1 /* GIO - GLib Input, Output and Streaming Library
3 * Copyright (C) 2006-2007 Red Hat, Inc.
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.
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.
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.
20 * Author: Alexander Larsson <alexl@redhat.com>
32 #define pipe(fds) _pipe(fds, 4096, _O_BINARY)
35 #include "gcancellable.h"
41 * SECTION:gcancellable
42 * @short_description: Thread-safe Operation Cancellation Stack
45 * GCancellable is a thread-safe operation cancellation stack used
46 * throughout GIO to allow for cancellation of synchronous and
47 * asynchronous operations.
57 GObject parent_instance;
60 guint allocated_pipe : 1;
64 static guint signals[LAST_SIGNAL] = { 0 };
66 G_DEFINE_TYPE (GCancellable, g_cancellable, G_TYPE_OBJECT);
68 static GStaticPrivate current_cancellable = G_STATIC_PRIVATE_INIT;
69 G_LOCK_DEFINE_STATIC(cancellable);
72 g_cancellable_finalize (GObject *object)
74 GCancellable *cancellable = G_CANCELLABLE (object);
76 if (cancellable->cancel_pipe[0] != -1)
77 close (cancellable->cancel_pipe[0]);
79 if (cancellable->cancel_pipe[1] != -1)
80 close (cancellable->cancel_pipe[1]);
82 G_OBJECT_CLASS (g_cancellable_parent_class)->finalize (object);
86 g_cancellable_class_init (GCancellableClass *klass)
88 GObjectClass *gobject_class = G_OBJECT_CLASS (klass);
90 gobject_class->finalize = g_cancellable_finalize;
93 * GCancellable::cancelled:
94 * @cancellable: a #GCancellable.
96 * Emitted when the operation has been cancelled from another thread.
98 * Can be used by implementations of cancellable operations. This will
99 * be emitted in the thread that tried to cancel the operation, not the
100 * thread the is running the operation.
103 g_signal_new (I_("cancelled"),
104 G_TYPE_FROM_CLASS (gobject_class),
106 G_STRUCT_OFFSET (GCancellableClass, cancelled),
108 g_cclosure_marshal_VOID__VOID,
114 set_fd_nonblocking (int fd)
118 fcntl_flags = fcntl (fd, F_GETFL);
121 fcntl_flags |= O_NONBLOCK;
123 fcntl_flags |= O_NDELAY;
126 fcntl (fd, F_SETFL, fcntl_flags);
131 g_cancellable_open_pipe (GCancellable *cancellable)
133 if (pipe (cancellable->cancel_pipe) == 0)
135 /* Make them nonblocking, just to be sure we don't block
136 * on errors and stuff
138 set_fd_nonblocking (cancellable->cancel_pipe[0]);
139 set_fd_nonblocking (cancellable->cancel_pipe[1]);
142 g_warning ("Failed to create pipe for GCancellable. Out of file descriptors?");
146 g_cancellable_init (GCancellable *cancellable)
148 cancellable->cancel_pipe[0] = -1;
149 cancellable->cancel_pipe[1] = -1;
155 * Creates a new #GCancellable object.
157 * Applications that want to start one or more operations
158 * that should be cancellable should create a #GCancellable
159 * and pass it to the operations.
161 * One #GCancellable can be used in multiple consecutive
162 * operations, but not in multiple concurrent operations.
164 * Returns: a #GCancellable.
167 g_cancellable_new (void)
169 return g_object_new (G_TYPE_CANCELLABLE, NULL);
173 * g_cancellable_push_current:
174 * @cancellable: optional #GCancellable object, %NULL to ignore.
176 * Pushes @cancellable onto the cancellable stack. The current
177 * cancllable can then be recieved using g_cancellable_get_current().
179 * This is useful when implementing cancellable operations in
180 * code that does not allow you to pass down the cancellable object.
182 * This is typically called automatically by e.g. #GFile operations,
183 * so you rarely have to call this yourself.
186 g_cancellable_push_current (GCancellable *cancellable)
190 g_return_if_fail (cancellable != NULL);
192 l = g_static_private_get (¤t_cancellable);
193 l = g_slist_prepend (l, cancellable);
194 g_static_private_set (¤t_cancellable, l, NULL);
198 * g_cancellable_pop_current:
199 * @cancellable: optional #GCancellable object, %NULL to ignore.
201 * Pops @cancellable off the cancellable stack (verifying that @cancellable
202 * is on the top of the stack).
205 g_cancellable_pop_current (GCancellable *cancellable)
209 l = g_static_private_get (¤t_cancellable);
211 g_return_if_fail (l != NULL);
212 g_return_if_fail (l->data == cancellable);
214 l = g_slist_delete_link (l, l);
215 g_static_private_set (¤t_cancellable, l, NULL);
219 * g_cancellable_get_current:
221 * Gets the top cancellable from the stack.
223 * Returns: a #GCancellable from the top of the stack, or %NULL
224 * if the stack is empty.
227 g_cancellable_get_current (void)
231 l = g_static_private_get (¤t_cancellable);
235 return G_CANCELLABLE (l->data);
239 * g_cancellable_reset:
240 * @cancellable: a #GCancellable object.
242 * Resets @cancellable to its uncancelled state.
245 g_cancellable_reset (GCancellable *cancellable)
247 g_return_if_fail (G_IS_CANCELLABLE (cancellable));
250 /* Make sure we're not leaving old cancel state around */
251 if (cancellable->cancelled)
254 if (cancellable->cancel_pipe[0] != -1)
255 read (cancellable->cancel_pipe[0], &ch, 1);
256 cancellable->cancelled = FALSE;
258 G_UNLOCK(cancellable);
262 * g_cancellable_is_cancelled:
263 * @cancellable: a #GCancellable or NULL.
265 * Checks if a cancellable job has been cancelled.
267 * Returns: %TRUE if @cancellable is cancelled,
268 * FALSE if called with %NULL or if item is not cancelled.
271 g_cancellable_is_cancelled (GCancellable *cancellable)
273 return cancellable != NULL && cancellable->cancelled;
277 * g_cancellable_set_error_if_cancelled:
278 * @cancellable: a #GCancellable object.
279 * @error: #GError to append error state to.
281 * If the @cancelalble is cancelled, sets the error to notify
282 * that the operation was cancelled.
284 * Returns: %TRUE if @cancellable was cancelled, %FALSE if it was not.
287 g_cancellable_set_error_if_cancelled (GCancellable *cancellable,
290 if (g_cancellable_is_cancelled (cancellable))
292 g_set_error_literal (error,
294 G_IO_ERROR_CANCELLED,
295 _("Operation was cancelled"));
303 * g_cancellable_get_fd:
304 * @cancellable: a #GCancellable.
306 * Gets the file descriptor for a cancellable job. This can be used to
307 * implement cancellable operations on Unix systems. The returned fd will
308 * turn readable when @cancellable is cancelled.
310 * Returns: A valid file descriptor. %-1 if the file descriptor
311 * is not supported, or on errors.
314 g_cancellable_get_fd (GCancellable *cancellable)
317 if (cancellable == NULL)
321 if (!cancellable->allocated_pipe)
323 cancellable->allocated_pipe = TRUE;
324 g_cancellable_open_pipe (cancellable);
327 fd = cancellable->cancel_pipe[0];
328 G_UNLOCK(cancellable);
334 * g_cancellable_cancel:
335 * @cancellable: a #GCancellable object.
337 * Will set @cancellable to cancelled, and will emit the CANCELLED
340 * This function is thread-safe. In other words, you can safely call it from
341 * another thread than the one running an operation that was passed
345 g_cancellable_cancel (GCancellable *cancellable)
352 if (cancellable != NULL &&
353 !cancellable->cancelled)
357 cancellable->cancelled = TRUE;
358 if (cancellable->cancel_pipe[1] != -1)
359 write (cancellable->cancel_pipe[1], &ch, 1);
361 G_UNLOCK(cancellable);
365 g_object_ref (cancellable);
366 g_signal_emit (cancellable, signals[CANCELLED], 0);
367 g_object_unref (cancellable);
371 #define __G_CANCELLABLE_C__
372 #include "gioaliasdef.c"