glib/gio/gasynchelper.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 "gasynchelper.h"


/**
 * SECTION:gasynchelper
 * @short_description: Asynchronous Helper Functions
 * @include: gio/gio.h
 * @see_also: #GAsyncReady
 * 
 * Provides helper functions for asynchronous operations.
 *
 **/

/*************************************************************************
 *             fd source                                                 *
 ************************************************************************/

typedef struct 
{
  GSource source;
  GPollFD pollfd;
  GCancellable *cancellable;
  gulong cancelled_tag;
} FDSource;

static gboolean 
fd_source_prepare (GSource *source,
		   gint    *timeout)
{
  FDSource *fd_source = (FDSource *)source;
  *timeout = -1;
  
  return g_cancellable_is_cancelled (fd_source->cancellable);
}

static gboolean 
fd_source_check (GSource *source)
{
  FDSource *fd_source = (FDSource *)source;

  return
    g_cancellable_is_cancelled  (fd_source->cancellable) ||
    fd_source->pollfd.revents != 0;
}

static gboolean
fd_source_dispatch (GSource     *source,
		    GSourceFunc  callback,
		    gpointer     user_data)

{
  GFDSourceFunc func = (GFDSourceFunc)callback;
  FDSource *fd_source = (FDSource *)source;

  g_warn_if_fail (func != NULL);

  return (*func) (user_data, fd_source->pollfd.revents, fd_source->pollfd.fd);
}

static void 
fd_source_finalize (GSource *source)
{
  FDSource *fd_source = (FDSource *)source;

  if (fd_source->cancelled_tag)
    g_cancellable_disconnect (fd_source->cancellable,
			      fd_source->cancelled_tag);

  if (fd_source->cancellable)
    g_object_unref (fd_source->cancellable);
}

static GSourceFuncs fd_source_funcs = {
  fd_source_prepare,
  fd_source_check,
  fd_source_dispatch,
  fd_source_finalize
};

/* Might be called on another thread */
static void
fd_source_cancelled_cb (GCancellable *cancellable,
			gpointer      data)
{
  /* Wake up the mainloop in case we're waiting on async calls with FDSource */
  g_main_context_wakeup (NULL);
}

GSource *
_g_fd_source_new (int           fd,
		  gushort       events,
		  GCancellable *cancellable)
{
  GSource *source;
  FDSource *fd_source;

  source = g_source_new (&fd_source_funcs, sizeof (FDSource));
  fd_source = (FDSource *)source;

  if (cancellable)
    fd_source->cancellable = g_object_ref (cancellable);
  
  fd_source->pollfd.fd = fd;
  fd_source->pollfd.events = events;
  g_source_add_poll (source, &fd_source->pollfd);

  if (cancellable)
    fd_source->cancelled_tag =
      g_cancellable_connect (cancellable, 
			     (GCallback)fd_source_cancelled_cb,
			     NULL, NULL);
  
  return source;
}