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_real_init_async  (GAsyncInitable       *initable,
  52                                                    int                   io_priority,
  53                                                    GCancellable         *cancellable,
  54                                                    GAsyncReadyCallback   callback,
  55                                                    gpointer              user_data);
  56 static gboolean g_async_initable_real_init_finish (GAsyncInitable       *initable,
  57                                                    GAsyncResult         *res,
  58                                                    GError              **error);
  59
  60
  61 typedef GAsyncInitableIface GAsyncInitableInterface;
  62 G_DEFINE_INTERFACE (GAsyncInitable, g_async_initable, G_TYPE_OBJECT)
  63
  64
  65 static void
  66 g_async_initable_default_init (GAsyncInitableInterface *iface)
  67 {
  68   iface->init_async = g_async_initable_real_init_async;
  69   iface->init_finish = g_async_initable_real_init_finish;
  70 }
  71
  72 /**
  73  * g_async_initable_init_async:
  74  * @initable: a #GAsyncInitable.
  75  * @io_priority: the <link linkend="io-priority">I/O priority</link>
  76  *     of the operation.
  77  * @cancellable: optional #GCancellable object, %NULL to ignore.
  78  * @callback: a #GAsyncReadyCallback to call when the request is satisfied
  79  * @user_data: the data to pass to callback function
  80  *
  81  * Starts asynchronous initialization of the object implementing the
  82  * interface. This must be done before any real use of the object after
  83  * initial construction. If the object also implements #GInitable you can
  84  * optionally call g_initable_init() instead.
  85  *
  86  * When the initialization is finished, @callback will be called. You can
  87  * then call g_async_initable_init_finish() to get the result of the
  88  * initialization.
  89  *
  90  * Implementations may also support cancellation. If @cancellable is not
  91  * %NULL, then initialization can be cancelled by triggering the cancellable
  92  * object from another thread. If the operation was cancelled, the error
  93  * %G_IO_ERROR_CANCELLED will be returned. If @cancellable is not %NULL, and
  94  * the object doesn't support cancellable initialization, the error
  95  * %G_IO_ERROR_NOT_SUPPORTED will be returned.
  96  *
  97  * If this function is not called, or returns with an error, then all
  98  * operations on the object should fail, generally returning the
  99  * error %G_IO_ERROR_NOT_INITIALIZED.
 100  *
 101  * Implementations of this method must be idempotent: i.e. multiple calls
 102  * to this function with the same argument should return the same results.
 103  * Only the first call initializes the object; further calls return the result
 104  * of the first call. This is so that it's safe to implement the singleton
 105  * pattern in the GObject constructor function.
 106  *
 107  * For classes that also support the #GInitable interface, the default
 108  * implementation of this method will run the g_initable_init() function
 109  * in a thread, so if you want to support asynchronous initialization via
 110  * threads, just implement the #GAsyncInitable interface without overriding
 111  * any interface methods.
 112  *
 113  * Since: 2.22
 114  */
 115 void
 116 g_async_initable_init_async (GAsyncInitable      *initable,
 117                              int                  io_priority,
 118                              GCancellable        *cancellable,
 119                              GAsyncReadyCallback  callback,
 120                              gpointer             user_data)
 121 {
 122   GAsyncInitableIface *iface;
 123
 124   g_return_if_fail (G_IS_ASYNC_INITABLE (initable));
 125
 126   iface = G_ASYNC_INITABLE_GET_IFACE (initable);
 127
 128   (* iface->init_async) (initable, io_priority, cancellable, callback, user_data);
 129 }
 130
 131 /**
 132  * g_async_initable_init_finish:
 133  * @initable: a #GAsyncInitable.
 134  * @res: a #GAsyncResult.
 135  * @error: a #GError location to store the error occuring, or %NULL to
 136  * ignore.
 137  *
 138  * Finishes asynchronous initialization and returns the result.
 139  * See g_async_initable_init_async().
 140  *
 141  * Returns: %TRUE if successful. If an error has occurred, this function
 142  * will return %FALSE and set @error appropriately if present.
 143  *
 144  * Since: 2.22
 145  */
 146 gboolean
 147 g_async_initable_init_finish (GAsyncInitable  *initable,
 148                               GAsyncResult    *res,
 149                               GError         **error)
 150 {
 151   GAsyncInitableIface *iface;
 152
 153   g_return_val_if_fail (G_IS_ASYNC_INITABLE (initable), FALSE);
 154   g_return_val_if_fail (G_IS_ASYNC_RESULT (res), FALSE);
 155
 156   if (G_IS_SIMPLE_ASYNC_RESULT (res))
 157     {
 158       GSimpleAsyncResult *simple = G_SIMPLE_ASYNC_RESULT (res);
 159       if (g_simple_async_result_propagate_error (simple, error))
 160         return FALSE;
 161     }
 162
 163   iface = G_ASYNC_INITABLE_GET_IFACE (initable);
 164
 165   return (* iface->init_finish) (initable, res, error);
 166 }
 167
 168 static void
 169 async_init_thread (GSimpleAsyncResult *res,
 170                    GObject            *object,
 171                    GCancellable       *cancellable)
 172 {
 173   GError *error = NULL;
 174
 175   if (!g_initable_init (G_INITABLE (object), cancellable, &error))
 176     {
 177       g_simple_async_result_set_from_error (res, error);
 178       g_error_free (error);
 179     }
 180 }
 181
 182 static void
 183 g_async_initable_real_init_async (GAsyncInitable      *initable,
 184                                   int                  io_priority,
 185                                   GCancellable        *cancellable,
 186                                   GAsyncReadyCallback  callback,
 187                                   gpointer             user_data)
 188 {
 189   GSimpleAsyncResult *res;
 190
 191   g_return_if_fail (G_IS_INITABLE (initable));
 192
 193   res = g_simple_async_result_new (G_OBJECT (initable), callback, user_data,
 194                                    g_async_initable_real_init_async);
 195   g_simple_async_result_run_in_thread (res, async_init_thread,
 196                                        io_priority, cancellable);
 197   g_object_unref (res);
 198 }
 199
 200 static gboolean
 201 g_async_initable_real_init_finish (GAsyncInitable  *initable,
 202                                    GAsyncResult    *res,
 203                                    GError         **error)
 204 {
 205   return TRUE; /* Errors handled by base impl */
 206 }
 207
 208 /**
 209  * g_async_initable_new_async:
 210  * @object_type: a #GType supporting #GAsyncInitable.
 211  * @io_priority: the <link linkend="io-priority">I/O priority</link>
 212  *     of the operation.
 213  * @cancellable: optional #GCancellable object, %NULL to ignore.
 214  * @callback: a #GAsyncReadyCallback to call when the initialization is
 215  *     finished
 216  * @user_data: the data to pass to callback function
 217  * @first_property_name: the name of the first property, or %NULL if no
 218  *     properties
 219  * @...:  the value of the first property, followed by other property
 220  *    value pairs, and ended by %NULL.
 221  *
 222  * Helper function for constructing #GAsyncInitiable object. This is
 223  * similar to g_object_new() but also initializes the object asynchronously.
 224  *
 225  * When the initialization is finished, @callback will be called. You can
 226  * then call g_async_initable_new_finish() to get the new object and check
 227  * for any errors.
 228  *
 229  * Since: 2.22
 230  */
 231 void
 232 g_async_initable_new_async (GType                object_type,
 233                             int                  io_priority,
 234                             GCancellable        *cancellable,
 235                             GAsyncReadyCallback  callback,
 236                             gpointer             user_data,
 237                             const gchar         *first_property_name,
 238                             ...)
 239 {
 240   va_list var_args;
 241
 242   va_start (var_args, first_property_name);
 243   g_async_initable_new_valist_async (object_type,
 244                                      first_property_name, var_args,
 245                                      io_priority, cancellable,
 246                                      callback, user_data);
 247   va_end (var_args);
 248 }
 249
 250 /**
 251  * g_async_initable_newv_async:
 252  * @object_type: a #GType supporting #GAsyncInitable.
 253  * @n_parameters: the number of parameters in @parameters
 254  * @parameters: the parameters to use to construct the object
 255  * @io_priority: the <link linkend="io-priority">I/O priority</link>
 256  *     of the operation.
 257  * @cancellable: optional #GCancellable object, %NULL to ignore.
 258  * @callback: a #GAsyncReadyCallback to call when the initialization is
 259  *     finished
 260  * @user_data: the data to pass to callback function
 261  *
 262  * Helper function for constructing #GAsyncInitiable object. This is
 263  * similar to g_object_newv() but also initializes the object asynchronously.
 264  *
 265  * When the initialization is finished, @callback will be called. You can
 266  * then call g_async_initable_new_finish() to get the new object and check
 267  * for any errors.
 268  *
 269  * Since: 2.22
 270  */
 271 void
 272 g_async_initable_newv_async (GType                object_type,
 273                              guint                n_parameters,
 274                              GParameter          *parameters,
 275                              int                  io_priority,
 276                              GCancellable        *cancellable,
 277                              GAsyncReadyCallback  callback,
 278                              gpointer             user_data)
 279 {
 280   GObject *obj;
 281
 282   g_return_if_fail (G_TYPE_IS_ASYNC_INITABLE (object_type));
 283
 284   obj = g_object_newv (object_type, n_parameters, parameters);
 285
 286   g_async_initable_init_async (G_ASYNC_INITABLE (obj),
 287                                io_priority, cancellable,
 288                                callback, user_data);
 289 }
 290
 291 /**
 292  * g_async_initable_new_valist_async:
 293  * @object_type: a #GType supporting #GAsyncInitable.
 294  * @first_property_name: the name of the first property, followed by
 295  * the value, and other property value pairs, and ended by %NULL.
 296  * @var_args: The var args list generated from @first_property_name.
 297  * @io_priority: the <link linkend="io-priority">I/O priority</link>
 298  *     of the operation.
 299  * @cancellable: optional #GCancellable object, %NULL to ignore.
 300  * @callback: a #GAsyncReadyCallback to call when the initialization is
 301  *     finished
 302  * @user_data: the data to pass to callback function
 303  *
 304  * Helper function for constructing #GAsyncInitiable object. This is
 305  * similar to g_object_new_valist() but also initializes the object
 306  * asynchronously.
 307  *
 308  * When the initialization is finished, @callback will be called. You can
 309  * then call g_async_initable_new_finish() to get the new object and check
 310  * for any errors.
 311  *
 312  * Since: 2.22
 313  */
 314 void
 315 g_async_initable_new_valist_async (GType                object_type,
 316                                    const gchar         *first_property_name,
 317                                    va_list              var_args,
 318                                    int                  io_priority,
 319                                    GCancellable        *cancellable,
 320                                    GAsyncReadyCallback  callback,
 321                                    gpointer             user_data)
 322 {
 323   GObject *obj;
 324
 325   g_return_if_fail (G_TYPE_IS_ASYNC_INITABLE (object_type));
 326
 327   obj = g_object_new_valist (object_type,
 328                              first_property_name,
 329                              var_args);
 330
 331   g_async_initable_init_async (G_ASYNC_INITABLE (obj),
 332                                io_priority, cancellable,
 333                                callback, user_data);
 334   g_object_unref (obj); /* Passed ownership to async call */
 335 }
 336
 337 /**
 338  * g_async_initable_new_finish:
 339  * @initable: the #GAsyncInitable from the callback
 340  * @res: the #GAsyncResult.from the callback
 341  * @error: a #GError location to store the error occuring, or %NULL to
 342  *     ignore.
 343  *
 344  * Finishes the async construction for the various g_async_initable_new calls,
 345  * returning the created object or %NULL on error.
 346  *
 347  * Returns: a newly created #GObject, or %NULL on error. Free with
 348  *     g_object_unref().
 349  *
 350  * Since: 2.22
 351  */
 352 GObject *
 353 g_async_initable_new_finish (GAsyncInitable  *initable,
 354                              GAsyncResult    *res,
 355                              GError         **error)
 356 {
 357   if (g_async_initable_init_finish (initable, res, error))
 358     return g_object_ref (initable);
 359   else
 360     return NULL;
 361 }
 362
 363 #define __G_ASYNC_INITABLE_C__
 364 #include "gioaliasdef.c"