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5609370de9
Usually, after g_pointer_bit_lock() we want to read the pointer that we have. In many cases, when we g_pointer_bit_lock() a pointer, we can access it afterwards without atomic, as nobody is going to modify the pointer then. However, gdataset also supports g_datalist_set_flags(), so the pointer may change at any time and we must always use atomics to read it. For that reason, g_datalist_lock_and_get() does an atomic read right after g_pointer_bit_lock(). g_pointer_bit_lock() can easily access the value that it just set. Add g_pointer_bit_lock_and_get() which can return the value that gets set afterwards. Aside from saving the second atomic-get in certain scenarios, the returned value is also atomically the one that we just set.
110 lines
4.3 KiB
C
110 lines
4.3 KiB
C
/*
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* Copyright © 2008 Ryan Lortie
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* Copyright © 2010 Codethink Limited
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*
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* SPDX-License-Identifier: LGPL-2.1-or-later
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, see <http://www.gnu.org/licenses/>.
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*
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* Author: Ryan Lortie <desrt@desrt.ca>
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*/
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#ifndef __G_BITLOCK_H__
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#define __G_BITLOCK_H__
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#include <glib/gtypes.h>
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#if !defined (__GLIB_H_INSIDE__) && !defined (GLIB_COMPILATION)
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#error "Only <glib.h> can be included directly."
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#endif
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G_BEGIN_DECLS
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GLIB_AVAILABLE_IN_ALL
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void g_bit_lock (volatile gint *address,
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gint lock_bit);
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GLIB_AVAILABLE_IN_ALL
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gboolean g_bit_trylock (volatile gint *address,
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gint lock_bit);
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GLIB_AVAILABLE_IN_ALL
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void g_bit_unlock (volatile gint *address,
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gint lock_bit);
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GLIB_AVAILABLE_IN_ALL
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void g_pointer_bit_lock (volatile void *address,
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gint lock_bit);
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GLIB_AVAILABLE_IN_2_80
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void g_pointer_bit_lock_and_get (gpointer address,
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guint lock_bit,
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guintptr *out_ptr);
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GLIB_AVAILABLE_IN_ALL
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gboolean g_pointer_bit_trylock (volatile void *address,
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gint lock_bit);
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GLIB_AVAILABLE_IN_ALL
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void g_pointer_bit_unlock (volatile void *address,
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gint lock_bit);
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GLIB_AVAILABLE_IN_2_80
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gpointer g_pointer_bit_lock_mask_ptr (gpointer ptr,
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guint lock_bit,
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gboolean set,
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guintptr preserve_mask,
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gpointer preserve_ptr);
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GLIB_AVAILABLE_IN_2_80
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void g_pointer_bit_unlock_and_set (void *address,
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guint lock_bit,
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gpointer ptr,
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guintptr preserve_mask);
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#ifdef __GNUC__
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#define g_pointer_bit_lock(address, lock_bit) \
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(G_GNUC_EXTENSION ({ \
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G_STATIC_ASSERT (sizeof *(address) == sizeof (gpointer)); \
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g_pointer_bit_lock ((address), (lock_bit)); \
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}))
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#define g_pointer_bit_lock_and_get(address, lock_bit, out_ptr) \
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(G_GNUC_EXTENSION ({ \
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G_STATIC_ASSERT (sizeof *(address) == sizeof (gpointer)); \
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g_pointer_bit_lock_and_get ((address), (lock_bit), (out_ptr)); \
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}))
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#define g_pointer_bit_trylock(address, lock_bit) \
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(G_GNUC_EXTENSION ({ \
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G_STATIC_ASSERT (sizeof *(address) == sizeof (gpointer)); \
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g_pointer_bit_trylock ((address), (lock_bit)); \
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}))
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#define g_pointer_bit_unlock(address, lock_bit) \
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(G_GNUC_EXTENSION ({ \
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G_STATIC_ASSERT (sizeof *(address) == sizeof (gpointer)); \
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g_pointer_bit_unlock ((address), (lock_bit)); \
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}))
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#define g_pointer_bit_unlock_and_set(address, lock_bit, ptr, preserve_mask) \
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(G_GNUC_EXTENSION ({ \
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G_STATIC_ASSERT (sizeof *(address) == sizeof (gpointer)); \
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g_pointer_bit_unlock_and_set ((address), (lock_bit), (ptr), (preserve_mask)); \
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}))
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#endif
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G_END_DECLS
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#endif /* __G_BITLOCK_H_ */
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