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/* 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_THREAD_MUTEX_H
#define APR_THREAD_MUTEX_H
/**
* @file apr_thread_mutex.h
* @brief APR Thread Mutex Routines
*/
#include "apr.h"
#include "apr_errno.h"
#ifdef __cplusplus
extern "C" {
#endif /* __cplusplus */
#if APR_HAS_THREADS || defined(DOXYGEN)
/**
* @defgroup apr_thread_mutex Thread Mutex Routines
* @ingroup APR
* @{
*/
/** Opaque thread-local mutex structure */
typedef struct apr_thread_mutex_t apr_thread_mutex_t;
#define APR_THREAD_MUTEX_DEFAULT 0x0 /**< platform-optimal lock behavior */
#define APR_THREAD_MUTEX_NESTED 0x1 /**< enable nested (recursive) locks */
#define APR_THREAD_MUTEX_UNNESTED 0x2 /**< disable nested locks */
#define APR_THREAD_MUTEX_TIMED 0x4 /**< enable timed locks */
/* Delayed the include to avoid a circular reference */
#include "apr_pools.h"
#include "apr_time.h"
/**
* Create and initialize a mutex that can be used to synchronize threads.
* @param mutex the memory address where the newly created mutex will be
* stored.
* @param flags Or'ed value of:
* <PRE>
* APR_THREAD_MUTEX_DEFAULT platform-optimal lock behavior.
* APR_THREAD_MUTEX_NESTED enable nested (recursive) locks.
* APR_THREAD_MUTEX_UNNESTED disable nested locks (non-recursive).
* </PRE>
* @param pool the pool from which to allocate the mutex.
* @warning Be cautious in using APR_THREAD_MUTEX_DEFAULT. While this is the
* most optimal mutex based on a given platform's performance characteristics,
* it will behave as either a nested or an unnested lock.
*/
APR_DECLARE(apr_status_t) apr_thread_mutex_create(apr_thread_mutex_t **mutex,
unsigned int flags,
apr_pool_t *pool);
/**
* Acquire the lock for the given mutex. If the mutex is already locked,
* the current thread will be put to sleep until the lock becomes available.
* @param mutex the mutex on which to acquire the lock.
*/
APR_DECLARE(apr_status_t) apr_thread_mutex_lock(apr_thread_mutex_t *mutex);
/**
* Attempt to acquire the lock for the given mutex. If the mutex has already
* been acquired, the call returns immediately with APR_EBUSY. Note: it
* is important that the APR_STATUS_IS_EBUSY(s) macro be used to determine
* if the return value was APR_EBUSY, for portability reasons.
* @param mutex the mutex on which to attempt the lock acquiring.
*/
APR_DECLARE(apr_status_t) apr_thread_mutex_trylock(apr_thread_mutex_t *mutex);
/**
* Attempt to acquire the lock for the given mutex until timeout expires.
* If the acquisition time outs, the call returns with APR_TIMEUP.
* @param mutex the mutex on which to attempt the lock acquiring.
* @param timeout the relative timeout (microseconds).
* @note A timeout negative or nul means immediate attempt, returning
* APR_TIMEUP without blocking if it the lock is already acquired.
*/
APR_DECLARE(apr_status_t) apr_thread_mutex_timedlock(apr_thread_mutex_t *mutex,
apr_interval_time_t timeout);
/**
* Release the lock for the given mutex.
* @param mutex the mutex from which to release the lock.
*/
APR_DECLARE(apr_status_t) apr_thread_mutex_unlock(apr_thread_mutex_t *mutex);
/**
* Destroy the mutex and free the memory associated with the lock.
* @param mutex the mutex to destroy.
*/
APR_DECLARE(apr_status_t) apr_thread_mutex_destroy(apr_thread_mutex_t *mutex);
/**
* Get the pool used by this thread_mutex.
* @return apr_pool_t the pool
*/
APR_POOL_DECLARE_ACCESSOR(thread_mutex);
#endif /* APR_HAS_THREADS */
/** @} */
#ifdef __cplusplus
}
#endif
#endif /* ! APR_THREAD_MUTEX_H */
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