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  *
  43  * Users of objects implementing this are not intended to use the interface
  44  * method directly; instead it will be used automatically in various ways.
  45  * For C applications you generally just call g_async_initable_new_async()
  46  * directly, or indirectly via a foo_thing_new_async() wrapper. This will call
  47  * g_async_initable_init_async() under the cover, calling back with %NULL and
  48  * a set %GError on failure.
  49  */
  50
  51 static void     g_async_initable_base_init        (gpointer              g_iface);
  52 static void     g_async_initable_real_init_async  (GAsyncInitable       *initable,
  53                                                    int                   io_priority,
  54                                                    GCancellable         *cancellable,
  55                                                    GAsyncReadyCallback   callback,
  56                                                    gpointer              user_data);
  57 static gboolean g_async_initable_real_init_finish (GAsyncInitable       *initable,
  58                                                    GAsyncResult         *res,
  59                                                    GError              **error);
  60
  61 GType
  62 g_async_initable_get_type (void)
  63 {
  64   static volatile gsize g_define_type_id__volatile = 0;
  65
  66   if (g_once_init_enter (&g_define_type_id__volatile))
  67     {
  68       const GTypeInfo initable_info =
  69       {
  70         sizeof (GAsyncInitableIface), /* class_size */
  71         g_async_initable_base_init,   /* base_init */
  72         NULL,           /* base_finalize */
  73         NULL,
  74         NULL,           /* class_finalize */
  75         NULL,           /* class_data */
  76         0,
  77         0,              /* n_preallocs */
  78         NULL
  79       };
  80       GType g_define_type_id =
  81         g_type_register_static (G_TYPE_INTERFACE, I_("GAsyncInitable"),
  82                                 &initable_info, 0);
  83
  84       g_type_interface_add_prerequisite (g_define_type_id, G_TYPE_OBJECT);
  85
  86       g_once_init_leave (&g_define_type_id__volatile, g_define_type_id);
  87     }
  88
  89   return g_define_type_id__volatile;
  90 }
  91
  92 static void
  93 g_async_initable_base_init (gpointer g_iface)
  94 {
  95   GAsyncInitableIface *iface = g_iface;
  96
  97   iface->init_async = g_async_initable_real_init_async;
  98   iface->init_finish = g_async_initable_real_init_finish;
  99 }
 100
 101 /**
 102  * g_async_initable_init_async:
 103  * @initable: a #GAsyncInitable.
 104  * @io_priority: the <link linkend="io-priority">I/O priority</link>
 105  *     of the operation.
 106  * @cancellable: optional #GCancellable object, %NULL to ignore.
 107  * @callback: a #GAsyncReadyCallback to call when the request is satisfied
 108  * @user_data: the data to pass to callback function
 109  *
 110  * Starts asynchronous initialization of the object implementing the
 111  * interface. This must be done before any real use of the object after
 112  * initial construction. If the object also implements #GInitable you can
 113  * optionally call g_initable_init() instead.
 114  *
 115  * When the initialization is finished, @callback will be called. You can
 116  * then call g_async_initable_init_finish() to get the result of the
 117  * initialization.
 118  *
 119  * Implementations may also support cancellation. If @cancellable is not
 120  * %NULL, then initialization can be cancelled by triggering the cancellable
 121  * object 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 it's 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   (* 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 has occurred, this function
 171  * will return %FALSE and set @error appropriately if present.
 172  *
 173  * Since: 2.22
 174  */
 175 gboolean
 176 g_async_initable_init_finish (GAsyncInitable  *initable,
 177                               GAsyncResult    *res,
 178                               GError         **error)
 179 {
 180   GAsyncInitableIface *iface;
 181
 182   g_return_val_if_fail (G_IS_ASYNC_INITABLE (initable), FALSE);
 183   g_return_val_if_fail (G_IS_ASYNC_RESULT (res), FALSE);
 184
 185   if (G_IS_SIMPLE_ASYNC_RESULT (res))
 186     {
 187       GSimpleAsyncResult *simple = G_SIMPLE_ASYNC_RESULT (res);
 188       if (g_simple_async_result_propagate_error (simple, error))
 189         return FALSE;
 190     }
 191
 192   iface = G_ASYNC_INITABLE_GET_IFACE (initable);
 193
 194   return (* iface->init_finish) (initable, res, error);
 195 }
 196
 197 static void
 198 async_init_thread (GSimpleAsyncResult *res,
 199                    GObject            *object,
 200                    GCancellable       *cancellable)
 201 {
 202   GError *error = NULL;
 203
 204   if (!g_initable_init (G_INITABLE (object), cancellable, &error))
 205     {
 206       g_simple_async_result_set_from_error (res, error);
 207       g_error_free (error);
 208     }
 209 }
 210
 211 static void
 212 g_async_initable_real_init_async (GAsyncInitable      *initable,
 213                                   int                  io_priority,
 214                                   GCancellable        *cancellable,
 215                                   GAsyncReadyCallback  callback,
 216                                   gpointer             user_data)
 217 {
 218   GSimpleAsyncResult *res;
 219
 220   g_return_if_fail (G_IS_INITABLE (initable));
 221
 222   res = g_simple_async_result_new (G_OBJECT (initable), callback, user_data,
 223                                    g_async_initable_real_init_async);
 224   g_simple_async_result_run_in_thread (res, async_init_thread,
 225                                        io_priority, cancellable);
 226   g_object_unref (res);
 227 }
 228
 229 static gboolean
 230 g_async_initable_real_init_finish (GAsyncInitable  *initable,
 231                                    GAsyncResult    *res,
 232                                    GError         **error)
 233 {
 234   return TRUE; /* Errors handled by base impl */
 235 }
 236
 237 /**
 238  * g_async_initable_new_async:
 239  * @object_type: a #GType supporting #GAsyncInitable.
 240  * @io_priority: the <link linkend="io-priority">I/O priority</link>
 241  *     of the operation.
 242  * @cancellable: optional #GCancellable object, %NULL to ignore.
 243  * @callback: a #GAsyncReadyCallback to call when the initialization is
 244  *     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
 247  *     properties
 248  * @...:  the value of the first property, followed by other property
 249  *    value pairs, and ended by %NULL.
 250  *
 251  * Helper function for constructing #GAsyncInitiable object. This is
 252  * similar to g_object_new() but also initializes the object asynchronously.
 253  *
 254  * When the initialization is finished, @callback will be called. You can
 255  * then call g_async_initable_new_finish() to get the new object and check
 256  * for any errors.
 257  *
 258  * Since: 2.22
 259  */
 260 void
 261 g_async_initable_new_async (GType                object_type,
 262                             int                  io_priority,
 263                             GCancellable        *cancellable,
 264                             GAsyncReadyCallback  callback,
 265                             gpointer             user_data,
 266                             const gchar         *first_property_name,
 267                             ...)
 268 {
 269   va_list var_args;
 270
 271   va_start (var_args, first_property_name);
 272   g_async_initable_new_valist_async (object_type,
 273                                      first_property_name, var_args,
 274                                      io_priority, cancellable,
 275                                      callback, user_data);
 276   va_end (var_args);
 277 }
 278
 279 /**
 280  * g_async_initable_newv_async:
 281  * @object_type: a #GType supporting #GAsyncInitable.
 282  * @n_parameters: the number of parameters in @parameters
 283  * @parameters: the parameters to use to construct the object
 284  * @io_priority: the <link linkend="io-priority">I/O priority</link>
 285  *     of the operation.
 286  * @cancellable: optional #GCancellable object, %NULL to ignore.
 287  * @callback: a #GAsyncReadyCallback to call when the initialization is
 288  *     finished
 289  * @user_data: the data to pass to callback function
 290  *
 291  * Helper function for constructing #GAsyncInitiable object. This is
 292  * similar to g_object_newv() but also initializes the object asynchronously.
 293  *
 294  * When the initialization is finished, @callback will be called. You can
 295  * then call g_async_initable_new_finish() to get the new object and check
 296  * for any errors.
 297  *
 298  * Since: 2.22
 299  */
 300 void
 301 g_async_initable_newv_async (GType                object_type,
 302                              guint                n_parameters,
 303                              GParameter          *parameters,
 304                              int                  io_priority,
 305                              GCancellable        *cancellable,
 306                              GAsyncReadyCallback  callback,
 307                              gpointer             user_data)
 308 {
 309   GObject *obj;
 310
 311   g_return_if_fail (G_TYPE_IS_ASYNC_INITABLE (object_type));
 312
 313   obj = g_object_newv (object_type, n_parameters, parameters);
 314
 315   g_async_initable_init_async (G_ASYNC_INITABLE (obj),
 316                                io_priority, cancellable,
 317                                callback, user_data);
 318 }
 319
 320 /**
 321  * g_async_initable_new_valist_async:
 322  * @object_type: a #GType supporting #GAsyncInitable.
 323  * @first_property_name: the name of the first property, followed by
 324  * the value, and other property value pairs, and ended by %NULL.
 325  * @var_args: The var args list generated from @first_property_name.
 326  * @io_priority: the <link linkend="io-priority">I/O priority</link>
 327  *     of the operation.
 328  * @cancellable: optional #GCancellable object, %NULL to ignore.
 329  * @callback: a #GAsyncReadyCallback to call when the initialization is
 330  *     finished
 331  * @user_data: the data to pass to callback function
 332  *
 333  * Helper function for constructing #GAsyncInitiable object. This is
 334  * similar to g_object_new_valist() but also initializes the object
 335  * asynchronously.
 336  *
 337  * When the initialization is finished, @callback will be called. You can
 338  * then call g_async_initable_new_finish() to get the new object and check
 339  * for any errors.
 340  *
 341  * Since: 2.22
 342  */
 343 void
 344 g_async_initable_new_valist_async (GType                object_type,
 345                                    const gchar         *first_property_name,
 346                                    va_list              var_args,
 347                                    int                  io_priority,
 348                                    GCancellable        *cancellable,
 349                                    GAsyncReadyCallback  callback,
 350                                    gpointer             user_data)
 351 {
 352   GObject *obj;
 353
 354   g_return_if_fail (G_TYPE_IS_ASYNC_INITABLE (object_type));
 355
 356   obj = g_object_new_valist (object_type,
 357                              first_property_name,
 358                              var_args);
 359
 360   g_async_initable_init_async (G_ASYNC_INITABLE (obj),
 361                                io_priority, cancellable,
 362                                callback, user_data);
 363   g_object_unref (obj); /* Passed ownership to async call */
 364 }
 365
 366 /**
 367  * g_async_initable_new_finish:
 368  * @initable: the #GAsyncInitable from the callback
 369  * @res: the #GAsyncResult.from the callback
 370  * @error: a #GError location to store the error occuring, or %NULL to
 371  *     ignore.
 372  *
 373  * Finishes the async construction for the various g_async_initable_new calls,
 374  * returning the created object or %NULL on error.
 375  *
 376  * Returns: a newly created #GObject, or %NULL on error. Free with
 377  *     g_object_unref().
 378  *
 379  * Since: 2.22
 380  */
 381 GObject *
 382 g_async_initable_new_finish (GAsyncInitable  *initable,
 383                              GAsyncResult    *res,
 384                              GError         **error)
 385 {
 386   if (g_async_initable_init_finish (initable, res, error))
 387     return g_object_ref (initable);
 388   else
 389     return NULL;
 390 }
 391
 392 #define __G_ASYNC_INITABLE_C__
 393 #include "gioaliasdef.c"