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#include "apr_perms_set.h" 29#include "apr_time.h" 30 31#ifdef __cplusplus 32extern "C" { 33#endif /* __cplusplus */ 34 35/** 36 * @defgroup apr_proc_mutex Process Locking Routines 37 * @ingroup APR 38 * @{ 39 */ 40 41/** 42 * Enumerated potential types for APR process locking methods 43 * @warning Check APR_HAS_foo_SERIALIZE defines to see if the platform supports 44 * APR_LOCK_foo. Only APR_LOCK_DEFAULT is portable. 45 */ 46typedef enum { 47 APR_LOCK_FCNTL, /**< fcntl() */ 48 APR_LOCK_FLOCK, /**< flock() */ 49 APR_LOCK_SYSVSEM, /**< System V Semaphores */ 50 APR_LOCK_PROC_PTHREAD, /**< POSIX pthread process-based locking */ 51 APR_LOCK_POSIXSEM, /**< POSIX semaphore process-based locking */ 52 APR_LOCK_DEFAULT, /**< Use the default process lock */ 53 APR_LOCK_DEFAULT_TIMED /**< Use the default process timed lock */ 54} apr_lockmech_e; 55 56/** Opaque structure representing a process mutex. */ 57typedef struct apr_proc_mutex_t apr_proc_mutex_t; 58 59/* Function definitions */ 60 61/** 62 * Create and initialize a mutex that can be used to synchronize processes. 63 * @param mutex the memory address where the newly created mutex will be 64 * stored. 65 * @param fname A file name to use if the lock mechanism requires one. This 66 * argument should always be provided. The lock code itself will 67 * determine if it should be used. 68 * @param mech The mechanism to use for the interprocess lock, if any; one of 69 * <PRE> 70 * APR_LOCK_FCNTL 71 * APR_LOCK_FLOCK 72 * APR_LOCK_SYSVSEM 73 * APR_LOCK_POSIXSEM 74 * APR_LOCK_PROC_PTHREAD 75 * APR_LOCK_DEFAULT pick the default mechanism for the platform 76 * </PRE> 77 * @param pool the pool from which to allocate the mutex. 78 * @see apr_lockmech_e 79 * @warning Check APR_HAS_foo_SERIALIZE defines to see if the platform supports 80 * APR_LOCK_foo. Only APR_LOCK_DEFAULT is portable. 81 */ 82APR_DECLARE(apr_status_t) apr_proc_mutex_create(apr_proc_mutex_t **mutex, 83 const char *fname, 84 apr_lockmech_e mech, 85 apr_pool_t *pool); 86 87/** 88 * Re-open a mutex in a child process. 89 * @param mutex The newly re-opened mutex structure. 90 * @param fname A file name to use if the mutex mechanism requires one. This 91 * argument should always be provided. The mutex code itself will 92 * determine if it should be used. This filename should be the 93 * same one that was passed to apr_proc_mutex_create(). 94 * @param pool The pool to operate on. 95 * @remark This function must be called to maintain portability, even 96 * if the underlying lock mechanism does not require it. 97 */ 98APR_DECLARE(apr_status_t) apr_proc_mutex_child_init(apr_proc_mutex_t **mutex, 99 const char *fname, 100 apr_pool_t *pool); 101 102/** 103 * Acquire the lock for the given mutex. If the mutex is already locked, 104 * the current thread will be put to sleep until the lock becomes available. 105 * @param mutex the mutex on which to acquire the lock. 106 */ 107APR_DECLARE(apr_status_t) apr_proc_mutex_lock(apr_proc_mutex_t *mutex); 108 109/** 110 * Attempt to acquire the lock for the given mutex. If the mutex has already 111 * been acquired, the call returns immediately with APR_EBUSY. Note: it 112 * is important that the APR_STATUS_IS_EBUSY(s) macro be used to determine 113 * if the return value was APR_EBUSY, for portability reasons. 114 * @param mutex the mutex on which to attempt the lock acquiring. 115 */ 116APR_DECLARE(apr_status_t) apr_proc_mutex_trylock(apr_proc_mutex_t *mutex); 117 118/** 119 * Attempt to acquire the lock for the given mutex until timeout expires. 120 * If the acquisition time outs, the call returns with APR_TIMEUP. 121 * @param mutex the mutex on which to attempt the lock acquiring. 122 * @param timeout the relative timeout (microseconds). 123 * @note A negative or nul timeout means immediate attempt, returning 124 * APR_TIMEUP without blocking if it the lock is already acquired. 125 */ 126APR_DECLARE(apr_status_t) apr_proc_mutex_timedlock(apr_proc_mutex_t *mutex, 127 apr_interval_time_t timeout); 128 129/** 130 * Release the lock for the given mutex. 131 * @param mutex the mutex from which to release the lock. 132 */ 133APR_DECLARE(apr_status_t) apr_proc_mutex_unlock(apr_proc_mutex_t *mutex); 134 135/** 136 * Destroy the mutex and free the memory associated with the lock. 137 * @param mutex the mutex to destroy. 138 */ 139APR_DECLARE(apr_status_t) apr_proc_mutex_destroy(apr_proc_mutex_t *mutex); 140 141/** 142 * Destroy the mutex and free the memory associated with the lock. 143 * @param mutex the mutex to destroy. 144 * @note This function is generally used to kill a cleanup on an already 145 * created mutex 146 */ 147APR_DECLARE(apr_status_t) apr_proc_mutex_cleanup(void *mutex); 148 149/** 150 * Return the name of the lockfile for the mutex, or NULL 151 * if the mutex doesn't use a lock file 152 */ 153 154APR_DECLARE(const char *) apr_proc_mutex_lockfile(apr_proc_mutex_t *mutex); 155 156/** 157 * Get the mechanism of the mutex, as it relates to the actual method 158 * used for the underlying apr_proc_mutex_t. 159 * @param mutex the mutex to get the mechanism from. 160 */ 161APR_DECLARE(apr_lockmech_e) apr_proc_mutex_mech(apr_proc_mutex_t *mutex); 162 163/** 164 * Get the mechanism's name of the mutex, as it relates to the actual method 165 * used for the underlying apr_proc_mutex_t. 166 * @param mutex the mutex to get the mechanism's name from. 167 */ 168APR_DECLARE(const char *) apr_proc_mutex_name(apr_proc_mutex_t *mutex); 169 170/** 171 * Display the name of the default mutex: APR_LOCK_DEFAULT 172 */ 173APR_DECLARE(const char *) apr_proc_mutex_defname(void); 174 175/** 176 * Set mutex permissions. 177 */ 178APR_PERMS_SET_IMPLEMENT(proc_mutex); 179 180/** 181 * Get the pool used by this proc_mutex. 182 * @return apr_pool_t the pool 183 */ 184APR_POOL_DECLARE_ACCESSOR(proc_mutex); 185 186/** @} */ 187 188#ifdef __cplusplus 189} 190#endif 191 192#endif /* ! APR_PROC_MUTEX_H */ 193