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
8 * http://www.apache.org/licenses/LICENSE-2.0
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.
17 #ifndef APR_PROC_MUTEX_H
18 #define APR_PROC_MUTEX_H
21 * @file apr_proc_mutex.h
22 * @brief APR Process Locking Routines
26 #include "apr_pools.h"
27 #include "apr_errno.h"
31 #endif /* __cplusplus */
34 * @defgroup apr_proc_mutex Process Locking Routines
40 * Enumerated potential types for APR process locking methods
41 * @warning Check APR_HAS_foo_SERIALIZE defines to see if the platform supports
42 * APR_LOCK_foo. Only APR_LOCK_DEFAULT is portable.
45 APR_LOCK_FCNTL, /**< fcntl() */
46 APR_LOCK_FLOCK, /**< flock() */
47 APR_LOCK_SYSVSEM, /**< System V Semaphores */
48 APR_LOCK_PROC_PTHREAD, /**< POSIX pthread process-based locking */
49 APR_LOCK_POSIXSEM, /**< POSIX semaphore process-based locking */
50 APR_LOCK_DEFAULT /**< Use the default process lock */
53 /** Opaque structure representing a process mutex. */
54 typedef struct apr_proc_mutex_t apr_proc_mutex_t;
56 /* Function definitions */
59 * Create and initialize a mutex that can be used to synchronize processes.
60 * @param mutex the memory address where the newly created mutex will be
62 * @param fname A file name to use if the lock mechanism requires one. This
63 * argument should always be provided. The lock code itself will
64 * determine if it should be used.
65 * @param mech The mechanism to use for the interprocess lock, if any; one of
71 * APR_LOCK_PROC_PTHREAD
72 * APR_LOCK_DEFAULT pick the default mechanism for the platform
74 * @param pool the pool from which to allocate the mutex.
76 * @warning Check APR_HAS_foo_SERIALIZE defines to see if the platform supports
77 * APR_LOCK_foo. Only APR_LOCK_DEFAULT is portable.
79 APR_DECLARE(apr_status_t) apr_proc_mutex_create(apr_proc_mutex_t **mutex,
85 * Re-open a mutex in a child process.
86 * @param mutex The newly re-opened mutex structure.
87 * @param fname A file name to use if the mutex mechanism requires one. This
88 * argument should always be provided. The mutex code itself will
89 * determine if it should be used. This filename should be the
90 * same one that was passed to apr_proc_mutex_create().
91 * @param pool The pool to operate on.
92 * @remark This function must be called to maintain portability, even
93 * if the underlying lock mechanism does not require it.
95 APR_DECLARE(apr_status_t) apr_proc_mutex_child_init(apr_proc_mutex_t **mutex,
100 * Acquire the lock for the given mutex. If the mutex is already locked,
101 * the current thread will be put to sleep until the lock becomes available.
102 * @param mutex the mutex on which to acquire the lock.
104 APR_DECLARE(apr_status_t) apr_proc_mutex_lock(apr_proc_mutex_t *mutex);
107 * Attempt to acquire the lock for the given mutex. If the mutex has already
108 * been acquired, the call returns immediately with APR_EBUSY. Note: it
109 * is important that the APR_STATUS_IS_EBUSY(s) macro be used to determine
110 * if the return value was APR_EBUSY, for portability reasons.
111 * @param mutex the mutex on which to attempt the lock acquiring.
113 APR_DECLARE(apr_status_t) apr_proc_mutex_trylock(apr_proc_mutex_t *mutex);
116 * Release the lock for the given mutex.
117 * @param mutex the mutex from which to release the lock.
119 APR_DECLARE(apr_status_t) apr_proc_mutex_unlock(apr_proc_mutex_t *mutex);
122 * Destroy the mutex and free the memory associated with the lock.
123 * @param mutex the mutex to destroy.
125 APR_DECLARE(apr_status_t) apr_proc_mutex_destroy(apr_proc_mutex_t *mutex);
128 * Destroy the mutex and free the memory associated with the lock.
129 * @param mutex the mutex to destroy.
130 * @note This function is generally used to kill a cleanup on an already
133 APR_DECLARE(apr_status_t) apr_proc_mutex_cleanup(void *mutex);
136 * Return the name of the lockfile for the mutex, or NULL
137 * if the mutex doesn't use a lock file
140 APR_DECLARE(const char *) apr_proc_mutex_lockfile(apr_proc_mutex_t *mutex);
143 * Display the name of the mutex, as it relates to the actual method used.
144 * This matches the valid options for Apache's AcceptMutex directive
145 * @param mutex the name of the mutex
147 APR_DECLARE(const char *) apr_proc_mutex_name(apr_proc_mutex_t *mutex);
150 * Display the name of the default mutex: APR_LOCK_DEFAULT
152 APR_DECLARE(const char *) apr_proc_mutex_defname(void);
155 * Get the pool used by this proc_mutex.
156 * @return apr_pool_t the pool
158 APR_POOL_DECLARE_ACCESSOR(proc_mutex);
166 #endif /* ! APR_PROC_MUTEX_H */