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_PROC_MUTEX_H 18 #define APR_PROC_MUTEX_H 19 20 /** 21 * @file apr_proc_mutex.h 22 * @brief APR Process Locking 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 /** 34 * @defgroup apr_proc_mutex Process Locking Routines 35 * @ingroup APR 36 * @{ 37 */ 38 39 /** 40 * Enumerated potential types for APR process locking methods 41 * @warning Check APR_HAS_foo_SERIALIZE defines to see if the platform supports 42 * APR_LOCK_foo. Only APR_LOCK_DEFAULT is portable. 43 */ 44 typedef enum { 45 APR_LOCK_FCNTL, /**< fcntl() */ 46 APR_LOCK_FLOCK, /**< flock() */ 47 APR_LOCK_SYSVSEM, /**< System V Semaphores */ 48 APR_LOCK_PROC_PTHREAD, /**< POSIX pthread process-based locking */ 49 APR_LOCK_POSIXSEM, /**< POSIX semaphore process-based locking */ 50 APR_LOCK_DEFAULT /**< Use the default process lock */ 51 } apr_lockmech_e; 52 53 /** Opaque structure representing a process mutex. */ 54 typedef struct apr_proc_mutex_t apr_proc_mutex_t; 55 56 /* Function definitions */ 57 58 /** 59 * Create and initialize a mutex that can be used to synchronize processes. 60 * @param mutex the memory address where the newly created mutex will be 61 * stored. 62 * @param fname A file name to use if the lock mechanism requires one. This 63 * argument should always be provided. The lock code itself will 64 * determine if it should be used. 65 * @param mech The mechanism to use for the interprocess lock, if any; one of 66 * <PRE> 67 * APR_LOCK_FCNTL 68 * APR_LOCK_FLOCK 69 * APR_LOCK_SYSVSEM 70 * APR_LOCK_POSIXSEM 71 * APR_LOCK_PROC_PTHREAD 72 * APR_LOCK_DEFAULT pick the default mechanism for the platform 73 * </PRE> 74 * @param pool the pool from which to allocate the mutex. 75 * @see apr_lockmech_e 76 * @warning Check APR_HAS_foo_SERIALIZE defines to see if the platform supports 77 * APR_LOCK_foo. Only APR_LOCK_DEFAULT is portable. 78 */ 79 APR_DECLARE(apr_status_t) apr_proc_mutex_create(apr_proc_mutex_t **mutex, 80 const char *fname, 81 apr_lockmech_e mech, 82 apr_pool_t *pool); 83 84 /** 85 * Re-open a mutex in a child process. 86 * @param mutex The newly re-opened mutex structure. 87 * @param fname A file name to use if the mutex mechanism requires one. This 88 * argument should always be provided. The mutex code itself will 89 * determine if it should be used. This filename should be the 90 * same one that was passed to apr_proc_mutex_create(). 91 * @param pool The pool to operate on. 92 * @remark This function must be called to maintain portability, even 93 * if the underlying lock mechanism does not require it. 94 */ 95 APR_DECLARE(apr_status_t) apr_proc_mutex_child_init(apr_proc_mutex_t **mutex, 96 const char *fname, 97 apr_pool_t *pool); 98 99 /** 100 * Acquire the lock for the given mutex. If the mutex is already locked, 101 * the current thread will be put to sleep until the lock becomes available. 102 * @param mutex the mutex on which to acquire the lock. 103 */ 104 APR_DECLARE(apr_status_t) apr_proc_mutex_lock(apr_proc_mutex_t *mutex); 105 106 /** 107 * Attempt to acquire the lock for the given mutex. If the mutex has already 108 * been acquired, the call returns immediately with APR_EBUSY. Note: it 109 * is important that the APR_STATUS_IS_EBUSY(s) macro be used to determine 110 * if the return value was APR_EBUSY, for portability reasons. 111 * @param mutex the mutex on which to attempt the lock acquiring. 112 */ 113 APR_DECLARE(apr_status_t) apr_proc_mutex_trylock(apr_proc_mutex_t *mutex); 114 115 /** 116 * Release the lock for the given mutex. 117 * @param mutex the mutex from which to release the lock. 118 */ 119 APR_DECLARE(apr_status_t) apr_proc_mutex_unlock(apr_proc_mutex_t *mutex); 120 121 /** 122 * Destroy the mutex and free the memory associated with the lock. 123 * @param mutex the mutex to destroy. 124 */ 125 APR_DECLARE(apr_status_t) apr_proc_mutex_destroy(apr_proc_mutex_t *mutex); 126 127 /** 128 * Destroy the mutex and free the memory associated with the lock. 129 * @param mutex the mutex to destroy. 130 * @note This function is generally used to kill a cleanup on an already 131 * created mutex 132 */ 133 APR_DECLARE(apr_status_t) apr_proc_mutex_cleanup(void *mutex); 134 135 /** 136 * Return the name of the lockfile for the mutex, or NULL 137 * if the mutex doesn't use a lock file 138 */ 139 140 APR_DECLARE(const char *) apr_proc_mutex_lockfile(apr_proc_mutex_t *mutex); 141 142 /** 143 * Display the name of the mutex, as it relates to the actual method used. 144 * This matches the valid options for Apache's AcceptMutex directive 145 * @param mutex the name of the mutex 146 */ 147 APR_DECLARE(const char *) apr_proc_mutex_name(apr_proc_mutex_t *mutex); 148 149 /** 150 * Display the name of the default mutex: APR_LOCK_DEFAULT 151 */ 152 APR_DECLARE(const char *) apr_proc_mutex_defname(void); 153 154 /** 155 * Get the pool used by this proc_mutex. 156 * @return apr_pool_t the pool 157 */ 158 APR_POOL_DECLARE_ACCESSOR(proc_mutex); 159 160 /** @} */ 161 162 #ifdef __cplusplus 163 } 164 #endif 165 166 #endif /* ! APR_PROC_MUTEX_H */ 167