apr_global_mutex.h revision 251886
1265038Sganbold/* Licensed to the Apache Software Foundation (ASF) under one or more 2265038Sganbold * contributor license agreements. See the NOTICE file distributed with 3265038Sganbold * this work for additional information regarding copyright ownership. 4265038Sganbold * The ASF licenses this file to You under the Apache License, Version 2.0 5265038Sganbold * (the "License"); you may not use this file except in compliance with 6265038Sganbold * the License. You may obtain a copy of the License at 7265038Sganbold * 8265038Sganbold * http://www.apache.org/licenses/LICENSE-2.0 9265038Sganbold * 10265038Sganbold * Unless required by applicable law or agreed to in writing, software 11265038Sganbold * distributed under the License is distributed on an "AS IS" BASIS, 12265038Sganbold * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13265038Sganbold * See the License for the specific language governing permissions and 14265038Sganbold * limitations under the License. 15265038Sganbold */ 16265038Sganbold 17265038Sganbold#ifndef APR_GLOBAL_MUTEX_H 18265038Sganbold#define APR_GLOBAL_MUTEX_H 19265038Sganbold 20265038Sganbold/** 21265038Sganbold * @file apr_global_mutex.h 22265038Sganbold * @brief APR Global Locking Routines 23265038Sganbold */ 24265038Sganbold 25265038Sganbold#include "apr.h" 26265038Sganbold#include "apr_proc_mutex.h" /* only for apr_lockmech_e */ 27265038Sganbold#include "apr_pools.h" 28265038Sganbold#include "apr_errno.h" 29265038Sganbold#if APR_PROC_MUTEX_IS_GLOBAL 30265038Sganbold#include "apr_proc_mutex.h" 31265038Sganbold#endif 32265038Sganbold 33265038Sganbold#ifdef __cplusplus 34265038Sganboldextern "C" { 35265038Sganbold#endif /* __cplusplus */ 36265038Sganbold 37265038Sganbold/** 38265038Sganbold * @defgroup APR_GlobalMutex Global Locking Routines 39265038Sganbold * @ingroup APR 40265038Sganbold * @{ 41265038Sganbold */ 42265038Sganbold 43265038Sganbold#if !APR_PROC_MUTEX_IS_GLOBAL || defined(DOXYGEN) 44265038Sganbold 45265038Sganbold/** Opaque global mutex structure. */ 46265038Sganboldtypedef struct apr_global_mutex_t apr_global_mutex_t; 47265038Sganbold 48265038Sganbold/* Function definitions */ 49265038Sganbold 50265038Sganbold/** 51265038Sganbold * Create and initialize a mutex that can be used to synchronize both 52265038Sganbold * processes and threads. Note: There is considerable overhead in using 53265038Sganbold * this API if only cross-process or cross-thread mutual exclusion is 54265038Sganbold * required. See apr_proc_mutex.h and apr_thread_mutex.h for more 55265038Sganbold * specialized lock routines. 56265038Sganbold * @param mutex the memory address where the newly created mutex will be 57265038Sganbold * stored. 58265038Sganbold * @param fname A file name to use if the lock mechanism requires one. This 59265038Sganbold * argument should always be provided. The lock code itself will 60265038Sganbold * determine if it should be used. 61265038Sganbold * @param mech The mechanism to use for the interprocess lock, if any; one of 62265038Sganbold * <PRE> 63265038Sganbold * APR_LOCK_FCNTL 64265038Sganbold * APR_LOCK_FLOCK 65265038Sganbold * APR_LOCK_SYSVSEM 66265038Sganbold * APR_LOCK_POSIXSEM 67265038Sganbold * APR_LOCK_PROC_PTHREAD 68265038Sganbold * APR_LOCK_DEFAULT pick the default mechanism for the platform 69265038Sganbold * </PRE> 70265038Sganbold * @param pool the pool from which to allocate the mutex. 71265038Sganbold * @warning Check APR_HAS_foo_SERIALIZE defines to see if the platform supports 72265038Sganbold * APR_LOCK_foo. Only APR_LOCK_DEFAULT is portable. 73265038Sganbold */ 74265038SganboldAPR_DECLARE(apr_status_t) apr_global_mutex_create(apr_global_mutex_t **mutex, 75265038Sganbold const char *fname, 76265038Sganbold apr_lockmech_e mech, 77265038Sganbold apr_pool_t *pool); 78265038Sganbold 79265038Sganbold/** 80265038Sganbold * Re-open a mutex in a child process. 81265038Sganbold * @param mutex The newly re-opened mutex structure. 82265038Sganbold * @param fname A file name to use if the mutex mechanism requires one. This 83265038Sganbold * argument should always be provided. The mutex code itself will 84265038Sganbold * determine if it should be used. This filename should be the 85265038Sganbold * same one that was passed to apr_global_mutex_create(). 86265038Sganbold * @param pool The pool to operate on. 87265038Sganbold * @remark This function must be called to maintain portability, even 88265038Sganbold * if the underlying lock mechanism does not require it. 89265038Sganbold */ 90265038SganboldAPR_DECLARE(apr_status_t) apr_global_mutex_child_init( 91265038Sganbold apr_global_mutex_t **mutex, 92265038Sganbold const char *fname, 93265038Sganbold apr_pool_t *pool); 94265038Sganbold 95265038Sganbold/** 96265038Sganbold * Acquire the lock for the given mutex. If the mutex is already locked, 97265038Sganbold * the current thread will be put to sleep until the lock becomes available. 98265038Sganbold * @param mutex the mutex on which to acquire the lock. 99265038Sganbold */ 100265038SganboldAPR_DECLARE(apr_status_t) apr_global_mutex_lock(apr_global_mutex_t *mutex); 101265038Sganbold 102265038Sganbold/** 103265038Sganbold * Attempt to acquire the lock for the given mutex. If the mutex has already 104265038Sganbold * been acquired, the call returns immediately with APR_EBUSY. Note: it 105265038Sganbold * is important that the APR_STATUS_IS_EBUSY(s) macro be used to determine 106265038Sganbold * if the return value was APR_EBUSY, for portability reasons. 107265038Sganbold * @param mutex the mutex on which to attempt the lock acquiring. 108265038Sganbold */ 109265038SganboldAPR_DECLARE(apr_status_t) apr_global_mutex_trylock(apr_global_mutex_t *mutex); 110265038Sganbold 111265038Sganbold/** 112265038Sganbold * Release the lock for the given mutex. 113265038Sganbold * @param mutex the mutex from which to release the lock. 114265038Sganbold */ 115265038SganboldAPR_DECLARE(apr_status_t) apr_global_mutex_unlock(apr_global_mutex_t *mutex); 116265038Sganbold 117265038Sganbold/** 118265038Sganbold * Destroy the mutex and free the memory associated with the lock. 119265038Sganbold * @param mutex the mutex to destroy. 120265038Sganbold */ 121265038SganboldAPR_DECLARE(apr_status_t) apr_global_mutex_destroy(apr_global_mutex_t *mutex); 122265038Sganbold 123265038Sganbold/** 124265038Sganbold * Return the name of the lockfile for the mutex, or NULL 125265038Sganbold * if the mutex doesn't use a lock file 126265038Sganbold */ 127265038SganboldAPR_DECLARE(const char *) apr_global_mutex_lockfile(apr_global_mutex_t *mutex); 128265038Sganbold 129265038Sganbold/** 130265038Sganbold * Display the name of the mutex, as it relates to the actual method used 131265038Sganbold * for the underlying apr_proc_mutex_t, if any. NULL is returned if 132265038Sganbold * there is no underlying apr_proc_mutex_t. 133265038Sganbold * @param mutex the name of the mutex 134265038Sganbold */ 135265038SganboldAPR_DECLARE(const char *) apr_global_mutex_name(apr_global_mutex_t *mutex); 136265038Sganbold 137265038Sganbold/** 138265038Sganbold * Get the pool used by this global_mutex. 139265038Sganbold * @return apr_pool_t the pool 140 */ 141APR_POOL_DECLARE_ACCESSOR(global_mutex); 142 143#else /* APR_PROC_MUTEX_IS_GLOBAL */ 144 145/* Some platforms [e.g. Win32] have cross process locks that are truly 146 * global locks, since there isn't the concept of cross-process locks. 147 * Define these platforms in terms of an apr_proc_mutex_t. 148 */ 149 150#define apr_global_mutex_t apr_proc_mutex_t 151#define apr_global_mutex_create apr_proc_mutex_create 152#define apr_global_mutex_child_init apr_proc_mutex_child_init 153#define apr_global_mutex_lock apr_proc_mutex_lock 154#define apr_global_mutex_trylock apr_proc_mutex_trylock 155#define apr_global_mutex_unlock apr_proc_mutex_unlock 156#define apr_global_mutex_destroy apr_proc_mutex_destroy 157#define apr_global_mutex_lockfile apr_proc_mutex_lockfile 158#define apr_global_mutex_name apr_proc_mutex_name 159#define apr_global_mutex_pool_get apr_proc_mutex_pool_get 160 161#endif 162 163/** @} */ 164 165#ifdef __cplusplus 166} 167#endif 168 169#endif /* ndef APR_GLOBAL_MUTEX_H */ 170