
   7  * License as published by the Free Software Foundation; either
   8  * version 2 of the License, or (at your option) any later version.
   9  *
  10  * This library is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13  * Lesser General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU Lesser General
  16  * Public License along with this library; if not, write to the
  17  * Free Software Foundation, Inc., 59 Temple Place, Suite 330,
  18  * Boston, MA 02111-1307, USA.
  19  *
  20  * Author: Alexander Larsson <alexl@redhat.com>
  21  */
  22
  23 #include "config.h"
  24 #include "gasyncinitable.h"
  25 #include "gasyncresult.h"
  26 #include "gsimpleasyncresult.h"
  27 #include "glibintl.h"
  28
  29 #include "gioalias.h"
  30
  31 /**
  32  * SECTION:gasyncinitable
  33  * @short_description: Asynchronously failable object initialization interface
  34  * @include: gio/gio.h
  35  * @see_also: #GInitable
  36  *
  37  * This is the asynchronous version of #GInitable, it behaves the same
  38  * in all ways except that initialization is asynchronous. For more details
  39  * see the descriptions on #GInitable.
  40  *
  41  * A class may implement both the #GInitable and #GAsyncInitable interfaces
  42  * or both.
  43  *
  44  * Users of objects implementing this are not intended to use
  45  * the interface method directly, instead it will be used automatically
  46  * in various ways. For C applications you generally just call
  47  * g_async_initable_new() directly, or indirectly via a foo_thing_new_async() wrapper.
  48  * This will call g_async_initable_init() under the cover, calling back with %NULL and
  49  * a set %GError on failure.
  50  **/
  51
  52 static void     g_async_initable_base_init        (gpointer              g_iface);
  53 static void     g_async_initable_real_init_async  (GAsyncInitable       *initable,
  54                                                    int                   io_priority,
  55                                                    GCancellable         *cancellable,
  56                                                    GAsyncReadyCallback   callback,
  57                                                    gpointer              user_data);
  58 static gboolean g_async_initable_real_init_finish (GAsyncInitable       *initable,
  59                                                    GAsyncResult         *res,
  60                                                    GError              **error);
  61
  62 GType
  63 g_async_initable_get_type (void)
  64 {
  65   static volatile gsize g_define_type_id__volatile = 0;
  66
  67   if (g_once_init_enter (&g_define_type_id__volatile))
  68     {
  69       const GTypeInfo initable_info =
  70       {
  71         sizeof (GAsyncInitableIface), /* class_size */
  72         g_async_initable_base_init,   /* base_init */
  73         NULL,           /* base_finalize */
  74         NULL,
  75         NULL,           /* class_finalize */
  76         NULL,           /* class_data */
  77         0,
  78         0,              /* n_preallocs */
  79         NULL
  80       };
  81       GType g_define_type_id =
  82         g_type_register_static (G_TYPE_INTERFACE, I_("GAsyncInitable"),
  83                                 &initable_info, 0);
  84
  85       g_type_interface_add_prerequisite (g_define_type_id, G_TYPE_OBJECT);
  86
  87       g_once_init_leave (&g_define_type_id__volatile, g_define_type_id);
  88     }
  89
  90   return g_define_type_id__volatile;
  91 }
  92
  93 static void
  94 g_async_initable_base_init (gpointer g_iface)
  95 {
  96   GAsyncInitableIface *iface = g_iface;
  97
  98   iface->init_async = g_async_initable_real_init_async;
  99   iface->init_finish = g_async_initable_real_init_finish;
 100 }
 101
 102 /**
 103  * g_async_initable_init_async:
 104  * @initable: a #GAsyncInitable.
 105  * @io_priority: the <link linkend="io-priority">I/O priority</link>
 106  *     of the operation.
 107  * @cancellable: optional #GCancellable object, %NULL to ignore.
 108  * @callback: a #GAsyncReadyCallback to call when the request is satisfied
 109  * @user_data: the data to pass to callback function
 110  *
 111  * Starts asynchronous initialization of the object implementing the interface.
 112  * This must be done before any real use of the object after initial construction.
 113  * If the object also implements #GInitable you can optionally call g_initable_init()
 114  * instead.
 115  *
 116  * When the initialization is finished, @callback will be called. You can then call
 117  * g_async_initable_init_finish() to get the result of the initialization.
 118  *
 119  * Implementations may also support cancellation. If @cancellable is not %NULL,
 120  * then initialization can be cancelled by triggering the cancellable object
 121  * from another thread. If the operation was cancelled, the error
 122  * %G_IO_ERROR_CANCELLED will be returned. If @cancellable is not %NULL and
 123  * the object doesn't support cancellable initialization the error
 124  * %G_IO_ERROR_NOT_SUPPORTED will be returned.
 125  *
 126  * If this function is not called, or returns with an error then all
 127  * operations on the object should fail, generally returning the
 128  * error %G_IO_ERROR_NOT_INITIALIZED.
 129  *
 130  * Implementations of this method must be idempotent, i.e. multiple calls
 131  * to this function with the same argument should return the same results.
 132  * Only the first call initializes the object, further calls return the result
 133  * of the first call. This is so that its safe to implement the singleton
 134  * pattern in the GObject constructor function.
 135  *
 136  * For classes that also support the #GInitable interface the default
 137  * implementation of this method will run the g_initable_init() function
 138  * in a thread, so if you want to support asynchronous initialization via
 139  * threads, just implement the #GAsyncInitable interface without overriding
 140  * any interface methods.
 141  *
 142  * Since: 2.22
 143  **/
 144 void
 145 g_async_initable_init_async (GAsyncInitable     *initable,
 146                              int                 io_priority,
 147                              GCancellable       *cancellable,
 148                              GAsyncReadyCallback callback,
 149                              gpointer            user_data)
 150 {
 151   GAsyncInitableIface *iface;
 152
 153   g_return_if_fail (G_IS_ASYNC_INITABLE (initable));
 154
 155   iface = G_ASYNC_INITABLE_GET_IFACE (initable);
 156
 157   return (* iface->init_async) (initable, io_priority, cancellable, callback, user_data);
 158 }
 159
 160 /**
 161  * g_async_initable_init_finish:
 162  * @initable: a #GAsyncInitable.
 163  * @res: a #GAsyncResult.
 164  * @error: a #GError location to store the error occuring, or %NULL to
 165  * ignore.
 166  *
 167  * Finishes asynchronous initialization and returns the result.
 168  * See g_async_initable_init_async().
 169  *
 170  * Returns: %TRUE if successful. If an error
 171  *     has occurred, this function will return %FALSE and set @error
 172  *     appropriately if present.
 173  *
 174  * Since: 2.22
 175  **/
 176 gboolean
 177 g_async_initable_init_finish (GAsyncInitable       *initable,
 178                               GAsyncResult         *res,
 179                               GError              **error)
 180 {
 181   GAsyncInitableIface *iface;
 182
 183   g_return_val_if_fail (G_IS_ASYNC_INITABLE (initable), FALSE);
 184   g_return_val_if_fail (G_IS_ASYNC_RESULT (res), FALSE);
 185
 186   if (G_IS_SIMPLE_ASYNC_RESULT (res))
 187     {
 188       GSimpleAsyncResult *simple = G_SIMPLE_ASYNC_RESULT (res);
 189       if (g_simple_async_result_propagate_error (simple, error))
 190         return FALSE;
 191     }
 192
 193   iface = G_ASYNC_INITABLE_GET_IFACE (initable);
 194
 195   return (* iface->init_finish) (initable, res, error);
 196 }
 197
 198 static void
 199 async_init_thread (GSimpleAsyncResult *res,
 200                    GObject            *object,
 201                    GCancellable       *cancellable)
 202 {
 203   GError *error = NULL;
 204
 205   if (!g_initable_init (G_INITABLE (res), cancellable, &error))
 206     {
 207       g_simple_async_result_set_from_error (res, error);
 208       g_error_free (error);
 209     }
 210 }
 211
 212 static void
 213 g_async_initable_real_init_async (GAsyncInitable     *initable,
 214                                   int                 io_priority,
 215                                   GCancellable       *cancellable,
 216                                   GAsyncReadyCallback callback,
 217                                   gpointer            user_data)
 218 {
 219   GSimpleAsyncResult *res;
 220
 221   g_return_if_fail (G_IS_INITABLE (initable));
 222
 223   res = g_simple_async_result_new (G_OBJECT (initable), callback, user_data,
 224                                    g_async_initable_real_init_async);
 225   g_simple_async_result_run_in_thread (res, async_init_thread,
 226                                        io_priority, cancellable);
 227   g_object_unref (res);
 228 }
 229
 230 static gboolean
 231 g_async_initable_real_init_finish (GAsyncInitable *initable,
 232                                    GAsyncResult *res,
 233                                    GError **error)
 234 {
 235   return TRUE; /* Errors handled by base impl */
 236 }
 237
 238 /**
 239  * g_async_initable_new_async:
 240  * @object_type: a #GType supporting #GAsyncInitable.
 241  * @io_priority: the <link linkend="io-priority">I/O priority</link>
 242  *     of the operation.
 243  * @cancellable: optional #GCancellable object, %NULL to ignore.
 244  * @callback: a #GAsyncReadyCallback to call when the initialization is finished
 245  * @user_data: the data to pass to callback function
 246  * @first_property_name: the name of the first property, or %NULL if no properties
 247  * @...:  the value if the first property, followed by and other property
 248  *    value pairs, and ended by %NULL.
 249  *
 250  * Helper function for constructing #GAsyncInitiable object. This is
 251  * similar to g_object_new() but also initializes the object asyncronously.
 252  *
 253  * When the initialization is finished, @callback will be called. You can then call
 254  * g_async_initable_new_finish() to get new object and check for any errors.
 255  *
 256  * Since: 2.22
 257  **/
 258 void
 259 g_async_initable_new_async (GType object_type,
 260                             int io_priority,
 261                             GCancellable  *cancellable,
 262                             GAsyncReadyCallback callback,
 263                             gpointer user_data,
 264                             const gchar *first_property_name,
 265                             ...)
 266 {
 267   va_list var_args;
 268
 269   va_start (var_args, first_property_name);
 270   g_async_initable_new_valist_async (object_type,
 271                                      first_property_name, var_args,
 272                                      io_priority, cancellable,
 273                                      callback, user_data);
 274   va_end (var_args);
 275 }
 276
 277 /**
 278  * g_async_initable_newv_async:
 279  * @object_type: a #GType supporting #GAsyncInitable.
 280  * @n_parameters: the number of parameters in @parameters
 281  * @parameters: the parameters to use to construct the object
 282  * @io_priority: the <link linkend="io-priority">I/O priority</link>
 283  *     of the operation.
 284  * @cancellable: optional #GCancellable object, %NULL to ignore.
 285  * @callback: a #GAsyncReadyCallback to call when the initialization is finished
 286  * @user_data: the data to pass to callback function
 287  *
 288  * Helper function for constructing #GAsyncInitiable object. This is
 289  * similar to g_object_newv() but also initializes the object asyncronously.
 290  *
 291  * When the initialization is finished, @callback will be called. You can then call
 292  * g_async_initable_new_finish() to get new object and check for any errors.
 293  *
 294  * Since: 2.22
 295  **/
 296 void
 297 g_async_initable_newv_async (GType object_type,
 298                              guint n_parameters,
 299                              GParameter *parameters,
 300                              int io_priority,
 301                              GCancellable *cancellable,
 302                              GAsyncReadyCallback callback,
 303                              gpointer user_data)
 304 {
 305   GObject *obj;
 306
 307   g_return_if_fail (G_TYPE_IS_ASYNC_INITABLE (object_type));
 308
 309   obj = g_object_newv (object_type, n_parameters, parameters);
 310
 311   g_async_initable_init_async (G_ASYNC_INITABLE (obj),
 312                                io_priority, cancellable,
 313                                callback, user_data);
 314 }
 315
 316 /**
 317  * g_async_initable_new_valist_async:
 318  * @object_type: a #GType supporting #GAsyncInitable.
 319  * @first_property_name: the name of the first property, followed by
 320  * the value, and other property value pairs, and ended by %NULL.
 321  * @var_args: The var args list generated from @first_property_name.
 322  * @io_priority: the <link linkend="io-priority">I/O priority</link>
 323  *     of the operation.
 324  * @cancellable: optional #GCancellable object, %NULL to ignore.
 325  * @callback: a #GAsyncReadyCallback to call when the initialization is finished
 326  * @user_data: the data to pass to callback function
 327  *
 328  * Helper function for constructing #GAsyncInitiable object. This is
 329  * similar to g_object_new_valist() but also initializes the object asyncronously.
 330  *
 331  * When the initialization is finished, @callback will be called. You can then call
 332  * g_async_initable_new_finish() to get new object and check for any errors.
 333  *
 334  * Since: 2.22
 335  **/
 336 void
 337 g_async_initable_new_valist_async (GType object_type,
 338                                    const gchar *first_property_name,
 339                                    va_list var_args,
 340                                    int io_priority,
 341                                    GCancellable *cancellable,
 342                                    GAsyncReadyCallback callback,
 343                                    gpointer user_data)
 344 {
 345   GObject *obj;
 346
 347   g_return_if_fail (G_TYPE_IS_ASYNC_INITABLE (object_type));
 348
 349   obj = g_object_new_valist (object_type,
 350                              first_property_name,
 351                              var_args);
 352
 353   g_async_initable_init_async (G_ASYNC_INITABLE (obj),
 354                                io_priority, cancellable,
 355                                callback, user_data);
 356   g_object_unref (obj); /* Passed ownership to async call */
 357 }
 358 /**
 359  * g_async_initable_new_finish:
 360  * @initable: the #GAsyncInitable from the callback
 361  * @res: the #GAsyncResult.from the callback
 362  * @error: a #GError location to store the error occuring, or %NULL to
 363  * ignore.
 364  *
 365  * Finishes the async construction for the various g_async_initable_new calls,
 366  * returning the created object or %NULL on error.
 367  *
 368  * Returns: a newly created #GObject, or %NULL on error. Free with g_object_unref().
 369  *
 370  * Since: 2.22
 371  **/
 372 GObject *
 373 g_async_initable_new_finish (GAsyncInitable       *initable,
 374                              GAsyncResult         *res,
 375                              GError              **error)
 376 {
 377   if (g_async_initable_init_finish (initable, res, error))
 378     return g_object_ref (initable);
 379   else
 380     return NULL;
 381 }
 382
 383 #define __G_ASYNC_INITABLE_C__
 384 #include "gioaliasdef.c"