00001 /* Licensed to the Apache Software Foundation (ASF) under one or more 00002 * contributor license agreements. See the NOTICE file distributed with 00003 * this work for additional information regarding copyright ownership. 00004 * The ASF licenses this file to You under the Apache License, Version 2.0 00005 * (the "License"); you may not use this file except in compliance with 00006 * the License. You may obtain a copy of the License at 00007 * 00008 * http://www.apache.org/licenses/LICENSE-2.0 00009 * 00010 * Unless required by applicable law or agreed to in writing, software 00011 * distributed under the License is distributed on an "AS IS" BASIS, 00012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 00013 * See the License for the specific language governing permissions and 00014 * limitations under the License. 00015 */ 00016 00017 #ifndef APR_GLOBAL_MUTEX_H 00018 #define APR_GLOBAL_MUTEX_H 00019 00020 /** 00021 * @file apr_global_mutex.h 00022 * @brief APR Global Locking Routines 00023 */ 00024 00025 #include "apr.h" 00026 #include "apr_proc_mutex.h" /* only for apr_lockmech_e */ 00027 #include "apr_pools.h" 00028 #include "apr_errno.h" 00029 #if APR_PROC_MUTEX_IS_GLOBAL 00030 #include "apr_proc_mutex.h" 00031 #endif 00032 00033 #ifdef __cplusplus 00034 extern "C" { 00035 #endif /* __cplusplus */ 00036 00037 /** 00038 * @defgroup APR_GlobalMutex Global Locking Routines 00039 * @ingroup APR 00040 * @{ 00041 */ 00042 00043 #if !APR_PROC_MUTEX_IS_GLOBAL || defined(DOXYGEN) 00044 00045 /** Opaque global mutex structure. */ 00046 typedef struct apr_global_mutex_t apr_global_mutex_t; 00047 00048 /* Function definitions */ 00049 00050 /** 00051 * Create and initialize a mutex that can be used to synchronize both 00052 * processes and threads. Note: There is considerable overhead in using 00053 * this API if only cross-process or cross-thread mutual exclusion is 00054 * required. See apr_proc_mutex.h and apr_thread_mutex.h for more 00055 * specialized lock routines. 00056 * @param mutex the memory address where the newly created mutex will be 00057 * stored. 00058 * @param fname A file name to use if the lock mechanism requires one. This 00059 * argument should always be provided. The lock code itself will 00060 * determine if it should be used. 00061 * @param mech The mechanism to use for the interprocess lock, if any; one of 00062 * <PRE> 00063 * APR_LOCK_FCNTL 00064 * APR_LOCK_FLOCK 00065 * APR_LOCK_SYSVSEM 00066 * APR_LOCK_POSIXSEM 00067 * APR_LOCK_PROC_PTHREAD 00068 * APR_LOCK_DEFAULT pick the default mechanism for the platform 00069 * </PRE> 00070 * @param pool the pool from which to allocate the mutex. 00071 * @warning Check APR_HAS_foo_SERIALIZE defines to see if the platform supports 00072 * APR_LOCK_foo. Only APR_LOCK_DEFAULT is portable. 00073 */ 00074 APR_DECLARE(apr_status_t) apr_global_mutex_create(apr_global_mutex_t **mutex, 00075 const char *fname, 00076 apr_lockmech_e mech, 00077 apr_pool_t *pool); 00078 00079 /** 00080 * Re-open a mutex in a child process. 00081 * @param mutex The newly re-opened mutex structure. 00082 * @param fname A file name to use if the mutex mechanism requires one. This 00083 * argument should always be provided. The mutex code itself will 00084 * determine if it should be used. This filename should be the 00085 * same one that was passed to apr_global_mutex_create(). 00086 * @param pool The pool to operate on. 00087 * @remark This function must be called to maintain portability, even 00088 * if the underlying lock mechanism does not require it. 00089 */ 00090 APR_DECLARE(apr_status_t) apr_global_mutex_child_init( 00091 apr_global_mutex_t **mutex, 00092 const char *fname, 00093 apr_pool_t *pool); 00094 00095 /** 00096 * Acquire the lock for the given mutex. If the mutex is already locked, 00097 * the current thread will be put to sleep until the lock becomes available. 00098 * @param mutex the mutex on which to acquire the lock. 00099 */ 00100 APR_DECLARE(apr_status_t) apr_global_mutex_lock(apr_global_mutex_t *mutex); 00101 00102 /** 00103 * Attempt to acquire the lock for the given mutex. If the mutex has already 00104 * been acquired, the call returns immediately with APR_EBUSY. Note: it 00105 * is important that the APR_STATUS_IS_EBUSY(s) macro be used to determine 00106 * if the return value was APR_EBUSY, for portability reasons. 00107 * @param mutex the mutex on which to attempt the lock acquiring. 00108 */ 00109 APR_DECLARE(apr_status_t) apr_global_mutex_trylock(apr_global_mutex_t *mutex); 00110 00111 /** 00112 * Release the lock for the given mutex. 00113 * @param mutex the mutex from which to release the lock. 00114 */ 00115 APR_DECLARE(apr_status_t) apr_global_mutex_unlock(apr_global_mutex_t *mutex); 00116 00117 /** 00118 * Destroy the mutex and free the memory associated with the lock. 00119 * @param mutex the mutex to destroy. 00120 */ 00121 APR_DECLARE(apr_status_t) apr_global_mutex_destroy(apr_global_mutex_t *mutex); 00122 00123 /** 00124 * Get the pool used by this global_mutex. 00125 * @return apr_pool_t the pool 00126 */ 00127 APR_POOL_DECLARE_ACCESSOR(global_mutex); 00128 00129 #else /* APR_PROC_MUTEX_IS_GLOBAL */ 00130 00131 /* Some platforms [e.g. Win32] have cross process locks that are truly 00132 * global locks, since there isn't the concept of cross-process locks. 00133 * Define these platforms in terms of an apr_proc_mutex_t. 00134 */ 00135 00136 #define apr_global_mutex_t apr_proc_mutex_t 00137 #define apr_global_mutex_create apr_proc_mutex_create 00138 #define apr_global_mutex_child_init apr_proc_mutex_child_init 00139 #define apr_global_mutex_lock apr_proc_mutex_lock 00140 #define apr_global_mutex_trylock apr_proc_mutex_trylock 00141 #define apr_global_mutex_unlock apr_proc_mutex_unlock 00142 #define apr_global_mutex_destroy apr_proc_mutex_destroy 00143 #define apr_global_mutex_pool_get apr_proc_mutex_pool_get 00144 00145 #endif 00146 00147 /** @} */ 00148 00149 #ifdef __cplusplus 00150 } 00151 #endif 00152 00153 #endif /* ndef APR_GLOBAL_MUTEX_H */
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