mutex.c revision 251886
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 19#ifdef USE_ATOMICS_GENERIC 20 21#include <stdlib.h> 22 23#if APR_HAS_THREADS 24# define DECLARE_MUTEX_LOCKED(name, mem) \ 25 apr_thread_mutex_t *name = mutex_hash(mem) 26# define MUTEX_UNLOCK(name) \ 27 do { \ 28 if (apr_thread_mutex_unlock(name) != APR_SUCCESS) \ 29 abort(); \ 30 } while (0) 31#else 32# define DECLARE_MUTEX_LOCKED(name, mem) 33# define MUTEX_UNLOCK(name) 34# warning Be warned: using stubs for all atomic operations 35#endif 36 37#if APR_HAS_THREADS 38 39static apr_thread_mutex_t **hash_mutex; 40 41#define NUM_ATOMIC_HASH 7 42/* shift by 2 to get rid of alignment issues */ 43#define ATOMIC_HASH(x) (unsigned int)(((unsigned long)(x)>>2)%(unsigned int)NUM_ATOMIC_HASH) 44 45static apr_status_t atomic_cleanup(void *data) 46{ 47 if (hash_mutex == data) 48 hash_mutex = NULL; 49 50 return APR_SUCCESS; 51} 52 53APR_DECLARE(apr_status_t) apr_atomic_init(apr_pool_t *p) 54{ 55 int i; 56 apr_status_t rv; 57 58 if (hash_mutex != NULL) 59 return APR_SUCCESS; 60 61 hash_mutex = apr_palloc(p, sizeof(apr_thread_mutex_t*) * NUM_ATOMIC_HASH); 62 apr_pool_cleanup_register(p, hash_mutex, atomic_cleanup, 63 apr_pool_cleanup_null); 64 65 for (i = 0; i < NUM_ATOMIC_HASH; i++) { 66 rv = apr_thread_mutex_create(&(hash_mutex[i]), 67 APR_THREAD_MUTEX_DEFAULT, p); 68 if (rv != APR_SUCCESS) { 69 return rv; 70 } 71 } 72 73 return APR_SUCCESS; 74} 75 76static APR_INLINE apr_thread_mutex_t *mutex_hash(volatile apr_uint32_t *mem) 77{ 78 apr_thread_mutex_t *mutex = hash_mutex[ATOMIC_HASH(mem)]; 79 80 if (apr_thread_mutex_lock(mutex) != APR_SUCCESS) { 81 abort(); 82 } 83 84 return mutex; 85} 86 87#else 88 89APR_DECLARE(apr_status_t) apr_atomic_init(apr_pool_t *p) 90{ 91 return APR_SUCCESS; 92} 93 94#endif /* APR_HAS_THREADS */ 95 96APR_DECLARE(apr_uint32_t) apr_atomic_read32(volatile apr_uint32_t *mem) 97{ 98 return *mem; 99} 100 101APR_DECLARE(void) apr_atomic_set32(volatile apr_uint32_t *mem, apr_uint32_t val) 102{ 103 DECLARE_MUTEX_LOCKED(mutex, mem); 104 105 *mem = val; 106 107 MUTEX_UNLOCK(mutex); 108} 109 110APR_DECLARE(apr_uint32_t) apr_atomic_add32(volatile apr_uint32_t *mem, apr_uint32_t val) 111{ 112 apr_uint32_t old_value; 113 DECLARE_MUTEX_LOCKED(mutex, mem); 114 115 old_value = *mem; 116 *mem += val; 117 118 MUTEX_UNLOCK(mutex); 119 120 return old_value; 121} 122 123APR_DECLARE(void) apr_atomic_sub32(volatile apr_uint32_t *mem, apr_uint32_t val) 124{ 125 DECLARE_MUTEX_LOCKED(mutex, mem); 126 *mem -= val; 127 MUTEX_UNLOCK(mutex); 128} 129 130APR_DECLARE(apr_uint32_t) apr_atomic_inc32(volatile apr_uint32_t *mem) 131{ 132 return apr_atomic_add32(mem, 1); 133} 134 135APR_DECLARE(int) apr_atomic_dec32(volatile apr_uint32_t *mem) 136{ 137 apr_uint32_t new; 138 DECLARE_MUTEX_LOCKED(mutex, mem); 139 140 (*mem)--; 141 new = *mem; 142 143 MUTEX_UNLOCK(mutex); 144 145 return new; 146} 147 148APR_DECLARE(apr_uint32_t) apr_atomic_cas32(volatile apr_uint32_t *mem, apr_uint32_t with, 149 apr_uint32_t cmp) 150{ 151 apr_uint32_t prev; 152 DECLARE_MUTEX_LOCKED(mutex, mem); 153 154 prev = *mem; 155 if (prev == cmp) { 156 *mem = with; 157 } 158 159 MUTEX_UNLOCK(mutex); 160 161 return prev; 162} 163 164APR_DECLARE(apr_uint32_t) apr_atomic_xchg32(volatile apr_uint32_t *mem, apr_uint32_t val) 165{ 166 apr_uint32_t prev; 167 DECLARE_MUTEX_LOCKED(mutex, mem); 168 169 prev = *mem; 170 *mem = val; 171 172 MUTEX_UNLOCK(mutex); 173 174 return prev; 175} 176 177APR_DECLARE(void*) apr_atomic_casptr(volatile void **mem, void *with, const void *cmp) 178{ 179 void *prev; 180 DECLARE_MUTEX_LOCKED(mutex, *mem); 181 182 prev = *(void **)mem; 183 if (prev == cmp) { 184 *mem = with; 185 } 186 187 MUTEX_UNLOCK(mutex); 188 189 return prev; 190} 191 192APR_DECLARE(void*) apr_atomic_xchgptr(volatile void **mem, void *with) 193{ 194 void *prev; 195 DECLARE_MUTEX_LOCKED(mutex, *mem); 196 197 prev = *(void **)mem; 198 *mem = with; 199 200 MUTEX_UNLOCK(mutex); 201 202 return prev; 203} 204 205#endif /* USE_ATOMICS_GENERIC */ 206