Edit File: apr_atomic.h
/* 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. */ #ifndef APR_ATOMIC_H #define APR_ATOMIC_H /** * @file apr_atomic.h * @brief APR Atomic Operations */ #include "apr.h" #include "apr_pools.h" #ifdef __cplusplus extern "C" { #endif /** * @defgroup apr_atomic Atomic Operations * @ingroup APR * @{ */ /** * this function is required on some platforms to initialize the * atomic operation's internal structures * @param p pool * @return APR_SUCCESS on successful completion * @remark Programs do NOT need to call this directly. APR will call this * automatically from apr_initialize. * @internal */ APR_DECLARE(apr_status_t) apr_atomic_init(apr_pool_t *p); /* * Atomic operations on 32-bit values * Note: Each of these functions internally implements a memory barrier * on platforms that require it */ /** * atomically read an apr_uint32_t from memory * @param mem the pointer */ APR_DECLARE(apr_uint32_t) apr_atomic_read32(volatile apr_uint32_t *mem); /** * atomically set an apr_uint32_t in memory * @param mem pointer to the object * @param val value that the object will assume */ APR_DECLARE(void) apr_atomic_set32(volatile apr_uint32_t *mem, apr_uint32_t val); /** * atomically add 'val' to an apr_uint32_t * @param mem pointer to the object * @param val amount to add * @return old value pointed to by mem */ APR_DECLARE(apr_uint32_t) apr_atomic_add32(volatile apr_uint32_t *mem, apr_uint32_t val); /** * atomically subtract 'val' from an apr_uint32_t * @param mem pointer to the object * @param val amount to subtract */ APR_DECLARE(void) apr_atomic_sub32(volatile apr_uint32_t *mem, apr_uint32_t val); /** * atomically increment an apr_uint32_t by 1 * @param mem pointer to the object * @return old value pointed to by mem */ APR_DECLARE(apr_uint32_t) apr_atomic_inc32(volatile apr_uint32_t *mem); /** * atomically decrement an apr_uint32_t by 1 * @param mem pointer to the atomic value * @return zero if the value becomes zero on decrement, otherwise non-zero */ APR_DECLARE(int) apr_atomic_dec32(volatile apr_uint32_t *mem); /** * compare an apr_uint32_t's value with 'cmp'. * If they are the same swap the value with 'with' * @param mem pointer to the value * @param with what to swap it with * @param cmp the value to compare it to * @return the old value of *mem */ APR_DECLARE(apr_uint32_t) apr_atomic_cas32(volatile apr_uint32_t *mem, apr_uint32_t with, apr_uint32_t cmp); /** * exchange an apr_uint32_t's value with 'val'. * @param mem pointer to the value * @param val what to swap it with * @return the old value of *mem */ APR_DECLARE(apr_uint32_t) apr_atomic_xchg32(volatile apr_uint32_t *mem, apr_uint32_t val); /** * compare the pointer's value with cmp. * If they are the same swap the value with 'with' * @param mem pointer to the pointer * @param with what to swap it with * @param cmp the value to compare it to * @return the old value of the pointer */ APR_DECLARE(void*) apr_atomic_casptr(volatile void **mem, void *with, const void *cmp); /** * exchange a pair of pointer values * @param mem pointer to the pointer * @param with what to swap it with * @return the old value of the pointer */ APR_DECLARE(void*) apr_atomic_xchgptr(volatile void **mem, void *with); /** @} */ #ifdef __cplusplus } #endif #endif /* !APR_ATOMIC_H */
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