1 /* GIO - GLib Input, Output and Streaming Library
2 *
3 * Copyright (C) 2009 Red Hat, Inc.
4 *
5 * SPDX-License-Identifier: LGPL-2.1-or-later
6 *
7 * This library is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Lesser General Public
9 * License as published by the Free Software Foundation; either
10 * version 2.1 of the License, or (at your option) any later version.
11 *
12 * This library is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * Lesser General Public License for more details.
16 *
17 * You should have received a copy of the GNU Lesser General
18 * Public License along with this library; if not, see <http://www.gnu.org/licenses/>.
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 "gtask.h"
28 #include "glibintl.h"
29
30
31 /**
32 * GAsyncInitable:
33 *
34 * `GAsyncInitable` is an interface for asynchronously initializable objects.
35 *
36 * This is the asynchronous version of [iface@Gio.Initable]; it behaves the same
37 * in all ways except that initialization is asynchronous. For more details
38 * see the descriptions on `GInitable`.
39 *
40 * A class may implement both the `GInitable` and `GAsyncInitable` interfaces.
41 *
42 * Users of objects implementing this are not intended to use the interface
43 * method directly; instead it will be used automatically in various ways.
44 * For C applications you generally just call [func@Gio.AsyncInitable.new_async]
45 * directly, or indirectly via a foo_thing_new_async() wrapper. This will call
46 * [method@Gio.AsyncInitable.init_async] under the covers, calling back with `NULL`
47 * and a set `GError` on failure.
48 *
49 * A typical implementation might look something like this:
50 *
51 * ```c
52 * enum {
53 * NOT_INITIALIZED,
54 * INITIALIZING,
55 * INITIALIZED
56 * };
57 *
58 * static void
59 * _foo_ready_cb (Foo *self)
60 * {
61 * GList *l;
62 *
63 * self->priv->state = INITIALIZED;
64 *
65 * for (l = self->priv->init_results; l != NULL; l = l->next)
66 * {
67 * GTask *task = l->data;
68 *
69 * if (self->priv->success)
70 * g_task_return_boolean (task, TRUE);
71 * else
72 * g_task_return_new_error (task, ...);
73 * g_object_unref (task);
74 * }
75 *
76 * g_list_free (self->priv->init_results);
77 * self->priv->init_results = NULL;
78 * }
79 *
80 * static void
81 * foo_init_async (GAsyncInitable *initable,
82 * int io_priority,
83 * GCancellable *cancellable,
84 * GAsyncReadyCallback callback,
85 * gpointer user_data)
86 * {
87 * Foo *self = FOO (initable);
88 * GTask *task;
89 *
90 * task = g_task_new (initable, cancellable, callback, user_data);
91 * g_task_set_name (task, G_STRFUNC);
92 *
93 * switch (self->priv->state)
94 * {
95 * case NOT_INITIALIZED:
96 * _foo_get_ready (self);
97 * self->priv->init_results = g_list_append (self->priv->init_results,
98 * task);
99 * self->priv->state = INITIALIZING;
100 * break;
101 * case INITIALIZING:
102 * self->priv->init_results = g_list_append (self->priv->init_results,
103 * task);
104 * break;
105 * case INITIALIZED:
106 * if (!self->priv->success)
107 * g_task_return_new_error (task, ...);
108 * else
109 * g_task_return_boolean (task, TRUE);
110 * g_object_unref (task);
111 * break;
112 * }
113 * }
114 *
115 * static gboolean
116 * foo_init_finish (GAsyncInitable *initable,
117 * GAsyncResult *result,
118 * GError **error)
119 * {
120 * g_return_val_if_fail (g_task_is_valid (result, initable), FALSE);
121 *
122 * return g_task_propagate_boolean (G_TASK (result), error);
123 * }
124 *
125 * static void
126 * foo_async_initable_iface_init (gpointer g_iface,
127 * gpointer data)
128 * {
129 * GAsyncInitableIface *iface = g_iface;
130 *
131 * iface->init_async = foo_init_async;
132 * iface->init_finish = foo_init_finish;
133 * }
134 * ```
135 *
136 * Since: 2.22
137 */
138
139 static void g_async_initable_real_init_async (GAsyncInitable *initable,
140 int io_priority,
141 GCancellable *cancellable,
142 GAsyncReadyCallback callback,
143 gpointer user_data);
144 static gboolean g_async_initable_real_init_finish (GAsyncInitable *initable,
145 GAsyncResult *res,
146 GError **error);
147
148
149 typedef GAsyncInitableIface GAsyncInitableInterface;
150 G_DEFINE_INTERFACE (GAsyncInitable, g_async_initable, G_TYPE_OBJECT)
151
152
153 static void
154 g_async_initable_default_init (GAsyncInitableInterface *iface)
155 {
156 iface->init_async = g_async_initable_real_init_async;
157 iface->init_finish = g_async_initable_real_init_finish;
158 }
159
160 /**
161 * g_async_initable_init_async:
162 * @initable: a #GAsyncInitable.
163 * @io_priority: the [I/O priority][io-priority] of the operation
164 * @cancellable: optional #GCancellable object, %NULL to ignore.
165 * @callback: a #GAsyncReadyCallback to call when the request is satisfied
166 * @user_data: the data to pass to callback function
167 *
168 * Starts asynchronous initialization of the object implementing the
169 * interface. This must be done before any real use of the object after
170 * initial construction. If the object also implements #GInitable you can
171 * optionally call g_initable_init() instead.
172 *
173 * This method is intended for language bindings. If writing in C,
174 * g_async_initable_new_async() should typically be used instead.
175 *
176 * When the initialization is finished, @callback will be called. You can
177 * then call g_async_initable_init_finish() to get the result of the
178 * initialization.
179 *
180 * Implementations may also support cancellation. If @cancellable is not
181 * %NULL, then initialization can be cancelled by triggering the cancellable
182 * object from another thread. If the operation was cancelled, the error
183 * %G_IO_ERROR_CANCELLED will be returned. If @cancellable is not %NULL, and
184 * the object doesn't support cancellable initialization, the error
185 * %G_IO_ERROR_NOT_SUPPORTED will be returned.
186 *
187 * As with #GInitable, if the object is not initialized, or initialization
188 * returns with an error, then all operations on the object except
189 * g_object_ref() and g_object_unref() are considered to be invalid, and
190 * have undefined behaviour. They will often fail with g_critical() or
191 * g_warning(), but this must not be relied on.
192 *
193 * Callers should not assume that a class which implements #GAsyncInitable can
194 * be initialized multiple times; for more information, see g_initable_init().
195 * If a class explicitly supports being initialized multiple times,
196 * implementation requires yielding all subsequent calls to init_async() on the
197 * results of the first call.
198 *
199 * For classes that also support the #GInitable interface, the default
200 * implementation of this method will run the g_initable_init() function
201 * in a thread, so if you want to support asynchronous initialization via
202 * threads, just implement the #GAsyncInitable interface without overriding
203 * any interface methods.
204 *
205 * Since: 2.22
206 */
207 void
208 g_async_initable_init_async (GAsyncInitable *initable,
209 int io_priority,
210 GCancellable *cancellable,
211 GAsyncReadyCallback callback,
212 gpointer user_data)
213 {
214 GAsyncInitableIface *iface;
215
216 g_return_if_fail (G_IS_ASYNC_INITABLE (initable));
217
218 iface = G_ASYNC_INITABLE_GET_IFACE (initable);
219
220 (* iface->init_async) (initable, io_priority, cancellable, callback, user_data);
221 }
222
223 /**
224 * g_async_initable_init_finish:
225 * @initable: a #GAsyncInitable.
226 * @res: a #GAsyncResult.
227 * @error: a #GError location to store the error occurring, or %NULL to
228 * ignore.
229 *
230 * Finishes asynchronous initialization and returns the result.
231 * See g_async_initable_init_async().
232 *
233 * Returns: %TRUE if successful. If an error has occurred, this function
234 * will return %FALSE and set @error appropriately if present.
235 *
236 * Since: 2.22
237 */
238 gboolean
239 g_async_initable_init_finish (GAsyncInitable *initable,
240 GAsyncResult *res,
241 GError **error)
242 {
243 GAsyncInitableIface *iface;
244
245 g_return_val_if_fail (G_IS_ASYNC_INITABLE (initable), FALSE);
246 g_return_val_if_fail (G_IS_ASYNC_RESULT (res), FALSE);
247
248 if (g_async_result_legacy_propagate_error (res, error))
249 return FALSE;
250
251 iface = G_ASYNC_INITABLE_GET_IFACE (initable);
252
253 return (* iface->init_finish) (initable, res, error);
254 }
255
256 static void
257 async_init_thread (GTask *task,
258 gpointer source_object,
259 gpointer task_data,
260 GCancellable *cancellable)
261 {
262 GError *error = NULL;
263
264 if (g_initable_init (G_INITABLE (source_object), cancellable, &error))
265 g_task_return_boolean (task, TRUE);
266 else
267 g_task_return_error (task, error);
268 }
269
270 static void
271 g_async_initable_real_init_async (GAsyncInitable *initable,
272 int io_priority,
273 GCancellable *cancellable,
274 GAsyncReadyCallback callback,
275 gpointer user_data)
276 {
277 GTask *task;
278
279 g_return_if_fail (G_IS_INITABLE (initable));
280
281 task = g_task_new (initable, cancellable, callback, user_data);
282 g_task_set_source_tag (task, g_async_initable_real_init_async);
283 g_task_set_priority (task, io_priority);
284 g_task_run_in_thread (task, async_init_thread);
285 g_object_unref (task);
286 }
287
288 static gboolean
289 g_async_initable_real_init_finish (GAsyncInitable *initable,
290 GAsyncResult *res,
291 GError **error)
292 {
293 /* For backward compatibility we have to process GSimpleAsyncResults
294 * even though g_async_initable_real_init_async doesn't generate
295 * them any more.
296 */
297 G_GNUC_BEGIN_IGNORE_DEPRECATIONS
298 if (G_IS_SIMPLE_ASYNC_RESULT (res))
299 {
300 GSimpleAsyncResult *simple = G_SIMPLE_ASYNC_RESULT (res);
301 if (g_simple_async_result_propagate_error (simple, error))
302 return FALSE;
303 else
304 return TRUE;
305 }
306 G_GNUC_END_IGNORE_DEPRECATIONS
307
308 g_return_val_if_fail (g_task_is_valid (res, initable), FALSE);
309
310 return g_task_propagate_boolean (G_TASK (res), error);
311 }
312
313 /**
314 * g_async_initable_new_async:
315 * @object_type: a #GType supporting #GAsyncInitable.
316 * @io_priority: the [I/O priority][io-priority] of the operation
317 * @cancellable: optional #GCancellable object, %NULL to ignore.
318 * @callback: a #GAsyncReadyCallback to call when the initialization is
319 * finished
320 * @user_data: the data to pass to callback function
321 * @first_property_name: (nullable): the name of the first property, or %NULL if no
322 * properties
323 * @...: the value of the first property, followed by other property
324 * value pairs, and ended by %NULL.
325 *
326 * Helper function for constructing #GAsyncInitable object. This is
327 * similar to g_object_new() but also initializes the object asynchronously.
328 *
329 * When the initialization is finished, @callback will be called. You can
330 * then call g_async_initable_new_finish() to get the new object and check
331 * for any errors.
332 *
333 * Since: 2.22
334 */
335 void
336 g_async_initable_new_async (GType object_type,
337 int io_priority,
338 GCancellable *cancellable,
339 GAsyncReadyCallback callback,
340 gpointer user_data,
341 const gchar *first_property_name,
342 ...)
343 {
344 va_list var_args;
345
346 va_start (var_args, first_property_name);
347 g_async_initable_new_valist_async (object_type,
348 first_property_name, var_args,
349 io_priority, cancellable,
350 callback, user_data);
351 va_end (var_args);
352 }
353
354 /**
355 * g_async_initable_newv_async:
356 * @object_type: a #GType supporting #GAsyncInitable.
357 * @n_parameters: the number of parameters in @parameters
358 * @parameters: the parameters to use to construct the object
359 * @io_priority: the [I/O priority][io-priority] of the operation
360 * @cancellable: optional #GCancellable object, %NULL to ignore.
361 * @callback: a #GAsyncReadyCallback to call when the initialization is
362 * finished
363 * @user_data: the data to pass to callback function
364 *
365 * Helper function for constructing #GAsyncInitable object. This is
366 * similar to g_object_newv() but also initializes the object asynchronously.
367 *
368 * When the initialization is finished, @callback will be called. You can
369 * then call g_async_initable_new_finish() to get the new object and check
370 * for any errors.
371 *
372 * Since: 2.22
373 * Deprecated: 2.54: Use g_object_new_with_properties() and
374 * g_async_initable_init_async() instead. See #GParameter for more information.
375 */
376 G_GNUC_BEGIN_IGNORE_DEPRECATIONS
377 void
378 g_async_initable_newv_async (GType object_type,
379 guint n_parameters,
380 GParameter *parameters,
381 int io_priority,
382 GCancellable *cancellable,
383 GAsyncReadyCallback callback,
384 gpointer user_data)
385 {
386 GObject *obj;
387
388 g_return_if_fail (G_TYPE_IS_ASYNC_INITABLE (object_type));
389
390 obj = g_object_newv (object_type, n_parameters, parameters);
391
392 g_async_initable_init_async (G_ASYNC_INITABLE (obj),
393 io_priority, cancellable,
394 callback, user_data);
395 g_object_unref (obj); /* Passed ownership to async call */
396 }
397 G_GNUC_END_IGNORE_DEPRECATIONS
398
399 /**
400 * g_async_initable_new_valist_async:
401 * @object_type: a #GType supporting #GAsyncInitable.
402 * @first_property_name: the name of the first property, followed by
403 * the value, and other property value pairs, and ended by %NULL.
404 * @var_args: The var args list generated from @first_property_name.
405 * @io_priority: the [I/O priority][io-priority] of the operation
406 * @cancellable: optional #GCancellable object, %NULL to ignore.
407 * @callback: a #GAsyncReadyCallback to call when the initialization is
408 * finished
409 * @user_data: the data to pass to callback function
410 *
411 * Helper function for constructing #GAsyncInitable object. This is
412 * similar to g_object_new_valist() but also initializes the object
413 * asynchronously.
414 *
415 * When the initialization is finished, @callback will be called. You can
416 * then call g_async_initable_new_finish() to get the new object and check
417 * for any errors.
418 *
419 * Since: 2.22
420 */
421 void
422 g_async_initable_new_valist_async (GType object_type,
423 const gchar *first_property_name,
424 va_list var_args,
425 int io_priority,
426 GCancellable *cancellable,
427 GAsyncReadyCallback callback,
428 gpointer user_data)
429 {
430 GObject *obj;
431
432 g_return_if_fail (G_TYPE_IS_ASYNC_INITABLE (object_type));
433
434 obj = g_object_new_valist (object_type,
435 first_property_name,
436 var_args);
437
438 g_async_initable_init_async (G_ASYNC_INITABLE (obj),
439 io_priority, cancellable,
440 callback, user_data);
441 g_object_unref (obj); /* Passed ownership to async call */
442 }
443
444 /**
445 * g_async_initable_new_finish:
446 * @initable: the #GAsyncInitable from the callback
447 * @res: the #GAsyncResult from the callback
448 * @error: return location for errors, or %NULL to ignore
449 *
450 * Finishes the async construction for the various g_async_initable_new
451 * calls, returning the created object or %NULL on error.
452 *
453 * Returns: (type GObject.Object) (transfer full): a newly created #GObject,
454 * or %NULL on error. Free with g_object_unref().
455 *
456 * Since: 2.22
457 */
458 GObject *
459 g_async_initable_new_finish (GAsyncInitable *initable,
460 GAsyncResult *res,
461 GError **error)
462 {
463 if (g_async_initable_init_finish (initable, res, error))
464 return g_object_ref (G_OBJECT (initable));
465 else
466 return NULL;
467 }