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Revision 72ed9e04394746495f021133915e6bf7c1d3b5b1 authored by Michael Catanzaro on 25 May 2019, 23:30:12 UTC, committed by Michael Catanzaro on 26 May 2019, 15:17:15 UTC 
gtask: ensure task is destroyed on its context's thread
 
The GTask must be destroyed on the thread that is running its
GMainContext, i.e. the thread that started the task. It must never be
destroyed on the actual task thread when running with
g_task_run_in_thread(), because when it is destroyed, it will unref its
source object and destroy its user data (if a GDestroyNotify was set for
the data using g_task_set_task_data()). The source object and task data
might not be safe to destroy on a secondary thread, though, so this is
incorrect. We have to ensure they are destroyed on the task's context's
thread.

There are different ways we could do this, but the simplest by far is to
ensure the task thread has unreffed the task before the context's thread
executes the callback. And that is simple enough to do using a condition
variable. We have to keep a static global map of all GTasks with
outstanding task threads, which is slightly unfortunate, but we already
have a bunch of global data in this file for managing the thread pool,
and the map will only contain tasks that are currently running in
threads, so it should be small.

Fixes #1346
1 parent e10eff1
Raw File
gcancellable.h 
/* 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>
 */

#ifndef __G_CANCELLABLE_H__
#define __G_CANCELLABLE_H__

#if !defined (__GIO_GIO_H_INSIDE__) && !defined (GIO_COMPILATION)
#error "Only <gio/gio.h> can be included directly."
#endif

#include <gio/giotypes.h>

G_BEGIN_DECLS

#define G_TYPE_CANCELLABLE         (g_cancellable_get_type ())
#define G_CANCELLABLE(o)           (G_TYPE_CHECK_INSTANCE_CAST ((o), G_TYPE_CANCELLABLE, GCancellable))
#define G_CANCELLABLE_CLASS(k)     (G_TYPE_CHECK_CLASS_CAST((k), G_TYPE_CANCELLABLE, GCancellableClass))
#define G_IS_CANCELLABLE(o)        (G_TYPE_CHECK_INSTANCE_TYPE ((o), G_TYPE_CANCELLABLE))
#define G_IS_CANCELLABLE_CLASS(k)  (G_TYPE_CHECK_CLASS_TYPE ((k), G_TYPE_CANCELLABLE))
#define G_CANCELLABLE_GET_CLASS(o) (G_TYPE_INSTANCE_GET_CLASS ((o), G_TYPE_CANCELLABLE, GCancellableClass))

/**
 * GCancellable:
 *
 * Allows actions to be cancelled.
 */
typedef struct _GCancellableClass   GCancellableClass;
typedef struct _GCancellablePrivate GCancellablePrivate;

struct _GCancellable
{
  GObject parent_instance;

  /*< private >*/
  GCancellablePrivate *priv;
};

struct _GCancellableClass
{
  GObjectClass parent_class;

  void (* cancelled) (GCancellable *cancellable);

  /*< private >*/
  /* Padding for future expansion */
  void (*_g_reserved1) (void);
  void (*_g_reserved2) (void);
  void (*_g_reserved3) (void);
  void (*_g_reserved4) (void);
  void (*_g_reserved5) (void);
};

GLIB_AVAILABLE_IN_ALL
GType         g_cancellable_get_type               (void) G_GNUC_CONST;

GLIB_AVAILABLE_IN_ALL
GCancellable *g_cancellable_new                    (void);

/* These are only safe to call inside a cancellable op */
GLIB_AVAILABLE_IN_ALL
gboolean      g_cancellable_is_cancelled           (GCancellable  *cancellable);
GLIB_AVAILABLE_IN_ALL
gboolean      g_cancellable_set_error_if_cancelled (GCancellable  *cancellable,
						    GError       **error);

GLIB_AVAILABLE_IN_ALL
int           g_cancellable_get_fd                 (GCancellable  *cancellable);
GLIB_AVAILABLE_IN_ALL
gboolean      g_cancellable_make_pollfd            (GCancellable  *cancellable,
						    GPollFD       *pollfd);
GLIB_AVAILABLE_IN_ALL
void          g_cancellable_release_fd             (GCancellable  *cancellable);

GLIB_AVAILABLE_IN_ALL
GSource *     g_cancellable_source_new             (GCancellable  *cancellable);

GLIB_AVAILABLE_IN_ALL
GCancellable *g_cancellable_get_current            (void);
GLIB_AVAILABLE_IN_ALL
void          g_cancellable_push_current           (GCancellable  *cancellable);
GLIB_AVAILABLE_IN_ALL
void          g_cancellable_pop_current            (GCancellable  *cancellable);
GLIB_AVAILABLE_IN_ALL
void          g_cancellable_reset                  (GCancellable  *cancellable);
GLIB_AVAILABLE_IN_ALL
gulong        g_cancellable_connect                (GCancellable  *cancellable,
						    GCallback      callback,
						    gpointer       data,
						    GDestroyNotify data_destroy_func);
GLIB_AVAILABLE_IN_ALL
void          g_cancellable_disconnect             (GCancellable  *cancellable,
						    gulong         handler_id);


/* This is safe to call from another thread */
GLIB_AVAILABLE_IN_ALL
void          g_cancellable_cancel       (GCancellable  *cancellable);

G_END_DECLS

#endif /* __G_CANCELLABLE_H__ */
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