* 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 <http://www.gnu.org/licenses/>.
*
* Author: Alexander Larsson <alexl@redhat.com>
*/
-#include <config.h>
-#include <unistd.h>
-#include <fcntl.h>
+#include "config.h"
+#include "glib.h"
#include <gioerror.h>
+#include "glib-private.h"
#include "gcancellable.h"
-
#include "glibintl.h"
-/*
+/**
+ * SECTION:gcancellable
+ * @short_description: Thread-safe Operation Cancellation Stack
+ * @include: gio/gio.h
+ *
* GCancellable is a thread-safe operation cancellation stack used
- * throughout GIO to allow for cancellation of asynchronous operations.
+ * throughout GIO to allow for cancellation of synchronous and
+ * asynchronous operations.
*/
enum {
LAST_SIGNAL
};
-struct _GCancellable
+struct _GCancellablePrivate
{
- GObject parent_instance;
-
guint cancelled : 1;
- guint allocated_pipe : 1;
- int cancel_pipe[2];
+ guint cancelled_running : 1;
+ guint cancelled_running_waiting : 1;
+
+ 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 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]);
-
- if (G_OBJECT_CLASS (g_cancellable_parent_class)->finalize)
- (*G_OBJECT_CLASS (g_cancellable_parent_class)->finalize) (object);
+ if (cancellable->priv->wakeup)
+ GLIB_PRIVATE_CALL (g_wakeup_free) (cancellable->priv->wakeup);
+
+ G_OBJECT_CLASS (g_cancellable_parent_class)->finalize (object);
}
static void
g_cancellable_class_init (GCancellableClass *klass)
{
GObjectClass *gobject_class = G_OBJECT_CLASS (klass);
-
+
gobject_class->finalize = g_cancellable_finalize;
+ /**
+ * GCancellable::cancelled:
+ * @cancellable: a #GCancellable.
+ *
+ * Emitted when the operation has been cancelled.
+ *
+ * Can be used by implementations of cancellable operations. If the
+ * operation is cancelled from another thread, the signal will be
+ * emitted in the thread that cancelled the operation, not the
+ * thread that is running the operation.
+ *
+ * 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.
+ *
+ * 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
+ * g_cancellable_disconnect() which protect against problems
+ * like this.
+ *
+ * An example of how to us this:
+ * |[<!-- language="C" -->
+ * // 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
+ * my_data = my_data_new (...);
+ *
+ * id = 0;
+ * if (cancellable)
+ * id = g_cancellable_connect (cancellable,
+ * G_CALLBACK (cancelled_handler)
+ * data, NULL);
+ *
+ * // cancellable operation here...
+ *
+ * g_cancellable_disconnect (cancellable, id);
+ *
+ * // cancelled_handler is never called after this, it is now safe
+ * // to free the data
+ * my_data_free (my_data);
+ * ]|
+ *
+ * Note that the cancelled signal is emitted in the thread that
+ * the user cancelled from, which may be the main thread. So, the
+ * cancellable signal should not do something that can block.
+ */
signals[CANCELLED] =
g_signal_new (I_("cancelled"),
G_TYPE_FROM_CLASS (gobject_class),
}
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);
}
/**
* g_cancellable_new:
+ *
+ * Creates a new #GCancellable object.
+ *
+ * Applications that want to start one or more operations
+ * that should be cancellable should create a #GCancellable
+ * and pass it to the operations.
+ *
+ * One #GCancellable can be used in multiple consecutive
+ * operations or in multiple concurrent operations.
*
- * Returns: a new #GCancellable object.
+ * Returns: a #GCancellable.
**/
GCancellable *
g_cancellable_new (void)
}
/**
- * g_push_current_cancellable:
- * @cancellable: optional #GCancellable object, %NULL to ignore.
- *
- * Pushes @cancellable onto the cancellable stack.
+ * g_cancellable_push_current:
+ * @cancellable: a #GCancellable object
+ *
+ * Pushes @cancellable onto the cancellable stack. The 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.
+ *
+ * This is typically called automatically by e.g. #GFile operations,
+ * so you rarely have to call this yourself.
**/
void
-g_push_current_cancellable (GCancellable *cancellable)
+g_cancellable_push_current (GCancellable *cancellable)
{
GSList *l;
- g_assert (cancellable != NULL);
-
- l = g_static_private_get (¤t_cancellable);
+ g_return_if_fail (cancellable != NULL);
+
+ 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_pop_current_cancellable:
- * @cancellable: optional #GCancellable object, %NULL to ignore.
+ * g_cancellable_pop_current:
+ * @cancellable: a #GCancellable object
*
- * Pops @cancellable off the cancellable stack if @cancellable
- * is on the top of the stack.
+ * Pops @cancellable off the cancellable stack (verifying that @cancellable
+ * is on the top of the stack).
**/
void
-g_pop_current_cancellable (GCancellable *cancellable)
+g_cancellable_pop_current (GCancellable *cancellable)
{
GSList *l;
-
- l = g_static_private_get (¤t_cancellable);
-
- g_assert (l != NULL);
- g_assert (l->data == 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:
- *
- * Returns: a #GCancellable from the top of the stack, or %NULL
- * if the stack is empty.
+ *
+ * Gets the top cancellable from the stack.
+ *
+ * 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;
* 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);
- /* Make sure we're not leaving old cancel state around */
- if (cancellable->cancelled)
+ g_mutex_lock (&cancellable_mutex);
+
+ priv = cancellable->priv;
+
+ while (priv->cancelled_running)
{
- char ch;
- if (cancellable->cancel_pipe[0] != -1)
- read (cancellable->cancel_pipe[0], &ch, 1);
- cancellable->cancelled = FALSE;
+ priv->cancelled_running_waiting = TRUE;
+ g_cond_wait (&cancellable_cond, &cancellable_mutex);
}
- G_UNLOCK(cancellable);
+
+ if (priv->cancelled)
+ {
+ if (priv->wakeup)
+ GLIB_PRIVATE_CALL (g_wakeup_acknowledge) (priv->wakeup);
+
+ priv->cancelled = FALSE;
+ }
+
+ g_mutex_unlock (&cancellable_mutex);
}
/**
* g_cancellable_is_cancelled:
- * @cancellable: a #GCancellable or NULL.
- *
- * Returns: %TRUE if @cancellable is is cancelled,
- * FALSE if called with %NULL or if item is not cancelled.
+ * @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.
**/
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.
- *
- * Sets the current error to notify that the operation was cancelled.
- *
- * Returns: %TRUE if @cancellable was cancelled, %FALSE if it was not.
- **/
+ * @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
+ */
gboolean
g_cancellable_set_error_if_cancelled (GCancellable *cancellable,
- GError **error)
+ GError **error)
{
if (g_cancellable_is_cancelled (cancellable))
{
- g_set_error (error,
- G_IO_ERROR,
- G_IO_ERROR_CANCELLED,
- _("Operation was cancelled"));
+ g_set_error_literal (error,
+ G_IO_ERROR,
+ G_IO_ERROR_CANCELLED,
+ _("Operation was cancelled"));
return TRUE;
}
-
+
return FALSE;
}
* g_cancellable_get_fd:
* @cancellable: a #GCancellable.
*
- * Returns: A valid file descriptor. -1 if the file descriptor
+ * Gets the file descriptor for a cancellable job. This can be used to
+ * implement cancellable operations on Unix systems. The returned fd will
+ * turn readable when @cancellable is cancelled.
+ *
+ * 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().
+ *
+ * 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
* is not supported, or on errors.
**/
int
g_cancellable_get_fd (GCancellable *cancellable)
{
- int fd;
+ GPollFD pollfd;
+
if (cancellable == NULL)
- return -1;
-
- G_LOCK(cancellable);
- if (!cancellable->allocated_pipe)
+ 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: (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. 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
+ **/
+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->allocated_pipe = TRUE;
- g_cancellable_open_pipe (cancellable);
+ cancellable->priv->wakeup = GLIB_PRIVATE_CALL (g_wakeup_new) ();
+
+ if (cancellable->priv->cancelled)
+ GLIB_PRIVATE_CALL (g_wakeup_signal) (cancellable->priv->wakeup);
}
-
- fd = cancellable->cancel_pipe[0];
- G_UNLOCK(cancellable);
-
- return fd;
+
+ 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 (cancellable->priv->fd_refcount > 0);
+
+ priv = cancellable->priv;
+
+ g_mutex_lock (&cancellable_mutex);
+
+ priv->fd_refcount--;
+ if (priv->fd_refcount == 0)
+ {
+ GLIB_PRIVATE_CALL (g_wakeup_free) (priv->wakeup);
+ priv->wakeup = NULL;
+ }
+
+ g_mutex_unlock (&cancellable_mutex);
}
/**
* g_cancellable_cancel:
* @cancellable: a #GCancellable object.
*
- * Will set @cancellable to cancelled, and will emit the CANCELLED
- * signal. This function is thread-safe.
- *
+ * Will set @cancellable to cancelled, and will emit the
+ * #GCancellable::cancelled signal. (However, see the warning about
+ * race conditions in the documentation for that signal if you are
+ * planning to connect to it.)
+ *
+ * This function is thread-safe. In other words, you can safely call
+ * it from a thread other than the one running the operation that was
+ * passed the @cancellable.
+ *
+ * The convention within gio is that cancelling an asynchronous
+ * operation causes it to complete asynchronously. That is, if you
+ * cancel the operation from the same thread in which it is running,
+ * then the operation's #GAsyncReadyCallback will not be invoked until
+ * the application returns to the main loop.
**/
void
g_cancellable_cancel (GCancellable *cancellable)
{
- gboolean cancel;
+ GCancellablePrivate *priv;
- cancel = FALSE;
-
- G_LOCK(cancellable);
- if (cancellable != NULL &&
- !cancellable->cancelled)
+ if (cancellable == NULL ||
+ cancellable->priv->cancelled)
+ return;
+
+ priv = cancellable->priv;
+
+ g_mutex_lock (&cancellable_mutex);
+
+ if (priv->cancelled)
+ {
+ g_mutex_unlock (&cancellable_mutex);
+ return;
+ }
+
+ priv->cancelled = TRUE;
+ priv->cancelled_running = TRUE;
+
+ if (priv->wakeup)
+ GLIB_PRIVATE_CALL (g_wakeup_signal) (priv->wakeup);
+
+ g_mutex_unlock (&cancellable_mutex);
+
+ g_object_ref (cancellable);
+ g_signal_emit (cancellable, signals[CANCELLED], 0);
+
+ 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);
+}
+
+/**
+ * g_cancellable_connect:
+ * @cancellable: A #GCancellable.
+ * @callback: The #GCallback to connect.
+ * @data: Data to pass to @callback.
+ * @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
+ * if the cancellable is cancelled right before connecting.
+ *
+ * @callback is called at most once, either directly at the
+ * time of the connect if @cancellable is already cancelled,
+ * or when @cancellable is cancelled in some thread.
+ *
+ * @data_destroy_func will be called when the handler is
+ * disconnected, or immediately if the cancellable is already
+ * cancelled.
+ *
+ * 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.
+ *
+ * Since: 2.22
+ */
+gulong
+g_cancellable_connect (GCancellable *cancellable,
+ GCallback callback,
+ gpointer data,
+ GDestroyNotify data_destroy_func)
+{
+ gulong id;
+
+ g_return_val_if_fail (G_IS_CANCELLABLE (cancellable), 0);
+
+ g_mutex_lock (&cancellable_mutex);
+
+ if (cancellable->priv->cancelled)
+ {
+ void (*_callback) (GCancellable *cancellable,
+ gpointer user_data);
+
+ g_mutex_unlock (&cancellable_mutex);
+
+ _callback = (void *)callback;
+ id = 0;
+
+ _callback (cancellable, data);
+
+ if (data_destroy_func)
+ data_destroy_func (data);
+ }
+ else
+ {
+ id = g_signal_connect_data (cancellable, "cancelled",
+ callback, data,
+ (GClosureNotify) data_destroy_func,
+ 0);
+
+ g_mutex_unlock (&cancellable_mutex);
+ }
+
+
+ return id;
+}
+
+/**
+ * g_cancellable_disconnect:
+ * @cancellable: (allow-none): A #GCancellable or %NULL.
+ * @handler_id: Handler id of the handler to be disconnected, or %0.
+ *
+ * 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
+ * signal handler is removed. See #GCancellable::cancelled for
+ * details on how to use this.
+ *
+ * If @cancellable is %NULL or @handler_id is %0 this function does
+ * nothing.
+ *
+ * Since: 2.22
+ */
+void
+g_cancellable_disconnect (GCancellable *cancellable,
+ gulong handler_id)
+{
+ GCancellablePrivate *priv;
+
+ if (handler_id == 0 || cancellable == NULL)
+ return;
+
+ g_mutex_lock (&cancellable_mutex);
+
+ priv = cancellable->priv;
+
+ while (priv->cancelled_running)
{
- char ch = 'x';
- cancel = TRUE;
- cancellable->cancelled = TRUE;
- if (cancellable->cancel_pipe[1] != -1)
- write (cancellable->cancel_pipe[1], &ch, 1);
+ priv->cancelled_running_waiting = TRUE;
+ g_cond_wait (&cancellable_cond, &cancellable_mutex);
}
- G_UNLOCK(cancellable);
- if (cancel)
+ g_signal_handler_disconnect (cancellable, handler_id);
+
+ g_mutex_unlock (&cancellable_mutex);
+}
+
+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_object_ref (cancellable);
- g_signal_emit (cancellable, signals[CANCELLED], 0);
- g_object_unref (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;
+}
projects / platform / upstream / glib.git / blobdiff