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/* Copyright 2000-2004 The Apache Software Foundation
*
* Licensed 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.
*/
/*Read/Write locking implementation based on the MultiLock code from
* Stephen Beaulieu <hippo@be.com>
*/
#include "apr_arch_thread_mutex.h"
#include "apr_strings.h"
#include "apr_portable.h"
static apr_status_t _thread_mutex_cleanup(void * data)
{
apr_thread_mutex_t *lock = (apr_thread_mutex_t*)data;
if (lock->LockCount != 0) {
/* we're still locked... */
while (atomic_add(&lock->LockCount , -1) > 1){
/* OK we had more than one person waiting on the lock so
* the sem is also locked. Release it until we have no more
* locks left.
*/
release_sem (lock->Lock);
}
}
delete_sem(lock->Lock);
return APR_SUCCESS;
}
APR_DECLARE(apr_status_t) apr_thread_mutex_create(apr_thread_mutex_t **mutex,
unsigned int flags,
apr_pool_t *pool)
{
apr_thread_mutex_t *new_m;
apr_status_t stat = APR_SUCCESS;
new_m = (apr_thread_mutex_t *)apr_pcalloc(pool, sizeof(apr_thread_mutex_t));
if (new_m == NULL){
return APR_ENOMEM;
}
if ((stat = create_sem(0, "APR_Lock")) < B_NO_ERROR) {
_thread_mutex_cleanup(new_m);
return stat;
}
new_m->LockCount = 0;
new_m->Lock = stat;
new_m->pool = pool;
/* Optimal default is APR_THREAD_MUTEX_UNNESTED,
* no additional checks required for either flag.
*/
new_m->nested = flags & APR_THREAD_MUTEX_NESTED;
apr_pool_cleanup_register(new_m->pool, (void *)new_m, _thread_mutex_cleanup,
apr_pool_cleanup_null);
(*mutex) = new_m;
return APR_SUCCESS;
}
#if APR_HAS_CREATE_LOCKS_NP
APR_DECLARE(apr_status_t) apr_thread_mutex_create_np(apr_thread_mutex_t **mutex,
const char *fname,
apr_lockmech_e_np mech,
apr_pool_t *pool)
{
return APR_ENOTIMPL;
}
#endif
APR_DECLARE(apr_status_t) apr_thread_mutex_lock(apr_thread_mutex_t *mutex)
{
int32 stat;
thread_id me = find_thread(NULL);
if (mutex->nested && mutex->owner == me) {
mutex->owner_ref++;
return APR_SUCCESS;
}
if (atomic_add(&mutex->LockCount, 1) > 0) {
if ((stat = acquire_sem(mutex->Lock)) < B_NO_ERROR) {
/* Oh dear, acquire_sem failed!! */
atomic_add(&mutex->LockCount, -1);
return stat;
}
}
mutex->owner = me;
mutex->owner_ref = 1;
return APR_SUCCESS;
}
APR_DECLARE(apr_status_t) apr_thread_mutex_trylock(apr_thread_mutex_t *mutex)
{
return APR_ENOTIMPL;
}
APR_DECLARE(apr_status_t) apr_thread_mutex_unlock(apr_thread_mutex_t *mutex)
{
int32 stat;
if (mutex->nested && mutex->owner == find_thread(NULL)) {
mutex->owner_ref--;
if (mutex->owner_ref > 0)
return APR_SUCCESS;
}
if (atomic_add(&mutex->LockCount, -1) > 1) {
if ((stat = release_sem(mutex->Lock)) < B_NO_ERROR) {
atomic_add(&mutex->LockCount, 1);
return stat;
}
}
mutex->owner = -1;
mutex->owner_ref = 0;
return APR_SUCCESS;
}
APR_DECLARE(apr_status_t) apr_thread_mutex_destroy(apr_thread_mutex_t *mutex)
{
apr_status_t stat;
if ((stat = _thread_mutex_cleanup(mutex)) == APR_SUCCESS) {
apr_pool_cleanup_kill(mutex->pool, mutex, _thread_mutex_cleanup);
return APR_SUCCESS;
}
return stat;
}
APR_POOL_IMPLEMENT_ACCESSOR(thread_mutex)
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