X-Git-Url: http://review.tizen.org/git/?a=blobdiff_plain;f=gio%2Fgcancellable.c;h=258b88da56a8c9260a6ef422772c999da54d3ad3;hb=d9ad40b4eaf1a9197ab363de4346a8d84f45f5c1;hp=c6a7b83326dd328b14e73142a927a89bbe0b878c;hpb=a28215fa909ef315e596ebd0b41132730aef909d;p=platform%2Fupstream%2Fglib.git
diff --git a/gio/gcancellable.c b/gio/gcancellable.c
index c6a7b83..258b88d 100644
--- a/gio/gcancellable.c
+++ b/gio/gcancellable.c
@@ -13,29 +13,18 @@
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General
- * Public License along with this library; if not, write to the
- * Free Software Foundation, Inc., 59 Temple Place, Suite 330,
- * Boston, MA 02111-1307, USA.
+ * Public License along with this library; if not, see .
*
* Author: Alexander Larsson
*/
#include "config.h"
-#ifdef HAVE_UNISTD_H
-#include
-#endif
-#include
+#include "glib.h"
#include
-#ifdef G_OS_WIN32
-#include
-#ifndef pipe
-#define pipe(fds) _pipe(fds, 4096, _O_BINARY)
-#endif
-#endif
+#include "glib-private.h"
#include "gcancellable.h"
#include "glibintl.h"
-#include "gioalias.h"
/**
* SECTION:gcancellable
@@ -52,44 +41,31 @@ enum {
LAST_SIGNAL
};
-struct _GCancellable
+struct _GCancellablePrivate
{
- GObject parent_instance;
-
guint cancelled : 1;
- guint allocated_pipe : 1;
guint cancelled_running : 1;
guint cancelled_running_waiting : 1;
- int cancel_pipe[2];
-#ifdef G_OS_WIN32
- GIOChannel *read_channel;
-#endif
+ guint fd_refcount;
+ GWakeup *wakeup;
};
static guint signals[LAST_SIGNAL] = { 0 };
-G_DEFINE_TYPE (GCancellable, g_cancellable, G_TYPE_OBJECT);
+G_DEFINE_TYPE_WITH_PRIVATE (GCancellable, g_cancellable, G_TYPE_OBJECT)
+
+static GPrivate current_cancellable;
+static GMutex cancellable_mutex;
+static GCond cancellable_cond;
-static GStaticPrivate current_cancellable = G_STATIC_PRIVATE_INIT;
-G_LOCK_DEFINE_STATIC(cancellable);
-static GCond *cancellable_cond = NULL;
-
static void
g_cancellable_finalize (GObject *object)
{
GCancellable *cancellable = G_CANCELLABLE (object);
- if (cancellable->cancel_pipe[0] != -1)
- close (cancellable->cancel_pipe[0]);
-
- if (cancellable->cancel_pipe[1] != -1)
- close (cancellable->cancel_pipe[1]);
-
-#ifdef G_OS_WIN32
- if (cancellable->read_channel)
- g_io_channel_unref (cancellable->read_channel);
-#endif
+ if (cancellable->priv->wakeup)
+ GLIB_PRIVATE_CALL (g_wakeup_free) (cancellable->priv->wakeup);
G_OBJECT_CLASS (g_cancellable_parent_class)->finalize (object);
}
@@ -99,9 +75,6 @@ g_cancellable_class_init (GCancellableClass *klass)
{
GObjectClass *gobject_class = G_OBJECT_CLASS (klass);
- if (cancellable_cond == NULL && g_thread_supported ())
- cancellable_cond = g_cond_new ();
-
gobject_class->finalize = g_cancellable_finalize;
/**
@@ -117,16 +90,14 @@ g_cancellable_class_init (GCancellableClass *klass)
*
* Note that disconnecting from this signal (or any signal) in a
* multi-threaded program is prone to race conditions. For instance
- * it is possible that a signal handler may be invoked even
- * after a call to
- * g_signal_handler_disconnect() for that handler has already
- * returned.
+ * it is possible that a signal handler may be invoked even after
+ * a call to g_signal_handler_disconnect() for that handler has
+ * already returned.
*
- * There is also a problem when cancellation happen
- * right before connecting to the signal. If this happens the
- * signal will unexpectedly not be emitted, and checking before
- * connecting to the signal leaves a race condition where this is
- * still happening.
+ * There is also a problem when cancellation happens right before
+ * connecting to the signal. If this happens the signal will
+ * unexpectedly not be emitted, and checking before connecting to
+ * the signal leaves a race condition where this is still happening.
*
* In order to make it safe and easy to connect handlers there
* are two helper functions: g_cancellable_connect() and
@@ -134,13 +105,13 @@ g_cancellable_class_init (GCancellableClass *klass)
* like this.
*
* An example of how to us this:
- * |[
- * /* Make sure we don't do any unnecessary work if already cancelled */
- * if (g_cancellable_set_error_if_cancelled (cancellable))
+ * |[
+ * // Make sure we don't do unnecessary work if already cancelled
+ * if (g_cancellable_set_error_if_cancelled (cancellable, error))
* return;
*
- * /* Set up all the data needed to be able to
- * * handle cancellation of the operation */
+ * // Set up all the data needed to be able to handle cancellation
+ * // of the operation
* my_data = my_data_new (...);
*
* id = 0;
@@ -149,12 +120,12 @@ g_cancellable_class_init (GCancellableClass *klass)
* G_CALLBACK (cancelled_handler)
* data, NULL);
*
- * /* cancellable operation here... */
+ * // cancellable operation here...
*
* g_cancellable_disconnect (cancellable, id);
*
- * /* cancelled_handler is never called after this, it
- * * is now safe to free the data */
+ * // cancelled_handler is never called after this, it is now safe
+ * // to free the data
* my_data_free (my_data);
* ]|
*
@@ -174,42 +145,9 @@ g_cancellable_class_init (GCancellableClass *klass)
}
static void
-set_fd_nonblocking (int fd)
-{
-#ifdef F_GETFL
- glong fcntl_flags;
- fcntl_flags = fcntl (fd, F_GETFL);
-
-#ifdef O_NONBLOCK
- fcntl_flags |= O_NONBLOCK;
-#else
- fcntl_flags |= O_NDELAY;
-#endif
-
- fcntl (fd, F_SETFL, fcntl_flags);
-#endif
-}
-
-static void
-g_cancellable_open_pipe (GCancellable *cancellable)
-{
- if (pipe (cancellable->cancel_pipe) == 0)
- {
- /* Make them nonblocking, just to be sure we don't block
- * on errors and stuff
- */
- set_fd_nonblocking (cancellable->cancel_pipe[0]);
- set_fd_nonblocking (cancellable->cancel_pipe[1]);
- }
- else
- g_warning ("Failed to create pipe for GCancellable. Out of file descriptors?");
-}
-
-static void
g_cancellable_init (GCancellable *cancellable)
{
- cancellable->cancel_pipe[0] = -1;
- cancellable->cancel_pipe[1] = -1;
+ cancellable->priv = g_cancellable_get_instance_private (cancellable);
}
/**
@@ -222,7 +160,7 @@ g_cancellable_init (GCancellable *cancellable)
* and pass it to the operations.
*
* One #GCancellable can be used in multiple consecutive
- * operations, but not in multiple concurrent operations.
+ * operations or in multiple concurrent operations.
*
* Returns: a #GCancellable.
**/
@@ -234,10 +172,10 @@ g_cancellable_new (void)
/**
* g_cancellable_push_current:
- * @cancellable: optional #GCancellable object, %NULL to ignore.
- *
+ * @cancellable: a #GCancellable object
+ *
* Pushes @cancellable onto the cancellable stack. The current
- * cancllable can then be recieved using g_cancellable_get_current().
+ * cancellable can then be received using g_cancellable_get_current().
*
* This is useful when implementing cancellable operations in
* code that does not allow you to pass down the cancellable object.
@@ -251,47 +189,47 @@ g_cancellable_push_current (GCancellable *cancellable)
GSList *l;
g_return_if_fail (cancellable != NULL);
-
- l = g_static_private_get (¤t_cancellable);
+
+ l = g_private_get (¤t_cancellable);
l = g_slist_prepend (l, cancellable);
- g_static_private_set (¤t_cancellable, l, NULL);
+ g_private_set (¤t_cancellable, l);
}
/**
* g_cancellable_pop_current:
- * @cancellable: optional #GCancellable object, %NULL to ignore.
+ * @cancellable: a #GCancellable object
*
- * Pops @cancellable off the cancellable stack (verifying that @cancellable
+ * Pops @cancellable off the cancellable stack (verifying that @cancellable
* is on the top of the stack).
**/
void
g_cancellable_pop_current (GCancellable *cancellable)
{
GSList *l;
-
- l = g_static_private_get (¤t_cancellable);
-
+
+ l = g_private_get (¤t_cancellable);
+
g_return_if_fail (l != NULL);
g_return_if_fail (l->data == cancellable);
l = g_slist_delete_link (l, l);
- g_static_private_set (¤t_cancellable, l, NULL);
+ g_private_set (¤t_cancellable, l);
}
/**
* g_cancellable_get_current:
- *
+ *
* Gets the top cancellable from the stack.
- *
- * Returns: a #GCancellable from the top of the stack, or %NULL
- * if the stack is empty.
+ *
+ * Returns: (nullable) (transfer none): a #GCancellable from the top
+ * of the stack, or %NULL if the stack is empty.
**/
GCancellable *
g_cancellable_get_current (void)
{
GSList *l;
-
- l = g_static_private_get (¤t_cancellable);
+
+ l = g_private_get (¤t_cancellable);
if (l == NULL)
return NULL;
@@ -302,72 +240,74 @@ g_cancellable_get_current (void)
* g_cancellable_reset:
* @cancellable: a #GCancellable object.
*
- * Resets @cancellable to its uncancelled state.
+ * Resets @cancellable to its uncancelled state.
+ *
+ * If cancellable is currently in use by any cancellable operation
+ * then the behavior of this function is undefined.
+ *
+ * Note that it is generally not a good idea to reuse an existing
+ * cancellable for more operations after it has been cancelled once,
+ * as this function might tempt you to do. The recommended practice
+ * is to drop the reference to a cancellable after cancelling it,
+ * and let it die with the outstanding async operations. You should
+ * create a fresh cancellable for further async operations.
**/
void
g_cancellable_reset (GCancellable *cancellable)
{
+ GCancellablePrivate *priv;
+
g_return_if_fail (G_IS_CANCELLABLE (cancellable));
- G_LOCK(cancellable);
-
- if (cancellable->cancelled_running)
+ g_mutex_lock (&cancellable_mutex);
+
+ priv = cancellable->priv;
+
+ while (priv->cancelled_running)
{
- g_critical ("Can't reset a cancellable during an active operation");
- G_UNLOCK(cancellable);
- return;
+ priv->cancelled_running_waiting = TRUE;
+ g_cond_wait (&cancellable_cond, &cancellable_mutex);
}
-
- if (!cancellable->cancelled)
+
+ if (priv->cancelled)
{
- char ch;
-
- /* Make sure we're not leaving old cancel state around */
-
-#ifdef G_OS_WIN32
- if (cancellable->read_channel)
- {
- gsize bytes_read;
- g_io_channel_read_chars (cancellable->read_channel, &ch, 1,
- &bytes_read, NULL);
- }
- else
-#endif
- if (cancellable->cancel_pipe[0] != -1)
- read (cancellable->cancel_pipe[0], &ch, 1);
- cancellable->cancelled = FALSE;
+ if (priv->wakeup)
+ GLIB_PRIVATE_CALL (g_wakeup_acknowledge) (priv->wakeup);
+
+ priv->cancelled = FALSE;
}
- G_UNLOCK(cancellable);
+
+ g_mutex_unlock (&cancellable_mutex);
}
/**
* g_cancellable_is_cancelled:
- * @cancellable: a #GCancellable or NULL.
- *
+ * @cancellable: (allow-none): a #GCancellable or %NULL
+ *
* Checks if a cancellable job has been cancelled.
- *
- * Returns: %TRUE if @cancellable is cancelled,
- * FALSE if called with %NULL or if item is not cancelled.
+ *
+ * Returns: %TRUE if @cancellable is cancelled,
+ * FALSE if called with %NULL or if item is not cancelled.
**/
gboolean
g_cancellable_is_cancelled (GCancellable *cancellable)
{
- return cancellable != NULL && cancellable->cancelled;
+ return cancellable != NULL && cancellable->priv->cancelled;
}
/**
* g_cancellable_set_error_if_cancelled:
- * @cancellable: a #GCancellable object.
- * @error: #GError to append error state to.
- *
+ * @cancellable: (allow-none): a #GCancellable or %NULL
+ * @error: #GError to append error state to
+ *
* If the @cancellable is cancelled, sets the error to notify
* that the operation was cancelled.
- *
- * Returns: %TRUE if @cancellable was cancelled, %FALSE if it was not.
- **/
+ *
+ * Returns: %TRUE if @cancellable was cancelled, %FALSE if it was not
+ */
gboolean
g_cancellable_set_error_if_cancelled (GCancellable *cancellable,
- GError **error)
+ GError **error)
{
if (g_cancellable_is_cancelled (cancellable))
{
@@ -377,7 +317,7 @@ g_cancellable_set_error_if_cancelled (GCancellable *cancellable,
_("Operation was cancelled"));
return TRUE;
}
-
+
return FALSE;
}
@@ -393,6 +333,10 @@ g_cancellable_set_error_if_cancelled (GCancellable *cancellable,
* readable status. Reading to unset the readable status is done
* with g_cancellable_reset().
*
+ * After a successful return from this function, you should use
+ * g_cancellable_release_fd() to free up resources allocated for
+ * the returned file descriptor.
+ *
* See also g_cancellable_make_pollfd().
*
* Returns: A valid file descriptor. %-1 if the file descriptor
@@ -401,61 +345,115 @@ g_cancellable_set_error_if_cancelled (GCancellable *cancellable,
int
g_cancellable_get_fd (GCancellable *cancellable)
{
- int fd;
+ GPollFD pollfd;
+
if (cancellable == NULL)
- return -1;
-
- G_LOCK(cancellable);
- if (!cancellable->allocated_pipe)
- {
- cancellable->allocated_pipe = TRUE;
- g_cancellable_open_pipe (cancellable);
- }
-
- fd = cancellable->cancel_pipe[0];
- G_UNLOCK(cancellable);
-
- return fd;
+ return -1;
+
+#ifdef G_OS_WIN32
+ pollfd.fd = -1;
+#else
+ g_cancellable_make_pollfd (cancellable, &pollfd);
+#endif
+
+ return pollfd.fd;
}
/**
* g_cancellable_make_pollfd:
- * @cancellable: a #GCancellable.
+ * @cancellable: (allow-none): a #GCancellable or %NULL
* @pollfd: a pointer to a #GPollFD
*
* Creates a #GPollFD corresponding to @cancellable; this can be passed
- * to g_poll() and used to poll for cancellation.
+ * to g_poll() and used to poll for cancellation. This is useful both
+ * for unix systems without a native poll and for portability to
+ * windows.
+ *
+ * When this function returns %TRUE, you should use
+ * g_cancellable_release_fd() to free up resources allocated for the
+ * @pollfd. After a %FALSE return, do not call g_cancellable_release_fd().
+ *
+ * If this function returns %FALSE, either no @cancellable was given or
+ * resource limits prevent this function from allocating the necessary
+ * structures for polling. (On Linux, you will likely have reached
+ * the maximum number of file descriptors.) The suggested way to handle
+ * these cases is to ignore the @cancellable.
*
* You are not supposed to read from the fd yourself, just check for
* readable status. Reading to unset the readable status is done
* with g_cancellable_reset().
+ *
+ * Returns: %TRUE if @pollfd was successfully initialized, %FALSE on
+ * failure to prepare the cancellable.
*
+ * Since: 2.22
**/
-void
+gboolean
g_cancellable_make_pollfd (GCancellable *cancellable, GPollFD *pollfd)
{
+ g_return_val_if_fail (pollfd != NULL, FALSE);
+ if (cancellable == NULL)
+ return FALSE;
+ g_return_val_if_fail (G_IS_CANCELLABLE (cancellable), FALSE);
+
+ g_mutex_lock (&cancellable_mutex);
+
+ cancellable->priv->fd_refcount++;
+
+ if (cancellable->priv->wakeup == NULL)
+ {
+ cancellable->priv->wakeup = GLIB_PRIVATE_CALL (g_wakeup_new) ();
+
+ if (cancellable->priv->cancelled)
+ GLIB_PRIVATE_CALL (g_wakeup_signal) (cancellable->priv->wakeup);
+ }
+
+ GLIB_PRIVATE_CALL (g_wakeup_get_pollfd) (cancellable->priv->wakeup, pollfd);
+
+ g_mutex_unlock (&cancellable_mutex);
+
+ return TRUE;
+}
+
+/**
+ * g_cancellable_release_fd:
+ * @cancellable: a #GCancellable
+ *
+ * Releases a resources previously allocated by g_cancellable_get_fd()
+ * or g_cancellable_make_pollfd().
+ *
+ * For compatibility reasons with older releases, calling this function
+ * is not strictly required, the resources will be automatically freed
+ * when the @cancellable is finalized. However, the @cancellable will
+ * block scarce file descriptors until it is finalized if this function
+ * is not called. This can cause the application to run out of file
+ * descriptors when many #GCancellables are used at the same time.
+ *
+ * Since: 2.22
+ **/
+void
+g_cancellable_release_fd (GCancellable *cancellable)
+{
+ GCancellablePrivate *priv;
+
+ if (cancellable == NULL)
+ return;
+
g_return_if_fail (G_IS_CANCELLABLE (cancellable));
- g_return_if_fail (pollfd != NULL);
+ g_return_if_fail (cancellable->priv->fd_refcount > 0);
-#ifdef G_OS_WIN32
- if (!cancellable->read_channel)
+ priv = cancellable->priv;
+
+ g_mutex_lock (&cancellable_mutex);
+
+ priv->fd_refcount--;
+ if (priv->fd_refcount == 0)
{
- int fd = g_cancellable_get_fd (cancellable);
- cancellable->read_channel = g_io_channel_win32_new_fd (fd);
- g_io_channel_set_buffered (cancellable->read_channel, FALSE);
- g_io_channel_set_flags (cancellable->read_channel,
- G_IO_FLAG_NONBLOCK, NULL);
- g_io_channel_set_encoding (cancellable->read_channel, NULL, NULL);
+ GLIB_PRIVATE_CALL (g_wakeup_free) (priv->wakeup);
+ priv->wakeup = NULL;
}
- g_io_channel_win32_make_pollfd (cancellable->read_channel, G_IO_IN, pollfd);
- /* (We need to keep cancellable->read_channel around, because it's
- * keeping track of state related to the pollfd.)
- */
-#else /* !G_OS_WIN32 */
- pollfd->fd = g_cancellable_get_fd (cancellable);
- pollfd->events = G_IO_IN;
-#endif /* G_OS_WIN32 */
- pollfd->revents = 0;
+
+ g_mutex_unlock (&cancellable_mutex);
}
/**
@@ -480,39 +478,43 @@ g_cancellable_make_pollfd (GCancellable *cancellable, GPollFD *pollfd)
void
g_cancellable_cancel (GCancellable *cancellable)
{
- gboolean cancel;
+ GCancellablePrivate *priv;
+
+ if (cancellable == NULL ||
+ cancellable->priv->cancelled)
+ return;
+
+ priv = cancellable->priv;
- cancel = FALSE;
+ g_mutex_lock (&cancellable_mutex);
- G_LOCK(cancellable);
- if (cancellable != NULL &&
- !cancellable->cancelled)
+ if (priv->cancelled)
{
- char ch = 'x';
- cancel = TRUE;
- cancellable->cancelled = TRUE;
- cancellable->cancelled_running = TRUE;
- if (cancellable->cancel_pipe[1] != -1)
- write (cancellable->cancel_pipe[1], &ch, 1);
+ g_mutex_unlock (&cancellable_mutex);
+ return;
}
- G_UNLOCK(cancellable);
- if (cancel)
- {
- g_object_ref (cancellable);
- g_signal_emit (cancellable, signals[CANCELLED], 0);
+ priv->cancelled = TRUE;
+ priv->cancelled_running = TRUE;
- G_LOCK(cancellable);
+ if (priv->wakeup)
+ GLIB_PRIVATE_CALL (g_wakeup_signal) (priv->wakeup);
- cancellable->cancelled_running = FALSE;
- if (cancellable->cancelled_running_waiting)
- g_cond_broadcast (cancellable_cond);
- cancellable->cancelled_running_waiting = FALSE;
+ g_mutex_unlock (&cancellable_mutex);
- G_UNLOCK(cancellable);
+ g_object_ref (cancellable);
+ g_signal_emit (cancellable, signals[CANCELLED], 0);
- g_object_unref (cancellable);
- }
+ g_mutex_lock (&cancellable_mutex);
+
+ priv->cancelled_running = FALSE;
+ if (priv->cancelled_running_waiting)
+ g_cond_broadcast (&cancellable_cond);
+ priv->cancelled_running_waiting = FALSE;
+
+ g_mutex_unlock (&cancellable_mutex);
+
+ g_object_unref (cancellable);
}
/**
@@ -520,7 +522,7 @@ g_cancellable_cancel (GCancellable *cancellable)
* @cancellable: A #GCancellable.
* @callback: The #GCallback to connect.
* @data: Data to pass to @callback.
- * @data_destroy_func: Free function for @data or %NULL.
+ * @data_destroy_func: (allow-none): Free function for @data or %NULL.
*
* Convenience function to connect to the #GCancellable::cancelled
* signal. Also handles the race condition that may happen
@@ -536,6 +538,11 @@ g_cancellable_cancel (GCancellable *cancellable)
*
* See #GCancellable::cancelled for details on how to use this.
*
+ * Since GLib 2.40, the lock protecting @cancellable is not held when
+ * @callback is invoked. This lifts a restriction in place for
+ * earlier GLib versions which now makes it easier to write cleanup
+ * code that unconditionally invokes e.g. g_cancellable_cancel().
+ *
* Returns: The id of the signal handler or 0 if @cancellable has already
* been cancelled.
*
@@ -551,13 +558,15 @@ g_cancellable_connect (GCancellable *cancellable,
g_return_val_if_fail (G_IS_CANCELLABLE (cancellable), 0);
- G_LOCK (cancellable);
+ g_mutex_lock (&cancellable_mutex);
- if (cancellable->cancelled)
+ if (cancellable->priv->cancelled)
{
void (*_callback) (GCancellable *cancellable,
gpointer user_data);
+ g_mutex_unlock (&cancellable_mutex);
+
_callback = (void *)callback;
id = 0;
@@ -572,20 +581,25 @@ g_cancellable_connect (GCancellable *cancellable,
callback, data,
(GClosureNotify) data_destroy_func,
0);
+
+ g_mutex_unlock (&cancellable_mutex);
}
- G_UNLOCK (cancellable);
+
return id;
}
/**
* g_cancellable_disconnect:
- * @cancellable: A #GCancellable or %NULL.
+ * @cancellable: (allow-none): A #GCancellable or %NULL.
* @handler_id: Handler id of the handler to be disconnected, or %0.
*
- * Disconnects a handler from an cancellable instance similar to
- * g_signal_handler_disconnect() but ensures that once this
- * function returns the handler will not run anymore in any thread.
+ * Disconnects a handler from a cancellable instance similar to
+ * g_signal_handler_disconnect(). Additionally, in the event that a
+ * signal handler is currently running, this call will block until the
+ * handler has finished. Calling this function from a
+ * #GCancellable::cancelled signal handler will therefore result in a
+ * deadlock.
*
* This avoids a race condition where a thread cancels at the
* same time as the cancellable operation is finished and the
@@ -601,20 +615,143 @@ void
g_cancellable_disconnect (GCancellable *cancellable,
gulong handler_id)
{
+ GCancellablePrivate *priv;
+
if (handler_id == 0 || cancellable == NULL)
return;
- G_LOCK (cancellable);
- while (cancellable->cancelled_running)
+ g_mutex_lock (&cancellable_mutex);
+
+ priv = cancellable->priv;
+
+ while (priv->cancelled_running)
{
- cancellable->cancelled_running_waiting = TRUE;
- g_cond_wait (cancellable_cond,
- g_static_mutex_get_mutex (& G_LOCK_NAME (cancellable)));
+ priv->cancelled_running_waiting = TRUE;
+ g_cond_wait (&cancellable_cond, &cancellable_mutex);
}
g_signal_handler_disconnect (cancellable, handler_id);
- G_UNLOCK (cancellable);
+
+ g_mutex_unlock (&cancellable_mutex);
}
-#define __G_CANCELLABLE_C__
-#include "gioaliasdef.c"
+typedef struct {
+ GSource source;
+
+ GCancellable *cancellable;
+ guint cancelled_handler;
+} GCancellableSource;
+
+static void
+cancellable_source_cancelled (GCancellable *cancellable,
+ gpointer user_data)
+{
+ GSource *source = user_data;
+
+ if (!g_source_is_destroyed (source))
+ g_source_set_ready_time (source, 0);
+}
+
+static gboolean
+cancellable_source_dispatch (GSource *source,
+ GSourceFunc callback,
+ gpointer user_data)
+{
+ GCancellableSourceFunc func = (GCancellableSourceFunc)callback;
+ GCancellableSource *cancellable_source = (GCancellableSource *)source;
+
+ g_source_set_ready_time (source, -1);
+ return (*func) (cancellable_source->cancellable, user_data);
+}
+
+static void
+cancellable_source_finalize (GSource *source)
+{
+ GCancellableSource *cancellable_source = (GCancellableSource *)source;
+
+ if (cancellable_source->cancellable)
+ {
+ g_cancellable_disconnect (cancellable_source->cancellable,
+ cancellable_source->cancelled_handler);
+ g_object_unref (cancellable_source->cancellable);
+ }
+}
+
+static gboolean
+cancellable_source_closure_callback (GCancellable *cancellable,
+ gpointer data)
+{
+ GClosure *closure = data;
+
+ GValue params = G_VALUE_INIT;
+ GValue result_value = G_VALUE_INIT;
+ gboolean result;
+
+ g_value_init (&result_value, G_TYPE_BOOLEAN);
+
+ g_value_init (¶ms, G_TYPE_CANCELLABLE);
+ g_value_set_object (¶ms, cancellable);
+
+ g_closure_invoke (closure, &result_value, 1, ¶ms, NULL);
+
+ result = g_value_get_boolean (&result_value);
+ g_value_unset (&result_value);
+ g_value_unset (¶ms);
+
+ return result;
+}
+
+static GSourceFuncs cancellable_source_funcs =
+{
+ NULL,
+ NULL,
+ cancellable_source_dispatch,
+ cancellable_source_finalize,
+ (GSourceFunc)cancellable_source_closure_callback,
+};
+
+/**
+ * g_cancellable_source_new: (skip)
+ * @cancellable: (allow-none): a #GCancellable, or %NULL
+ *
+ * Creates a source that triggers if @cancellable is cancelled and
+ * calls its callback of type #GCancellableSourceFunc. This is
+ * primarily useful for attaching to another (non-cancellable) source
+ * with g_source_add_child_source() to add cancellability to it.
+ *
+ * For convenience, you can call this with a %NULL #GCancellable,
+ * in which case the source will never trigger.
+ *
+ * The new #GSource will hold a reference to the #GCancellable.
+ *
+ * Returns: (transfer full): the new #GSource.
+ *
+ * Since: 2.28
+ */
+GSource *
+g_cancellable_source_new (GCancellable *cancellable)
+{
+ GSource *source;
+ GCancellableSource *cancellable_source;
+
+ source = g_source_new (&cancellable_source_funcs, sizeof (GCancellableSource));
+ g_source_set_name (source, "GCancellable");
+ cancellable_source = (GCancellableSource *)source;
+
+ if (cancellable)
+ {
+ cancellable_source->cancellable = g_object_ref (cancellable);
+
+ /* We intentionally don't use g_cancellable_connect() here,
+ * because we don't want the "at most once" behavior.
+ */
+ cancellable_source->cancelled_handler =
+ g_signal_connect (cancellable, "cancelled",
+ G_CALLBACK (cancellable_source_cancelled),
+ source);
+ if (g_cancellable_is_cancelled (cancellable))
+ g_source_set_ready_time (source, 0);
+ }
+
+ return source;
+}