/* GIO - GLib Input, Output and Streaming Library

 *

 * Copyright (C) 2006-2007 Red Hat, Inc.

 *

 * This library is free software; you can redistribute it and/or

 * modify it under the terms of the GNU Lesser General Public

 * License as published by the Free Software Foundation; either

 * version 2.1 of the License, or (at your option) any later version.

 *

 * This library is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

 * 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, see <http://www.gnu.org/licenses/>.

 *

 * Author: Alexander Larsson <alexl@redhat.com>

 */

#include "config.h"

#include "gasyncresult.h"

#include "gsimpleasyncresult.h"

#include "glibintl.h"

/**

 * SECTION:gasyncresult

 * @short_description: Asynchronous Function Results

 * @include: gio/gio.h

 * @see_also: #GTask

 *

 * Provides a base class for implementing asynchronous function results.

 *

 * Asynchronous operations are broken up into two separate operations

 * which are chained together by a #GAsyncReadyCallback. To begin

 * an asynchronous operation, provide a #GAsyncReadyCallback to the

 * asynchronous function. This callback will be triggered when the

 * operation has completed, and must be run in a later iteration of

 * the [thread-default main context][g-main-context-push-thread-default]

 * from where the operation was initiated. It will be passed a

 * #GAsyncResult instance filled with the details of the operation's

 * success or failure, the object the asynchronous function was

 * started for and any error codes returned. The asynchronous callback

 * function is then expected to call the corresponding "_finish()"

 * function, passing the object the function was called for, the

 * #GAsyncResult instance, and (optionally) an @error to grab any

 * error conditions that may have occurred.

 *

 * The "_finish()" function for an operation takes the generic result

 * (of type #GAsyncResult) and returns the specific result that the

 * operation in question yields (e.g. a #GFileEnumerator for a

 * "enumerate children" operation). If the result or error status of the

 * operation is not needed, there is no need to call the "_finish()"

 * function; GIO will take care of cleaning up the result and error

 * information after the #GAsyncReadyCallback returns. You can pass

 * %NULL for the #GAsyncReadyCallback if you don't need to take any

 * action at all after the operation completes. Applications may also

 * take a reference to the #GAsyncResult and call "_finish()" later;

 * however, the "_finish()" function may be called at most once.

 *

 * Example of a typical asynchronous operation flow:

 * |[<!-- language="C" -->

 * void _theoretical_frobnitz_async (Theoretical         *t,

 *                                   GCancellable        *c,

 *                                   GAsyncReadyCallback  cb,

 *                                   gpointer             u);

 *

 * gboolean _theoretical_frobnitz_finish (Theoretical   *t,

 *                                        GAsyncResult  *res,

 *                                        GError       **e);

 *

 * static void

 * frobnitz_result_func (GObject      *source_object,

 *       GAsyncResult *res,

 *       gpointer      user_data)

 * {

 *   gboolean success = FALSE;

 *

 *   success = _theoretical_frobnitz_finish (source_object, res, NULL);

 *

 *   if (success)

 *     g_printf ("Hurray!\n");

 *   else

 *     g_printf ("Uh oh!\n");

 *

 *   ...

 *

 * }

 *

 * int main (int argc, void *argv[])

 * {

 *    ...

 *

 *    _theoretical_frobnitz_async (theoretical_data,

 *                                 NULL,

 *                                 frobnitz_result_func,

 *                                 NULL);

 *

 *    ...

 * }

 * ]|

 *

 * The callback for an asynchronous operation is called only once, and is

 * always called, even in the case of a cancelled operation. On cancellation

 * the result is a %G_IO_ERROR_CANCELLED error.

 *

 * ## I/O Priority # {#io-priority}

 *

 * Many I/O-related asynchronous operations have a priority parameter,

 * which is used in certain cases to determine the order in which

 * operations are executed. They are not used to determine system-wide

 * I/O scheduling. Priorities are integers, with lower numbers indicating

 * higher priority. It is recommended to choose priorities between

 * %G_PRIORITY_LOW and %G_PRIORITY_HIGH, with %G_PRIORITY_DEFAULT

 * as a default.

 */

typedef GAsyncResultIface GAsyncResultInterface;

G_DEFINE_INTERFACE (GAsyncResult, g_async_result, G_TYPE_OBJECT)

static void

g_async_result_default_init (GAsyncResultInterface *iface)

{

}

/**

 * g_async_result_get_user_data:

 * @res: a #GAsyncResult.

 *

 * Gets the user data from a #GAsyncResult.

 *

 * Returns: (transfer full): the user data for @res.

 **/

gpointer

g_async_result_get_user_data (GAsyncResult *res)

{

  GAsyncResultIface *iface;

  g_return_val_if_fail (G_IS_ASYNC_RESULT (res), NULL);

  iface = G_ASYNC_RESULT_GET_IFACE (res);

  return (* iface->get_user_data) (res);

}

/**

 * g_async_result_get_source_object:

 * @res: a #GAsyncResult

 *

 * Gets the source object from a #GAsyncResult.

 *

 * Returns: (transfer full) (nullable): a new reference to the source

 *    object for the @res, or %NULL if there is none.

 */

GObject *

g_async_result_get_source_object (GAsyncResult *res)

{

  GAsyncResultIface *iface;

  g_return_val_if_fail (G_IS_ASYNC_RESULT (res), NULL);

  iface = G_ASYNC_RESULT_GET_IFACE (res);

  return (* iface->get_source_object) (res);

}

/**

 * g_async_result_legacy_propagate_error:

 * @res: a #GAsyncResult

 * @error: (out): a location to propagate the error to.

 *

 * If @res is a #GSimpleAsyncResult, this is equivalent to

 * g_simple_async_result_propagate_error(). Otherwise it returns

 * %FALSE.

 *

 * This can be used for legacy error handling in async *_finish()

 * wrapper functions that traditionally handled #GSimpleAsyncResult

 * error returns themselves rather than calling into the virtual method.

 * This should not be used in new code; #GAsyncResult errors that are

 * set by virtual methods should also be extracted by virtual methods,

 * to enable subclasses to chain up correctly.

 *

 * Returns: %TRUE if @error is has been filled in with an error from

 *   @res, %FALSE if not.

 *

 * Since: 2.34

 **/

gboolean

g_async_result_legacy_propagate_error (GAsyncResult  *res,

               GError       **error)

{

  /* This doesn't use a vmethod, because it's only for code that used

   * to use GSimpleAsyncResult. (But it's a GAsyncResult method so

   * that callers don't need to worry about GSimpleAsyncResult

   * deprecation warnings in the future.)

   */

  G_GNUC_BEGIN_IGNORE_DEPRECATIONS

  if (G_IS_SIMPLE_ASYNC_RESULT (res))

    {

      return g_simple_async_result_propagate_error (G_SIMPLE_ASYNC_RESULT (res),

                error);

    }

  else

    return FALSE;

  G_GNUC_END_IGNORE_DEPRECATIONS

}

/**

 * g_async_result_is_tagged:

 * @res: a #GAsyncResult

 * @source_tag: an application-defined tag

 *

 * Checks if @res has the given @source_tag (generally a function

 * pointer indicating the function @res was created by).

 *

 * Returns: %TRUE if @res has the indicated @source_tag, %FALSE if

 *   not.

 *

 * Since: 2.34

 **/

gboolean

g_async_result_is_tagged (GAsyncResult  *res,

        gpointer       source_tag)

{

  GAsyncResultIface *iface;

  g_return_val_if_fail (G_IS_ASYNC_RESULT (res), FALSE);

  iface = G_ASYNC_RESULT_GET_IFACE (res);

  if (!iface->is_tagged)

    return FALSE;

  return (* iface->is_tagged) (res, source_tag);

}