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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_PROC_MUTEX_H
#define APR_PROC_MUTEX_H
/**
* @file apr_proc_mutex.h
* @brief APR Process Locking Routines
*/
#include "apr.h"
#include "apr_pools.h"
#include "apr_errno.h"
#ifdef __cplusplus
extern "C" {
#endif /* __cplusplus */
/**
* @defgroup apr_proc_mutex Process Locking Routines
* @ingroup APR
* @{
*/
/**
* Enumerated potential types for APR process locking methods
* @warning Check APR_HAS_foo_SERIALIZE defines to see if the platform supports
* APR_LOCK_foo. Only APR_LOCK_DEFAULT is portable.
*/
typedef enum {
APR_LOCK_FCNTL, /**< fcntl() */
APR_LOCK_FLOCK, /**< flock() */
APR_LOCK_SYSVSEM, /**< System V Semaphores */
APR_LOCK_PROC_PTHREAD, /**< POSIX pthread process-based locking */
APR_LOCK_POSIXSEM, /**< POSIX semaphore process-based locking */
APR_LOCK_DEFAULT /**< Use the default process lock */
} apr_lockmech_e;
/** Opaque structure representing a process mutex. */
typedef struct apr_proc_mutex_t apr_proc_mutex_t;
/* Function definitions */
/**
* Create and initialize a mutex that can be used to synchronize processes.
* @param mutex the memory address where the newly created mutex will be
* stored.
* @param fname A file name to use if the lock mechanism requires one. This
* argument should always be provided. The lock code itself will
* determine if it should be used.
* @param mech The mechanism to use for the interprocess lock, if any; one of
* <PRE>
* APR_LOCK_FCNTL
* APR_LOCK_FLOCK
* APR_LOCK_SYSVSEM
* APR_LOCK_POSIXSEM
* APR_LOCK_PROC_PTHREAD
* APR_LOCK_DEFAULT pick the default mechanism for the platform
* </PRE>
* @param pool the pool from which to allocate the mutex.
* @see apr_lockmech_e
* @warning Check APR_HAS_foo_SERIALIZE defines to see if the platform supports
* APR_LOCK_foo. Only APR_LOCK_DEFAULT is portable.
*/
APR_DECLARE(apr_status_t) apr_proc_mutex_create(apr_proc_mutex_t **mutex,
const char *fname,
apr_lockmech_e mech,
apr_pool_t *pool);
/**
* Re-open a mutex in a child process.
* @param mutex The newly re-opened mutex structure.
* @param fname A file name to use if the mutex mechanism requires one. This
* argument should always be provided. The mutex code itself will
* determine if it should be used. This filename should be the
* same one that was passed to apr_proc_mutex_create().
* @param pool The pool to operate on.
* @remark This function must be called to maintain portability, even
* if the underlying lock mechanism does not require it.
*/
APR_DECLARE(apr_status_t) apr_proc_mutex_child_init(apr_proc_mutex_t **mutex,
const char *fname,
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_proc_mutex_lock(apr_proc_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_proc_mutex_trylock(apr_proc_mutex_t *mutex);
/**
* Release the lock for the given mutex.
* @param mutex the mutex from which to release the lock.
*/
APR_DECLARE(apr_status_t) apr_proc_mutex_unlock(apr_proc_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_proc_mutex_destroy(apr_proc_mutex_t *mutex);
/**
* Destroy the mutex and free the memory associated with the lock.
* @param mutex the mutex to destroy.
* @note This function is generally used to kill a cleanup on an already
* created mutex
*/
APR_DECLARE(apr_status_t) apr_proc_mutex_cleanup(void *mutex);
/**
* Return the name of the lockfile for the mutex, or NULL
* if the mutex doesn't use a lock file
*/
APR_DECLARE(const char *) apr_proc_mutex_lockfile(apr_proc_mutex_t *mutex);
/**
* Display the name of the mutex, as it relates to the actual method used.
* This matches the valid options for Apache's AcceptMutex directive
* @param mutex the name of the mutex
*/
APR_DECLARE(const char *) apr_proc_mutex_name(apr_proc_mutex_t *mutex);
/**
* Display the name of the default mutex: APR_LOCK_DEFAULT
*/
APR_DECLARE(const char *) apr_proc_mutex_defname(void);
/**
* Get the pool used by this proc_mutex.
* @return apr_pool_t the pool
*/
APR_POOL_DECLARE_ACCESSOR(proc_mutex);
/** @} */
#ifdef __cplusplus
}
#endif
#endif /* ! APR_PROC_MUTEX_H */
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