170 lines
6.1 KiB
C
170 lines
6.1 KiB
C
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/* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership.
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* The ASF licenses this file to You under the Apache License, Version 2.0
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* (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#ifndef APR_GLOBAL_MUTEX_H
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#define APR_GLOBAL_MUTEX_H
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/**
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* @file apr_global_mutex.h
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* @brief APR Global Locking Routines
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*/
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#include "apr.h"
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#include "apr_proc_mutex.h" /* only for apr_lockmech_e */
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#include "apr_pools.h"
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#include "apr_errno.h"
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#if APR_PROC_MUTEX_IS_GLOBAL
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#include "apr_proc_mutex.h"
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#endif
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#ifdef __cplusplus
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extern "C" {
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#endif /* __cplusplus */
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/**
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* @defgroup APR_GlobalMutex Global Locking Routines
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* @ingroup APR
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* @{
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*/
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#if !APR_PROC_MUTEX_IS_GLOBAL || defined(DOXYGEN)
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/** Opaque global mutex structure. */
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typedef struct apr_global_mutex_t apr_global_mutex_t;
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/* Function definitions */
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/**
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* Create and initialize a mutex that can be used to synchronize both
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* processes and threads. Note: There is considerable overhead in using
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* this API if only cross-process or cross-thread mutual exclusion is
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* required. See apr_proc_mutex.h and apr_thread_mutex.h for more
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* specialized lock routines.
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* @param mutex the memory address where the newly created mutex will be
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* stored.
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* @param fname A file name to use if the lock mechanism requires one. This
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* argument should always be provided. The lock code itself will
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* determine if it should be used.
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* @param mech The mechanism to use for the interprocess lock, if any; one of
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* <PRE>
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* APR_LOCK_FCNTL
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* APR_LOCK_FLOCK
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* APR_LOCK_SYSVSEM
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* APR_LOCK_POSIXSEM
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* APR_LOCK_PROC_PTHREAD
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* APR_LOCK_DEFAULT pick the default mechanism for the platform
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* </PRE>
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* @param pool the pool from which to allocate the mutex.
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* @warning Check APR_HAS_foo_SERIALIZE defines to see if the platform supports
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* APR_LOCK_foo. Only APR_LOCK_DEFAULT is portable.
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*/
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APR_DECLARE(apr_status_t) apr_global_mutex_create(apr_global_mutex_t **mutex,
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const char *fname,
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apr_lockmech_e mech,
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apr_pool_t *pool);
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/**
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* Re-open a mutex in a child process.
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* @param mutex The newly re-opened mutex structure.
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* @param fname A file name to use if the mutex mechanism requires one. This
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* argument should always be provided. The mutex code itself will
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* determine if it should be used. This filename should be the
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* same one that was passed to apr_global_mutex_create().
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* @param pool The pool to operate on.
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* @remark This function must be called to maintain portability, even
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* if the underlying lock mechanism does not require it.
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*/
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APR_DECLARE(apr_status_t) apr_global_mutex_child_init(
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apr_global_mutex_t **mutex,
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const char *fname,
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apr_pool_t *pool);
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/**
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* Acquire the lock for the given mutex. If the mutex is already locked,
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* the current thread will be put to sleep until the lock becomes available.
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* @param mutex the mutex on which to acquire the lock.
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*/
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APR_DECLARE(apr_status_t) apr_global_mutex_lock(apr_global_mutex_t *mutex);
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/**
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* Attempt to acquire the lock for the given mutex. If the mutex has already
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* been acquired, the call returns immediately with APR_EBUSY. Note: it
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* is important that the APR_STATUS_IS_EBUSY(s) macro be used to determine
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* if the return value was APR_EBUSY, for portability reasons.
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* @param mutex the mutex on which to attempt the lock acquiring.
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*/
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APR_DECLARE(apr_status_t) apr_global_mutex_trylock(apr_global_mutex_t *mutex);
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/**
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* Release the lock for the given mutex.
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* @param mutex the mutex from which to release the lock.
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*/
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APR_DECLARE(apr_status_t) apr_global_mutex_unlock(apr_global_mutex_t *mutex);
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/**
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* Destroy the mutex and free the memory associated with the lock.
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* @param mutex the mutex to destroy.
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*/
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APR_DECLARE(apr_status_t) apr_global_mutex_destroy(apr_global_mutex_t *mutex);
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/**
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* Return the name of the lockfile for the mutex, or NULL
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* if the mutex doesn't use a lock file
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*/
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APR_DECLARE(const char *) apr_global_mutex_lockfile(apr_global_mutex_t *mutex);
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/**
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* Display the name of the mutex, as it relates to the actual method used
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* for the underlying apr_proc_mutex_t, if any. NULL is returned if
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* there is no underlying apr_proc_mutex_t.
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* @param mutex the name of the mutex
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*/
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APR_DECLARE(const char *) apr_global_mutex_name(apr_global_mutex_t *mutex);
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/**
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* Get the pool used by this global_mutex.
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* @return apr_pool_t the pool
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*/
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APR_POOL_DECLARE_ACCESSOR(global_mutex);
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#else /* APR_PROC_MUTEX_IS_GLOBAL */
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/* Some platforms [e.g. Win32] have cross process locks that are truly
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* global locks, since there isn't the concept of cross-process locks.
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* Define these platforms in terms of an apr_proc_mutex_t.
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*/
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#define apr_global_mutex_t apr_proc_mutex_t
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#define apr_global_mutex_create apr_proc_mutex_create
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#define apr_global_mutex_child_init apr_proc_mutex_child_init
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#define apr_global_mutex_lock apr_proc_mutex_lock
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#define apr_global_mutex_trylock apr_proc_mutex_trylock
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#define apr_global_mutex_unlock apr_proc_mutex_unlock
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#define apr_global_mutex_destroy apr_proc_mutex_destroy
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#define apr_global_mutex_lockfile apr_proc_mutex_lockfile
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#define apr_global_mutex_name apr_proc_mutex_name
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#define apr_global_mutex_pool_get apr_proc_mutex_pool_get
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#endif
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/** @} */
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#ifdef __cplusplus
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}
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#endif
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#endif /* ndef APR_GLOBAL_MUTEX_H */
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