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/**
* @copyright
* ====================================================================
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
* ====================================================================
* @endcopyright
*
* @file svn_atomic.h
* @brief Macros and functions for atomic operations
*/
#ifndef SVN_ATOMIC_H
#define SVN_ATOMIC_H
#include <apr_version.h>
#include <apr_atomic.h>
#include "svn_error.h"
#include "private/svn_dep_compat.h"
#ifdef __cplusplus
extern "C" {
#endif /* __cplusplus */
/**
* @name Macro definitions for atomic types and operations
*
* @note These are necessary because the apr_atomic API changed somewhat
* between apr-0.x and apr-1.x.
* @{
*/
/** The type used by all the other atomic operations. */
#if APR_VERSION_AT_LEAST(1, 0, 0)
#define svn_atomic_t apr_uint32_t
#else
#define svn_atomic_t apr_atomic_t
#endif
/** Atomically read an #svn_atomic_t from memory. */
#if APR_VERSION_AT_LEAST(1, 0, 0)
#define svn_atomic_read(mem) apr_atomic_read32((mem))
#else
#define svn_atomic_read(mem) apr_atomic_read((mem))
#endif
/** Atomically set an #svn_atomic_t in memory. */
#if APR_VERSION_AT_LEAST(1, 0, 0)
#define svn_atomic_set(mem, val) apr_atomic_set32((mem), (val))
#else
#define svn_atomic_set(mem, val) apr_atomic_set((mem), (val))
#endif
/** Atomically increment an #svn_atomic_t. */
#if APR_VERSION_AT_LEAST(1, 0, 0)
#define svn_atomic_inc(mem) apr_atomic_inc32(mem)
#else
#define svn_atomic_inc(mem) apr_atomic_inc(mem)
#endif
/** Atomically decrement an #svn_atomic_t. */
#if APR_VERSION_AT_LEAST(1, 0, 0)
#define svn_atomic_dec(mem) apr_atomic_dec32(mem)
#else
#define svn_atomic_dec(mem) apr_atomic_dec(mem)
#endif
/**
* Atomic compare-and-swap.
*
* Compare the value that @a mem points to with @a cmp. If they are
* the same swap the value with @a with.
*
* @note svn_atomic_cas should not be combined with the other
* svn_atomic operations. A comment in apr_atomic.h explains
* that on some platforms, the CAS function is implemented in a
* way that is incompatible with the other atomic operations.
*/
#if APR_VERSION_AT_LEAST(1, 0, 0)
#define svn_atomic_cas(mem, with, cmp) \
apr_atomic_cas32((mem), (with), (cmp))
#else
#define svn_atomic_cas(mem, with, cmp) \
apr_atomic_cas((mem), (with), (cmp))
#endif
/** @} */
/**
* Call an initialization function in a thread-safe manner.
*
* @a global_status must be a pointer to a global, zero-initialized
* #svn_atomic_t. @a init_func is a pointer to the function that performs
* the actual initialization. @a baton and and @a pool are passed on to the
* init_func for its use.
*
* @since New in 1.5.
*/
svn_error_t *
svn_atomic__init_once(volatile svn_atomic_t *global_status,
svn_error_t *(*init_func)(void*,apr_pool_t*),
void *baton,
apr_pool_t* pool);
#ifdef __cplusplus
}
#endif /* __cplusplus */
#endif /* SVN_ATOMIC_H */
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