src/TortoiseMerge/libsvn_diff/private/svn_atomic.h

   1 /**
   2  * @copyright
   3  * ====================================================================
   4  *    Licensed to the Apache Software Foundation (ASF) under one
   5  *    or more contributor license agreements.  See the NOTICE file
   6  *    distributed with this work for additional information
   7  *    regarding copyright ownership.  The ASF licenses this file
   8  *    to you under the Apache License, Version 2.0 (the
   9  *    "License"); you may not use this file except in compliance
  10  *    with the License.  You may obtain a copy of the License at
  11  *
  12  *      http://www.apache.org/licenses/LICENSE-2.0
  13  *
  14  *    Unless required by applicable law or agreed to in writing,
  15  *    software distributed under the License is distributed on an
  16  *    "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
  17  *    KIND, either express or implied.  See the License for the
  18  *    specific language governing permissions and limitations
  19  *    under the License.
  20  * ====================================================================
  21  * @endcopyright
  22  *
  23  * @file svn_atomic.h
  24  * @brief Macros and functions for atomic operations
  25  */
  26
  27 #ifndef SVN_ATOMIC_H
  28 #define SVN_ATOMIC_H
  29
  30 #include <apr_version.h>
  31 #include <apr_atomic.h>
  32
  33 #include "svn_error.h"
  34 #include "private/svn_dep_compat.h"
  35
  36 #ifdef __cplusplus
  37 extern "C" {
  38 #endif /* __cplusplus */
  39
  40 /**
  41  * @name Macro definitions for atomic types and operations
  42  *
  43  * @note These are necessary because the apr_atomic API changed somewhat
  44  *       between apr-0.x and apr-1.x.
  45  * @{
  46  */
  47
  48 /** The type used by all the other atomic operations. */
  49 #if APR_VERSION_AT_LEAST(1, 0, 0)
  50 #define svn_atomic_t apr_uint32_t
  51 #else
  52 #define svn_atomic_t apr_atomic_t
  53 #endif
  54
  55 /** Atomically read an #svn_atomic_t from memory. */
  56 #if APR_VERSION_AT_LEAST(1, 0, 0)
  57 #define svn_atomic_read(mem) apr_atomic_read32((mem))
  58 #else
  59 #define svn_atomic_read(mem) apr_atomic_read((mem))
  60 #endif
  61
  62 /** Atomically set an #svn_atomic_t in memory. */
  63 #if APR_VERSION_AT_LEAST(1, 0, 0)
  64 #define svn_atomic_set(mem, val) apr_atomic_set32((mem), (val))
  65 #else
  66 #define svn_atomic_set(mem, val) apr_atomic_set((mem), (val))
  67 #endif
  68
  69 /** Atomically increment an #svn_atomic_t. */
  70 #if APR_VERSION_AT_LEAST(1, 0, 0)
  71 #define svn_atomic_inc(mem) apr_atomic_inc32(mem)
  72 #else
  73 #define svn_atomic_inc(mem) apr_atomic_inc(mem)
  74 #endif
  75
  76 /** Atomically decrement an #svn_atomic_t. */
  77 #if APR_VERSION_AT_LEAST(1, 0, 0)
  78 #define svn_atomic_dec(mem) apr_atomic_dec32(mem)
  79 #else
  80 #define svn_atomic_dec(mem) apr_atomic_dec(mem)
  81 #endif
  82
  83 /**
  84  * Atomic compare-and-swap.
  85  *
  86  * Compare the value that @a mem points to with @a cmp. If they are
  87  * the same swap the value with @a with.
  88  *
  89  * @note svn_atomic_cas should not be combined with the other
  90  *       svn_atomic operations.  A comment in apr_atomic.h explains
  91  *       that on some platforms, the CAS function is implemented in a
  92  *       way that is incompatible with the other atomic operations.
  93  */
  94 #if APR_VERSION_AT_LEAST(1, 0, 0)
  95 #define svn_atomic_cas(mem, with, cmp) \
  96     apr_atomic_cas32((mem), (with), (cmp))
  97 #else
  98 #define svn_atomic_cas(mem, with, cmp) \
  99     apr_atomic_cas((mem), (with), (cmp))
 100 #endif
 101 /** @} */
 102
 103 /**
 104  * Call an initialization function in a thread-safe manner.
 105  *
 106  * @a global_status must be a pointer to a global, zero-initialized
 107  * #svn_atomic_t. @a init_func is a pointer to the function that performs
 108  * the actual initialization. @a baton and and @a pool are passed on to the
 109  * init_func for its use.
 110  *
 111  * @since New in 1.5.
 112  */
 113 svn_error_t *
 114 svn_atomic__init_once(volatile svn_atomic_t *global_status,
 115                       svn_error_t *(*init_func)(void*,apr_pool_t*),
 116                       void *baton,
 117                       apr_pool_t* pool);
 118
 119 #ifdef __cplusplus
 120 }
 121 #endif /* __cplusplus */
 122
 123 #endif /* SVN_ATOMIC_H */