/** * @copyright * ==================================================================== * Copyright (c) 2006 CollabNet. All rights reserved. * * This software is licensed as described in the file COPYING, which * you should have received as part of this distribution. The terms * are also available at http://subversion.tigris.org/license-1.html. * If newer versions of this license are posted there, you may use a * newer version instead, at your option. * * This software consists of voluntary contributions made by many * individuals. For exact contribution history, see the revision * history and logs, available at http://subversion.tigris.org/. * ==================================================================== * @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 */