Apache Portable Runtime
apr_thread_rwlock.h
Go to the documentation of this file.
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_RWLOCK_H
18 #define APR_THREAD_RWLOCK_H
19 
20 /**
21  * @file apr_thread_rwlock.h
22  * @brief APR Reader/Writer Lock Routines
23  */
24 
25 #include "apr.h"
26 #include "apr_pools.h"
27 #include "apr_errno.h"
28 
29 #ifdef __cplusplus
30 extern "C" {
31 #endif /* __cplusplus */
32 
33 #if APR_HAS_THREADS
34 
35 /**
36  * @defgroup apr_thread_rwlock Reader/Writer Lock Routines
37  * @ingroup APR
38  * @{
39  */
40 
41 /** Opaque read-write thread-safe lock. */
43 
44 /**
45  * Note: The following operations have undefined results: unlocking a
46  * read-write lock which is not locked in the calling thread; write
47  * locking a read-write lock which is already locked by the calling
48  * thread; destroying a read-write lock more than once; clearing or
49  * destroying the pool from which a <b>locked</b> read-write lock is
50  * allocated.
51  */
52 
53 /**
54  * Create and initialize a read-write lock that can be used to synchronize
55  * threads.
56  * @param rwlock the memory address where the newly created readwrite lock
57  * will be stored.
58  * @param pool the pool from which to allocate the mutex.
59  */
61  apr_pool_t *pool);
62 /**
63  * Acquire a shared-read lock on the given read-write lock. This will allow
64  * multiple threads to enter the same critical section while they have acquired
65  * the read lock.
66  * @param rwlock the read-write lock on which to acquire the shared read.
67  */
69 
70 /**
71  * Attempt to acquire the shared-read lock on the given read-write lock. This
72  * is the same as apr_thread_rwlock_rdlock(), only that the function fails
73  * if there is another thread holding the write lock, or if there are any
74  * write threads blocking on the lock. If the function fails for this case,
75  * APR_EBUSY will be returned. Note: it is important that the
76  * APR_STATUS_IS_EBUSY(s) macro be used to determine if the return value was
77  * APR_EBUSY, for portability reasons.
78  * @param rwlock the rwlock on which to attempt the shared read.
79  */
81 
82 /**
83  * Acquire an exclusive-write lock on the given read-write lock. This will
84  * allow only one single thread to enter the critical sections. If there
85  * are any threads currently holding the read-lock, this thread is put to
86  * sleep until it can have exclusive access to the lock.
87  * @param rwlock the read-write lock on which to acquire the exclusive write.
88  */
90 
91 /**
92  * Attempt to acquire the exclusive-write lock on the given read-write lock.
93  * This is the same as apr_thread_rwlock_wrlock(), only that the function fails
94  * if there is any other thread holding the lock (for reading or writing),
95  * in which case the function will return APR_EBUSY. Note: it is important
96  * that the APR_STATUS_IS_EBUSY(s) macro be used to determine if the return
97  * value was APR_EBUSY, for portability reasons.
98  * @param rwlock the rwlock on which to attempt the exclusive write.
99  */
101 
102 /**
103  * Release either the read or write lock currently held by the calling thread
104  * associated with the given read-write lock.
105  * @param rwlock the read-write lock to be released (unlocked).
106  */
108 
109 /**
110  * Destroy the read-write lock and free the associated memory.
111  * @param rwlock the rwlock to destroy.
112  */
114 
115 /**
116  * Get the pool used by this thread_rwlock.
117  * @return apr_pool_t the pool
118  */
119 APR_POOL_DECLARE_ACCESSOR(thread_rwlock);
120 
121 #endif /* APR_HAS_THREADS */
122 
123 /** @} */
124 
125 #ifdef __cplusplus
126 }
127 #endif
128 
129 #endif /* ! APR_THREAD_RWLOCK_H */
apr_status_t apr_thread_rwlock_rdlock(apr_thread_rwlock_t *rwlock)
apr_status_t apr_thread_rwlock_create(apr_thread_rwlock_t **rwlock, apr_pool_t *pool)
apr_status_t apr_thread_rwlock_unlock(apr_thread_rwlock_t *rwlock)
APR memory allocation.
apr_status_t apr_thread_rwlock_tryrdlock(apr_thread_rwlock_t *rwlock)
apr_status_t apr_thread_rwlock_trywrlock(apr_thread_rwlock_t *rwlock)
APR Error Codes.
#define APR_DECLARE(type)
Definition: apr.h:480
APR Platform Definitions.
apr_status_t apr_thread_rwlock_wrlock(apr_thread_rwlock_t *rwlock)
struct apr_pool_t apr_pool_t
Definition: apr_pools.h:60
apr_status_t apr_thread_rwlock_destroy(apr_thread_rwlock_t *rwlock)
int apr_status_t
Definition: apr_errno.h:44
struct apr_thread_rwlock_t apr_thread_rwlock_t
Definition: apr_thread_rwlock.h:42
#define APR_POOL_DECLARE_ACCESSOR(type)
Definition: apr_pools.h:81