gobject/gatomicarray.h

   1 /* GObject - GLib Type, Object, Parameter and Signal Library
   2  * Copyright (C) 2009 Benjamin Otte <otte@gnome.org>
   3  *
   4  * SPDX-License-Identifier: LGPL-2.1-or-later
   5  *
   6  * This library is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU Lesser General Public
   8  * License as published by the Free Software Foundation; either
   9  * version 2.1 of the License, or (at your option) any later version.
  10  *
  11  * This library is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  * Lesser General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU Lesser General
  17  * Public License along with this library; if not, see <http://www.gnu.org/licenses/>.
  18  */
  19 #ifndef __G_ATOMIC_ARRAY_H__
  20 #define __G_ATOMIC_ARRAY_H__
  21
  22 #if !defined (__GLIB_GOBJECT_H_INSIDE__) && !defined (GOBJECT_COMPILATION)
  23 #error "Only <glib-object.h> can be included directly."
  24 #endif
  25
  26 #include <glib/glib.h>
  27
  28 G_BEGIN_DECLS
  29
  30 typedef union _GAtomicArrayMetadata
  31 {
  32   gsize size;
  33   /* We have to ensure that the memory location is sufficiently aligned to
  34    * store any object. With C11 this would be max_align_t, but in practise
  35    * gpointer is sufficient for all known architectures. We could change
  36    * this to `_Alignas(max_align_t) char pad` once we depend on C11. */
  37   gpointer _alignment_padding;
  38 } GAtomicArrayMetadata;
  39 #define G_ATOMIC_ARRAY_DATA_SIZE(mem) (((GAtomicArrayMetadata *) (mem) - 1)->size)
  40
  41 typedef struct _GAtomicArray GAtomicArray;
  42 struct _GAtomicArray {
  43   gpointer data;  /* elements - atomic */
  44 };
  45
  46 void     _g_atomic_array_init   (GAtomicArray *array);
  47 gpointer _g_atomic_array_copy   (GAtomicArray *array,
  48                                  gsize         header_size,
  49                                  gsize         additional_element_size);
  50 void     _g_atomic_array_update (GAtomicArray *array,
  51                                  gpointer      new_data);
  52
  53 #define  G_ATOMIC_ARRAY_GET_LOCKED(_array, _type) ((_type *)((_array)->data))
  54
  55 #define G_ATOMIC_ARRAY_DO_TRANSACTION(_array, _type, _C_) G_STMT_START {        \
  56     gpointer *_datap  = &(_array)->data;                                \
  57     _type *transaction_data, *__check;                                          \
  58                                                                                 \
  59     __check = g_atomic_pointer_get (_datap);                                    \
  60     do {                                                                        \
  61       transaction_data = __check;                                               \
  62       {_C_;}                                                                    \
  63       __check = g_atomic_pointer_get (_datap);                                  \
  64     } while (transaction_data != __check);                                      \
  65   } G_STMT_END
  66
  67 G_END_DECLS
  68
  69 #endif  /* __G_ATOMIC_ARRAY_H__ */