apr_thread_mutex.h revision 269847 
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
7 *
8 *     http://www.apache.org/licenses/LICENSE-2.0
9 *
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.
15 */
16
17#ifndef APR_THREAD_MUTEX_H
18#define APR_THREAD_MUTEX_H
19
20/**
21 * @file apr_thread_mutex.h
22 * @brief APR Thread Mutex Routines
23 */
24
25#include "apr.h"
26#include "apr_errno.h"
27
28#ifdef __cplusplus
29extern "C" {
30#endif /* __cplusplus */
31
32#if APR_HAS_THREADS || defined(DOXYGEN)
33
34/**
35 * @defgroup apr_thread_mutex Thread Mutex Routines
36 * @ingroup APR
37 * @{
38 */
39
40/** Opaque thread-local mutex structure */
41typedef struct apr_thread_mutex_t apr_thread_mutex_t;
42
43#define APR_THREAD_MUTEX_DEFAULT  0x0   /**< platform-optimal lock behavior */
44#define APR_THREAD_MUTEX_NESTED   0x1   /**< enable nested (recursive) locks */
45#define APR_THREAD_MUTEX_UNNESTED 0x2   /**< disable nested locks */
46
47/* Delayed the include to avoid a circular reference */
48#include "apr_pools.h"
49
50/**
51 * Create and initialize a mutex that can be used to synchronize threads.
52 * @param mutex the memory address where the newly created mutex will be
53 *        stored.
54 * @param flags Or'ed value of:
55 * <PRE>
56 *           APR_THREAD_MUTEX_DEFAULT   platform-optimal lock behavior.
57 *           APR_THREAD_MUTEX_NESTED    enable nested (recursive) locks.
58 *           APR_THREAD_MUTEX_UNNESTED  disable nested locks (non-recursive).
59 * </PRE>
60 * @param pool the pool from which to allocate the mutex.
61 * @warning Be cautious in using APR_THREAD_MUTEX_DEFAULT.  While this is the
62 * most optimal mutex based on a given platform's performance characteristics,
63 * it will behave as either a nested or an unnested lock.
64 */
65APR_DECLARE(apr_status_t) apr_thread_mutex_create(apr_thread_mutex_t **mutex,
66                                                  unsigned int flags,
67                                                  apr_pool_t *pool);
68/**
69 * Acquire the lock for the given mutex. If the mutex is already locked,
70 * the current thread will be put to sleep until the lock becomes available.
71 * @param mutex the mutex on which to acquire the lock.
72 */
73APR_DECLARE(apr_status_t) apr_thread_mutex_lock(apr_thread_mutex_t *mutex);
74
75/**
76 * Attempt to acquire the lock for the given mutex. If the mutex has already
77 * been acquired, the call returns immediately with APR_EBUSY. Note: it
78 * is important that the APR_STATUS_IS_EBUSY(s) macro be used to determine
79 * if the return value was APR_EBUSY, for portability reasons.
80 * @param mutex the mutex on which to attempt the lock acquiring.
81 */
82APR_DECLARE(apr_status_t) apr_thread_mutex_trylock(apr_thread_mutex_t *mutex);
83
84/**
85 * Release the lock for the given mutex.
86 * @param mutex the mutex from which to release the lock.
87 */
88APR_DECLARE(apr_status_t) apr_thread_mutex_unlock(apr_thread_mutex_t *mutex);
89
90/**
91 * Destroy the mutex and free the memory associated with the lock.
92 * @param mutex the mutex to destroy.
93 */
94APR_DECLARE(apr_status_t) apr_thread_mutex_destroy(apr_thread_mutex_t *mutex);
95
96/**
97 * Get the pool used by this thread_mutex.
98 * @return apr_pool_t the pool
99 */
100APR_POOL_DECLARE_ACCESSOR(thread_mutex);
101
102#endif /* APR_HAS_THREADS */
103
104/** @} */
105
106#ifdef __cplusplus
107}
108#endif
109
110#endif  /* ! APR_THREAD_MUTEX_H */
111