glib/gio/gsimpleasyncresult.c

/* 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 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, write to the
 * Free Software Foundation, Inc., 59 Temple Place, Suite 330,
 * Boston, MA 02111-1307, USA.
 *
 * Author: Alexander Larsson <alexl@redhat.com>
 */

#include "config.h"

#include <sys/types.h>
#include <sys/stat.h>
#include <string.h>
#include <errno.h>
#include <fcntl.h>
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif

#include "gsimpleasyncresult.h"
#include "gasyncresult.h"
#include "gcancellable.h"
#include "gioscheduler.h"
#include <gio/gioerror.h>
#include "glibintl.h"

#include "gioalias.h"

/**
 * SECTION:gsimpleasyncresult
 * @short_description: Simple asynchronous results implementation
 * @include: gio/gio.h
 * @see_also: #GAsyncResult
 *
 * Implements #GAsyncResult for simple cases. Most of the time, this 
 * will be all an application needs, and will be used transparently. 
 * Because of this, #GSimpleAsyncResult is used throughout GIO for 
 * handling asynchronous functions. 
 * 
 * GSimpleAsyncResult handles #GAsyncReadyCallback<!-- -->s, error 
 * reporting, operation cancellation and the final state of an operation, 
 * completely transparent to the application. Results can be returned 
 * as a pointer e.g. for functions that return data that is collected 
 * asynchronously, a boolean value for checking the success or failure 
 * of an operation, or a #gssize for operations which return the number 
 * of bytes modified by the operation; all of the simple return cases 
 * are covered.
 * 
 * Most of the time, an application will not need to know of the details 
 * of this API; it is handled transparently, and any necessary operations 
 * are handled by #GAsyncResult's interface. However, if implementing a 
 * new GIO module, for writing language bindings, or for complex 
 * applications that need better control of how asynchronous operations 
 * are completed, it is important to understand this functionality.
 * 
 * GSimpleAsyncResults are tagged with the calling function to ensure 
 * that asynchronous functions and their finishing functions are used 
 * together correctly.
 * 
 * To create a new #GSimpleAsyncResult, call g_simple_async_result_new(). 
 * If the result needs to be created for a #GError, use 
 * g_simple_async_result_new_from_error(). If a #GError is not available 
 * (e.g. the asynchronous operation's doesn't take a #GError argument), 
 * but the result still needs to be created for an error condition, use
 * g_simple_async_result_new_error() (or g_simple_async_result_set_error_va()
 * if your application or binding requires passing a variable argument list 
 * directly), and the error can then be propegated through the use of 
 * g_simple_async_result_propagate_error().
 * 
 * An asynchronous operation can be made to ignore a cancellation event by 
 * calling g_simple_async_result_set_handle_cancellation() with a 
 * #GSimpleAsyncResult for the operation and %FALSE. This is useful for
 * operations that are dangerous to cancel, such as close (which would
 * cause a leak if cancelled before being run).
 * 
 * GSimpleAsyncResult can integrate into GLib's event loop, #GMainLoop, 
 * or it can use #GThread<!-- -->s if available. 
 * g_simple_async_result_complete() will finish an I/O task directly within 
 * the main event loop. g_simple_async_result_complete_in_idle() will 
 * integrate the I/O task into the main event loop as an idle function and 
 * g_simple_async_result_run_in_thread() will run the job in a separate 
 * thread.
 * 
 * To set the results of an asynchronous function, 
 * g_simple_async_result_set_op_res_gpointer(), 
 * g_simple_async_result_set_op_res_gboolean(), and 
 * g_simple_async_result_set_op_res_gssize()
 * are provided, setting the operation's result to a gpointer, gboolean, or 
 * gssize, respectively.
 * 
 * Likewise, to get the result of an asynchronous function, 
 * g_simple_async_result_get_op_res_gpointer(),
 * g_simple_async_result_get_op_res_gboolean(), and 
 * g_simple_async_result_get_op_res_gssize() are 
 * provided, getting the operation's result as a gpointer, gboolean, and 
 * gssize, respectively.
 **/

static void g_simple_async_result_async_result_iface_init (GAsyncResultIface       *iface);

struct _GSimpleAsyncResult
{
  GObject parent_instance;

  GObject *source_object;
  GAsyncReadyCallback callback;
  gpointer user_data;
  GError *error;
  gboolean failed;
  gboolean handle_cancellation;

  gpointer source_tag;

  union {
    gpointer v_pointer;
    gboolean v_boolean;
    gssize   v_ssize;
  } op_res;

  GDestroyNotify destroy_op_res;
};

struct _GSimpleAsyncResultClass
{
  GObjectClass parent_class;
};


G_DEFINE_TYPE_WITH_CODE (GSimpleAsyncResult, g_simple_async_result, G_TYPE_OBJECT,
			 G_IMPLEMENT_INTERFACE (G_TYPE_ASYNC_RESULT,
						g_simple_async_result_async_result_iface_init))

static void
g_simple_async_result_finalize (GObject *object)
{
  GSimpleAsyncResult *simple;

  simple = G_SIMPLE_ASYNC_RESULT (object);

  if (simple->source_object)
    g_object_unref (simple->source_object);

  if (simple->destroy_op_res)
    simple->destroy_op_res (simple->op_res.v_pointer);

  if (simple->error)
    g_error_free (simple->error);

  G_OBJECT_CLASS (g_simple_async_result_parent_class)->finalize (object);
}

static void
g_simple_async_result_class_init (GSimpleAsyncResultClass *klass)
{
  GObjectClass *gobject_class = G_OBJECT_CLASS (klass);
  
  gobject_class->finalize = g_simple_async_result_finalize;
}

static void
g_simple_async_result_init (GSimpleAsyncResult *simple)
{
  simple->handle_cancellation = TRUE;
}

/**
 * g_simple_async_result_new:
 * @source_object: a #GObject the asynchronous function was called with.
 * @callback: a #GAsyncReadyCallback.
 * @user_data: user data passed to @callback.
 * @source_tag: the asynchronous function.
 * 
 * Creates a #GSimpleAsyncResult.
 * 
 * Returns: a #GSimpleAsyncResult.
 **/
GSimpleAsyncResult *
g_simple_async_result_new (GObject             *source_object,
                           GAsyncReadyCallback  callback,
                           gpointer             user_data,
                           gpointer             source_tag)
{
  GSimpleAsyncResult *simple;

  g_return_val_if_fail (G_IS_OBJECT (source_object), NULL);

  simple = g_object_new (G_TYPE_SIMPLE_ASYNC_RESULT, NULL);
  simple->callback = callback;
  simple->source_object = g_object_ref (source_object);
  simple->user_data = user_data;
  simple->source_tag = source_tag;
  
  return simple;
}

/**
 * g_simple_async_result_new_from_error:
 * @source_object: a #GObject.
 * @callback: a #GAsyncReadyCallback.
 * @user_data: user data passed to @callback.
 * @error: a #GError location.
 * 
 * Creates a #GSimpleAsyncResult from an error condition.
 * 
 * Returns: a #GSimpleAsyncResult.
 **/
GSimpleAsyncResult *
g_simple_async_result_new_from_error (GObject             *source_object,
                                      GAsyncReadyCallback  callback,
                                      gpointer             user_data,
                                      GError              *error)
{
  GSimpleAsyncResult *simple;

  g_return_val_if_fail (G_IS_OBJECT (source_object), NULL);

  simple = g_simple_async_result_new (source_object,
				      callback,
				      user_data, NULL);
  g_simple_async_result_set_from_error (simple, error);

  return simple;
}

/**
 * g_simple_async_result_new_error:
 * @source_object: a #GObject.
 * @callback: a #GAsyncReadyCallback. 
 * @user_data: user data passed to @callback.
 * @domain: a #GQuark.
 * @code: an error code.
 * @format: a string with format characters.
 * @...: a list of values to insert into @format.
 * 
 * Creates a new #GSimpleAsyncResult with a set error.
 * 
 * Returns: a #GSimpleAsyncResult.
 **/
GSimpleAsyncResult *
g_simple_async_result_new_error (GObject             *source_object,
                                 GAsyncReadyCallback  callback,
                                 gpointer             user_data,
                                 GQuark               domain,
                                 gint                 code,
                                 const char          *format,
                                 ...)
{
  GSimpleAsyncResult *simple;
  va_list args;
  
  g_return_val_if_fail (G_IS_OBJECT (source_object), NULL);
  g_return_val_if_fail (domain != 0, NULL);
  g_return_val_if_fail (format != NULL, NULL);

  simple = g_simple_async_result_new (source_object,
				      callback,
				      user_data, NULL);

  va_start (args, format);
  g_simple_async_result_set_error_va (simple, domain, code, format, args);
  va_end (args);
  
  return simple;
}


static gpointer
g_simple_async_result_get_user_data (GAsyncResult *res)
{
  return G_SIMPLE_ASYNC_RESULT (res)->user_data;
}

static GObject *
g_simple_async_result_get_source_object (GAsyncResult *res)
{
  if (G_SIMPLE_ASYNC_RESULT (res)->source_object)
    return g_object_ref (G_SIMPLE_ASYNC_RESULT (res)->source_object);
  return NULL;
}

static void
g_simple_async_result_async_result_iface_init (GAsyncResultIface *iface)
{
  iface->get_user_data = g_simple_async_result_get_user_data;
  iface->get_source_object = g_simple_async_result_get_source_object;
}

/**
 * g_simple_async_result_set_handle_cancellation:
 * @simple: a #GSimpleAsyncResult.
 * @handle_cancellation: a #gboolean.
 * 
 * Sets whether to handle cancellation within the asynchronous operation.
 * 
 **/
void
g_simple_async_result_set_handle_cancellation (GSimpleAsyncResult *simple,
                                               gboolean            handle_cancellation)
{
  g_return_if_fail (G_IS_SIMPLE_ASYNC_RESULT (simple));
  simple->handle_cancellation = handle_cancellation;
}

/**
 * g_simple_async_result_get_source_tag:
 * @simple: a #GSimpleAsyncResult.
 * 
 * Gets the source tag for the #GSimpleAsyncResult.
 * 
 * Returns: a #gpointer to the source object for the #GSimpleAsyncResult.
 **/
gpointer
g_simple_async_result_get_source_tag (GSimpleAsyncResult *simple)
{
  g_return_val_if_fail (G_IS_SIMPLE_ASYNC_RESULT (simple), NULL);
  return simple->source_tag;
}

/**
 * g_simple_async_result_propagate_error:
 * @simple: a #GSimpleAsyncResult.
 * @dest: a location to propegate the error to.
 * 
 * Propagates an error from within the simple asynchronous result to
 * a given destination.
 * 
 * Returns: %TRUE if the error was propegated to @dest. %FALSE otherwise.
 **/
gboolean
g_simple_async_result_propagate_error (GSimpleAsyncResult  *simple,
                                       GError             **dest)
{
  g_return_val_if_fail (G_IS_SIMPLE_ASYNC_RESULT (simple), FALSE);

  if (simple->failed)
    {
      g_propagate_error (dest, simple->error);
      simple->error = NULL;
      return TRUE;
    }

  return FALSE;
}

/**
 * g_simple_async_result_set_op_res_gpointer:
 * @simple: a #GSimpleAsyncResult.
 * @op_res: a pointer result from an asynchronous function.
 * @destroy_op_res: a #GDestroyNotify function.
 * 
 * Sets the operation result within the asynchronous result to a pointer.
 **/
void
g_simple_async_result_set_op_res_gpointer (GSimpleAsyncResult *simple,
                                           gpointer            op_res,
                                           GDestroyNotify      destroy_op_res)
{
  g_return_if_fail (G_IS_SIMPLE_ASYNC_RESULT (simple));

  simple->op_res.v_pointer = op_res;
  simple->destroy_op_res = destroy_op_res;
}

/**
 * g_simple_async_result_get_op_res_gpointer:
 * @simple: a #GSimpleAsyncResult.
 * 
 * Gets a pointer result as returned by the asynchronous function.
 * 
 * Returns: a pointer from the result.
 **/
gpointer
g_simple_async_result_get_op_res_gpointer (GSimpleAsyncResult *simple)
{
  g_return_val_if_fail (G_IS_SIMPLE_ASYNC_RESULT (simple), NULL);
  return simple->op_res.v_pointer;
}

/**
 * g_simple_async_result_set_op_res_gssize:
 * @simple: a #GSimpleAsyncResult.
 * @op_res: a #gssize.
 * 
 * Sets the operation result within the asynchronous result to 
 * the given @op_res. 
 **/
void
g_simple_async_result_set_op_res_gssize (GSimpleAsyncResult *simple,
                                         gssize              op_res)
{
  g_return_if_fail (G_IS_SIMPLE_ASYNC_RESULT (simple));
  simple->op_res.v_ssize = op_res;
}

/**
 * g_simple_async_result_get_op_res_gssize:
 * @simple: a #GSimpleAsyncResult.
 * 
 * Gets a gssize from the asynchronous result.
 * 
 * Returns: a gssize returned from the asynchronous function.
 **/
gssize
g_simple_async_result_get_op_res_gssize (GSimpleAsyncResult *simple)
{
  g_return_val_if_fail (G_IS_SIMPLE_ASYNC_RESULT (simple), 0);
  return simple->op_res.v_ssize;
}

/**
 * g_simple_async_result_set_op_res_gboolean:
 * @simple: a #GSimpleAsyncResult.
 * @op_res: a #gboolean.
 * 
 * Sets the operation result to a boolean within the asynchronous result.
 **/
void
g_simple_async_result_set_op_res_gboolean (GSimpleAsyncResult *simple,
                                           gboolean            op_res)
{
  g_return_if_fail (G_IS_SIMPLE_ASYNC_RESULT (simple));
  simple->op_res.v_boolean = !!op_res;
}

/**
 * g_simple_async_result_get_op_res_gboolean:
 * @simple: a #GSimpleAsyncResult.
 * 
 * Gets the operation result boolean from within the asynchronous result.
 * 
 * Returns: %TRUE if the operation's result was %TRUE, %FALSE 
 *     if the operation's result was %FALSE. 
 **/
gboolean
g_simple_async_result_get_op_res_gboolean (GSimpleAsyncResult *simple)
{
  g_return_val_if_fail (G_IS_SIMPLE_ASYNC_RESULT (simple), FALSE);
  return simple->op_res.v_boolean;
}

/**
 * g_simple_async_result_set_from_error:
 * @simple: a #GSimpleAsyncResult.
 * @error: #GError.
 * 
 * Sets the result from a #GError. 
 **/
void
g_simple_async_result_set_from_error (GSimpleAsyncResult *simple,
                                      GError             *error)
{
  g_return_if_fail (G_IS_SIMPLE_ASYNC_RESULT (simple));
  g_return_if_fail (error != NULL);

  if (simple->error)
    g_error_free (simple->error);
  simple->error = g_error_copy (error);
  simple->failed = TRUE;
}

static GError* 
_g_error_new_valist (GQuark     domain,
                    gint        code,
                    const char *format,
                    va_list     args)
{
  GError *error;
  char *message;

  message = g_strdup_vprintf (format, args);

  error = g_error_new_literal (domain, code, message);
  g_free (message);
  
  return error;
}

/**
 * g_simple_async_result_set_error_va:
 * @simple: a #GSimpleAsyncResult.
 * @domain: a #GQuark (usually #G_IO_ERROR).
 * @code: an error code.
 * @format: a formatted error reporting string.
 * @args: va_list of arguments. 
 * 
 * Sets an error within the asynchronous result without a #GError. 
 * Unless writing a binding, see g_simple_async_result_set_error().
 **/
void
g_simple_async_result_set_error_va (GSimpleAsyncResult *simple,
                                    GQuark              domain,
                                    gint                code,
                                    const char         *format,
                                    va_list             args)
{
  g_return_if_fail (G_IS_SIMPLE_ASYNC_RESULT (simple));
  g_return_if_fail (domain != 0);
  g_return_if_fail (format != NULL);

  if (simple->error)
    g_error_free (simple->error);
  simple->error = _g_error_new_valist (domain, code, format, args);
  simple->failed = TRUE;
}

/**
 * g_simple_async_result_set_error:
 * @simple: a #GSimpleAsyncResult.
 * @domain: a #GQuark (usually #G_IO_ERROR).
 * @code: an error code.
 * @format: a formatted error reporting string.
 * @...: a list of variables to fill in @format.
 * 
 * Sets an error within the asynchronous result without a #GError.
 **/
void
g_simple_async_result_set_error (GSimpleAsyncResult *simple,
                                 GQuark              domain,
                                 gint                code,
                                 const char         *format,
                                 ...)
{
  va_list args;

  g_return_if_fail (G_IS_SIMPLE_ASYNC_RESULT (simple));
  g_return_if_fail (domain != 0);
  g_return_if_fail (format != NULL);

  va_start (args, format);
  g_simple_async_result_set_error_va (simple, domain, code, format, args);
  va_end (args);
}

/**
 * g_simple_async_result_complete:
 * @simple: a #GSimpleAsyncResult.
 * 
 * Completes an asynchronous I/O job.
 * Must be called in the main thread, as it invokes the callback that
 * should be called in the main thread. If you are in a different thread
 * use g_simple_async_result_complete_in_idle().
 **/
void
g_simple_async_result_complete (GSimpleAsyncResult *simple)
{
  g_return_if_fail (G_IS_SIMPLE_ASYNC_RESULT (simple));

  if (simple->callback)
    simple->callback (simple->source_object,
		      G_ASYNC_RESULT (simple),
		      simple->user_data);
}

static gboolean
complete_in_idle_cb (gpointer data)
{
  GSimpleAsyncResult *simple = G_SIMPLE_ASYNC_RESULT (data);

  g_simple_async_result_complete (simple);

  return FALSE;
}

/**
 * g_simple_async_result_complete_in_idle:
 * @simple: a #GSimpleAsyncResult.
 * 
 * Completes an asynchronous function in the main event loop using 
 * an idle function.
 **/
void
g_simple_async_result_complete_in_idle (GSimpleAsyncResult *simple)
{
  GSource *source;
  guint id;
  
  g_return_if_fail (G_IS_SIMPLE_ASYNC_RESULT (simple));
  
  g_object_ref (simple);
  
  source = g_idle_source_new ();
  g_source_set_priority (source, G_PRIORITY_DEFAULT);
  g_source_set_callback (source, complete_in_idle_cb, simple, g_object_unref);

  id = g_source_attach (source, NULL);
  g_source_unref (source);
}

typedef struct {
  GSimpleAsyncResult *simple;
  GCancellable *cancellable;
  GSimpleAsyncThreadFunc func;
} RunInThreadData;


static gboolean
complete_in_idle_cb_for_thread (gpointer _data)
{
  RunInThreadData *data = _data;
  GSimpleAsyncResult *simple;

  simple = data->simple;
  
  if (simple->handle_cancellation &&
      g_cancellable_is_cancelled (data->cancellable))
    g_simple_async_result_set_error (simple,
                                     G_IO_ERROR,
                                     G_IO_ERROR_CANCELLED,
                                     "%s", _("Operation was cancelled"));
  
  g_simple_async_result_complete (simple);

  if (data->cancellable)
    g_object_unref (data->cancellable);
  g_object_unref (data->simple);
  g_free (data);
  
  return FALSE;
}

static gboolean
run_in_thread (GIOSchedulerJob *job,
               GCancellable    *c,
               gpointer         _data)
{
  RunInThreadData *data = _data;
  GSimpleAsyncResult *simple = data->simple;
  GSource *source;
  guint id;
  
  if (simple->handle_cancellation &&
      g_cancellable_is_cancelled (c))
    g_simple_async_result_set_error (simple,
                                     G_IO_ERROR,
                                     G_IO_ERROR_CANCELLED,
                                     "%s", _("Operation was cancelled"));
  else
    data->func (simple,
                simple->source_object,
                c);

  source = g_idle_source_new ();
  g_source_set_priority (source, G_PRIORITY_DEFAULT);
  g_source_set_callback (source, complete_in_idle_cb_for_thread, data, NULL);

  id = g_source_attach (source, NULL);
  g_source_unref (source);

  return FALSE;
}

/**
 * g_simple_async_result_run_in_thread:
 * @simple: a #GSimpleAsyncResult.
 * @func: a #GSimpleAsyncThreadFunc.
 * @io_priority: the io priority of the request.
 * @cancellable: optional #GCancellable object, %NULL to ignore. 
 * 
 * Runs the asynchronous job in a separated thread.
 **/
void
g_simple_async_result_run_in_thread (GSimpleAsyncResult     *simple,
                                     GSimpleAsyncThreadFunc  func,
                                     int                     io_priority, 
                                     GCancellable           *cancellable)
{
  RunInThreadData *data;
  
  g_return_if_fail (G_IS_SIMPLE_ASYNC_RESULT (simple));
  g_return_if_fail (func != NULL);

  data = g_new (RunInThreadData, 1);
  data->func = func;
  data->simple = g_object_ref (simple);
  data->cancellable = cancellable;
  if (cancellable)
    g_object_ref (cancellable);
  g_io_scheduler_push_job (run_in_thread, data, NULL, io_priority, cancellable);
}

/**
 * g_simple_async_report_error_in_idle:
 * @object: a #GObject.
 * @callback: a #GAsyncReadyCallback. 
 * @user_data: user data passed to @callback.
 * @domain: a #GQuark containing the error domain (usually #G_IO_ERROR).
 * @code: a specific error code.
 * @format: a formatted error reporting string.
 * @...: a list of variables to fill in @format.
 * 
 * Reports an error in an asynchronous function in an idle function by 
 * directly setting the contents of the #GAsyncResult with the given error
 * information.
 **/
void
g_simple_async_report_error_in_idle (GObject             *object,
                                     GAsyncReadyCallback  callback,
                                     gpointer             user_data,
                                     GQuark               domain,
                                     gint                 code,
                                     const char          *format,
                                     ...)
{
  GSimpleAsyncResult *simple;
  va_list args;
  
  g_return_if_fail (G_IS_OBJECT (object));
  g_return_if_fail (domain != 0);
  g_return_if_fail (format != NULL);

  simple = g_simple_async_result_new (object,
				      callback,
				      user_data, NULL);

  va_start (args, format);
  g_simple_async_result_set_error_va (simple, domain, code, format, args);
  va_end (args);
  g_simple_async_result_complete_in_idle (simple);
  g_object_unref (simple);
}

/**
 * g_simple_async_report_gerror_in_idle:
 * @object: a #GObject.
 * @callback: a #GAsyncReadyCallback. 
 * @user_data: user data passed to @callback.
 * @error: the #GError to report
 * 
 * Reports an error in an idle function. Similar to 
 * g_simple_async_report_error_in_idle(), but takes a #GError rather 
 * than building a new one.
 **/
void
g_simple_async_report_gerror_in_idle (GObject *object,
				      GAsyncReadyCallback callback,
				      gpointer user_data,
				      GError *error)
{
  GSimpleAsyncResult *simple;
  
  g_return_if_fail (G_IS_OBJECT (object));
  g_return_if_fail (error != NULL);

  simple = g_simple_async_result_new_from_error (object,
						 callback,
						 user_data,
						 error);
  g_simple_async_result_complete_in_idle (simple);
  g_object_unref (simple);
}

#define __G_SIMPLE_ASYNC_RESULT_C__
#include "gioaliasdef.c"