Apache Portable Runtime
apr_global_mutex.h
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2  * contributor license agreements. See the NOTICE file distributed with
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4  * The ASF licenses this file to You under the Apache License, Version 2.0
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7  *
8  * http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
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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_GLOBAL_MUTEX_H
18 #define APR_GLOBAL_MUTEX_H
19 
20 /**
21  * @file apr_global_mutex.h
22  * @brief APR Global Locking Routines
23  */
24 
25 #include "apr.h"
26 #include "apr_proc_mutex.h" /* only for apr_lockmech_e */
27 #include "apr_pools.h"
28 #include "apr_errno.h"
29 #if APR_PROC_MUTEX_IS_GLOBAL
30 #include "apr_proc_mutex.h"
31 #endif
32 #include "apr_time.h"
33 
34 #ifdef __cplusplus
35 extern "C" {
36 #endif /* __cplusplus */
37 
38 /**
39  * @defgroup APR_GlobalMutex Global Locking Routines
40  * @ingroup APR
41  * @{
42  */
43 
44 #if !APR_PROC_MUTEX_IS_GLOBAL || defined(DOXYGEN)
45 
46 /** Opaque global mutex structure. */
48 
49 /* Function definitions */
50 
51 /**
52  * Create and initialize a mutex that can be used to synchronize both
53  * processes and threads. Note: There is considerable overhead in using
54  * this API if only cross-process or cross-thread mutual exclusion is
55  * required. See apr_proc_mutex.h and apr_thread_mutex.h for more
56  * specialized lock routines.
57  * @param mutex the memory address where the newly created mutex will be
58  * stored.
59  * @param fname A file name to use if the lock mechanism requires one. This
60  * argument should always be provided. The lock code itself will
61  * determine if it should be used.
62  * @param mech The mechanism to use for the interprocess lock, if any; one of
63  * <PRE>
64  * APR_LOCK_FCNTL
65  * APR_LOCK_FLOCK
66  * APR_LOCK_SYSVSEM
67  * APR_LOCK_POSIXSEM
68  * APR_LOCK_PROC_PTHREAD
69  * APR_LOCK_DEFAULT pick the default mechanism for the platform
70  * APR_LOCK_DEFAULT_TIMED pick the default timed mechanism
71  * </PRE>
72  * @param pool the pool from which to allocate the mutex.
73  * @warning Check APR_HAS_foo_SERIALIZE defines to see if the platform supports
74  * APR_LOCK_foo. Only APR_LOCK_DEFAULT is portable.
75  */
77  const char *fname,
78  apr_lockmech_e mech,
79  apr_pool_t *pool);
80 
81 /**
82  * Re-open a mutex in a child process.
83  * @param mutex The newly re-opened mutex structure.
84  * @param fname A file name to use if the mutex mechanism requires one. This
85  * argument should always be provided. The mutex code itself will
86  * determine if it should be used. This filename should be the
87  * same one that was passed to apr_global_mutex_create().
88  * @param pool The pool to operate on.
89  * @remark This function must be called to maintain portability, even
90  * if the underlying lock mechanism does not require it.
91  */
93  apr_global_mutex_t **mutex,
94  const char *fname,
95  apr_pool_t *pool);
96 
97 /**
98  * Acquire the lock for the given mutex. If the mutex is already locked,
99  * the current thread will be put to sleep until the lock becomes available.
100  * @param mutex the mutex on which to acquire the lock.
101  */
103 
104 /**
105  * Attempt to acquire the lock for the given mutex. If the mutex has already
106  * been acquired, the call returns immediately with APR_EBUSY. Note: it
107  * is important that the APR_STATUS_IS_EBUSY(s) macro be used to determine
108  * if the return value was APR_EBUSY, for portability reasons.
109  * @param mutex the mutex on which to attempt the lock acquiring.
110  */
112 
113 /**
114  * Attempt to acquire the lock for the given mutex until timeout expires.
115  * If the acquisition time outs, the call returns with APR_TIMEUP.
116  * @param mutex the mutex on which to attempt the lock acquiring.
117  * @param timeout the absolute time or relative timeout (microseconds)
118  * @param absolute whether the timeout given is absolute (!0) or relative (0)
119  */
121  apr_time_t timeout,
122  int absolute);
123 
124 /**
125  * Release the lock for the given mutex.
126  * @param mutex the mutex from which to release the lock.
127  */
129 
130 /**
131  * Destroy the mutex and free the memory associated with the lock.
132  * @param mutex the mutex to destroy.
133  */
135 
136 /**
137  * Return the name of the lockfile for the mutex, or NULL
138  * if the mutex doesn't use a lock file
139  */
140 
142 
143 /**
144  * Get the mechanism of the mutex, as it relates to the actual method
145  * used for the underlying apr_proc_mutex_t.
146  * @param mutex the mutex to get the mechanism from.
147  */
149 
150 /**
151  * Get the mechanism's name of the mutex, as it relates to the actual method
152  * used for the underlying apr_proc_mutex_t.
153  * @param mutex the mutex to get the mechanism's name from.
154  */
156 
157 /**
158  * Set mutex permissions.
159  */
160 APR_PERMS_SET_IMPLEMENT(global_mutex);
161 
162 /**
163  * Get the pool used by this global_mutex.
164  * @return apr_pool_t the pool
165  */
166 APR_POOL_DECLARE_ACCESSOR(global_mutex);
167 
168 #else /* APR_PROC_MUTEX_IS_GLOBAL */
169 
170 /* Some platforms [e.g. Win32] have cross process locks that are truly
171  * global locks, since there isn't the concept of cross-process locks.
172  * Define these platforms in terms of an apr_proc_mutex_t.
173  */
174 
175 #define apr_global_mutex_t apr_proc_mutex_t
176 #define apr_global_mutex_create apr_proc_mutex_create
177 #define apr_global_mutex_child_init apr_proc_mutex_child_init
178 #define apr_global_mutex_lock apr_proc_mutex_lock
179 #define apr_global_mutex_trylock apr_proc_mutex_trylock
180 #define apr_global_mutex_unlock apr_proc_mutex_unlock
181 #define apr_global_mutex_destroy apr_proc_mutex_destroy
182 #define apr_global_mutex_lockfile apr_proc_mutex_lockfile
183 #define apr_global_mutex_mech apr_proc_mutex_mech
184 #define apr_global_mutex_name apr_proc_mutex_name
185 #define apr_global_mutex_perms_set apr_proc_mutex_perms_set
186 #define apr_global_mutex_pool_get apr_proc_mutex_pool_get
187 
188 #endif
189 
190 /** @} */
191 
192 #ifdef __cplusplus
193 }
194 #endif
195 
196 #endif /* ndef APR_GLOBAL_MUTEX_H */
apr_status_t apr_global_mutex_lock(apr_global_mutex_t *mutex)
struct apr_global_mutex_t apr_global_mutex_t
Definition: apr_global_mutex.h:47
apr_status_t apr_global_mutex_create(apr_global_mutex_t **mutex, const char *fname, apr_lockmech_e mech, apr_pool_t *pool)
apr_status_t apr_global_mutex_destroy(apr_global_mutex_t *mutex)
apr_int64_t apr_time_t
Definition: apr_time.h:45
APR memory allocation.
apr_status_t apr_global_mutex_unlock(apr_global_mutex_t *mutex)
APR Error Codes.
#define APR_DECLARE(type)
Definition: apr.h:500
apr_lockmech_e
Definition: apr_proc_mutex.h:46
APR Platform Definitions.
apr_status_t apr_global_mutex_trylock(apr_global_mutex_t *mutex)
APR_PERMS_SET_IMPLEMENT(global_mutex)
apr_status_t apr_global_mutex_child_init(apr_global_mutex_t **mutex, const char *fname, apr_pool_t *pool)
apr_lockmech_e apr_global_mutex_mech(apr_global_mutex_t *mutex)
APR Process Locking Routines.
apr_status_t apr_global_mutex_timedlock(apr_global_mutex_t *mutex, apr_time_t timeout, int absolute)
const char * apr_global_mutex_lockfile(apr_global_mutex_t *mutex)
struct apr_pool_t apr_pool_t
Definition: apr_pools.h:60
int apr_status_t
Definition: apr_errno.h:44
APR Time Library.
const char * apr_global_mutex_name(apr_global_mutex_t *mutex)
#define APR_POOL_DECLARE_ACCESSOR(type)
Definition: apr_pools.h:81