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Member "apr-1.7.0/atomic/unix/mutex.c" (7 Mar 2019, 4890 Bytes) of package /linux/www/apr-1.7.0.tar.bz2:


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    1 /* Licensed to the Apache Software Foundation (ASF) under one or more
    2  * contributor license agreements.  See the NOTICE file distributed with
    3  * this work for additional information regarding copyright ownership.
    4  * The ASF licenses this file to You under the Apache License, Version 2.0
    5  * (the "License"); you may not use this file except in compliance with
    6  * the License.  You may obtain a copy of the License at
    7  *
    8  *     http://www.apache.org/licenses/LICENSE-2.0
    9  *
   10  * Unless required by applicable law or agreed to in writing, software
   11  * distributed under the License is distributed on an "AS IS" BASIS,
   12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   13  * See the License for the specific language governing permissions and
   14  * limitations under the License.
   15  */
   16 
   17 #include "apr_arch_atomic.h"
   18 #include "apr_thread_mutex.h"
   19 
   20 #ifdef USE_ATOMICS_GENERIC
   21 
   22 #include <stdlib.h>
   23 
   24 #if APR_HAS_THREADS
   25 #   define DECLARE_MUTEX_LOCKED(name, mem)  \
   26         apr_thread_mutex_t *name = mutex_hash(mem)
   27 #   define MUTEX_UNLOCK(name)                                   \
   28         do {                                                    \
   29             if (apr_thread_mutex_unlock(name) != APR_SUCCESS)   \
   30                 abort();                                        \
   31         } while (0)
   32 #else
   33 #   define DECLARE_MUTEX_LOCKED(name, mem)
   34 #   define MUTEX_UNLOCK(name)
   35 #   warning Be warned: using stubs for all atomic operations
   36 #endif
   37 
   38 #if APR_HAS_THREADS
   39 
   40 static apr_thread_mutex_t **hash_mutex;
   41 
   42 #define NUM_ATOMIC_HASH 7
   43 /* shift by 2 to get rid of alignment issues */
   44 #define ATOMIC_HASH(x) (unsigned int)(((unsigned long)(x)>>2)%(unsigned int)NUM_ATOMIC_HASH)
   45 
   46 static apr_status_t atomic_cleanup(void *data)
   47 {
   48     if (hash_mutex == data)
   49         hash_mutex = NULL;
   50 
   51     return APR_SUCCESS;
   52 }
   53 
   54 APR_DECLARE(apr_status_t) apr_atomic_init(apr_pool_t *p)
   55 {
   56     int i;
   57     apr_status_t rv;
   58 
   59     if (hash_mutex != NULL)
   60         return APR_SUCCESS;
   61 
   62     hash_mutex = apr_palloc(p, sizeof(apr_thread_mutex_t*) * NUM_ATOMIC_HASH);
   63     apr_pool_cleanup_register(p, hash_mutex, atomic_cleanup,
   64                               apr_pool_cleanup_null);
   65 
   66     for (i = 0; i < NUM_ATOMIC_HASH; i++) {
   67         rv = apr_thread_mutex_create(&(hash_mutex[i]),
   68                                      APR_THREAD_MUTEX_DEFAULT, p);
   69         if (rv != APR_SUCCESS) {
   70            return rv;
   71         }
   72     }
   73 
   74     return apr__atomic_generic64_init(p);
   75 }
   76 
   77 static APR_INLINE apr_thread_mutex_t *mutex_hash(volatile apr_uint32_t *mem)
   78 {
   79     apr_thread_mutex_t *mutex = hash_mutex[ATOMIC_HASH(mem)];
   80 
   81     if (apr_thread_mutex_lock(mutex) != APR_SUCCESS) {
   82         abort();
   83     }
   84 
   85     return mutex;
   86 }
   87 
   88 #else
   89 
   90 APR_DECLARE(apr_status_t) apr_atomic_init(apr_pool_t *p)
   91 {
   92     return apr__atomic_generic64_init(p);
   93 }
   94 
   95 #endif /* APR_HAS_THREADS */
   96 
   97 APR_DECLARE(apr_uint32_t) apr_atomic_read32(volatile apr_uint32_t *mem)
   98 {
   99     return *mem;
  100 }
  101 
  102 APR_DECLARE(void) apr_atomic_set32(volatile apr_uint32_t *mem, apr_uint32_t val)
  103 {
  104     DECLARE_MUTEX_LOCKED(mutex, mem);
  105 
  106     *mem = val;
  107 
  108     MUTEX_UNLOCK(mutex);
  109 }
  110 
  111 APR_DECLARE(apr_uint32_t) apr_atomic_add32(volatile apr_uint32_t *mem, apr_uint32_t val)
  112 {
  113     apr_uint32_t old_value;
  114     DECLARE_MUTEX_LOCKED(mutex, mem);
  115 
  116     old_value = *mem;
  117     *mem += val;
  118 
  119     MUTEX_UNLOCK(mutex);
  120 
  121     return old_value;
  122 }
  123 
  124 APR_DECLARE(void) apr_atomic_sub32(volatile apr_uint32_t *mem, apr_uint32_t val)
  125 {
  126     DECLARE_MUTEX_LOCKED(mutex, mem);
  127     *mem -= val;
  128     MUTEX_UNLOCK(mutex);
  129 }
  130 
  131 APR_DECLARE(apr_uint32_t) apr_atomic_inc32(volatile apr_uint32_t *mem)
  132 {
  133     return apr_atomic_add32(mem, 1);
  134 }
  135 
  136 APR_DECLARE(int) apr_atomic_dec32(volatile apr_uint32_t *mem)
  137 {
  138     apr_uint32_t new;
  139     DECLARE_MUTEX_LOCKED(mutex, mem);
  140 
  141     (*mem)--;
  142     new = *mem;
  143 
  144     MUTEX_UNLOCK(mutex);
  145 
  146     return new;
  147 }
  148 
  149 APR_DECLARE(apr_uint32_t) apr_atomic_cas32(volatile apr_uint32_t *mem, apr_uint32_t with,
  150                               apr_uint32_t cmp)
  151 {
  152     apr_uint32_t prev;
  153     DECLARE_MUTEX_LOCKED(mutex, mem);
  154 
  155     prev = *mem;
  156     if (prev == cmp) {
  157         *mem = with;
  158     }
  159 
  160     MUTEX_UNLOCK(mutex);
  161 
  162     return prev;
  163 }
  164 
  165 APR_DECLARE(apr_uint32_t) apr_atomic_xchg32(volatile apr_uint32_t *mem, apr_uint32_t val)
  166 {
  167     apr_uint32_t prev;
  168     DECLARE_MUTEX_LOCKED(mutex, mem);
  169 
  170     prev = *mem;
  171     *mem = val;
  172 
  173     MUTEX_UNLOCK(mutex);
  174 
  175     return prev;
  176 }
  177 
  178 APR_DECLARE(void*) apr_atomic_casptr(volatile void **mem, void *with, const void *cmp)
  179 {
  180     void *prev;
  181     DECLARE_MUTEX_LOCKED(mutex, *mem);
  182 
  183     prev = *(void **)mem;
  184     if (prev == cmp) {
  185         *mem = with;
  186     }
  187 
  188     MUTEX_UNLOCK(mutex);
  189 
  190     return prev;
  191 }
  192 
  193 APR_DECLARE(void*) apr_atomic_xchgptr(volatile void **mem, void *with)
  194 {
  195     void *prev;
  196     DECLARE_MUTEX_LOCKED(mutex, *mem);
  197 
  198     prev = *(void **)mem;
  199     *mem = with;
  200 
  201     MUTEX_UNLOCK(mutex);
  202 
  203     return prev;
  204 }
  205 
  206 #endif /* USE_ATOMICS_GENERIC */