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1 office 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, see <http://www.gnu.org/licenses/>.
17 *
18 * Author: Alexander Larsson <alexl@redhat.com>
19 */
20  
21 #include "config.h"
22 #include "gasyncinitable.h"
23 #include "gasyncresult.h"
24 #include "gsimpleasyncresult.h"
25 #include "gtask.h"
26 #include "glibintl.h"
27  
28  
29 /**
30 * SECTION:gasyncinitable
31 * @short_description: Asynchronously failable object initialization interface
32 * @include: gio/gio.h
33 * @see_also: #GInitable
34 *
35 * This is the asynchronous version of #GInitable; it behaves the same
36 * in all ways except that initialization is asynchronous. For more details
37 * see the descriptions on #GInitable.
38 *
39 * A class may implement both the #GInitable and #GAsyncInitable interfaces.
40 *
41 * Users of objects implementing this are not intended to use the interface
42 * method directly; instead it will be used automatically in various ways.
43 * For C applications you generally just call g_async_initable_new_async()
44 * directly, or indirectly via a foo_thing_new_async() wrapper. This will call
45 * g_async_initable_init_async() under the cover, calling back with %NULL and
46 * a set %GError on failure.
47 *
48 * A typical implementation might look something like this:
49 *
50 * |[<!-- language="C" -->
51 * enum {
52 * NOT_INITIALIZED,
53 * INITIALIZING,
54 * INITIALIZED
55 * };
56 *
57 * static void
58 * _foo_ready_cb (Foo *self)
59 * {
60 * GList *l;
61 *
62 * self->priv->state = INITIALIZED;
63 *
64 * for (l = self->priv->init_results; l != NULL; l = l->next)
65 * {
66 * GTask *task = l->data;
67 *
68 * if (self->priv->success)
69 * g_task_return_boolean (task, TRUE);
70 * else
71 * g_task_return_new_error (task, ...);
72 * g_object_unref (task);
73 * }
74 *
75 * g_list_free (self->priv->init_results);
76 * self->priv->init_results = NULL;
77 * }
78 *
79 * static void
80 * foo_init_async (GAsyncInitable *initable,
81 * int io_priority,
82 * GCancellable *cancellable,
83 * GAsyncReadyCallback callback,
84 * gpointer user_data)
85 * {
86 * Foo *self = FOO (initable);
87 * GTask *task;
88 *
89 * task = g_task_new (initable, cancellable, callback, user_data);
90 *
91 * switch (self->priv->state)
92 * {
93 * case NOT_INITIALIZED:
94 * _foo_get_ready (self);
95 * self->priv->init_results = g_list_append (self->priv->init_results,
96 * task);
97 * self->priv->state = INITIALIZING;
98 * break;
99 * case INITIALIZING:
100 * self->priv->init_results = g_list_append (self->priv->init_results,
101 * task);
102 * break;
103 * case INITIALIZED:
104 * if (!self->priv->success)
105 * g_task_return_new_error (task, ...);
106 * else
107 * g_task_return_boolean (task, TRUE);
108 * g_object_unref (task);
109 * break;
110 * }
111 * }
112 *
113 * static gboolean
114 * foo_init_finish (GAsyncInitable *initable,
115 * GAsyncResult *result,
116 * GError **error)
117 * {
118 * g_return_val_if_fail (g_task_is_valid (result, initable), FALSE);
119 *
120 * return g_task_propagate_boolean (G_TASK (result), error);
121 * }
122 *
123 * static void
124 * foo_async_initable_iface_init (gpointer g_iface,
125 * gpointer data)
126 * {
127 * GAsyncInitableIface *iface = g_iface;
128 *
129 * iface->init_async = foo_init_async;
130 * iface->init_finish = foo_init_finish;
131 * }
132 * ]|
133 */
134  
135 static void g_async_initable_real_init_async (GAsyncInitable *initable,
136 int io_priority,
137 GCancellable *cancellable,
138 GAsyncReadyCallback callback,
139 gpointer user_data);
140 static gboolean g_async_initable_real_init_finish (GAsyncInitable *initable,
141 GAsyncResult *res,
142 GError **error);
143  
144  
145 typedef GAsyncInitableIface GAsyncInitableInterface;
146 G_DEFINE_INTERFACE (GAsyncInitable, g_async_initable, G_TYPE_OBJECT)
147  
148  
149 static void
150 g_async_initable_default_init (GAsyncInitableInterface *iface)
151 {
152 iface->init_async = g_async_initable_real_init_async;
153 iface->init_finish = g_async_initable_real_init_finish;
154 }
155  
156 /**
157 * g_async_initable_init_async:
158 * @initable: a #GAsyncInitable.
159 * @io_priority: the [I/O priority][io-priority] of the operation
160 * @cancellable: optional #GCancellable object, %NULL to ignore.
161 * @callback: a #GAsyncReadyCallback to call when the request is satisfied
162 * @user_data: the data to pass to callback function
163 *
164 * Starts asynchronous initialization of the object implementing the
165 * interface. This must be done before any real use of the object after
166 * initial construction. If the object also implements #GInitable you can
167 * optionally call g_initable_init() instead.
168 *
169 * When the initialization is finished, @callback will be called. You can
170 * then call g_async_initable_init_finish() to get the result of the
171 * initialization.
172 *
173 * Implementations may also support cancellation. If @cancellable is not
174 * %NULL, then initialization can be cancelled by triggering the cancellable
175 * object from another thread. If the operation was cancelled, the error
176 * %G_IO_ERROR_CANCELLED will be returned. If @cancellable is not %NULL, and
177 * the object doesn't support cancellable initialization, the error
178 * %G_IO_ERROR_NOT_SUPPORTED will be returned.
179 *
180 * As with #GInitable, if the object is not initialized, or initialization
181 * returns with an error, then all operations on the object except
182 * g_object_ref() and g_object_unref() are considered to be invalid, and
183 * have undefined behaviour. They will often fail with g_critical() or
184 * g_warning(), but this must not be relied on.
185 *
186 * Implementations of this method must be idempotent: i.e. multiple calls
187 * to this function with the same argument should return the same results.
188 * Only the first call initializes the object; further calls return the result
189 * of the first call. This is so that it's safe to implement the singleton
190 * pattern in the GObject constructor function.
191 *
192 * For classes that also support the #GInitable interface, the default
193 * implementation of this method will run the g_initable_init() function
194 * in a thread, so if you want to support asynchronous initialization via
195 * threads, just implement the #GAsyncInitable interface without overriding
196 * any interface methods.
197 *
198 * Since: 2.22
199 */
200 void
201 g_async_initable_init_async (GAsyncInitable *initable,
202 int io_priority,
203 GCancellable *cancellable,
204 GAsyncReadyCallback callback,
205 gpointer user_data)
206 {
207 GAsyncInitableIface *iface;
208  
209 g_return_if_fail (G_IS_ASYNC_INITABLE (initable));
210  
211 iface = G_ASYNC_INITABLE_GET_IFACE (initable);
212  
213 (* iface->init_async) (initable, io_priority, cancellable, callback, user_data);
214 }
215  
216 /**
217 * g_async_initable_init_finish:
218 * @initable: a #GAsyncInitable.
219 * @res: a #GAsyncResult.
220 * @error: a #GError location to store the error occurring, or %NULL to
221 * ignore.
222 *
223 * Finishes asynchronous initialization and returns the result.
224 * See g_async_initable_init_async().
225 *
226 * Returns: %TRUE if successful. If an error has occurred, this function
227 * will return %FALSE and set @error appropriately if present.
228 *
229 * Since: 2.22
230 */
231 gboolean
232 g_async_initable_init_finish (GAsyncInitable *initable,
233 GAsyncResult *res,
234 GError **error)
235 {
236 GAsyncInitableIface *iface;
237  
238 g_return_val_if_fail (G_IS_ASYNC_INITABLE (initable), FALSE);
239 g_return_val_if_fail (G_IS_ASYNC_RESULT (res), FALSE);
240  
241 if (g_async_result_legacy_propagate_error (res, error))
242 return FALSE;
243  
244 iface = G_ASYNC_INITABLE_GET_IFACE (initable);
245  
246 return (* iface->init_finish) (initable, res, error);
247 }
248  
249 static void
250 async_init_thread (GTask *task,
251 gpointer source_object,
252 gpointer task_data,
253 GCancellable *cancellable)
254 {
255 GError *error = NULL;
256  
257 if (g_initable_init (G_INITABLE (source_object), cancellable, &error))
258 g_task_return_boolean (task, TRUE);
259 else
260 g_task_return_error (task, error);
261 }
262  
263 static void
264 g_async_initable_real_init_async (GAsyncInitable *initable,
265 int io_priority,
266 GCancellable *cancellable,
267 GAsyncReadyCallback callback,
268 gpointer user_data)
269 {
270 GTask *task;
271  
272 g_return_if_fail (G_IS_INITABLE (initable));
273  
274 task = g_task_new (initable, cancellable, callback, user_data);
275 g_task_set_priority (task, io_priority);
276 g_task_run_in_thread (task, async_init_thread);
277 g_object_unref (task);
278 }
279  
280 static gboolean
281 g_async_initable_real_init_finish (GAsyncInitable *initable,
282 GAsyncResult *res,
283 GError **error)
284 {
285 /* For backward compatibility we have to process GSimpleAsyncResults
286 * even though g_async_initable_real_init_async doesn't generate
287 * them any more.
288 */
289 G_GNUC_BEGIN_IGNORE_DEPRECATIONS
290 if (G_IS_SIMPLE_ASYNC_RESULT (res))
291 {
292 GSimpleAsyncResult *simple = G_SIMPLE_ASYNC_RESULT (res);
293 if (g_simple_async_result_propagate_error (simple, error))
294 return FALSE;
295 else
296 return TRUE;
297 }
298 G_GNUC_END_IGNORE_DEPRECATIONS
299  
300 g_return_val_if_fail (g_task_is_valid (res, initable), FALSE);
301  
302 return g_task_propagate_boolean (G_TASK (res), error);
303 }
304  
305 /**
306 * g_async_initable_new_async:
307 * @object_type: a #GType supporting #GAsyncInitable.
308 * @io_priority: the [I/O priority][io-priority] of the operation
309 * @cancellable: optional #GCancellable object, %NULL to ignore.
310 * @callback: a #GAsyncReadyCallback to call when the initialization is
311 * finished
312 * @user_data: the data to pass to callback function
313 * @first_property_name: (allow-none): the name of the first property, or %NULL if no
314 * properties
315 * @...: the value of the first property, followed by other property
316 * value pairs, and ended by %NULL.
317 *
318 * Helper function for constructing #GAsyncInitable object. This is
319 * similar to g_object_new() but also initializes the object asynchronously.
320 *
321 * When the initialization is finished, @callback will be called. You can
322 * then call g_async_initable_new_finish() to get the new object and check
323 * for any errors.
324 *
325 * Since: 2.22
326 */
327 void
328 g_async_initable_new_async (GType object_type,
329 int io_priority,
330 GCancellable *cancellable,
331 GAsyncReadyCallback callback,
332 gpointer user_data,
333 const gchar *first_property_name,
334 ...)
335 {
336 va_list var_args;
337  
338 va_start (var_args, first_property_name);
339 g_async_initable_new_valist_async (object_type,
340 first_property_name, var_args,
341 io_priority, cancellable,
342 callback, user_data);
343 va_end (var_args);
344 }
345  
346 /**
347 * g_async_initable_newv_async:
348 * @object_type: a #GType supporting #GAsyncInitable.
349 * @n_parameters: the number of parameters in @parameters
350 * @parameters: the parameters to use to construct the object
351 * @io_priority: the [I/O priority][io-priority] of the operation
352 * @cancellable: optional #GCancellable object, %NULL to ignore.
353 * @callback: a #GAsyncReadyCallback to call when the initialization is
354 * finished
355 * @user_data: the data to pass to callback function
356 *
357 * Helper function for constructing #GAsyncInitable object. This is
358 * similar to g_object_newv() but also initializes the object asynchronously.
359 *
360 * When the initialization is finished, @callback will be called. You can
361 * then call g_async_initable_new_finish() to get the new object and check
362 * for any errors.
363 *
364 * Since: 2.22
365 */
366 void
367 g_async_initable_newv_async (GType object_type,
368 guint n_parameters,
369 GParameter *parameters,
370 int io_priority,
371 GCancellable *cancellable,
372 GAsyncReadyCallback callback,
373 gpointer user_data)
374 {
375 GObject *obj;
376  
377 g_return_if_fail (G_TYPE_IS_ASYNC_INITABLE (object_type));
378  
379 obj = g_object_newv (object_type, n_parameters, parameters);
380  
381 g_async_initable_init_async (G_ASYNC_INITABLE (obj),
382 io_priority, cancellable,
383 callback, user_data);
384 g_object_unref (obj); /* Passed ownership to async call */
385 }
386  
387 /**
388 * g_async_initable_new_valist_async:
389 * @object_type: a #GType supporting #GAsyncInitable.
390 * @first_property_name: the name of the first property, followed by
391 * the value, and other property value pairs, and ended by %NULL.
392 * @var_args: The var args list generated from @first_property_name.
393 * @io_priority: the [I/O priority][io-priority] of the operation
394 * @cancellable: optional #GCancellable object, %NULL to ignore.
395 * @callback: a #GAsyncReadyCallback to call when the initialization is
396 * finished
397 * @user_data: the data to pass to callback function
398 *
399 * Helper function for constructing #GAsyncInitable object. This is
400 * similar to g_object_new_valist() but also initializes the object
401 * asynchronously.
402 *
403 * When the initialization is finished, @callback will be called. You can
404 * then call g_async_initable_new_finish() to get the new object and check
405 * for any errors.
406 *
407 * Since: 2.22
408 */
409 void
410 g_async_initable_new_valist_async (GType object_type,
411 const gchar *first_property_name,
412 va_list var_args,
413 int io_priority,
414 GCancellable *cancellable,
415 GAsyncReadyCallback callback,
416 gpointer user_data)
417 {
418 GObject *obj;
419  
420 g_return_if_fail (G_TYPE_IS_ASYNC_INITABLE (object_type));
421  
422 obj = g_object_new_valist (object_type,
423 first_property_name,
424 var_args);
425  
426 g_async_initable_init_async (G_ASYNC_INITABLE (obj),
427 io_priority, cancellable,
428 callback, user_data);
429 g_object_unref (obj); /* Passed ownership to async call */
430 }
431  
432 /**
433 * g_async_initable_new_finish:
434 * @initable: the #GAsyncInitable from the callback
435 * @res: the #GAsyncResult from the callback
436 * @error: return location for errors, or %NULL to ignore
437 *
438 * Finishes the async construction for the various g_async_initable_new
439 * calls, returning the created object or %NULL on error.
440 *
441 * Returns: (type GObject.Object) (transfer full): a newly created #GObject,
442 * or %NULL on error. Free with g_object_unref().
443 *
444 * Since: 2.22
445 */
446 GObject *
447 g_async_initable_new_finish (GAsyncInitable *initable,
448 GAsyncResult *res,
449 GError **error)
450 {
451 if (g_async_initable_init_finish (initable, res, error))
452 return g_object_ref (initable);
453 else
454 return NULL;
455 }